Liver Diseases And Hepatic Encephalopathy

Merz Pharmaceuticals GmbHFrankfurt am Main

LIVER DISEASES AND HEPATIC ENCEPHALOPATHYScientific Product Monograph

43 057 Umschlag engl. 28.04.2004 11:11 Uhr Seite 1

Merz Pharmaceuticals GmbHFrankfurt am Main

LIVER DISEASES AND HEPATIC ENCEPHALOPATHYScientific Product Monograph

43 057 WiBro englisch 13.05.2004 17:18 Uhr Seite 3

54

Product profile 6

1 Liver function and hepatic encephalopathy 91.1 Ammonia metabolism and detoxification function of the liver 91.2 Liver diseases as the cause of hepatic encephalopathy 13

2 Hepatic encephalopathy – clinical picture and pathogenesis 232.1 Definition and clinical forms of hepatic encephalopathy 232.2 Precipitating factors in hepatic encephalopathy 272.3 Pathogenesis of hepatic encephalopathy 30

2.3.1 Neuropathological changes 302.3.2 Ammonia and the glial hypothesis 322.3.3 Additional pathological mechanisms 35

3 Diagnosis of hepatic encephalopathy 403.1 Diagnostic procedures 403.2 Early diagnosis 423.3 Criteria for assessing degree of severity

and monitoring the course of disease 45

4 Treatment of hepatic encephalopathy 514.1 General therapeutic concepts 514.2 Dietary therapy 524.3 Drug therapy 53

5 Mechanism of action and pharmacodynamics of Hepa-Merz® 595.1 Mechanism of action 595.2 Pharmacodynamic effects in animal experiments 62

5.2.1 Effects of Hepa-Merz® on ammonia metabolism 625.2.2 Effects of Hepa-Merz® on metabolism in the brain 64

6 Clinical results with Hepa-Merz® 726.1 Clinical research with Hepa-Merz® 746.2 Experimental clinical studies with Hepa-Merz® 75

6.2.1 Effects of Hepa-Merz® on ammonia concentration 756.2.2 Effects of Hepa-Merz® on protein synthesis in muscle 826.2.3 Effects of Hepa-Merz® on neurometabolites 84

6.3 Clinical results with intravenous Hepa-Merz® therapy 866.3.1 Hepa-Merz® infusion in comparison with placebo 866.3.2 Meta-analysis of placebo-controlled trials 93

6.4 Clinical results with oral Hepa-Merz® therapy 966.4.1 Hepa-Merz® Granules in comparison with placebo 966.4.2 Hepa-Merz® Granules in the medical practice 1006.4.3 Hepa-Merz® Granules in comparison with lactulose 105

6.5 Summary of results with Hepa-Merz® 106

7 Safety and tolerability 108

8 Chemistry, toxicology and pharmacokinetics of Hepa-Merz® 1108.1 Chemico-physical data 1108.2 Toxicology 1118.3 Pharmacokinetics 111

9 Basic information 112

10 Abbreviations 11711 References 119

CONTENTS


7

The clinical picture of hepatic encephalopathy (HE) ari-ses as a complication of chronic and, more rarely, acuteliver disease. It is a potentially reversible functionaldisorder of the brain with neurological and psychiatricsymptoms which may occur with different degrees ofseverity (HE grades 0-4) and in varying combinations.Deficits of psychomotor function can be demonstratedin the early stages; even at the start, these represent acertain risk especially at work and in traffic. At first thereare mild non-specific disturbances of sleep, drive,mood and cognitive function. As the condition prog-resses, symptoms of psychomotor retardation and neuro-muscular disturbances (e.g. asterixis) occur as well asdisorientation and memory defects. With higher gradesof HE, the clinical picture is characterised by increas-ingly altered levels of consciousness (hepatic coma). The early diagnosis of hepatic encephalopathy is ofgreat importance for the future course of the conditionand is possible with e.g. psychometric tests that areeasy to perform.

The most common cause of hepatic encephalopathy iscirrhosis of the liver. Hepatic encephalopathy occurs inup to 70% of patients with cirrhosis at some time duringthe course of their disease. These patients in particularshould be carefully monitored for signs of hepatic en-cephalopathy. Increasing structural replacement with con-nective tissue leads to the loss of functioning hepaticparenchymal tissue and a reduction in the detoxificationcapacity of the liver. In addition, developing portalhypertension leads to the formation of a collateral circu-lation through which non-detoxified blood can by-passthe liver to reach the systemic circulation. Both these

Hepatic encephalopathy

PRODUCT PROFILE

6

Functional impairmentof the liver

mechanisms contribute to the neurotoxins present inportal vein blood reaching the brain via the systemic cir-culation. Once there, neurotoxic ammonia in particulardisrupts the function of neurones and astrocytes, givingrise to the symptoms of hepatic encephalopathy. Animportant aim of treatment is therefore the reduction ofthe ammonia present in the body by lowering theamount of ammonia produced and increasing its detox-ification.

The active ingredient of Hepa-Merz® infusion concen-trate, granules and chewable tablets is L-ornithine-L-aspartate, the salt of the natural amino acids ornithineand aspartate. Through the mechanism of substrateactivation, the two substances stimulate the urea cycle(which metabolises ammonia to urea) in the liver andglutamine synthesis in the liver, muscle and brain. Ureaand glutamine (after further metabolism) can be excret-ed via the kidneys. L-ornithine-L-aspartate thus activa-tes the two important metabolic pathways in the humanbody for the detoxification of ammonia.

L-ornithine-L-aspartate has been used for many yearsfor the treatment of conditions associated with impairedhepatic detoxification (e.g. in cirrhosis of the liver) andits sequelae, when there are symptoms of minimal (sub-clinical) and overt hepatic encephalopathy. Hepa-Merz®

is usually well tolerated or very well tolerated.

In the most recent clinical trials, the efficacy of Hepa-Merz® infusion concentrate and granules was testedagainst placebo. L-ornithine-L-aspartate showed a sta-tistically significant effect with respect to an improve-

L-ornithine-L-aspartate lowers neurotoxic NH3

L-ornithine-L-aspartate is effective and well-tolerated

L-ornithine-L-aspartate evidence-based medicine


8

Hepatic encephalopathy is a complication of both chronicand acute liver diseases. The most common underlyingcause is the reduced detoxification capacity of thedamaged liver in combination with a collateral porto-systemic circulation through which ammonia-containingblood by-passes the liver to reach the systemic circula-tion.

1.1 Ammonia metabolism and detoxifi-cation function of the liver

An important function of the liver as a metabolic organis the detoxification of ammonia produced from nitro-gen-containing compounds. In the hepatic cells ammo-nia is converted to urea and glutamine which can beexcreted via the kidneys.The ammonia present in the blood is released endoge-nously during cell metabolism from nitrogen-containingcompounds such as proteins, amino acids, nucleicacids and amines, or synthesised by the intestinal floraand absorbed into the blood stream. A large quantity ofammonia originates in the intestines. Mention should bemade of both bacterial ammonia production in the largeintestine and abacterial degrading of nitrogen-contain-ing metabolites in the small intestine.

Ammonia synthesis in the muscles and kidneys contrib-utes to the ammonia concentration in the blood to asmaller extent. Ammonia produced in the muscle in-creases in proportion to the work of the muscle; inresting muscle, ammonia uptake and excretion areapproximately in equilibrium. In the kidneys, only a smallquantity of ammonia is produced under normal conditions.

Ammonia productionin the intestine, muscle and kidneys

ment in mental state (reduction in the HE grade), in-creased detoxification (reduction of the ammonia con-centration in the blood) and positive effects on psycho-motor function (reduction of time required in the numberconnection test). With these findings, evidence-basedmedicine criteria for demonstrating efficacy have beenfulfilled.

Summary:The efficacy of Hepa-Merz® infusion concentrate and granules in the treatment of minimal (subclinical) and overt hepatic encephalopathy inliver disease associated with impaired hepatic detoxification (e.g. in cirrhosis of the liver) has been clearly demonstrated in placebo-control-led clinical trials. Treatment with L-ornithine-L-aspartate lowers theammonia concentration and thus improves the mental state and psycho-motor performance. Hepa-Merz® is well or very well tolerated in themajority of cases.

1 LIVER FUNCTION AND HEPATIC ENCEPHALOPATHY

9


1110

type of (reversible) detoxification also takes place in thebrain and the liver.Glutamine is broken down in the kidneys by the actionof glutaminase to give glutamate and ammonia; gluta-mate is further converted to a-ketoglutarate by therelease of a second ammonia molecule. The ammoniareleased in the kidneys can be excreted in the urine; asmall quantity is re-absorbed.

An increase in ammonia synthesis is seen in special circumstances e.g. on treatment with diuretics and inhypokalaemia.In the liver itself, large quantities of ammonia are alsoproduced during protein breakdown. This is immediate-ly detoxified, however, so that the liver does not contrib-ute to the blood ammonia concentration when its functionis intact.

Ammonia is physically dissolved in the blood and is inequilibrium with ammonium ions (NH3/NH4

+); this is pH-dependent. With a rise in the pH (alkalosis), the propor-tion of diffusible toxic ammonia (NH3) increases.

Under physiological conditions there is a natural equi-librium between ammonia production and ammoniadetoxification. The normal non-toxic serum levels in theperipheral blood are in the region of 30 µmol/l. The highest ammonia concentrations are found in the portalvein blood, which carries the ammonia produced in theintestinal tract.

Figure 1.1 summarises the pathways involved in themetabolism of ammonia in the human body.The liver is the most important organ to detoxify am-monia produced in the large and small intestine, muscles and kidneys. Most of the urea produced thereis excreted via the kidneys, with a small proportionbeing excreted via the gastrointestinal tract.

Some of the ammonia present in the human body isdetoxified in the muscles. Glutamine is produced fromammonia and glutamate. Apart from muscle tissue, this

Ammonia metabolism in the body

Large intestineSmall intestine

LiverMuscle

Kidney

Urea

Glutamine

Urea

Urea

Fig 1.1: Ammonia metabolism in the body


1312

These highly specialized cells, also referred to as scav-enger cells, form only 5-10% of the liver parenchymalcells.

1.2 Liver diseases as the cause ofhepatic encephalopathy

The most common liver disease that causes hepaticencephalopathy is cirrhosis of the liver. This can alsoarise as the result of other liver diseases (e.g. hepatitis,fatty liver). Genetic enzyme deficiencies and acute liverfailure are much less common causes of hepatic en-cephalopathy.

Hepatic encephalopathy is a relatively frequent complica-tion of cirrhosis of the liver, particularly if there is a collat-eral portosystemic circulation. Hepatic encephalopathycan be demonstrated in 30-70% of these patients. Thepathology of cirrhosis of the liver consists of destruction ofthe normal parenchymal structure and replacement of theparenchyma with nodular connective tissue. This is acommon chronic liver disease with a prevalence of about1%.

Hepatic encephalopa-thy is a common com-plication of cirrhosisof the liver

Some 70-80% of the ammonia present in the portalvein blood is removed during passage through the liver.This is due to the synthesis of urea and glutamine.

Urea synthesis and glutamine synthesis take place intwo different cell systems organized sequentially in thehepatic acinus (Figure 1.2).

In periportal hepatocytes, ammonia is converted to ureain the urea cycle. In the subsequently activated perive-nous hepatocytes, the ammonia is metabolised to glu-tamine by the action of glutamine synthetase.

Ammoniadetoxification

in the liver

Mitochondrion

Glutamine synthetase

Cytosol Cytosol

Mitochondrion

Perivenous hepatocytesPeriportal hepatocytes

Glutamine

Urea

Urea

Glutamine

Glutamine

Glutamine

Carbamylphosphatesynthetase I

Glutaminase

Figure 1.2: Detoxification of ammonia in the liver. Formation of urea and glutamine in periportal andperivenous hepatocytes (after Häussinger, 1990) NH4

+: Ammonia; Cbm-P: Carbamyl phosphate; Orn:Ornithine; Cit: Citrulline; Arg-Suc: Arginine succinate; Arg: Arginine

Summary:A large proportion of the ammonia present in the blood comes from thegastrointestinal tract, with contributions in the internal milieu from mus-cles and kidneys. Ammonia-containing blood is transported through theportal vein to the liver where it is detoxified by the formation of urea andglutamine. Functional units of periportal and perivenous hepatocytes inthe acini of the liver control the ammonia concentration in the blood.


Haemodynamic consequences of cirrhosisof the liver

The connective tissue changes with resultant loss ofvital hepatic parenchyma increase the vascular resis-tance of the liver leading to the development of portalhypertension. Raised pressure in the portal vein inducesthe formation of a collateral circulation between the por-tal system and other veins, known as a portosystemicshunt. Portal vein blood by-passes the liver throughoesophageal and abdominal varices, rectal varices,abdominal wall vessels and intrahepatic collaterals tohepatic veins. This means that portal vein blood whichis particularly rich in ammonia (due to absorption of theammonia produced in the gastrointestinal tract) flowsdirectly into the systemic circulation, by-passing theliver through these collateral vessels. Because of theresultant hyperammonaemia, muscles and the braintake up greater amounts of ammonia to compensate;this gives rise to toxic ammonia concentrations in thebrain.

Reduced ammonia detoxification in the liver

At the same time, the loss of functioning hepatic tissuehas an effect on the detoxification capacity of the liver.Ammonia can no longer be broken down in sufficientquantities. Urea synthesis and glutamine synthesis arereduced in patients with cirrhosis. In contrast, there isincreased activity of glutaminase, which converts gluta-mine into ammonia, i.e. release of ammonia is greatlyincreased in the cirrhotic liver (Figure 1.3).

Portal hypertensionand toxic NH3-concentration in the brain

15

The cause of cirrhotic changes in the liver in more thanhalf of the patients is chronic alcohol intoxication. In athird, cirrhosis is the result of hepatitis. More rarely thereis a metabolic cause (e.g. Wilson’s disease, haemo-chromatosis, alpha-1-antitrypsin deficiency etc.) or vascular cause (e.g. chronic right ventricular failure)or an unexplained disease process. Progression of cirrhosis is more or less the same whatever the aetiology.The degree of severity of cirrhosis is usually expressedby the Child-Pugh classification, stages A, B and C,which takes into account the laboratory parameters ofbilirubin, albumin and the prothrombin time as well asascites and encephalopathy (Table 1.1).

Cirrhosis: causes and

degree of severity

14

Parameter Number of Points1 2 3

Encephalopathy Grade 0 Grade I/II Grade III/IVAscites none slight severeBilirubin (mg/dl) ≤2 2–3 >3Bilirubin (µmol/l) (≤34) (34–51) (>51)Albumin (g/dl) >3,5 2,8–3,5 <2,8Prothrombin time (seconds above standard) 1–3 4–6 >6or INR <1,7 1,8–2,3 >2,3

Table 1.1: Assessment of hepatic function reserve based on Child-Turcotte criteria, modified by Pugh.Addition of the points gives the Child-Pugh stage: A (5-6 points), B (7-9) and C (10-15)


1716

Data on the incidence of subclinical hepatic encephalop-athy vary, ranging from 30% to 80% (Häussinger andMaier, 1996). Early stages in particular often remainunrecognized.

Fatty liver (steatosis) is the most widespread liver dis-ease in the population. It may be the result of variousconditions (e.g. diabetes mellitus, disorders of lipidmetabolism) or toxic effects (alcohol, drugs, industrialtoxins). The most common cause is toxic damage dueto alcohol misuse.

An increased deposit of triglycerides in the hepatic cellsis characteristic of fatty liver. Firstly small deposits canbe seen (fine droplet fatty change). As the conditionprogresses, the size of the fat droplets in the hepaticcells increases (large droplet steatosis).

Fatty liver and cirrhosis

Figure 1.4 gives an overview of the factors playing a rolein portosystemic encephalopathy – pathological hae-modynamics and reduced detoxification in the liver.Both mechanisms contribute to the increased ammoniain the blood and the occurrence of hepatic encephalop-athy.

The clinical course of cirrhosis of the liver is generallychronic and progressive. The most important complica-tions are bleeding from oesophageal or abdominal var-ices, ascites, jaundice, clotting disorders, renal failureand hepatic encephalopathy. On average, about 40%of patients with cirrhosis develop overt hepatic en-cephalopathy during the course of the disease.

µmol/hxg

500

400

300

200

100

0

Urea synthesis Glutamine synthesis Glutaminase activity

% synthesis rate/wet liver weight Percentage ± SEM

* ** * * *

* *

*

*p<0,01 **p<0.0005 vs control

ControlFatty liverCirrhosis

Figure 1.3: Activity of urea synthesis, glutamine synthesis and glu-taminase in biopsies of histologically-confirmed normal liver tissue,fatty liver tissue and cirrhotic liver tissue. The data are based on thecalculation of synthesis rate per wet liver weight (µmol/h x g). Thesynthesis rate of control liver tissue corresponds to 100% (afterGerok, 1996)

Metabolic causesHaemodynamic causesNormal state

UreaGlutamine

UreaGlutamine

UreaGlutamine

NH 4+ NH 4

+ NH 4+

Figure 1.4: Pathophysiology of hepatic encephalopathy in cirrhosisof the liver (after Gerok, 1995)


1918

Non-alcoholic steatohepatitis (NASH) also belongs inthe group of non-alcoholic fatty changes in the liver,with a spectrum ranging from steatosis through steato-hepatitis and steatofibrosis up to cirrhosis.

Inflammation of the liver may have various underlyingcauses. The most important of these are hepatitis vi-ruses, autoimmune processes and drugs. On occasionthe cause may not be identified. Chronic hepatitis maydevelop into cirrhosis of the liver and hence be an indi-rect cause of hepatic encephalopathy.

Viral hepatitis is the most common. Table 1.2 gives anup-to-date overview of hepatotropic viruses (Caspary2001). As a rule, acute viral hepatitis heals without caus-ing cirrhosis. Hepatic encephalopathy may occur infulminant viral hepatitis even without cirrhosis. In chron-ic hepatitis, cirrhotic changes in the liver arise as part ofthe inflammatory process. Chronic viral hepatitis cantherefore be an indirect cause of hepatic encephalop-athy. Hepatitis B, for example, becomes chronic insome 10% of cases and a number of these patients goon to develop cirrhosis. In contrast, hepatitis C followsa chronic course in some 80% of cases and oftendevelops into cirrhosis of the liver.

Non-alcoholic steatohepatitis (NASH)

Hepatitis and cirrhosis of the liver

The fatty deposits lead to an overall enlargement of theliver.

Symptoms of a fatty liver include sensations of pressureand fullness in the right side of the upper abdomen andfrequently also pain in the region of the liver, as well asflatulence, fullness, nausea and reduced performance.The enlarged liver is usually easily palpable through theabdominal wall. Results of liver-specific laboratory testsmay occasionally be abnormal, depending on the extentof liver damage and loss of function.

With fatty liver the detoxification function may already belimited. Studies have shown that urea and glutaminesynthesis are reduced in fatty livers (see Figure 1.3).Values lie somewhere between those in cirrhotic tissuesand those found in healthy livers. It is therefore probablethat minimal hepatic encephalopathy is also present inpatients with fatty livers, or can develop under theinfluence of additional precipitating factors (see section2.2).

At first these processes are reversible with the removalof the cause, i.e. in most cases misuse of alcohol. Withcontinued presence of the toxin, the process frequentlyprogresses with increasing fibrosis developing into cir-rhosis of the liver. The effects of alcohol may also giverise to inflammation of the liver with hepatic cell necrosisand cell infiltration – alcoholic hepatitis – which may alsodevelop into cirrhosis of the liver.


20

Fulminant viral hepatitis in particular but also drug-induc-ed toxic reactions may rarely lead to acute liver failurewhich has a dramatic clinical picture. This is defined bythe combination of severe liver insufficiency and alter-ation in the level of consciousness with hepatic en-cephalopathy. The diminution in liver function is character-ized by a rapid fall in clotting factors, with a sharp risein transaminases and accompanying jaundice. Theappearance of hepatic encephalopathy is an unfavour-able prognostic sign. Various classifications of thedegree of severity of acute liver failure have been de-fined based on the interval between the appearance ofjaundice and encephalopathy. In general it can be saidthat the more quickly hepatic encephalopathy followsthe signs of jaundice, the worse the prognosis, i.e. 1 week

Acute liver failure

21

In less common autoimmune hepatitis, loss of immunologi-cal tolerance leads to self-destruction of the liver. The etiology and mechanisms are mostly unclear. Theinflammatory process leads to loss of functioning paren-chyma and to fibrotic changes in the liver.

In chronic hepatitis, the reduced detoxification capacity ofthe damaged liver tissue appears even before cirrhosisdevelops. A study on patients with chronic hepatitis showedthat even before the formation of a by-pass circulation –associated with progressive liver damage – there is an in-crease in the blood ammonia concentration (Figure 1.5).

HAV HEV HBV HDV HCVPicorna- Calici- Hepadna- Delta- Flavi-

Virus family viridae viridae viridae viridae viridae

Genome RNA RNA DNA RNA RNAIncubation time (days) 14–45 14–60 30–180 30–180 14–180Transmission faecal-oral faecal-oral parenteral parenteral parenteralDiagnositics (acute infection) anti-HAV anti-HEV HbsAg anti-HDV anti-HCV

IgM IgM anti-HBc-IgM IgM HCV-RNABecomes chronic no no <5 % <10 % 50–80 %

(adult) (co-infection)90 % <80 %(perennial) (super-infection)

Cirrhosis of the liver – – 20–30 % 30–40 % 20–30 %with chronic hepatitisOncogenicity no no yes ? yesNotifiable disease* I, D I, D I, D I, D I, D

Table 1.2: Characteristics of hepatotropic viruses (after Caspary 2001); I = illness; D = death; *Obligation to notify disease in accordance with §3 of the Federal Infectious Diseases Protection Law

160

120

80

40

0

Normaln=50

CAH IIan=44

CAH IIbn=41

CAH � cirrhosisn=37

arterial

venous

**

*

Amm

onia

(µg/

dl)

Figure 1.5: Arterial and venous plasma ammonia concentrations indifferent stages of chronic active hepatitis (mean ± standard devia-tion). The statistical significance * (p<0.05) refers to the comparisonwith normal controls (after Müting et al., 1988).CAH: chronic active hepatitis


22

2.1 Definition and clinical forms ofhepatic encephalopathy

Hepatic encephalopathy (HE) is a metabolically induc-ed, potentially reversible, functional disturbance of thebrain which may occur during the course of chronic andacute liver diseases (see section 1.2). The term encom-passes a syndrome of individual neurological andpsychological components that may occur in differentcombinations and with varying degrees of severity. Thesymptoms and signs of hepatic encephalopathy do notbasically differ from encephalopathies of other genesis;the definition therefore includes a concurrently demon-strable liver disease.Occasionally, portosystemic encephalopathy (PSE) isclassified as a subgroup of hepatic encephalopathy.This refers to encephalopathy in cirrhosis of the liver incombination with portosystemic collateral circulations(see section 1.2). However, this form cannot basicallybe distinguished from other forms of hepatic encepha-lopathy.

The clinical picture of hepatic encephalopathy is veryvariable and can be associated with impairment of intel-lectual and psychomotor functions as well as changesin personality and level of consciousness. Clinical pro-gression varies greatly: acute, episodic, fluctuating andchronic forms are possible.

Hepatic encephalopathy is divided into five degreesof severity according to the West Haven criteria, onthe basis of clinical symptoms and signs as well asthe findings of psychometric tests (Table 2.1). These

Definition of hepaticencephalopathy

Clinical picture anddegree of severity

2 HEPATIC ENCEPHALOPATHY – CLINICAL PICTURE AND PATHOGENESIS

23

in hyperacute forms and more than 4 weeks in sub-acute.

The symptoms of encephalopathy in acute liver failuredo not basically differ from hepatic encephalopathy dueto other causes. However, there is a risk of cerebraloedema and fatal cerebral herniation as a result of raised intracranial pressure. The prognosis in acute liverfailure is poor; mortality without a liver transplant isabout 80%.

Summary: The most common liver disease which causes hepatic encephalopathyis cirrhosis of the liver. The typical picture of disease includes liver celldamage with reduced detoxification capacity in combination with colla-teral portosystemic circulations. Other liver conditions may develop intocirrhosis during the course of the disease e.g. fatty liver or hepatitis. Inacute liver failure, hepatic encephalopathy may occur without cirrhosisor portosystemic shunts.


2524

Minimal (subclinical) encephalopathy is present in 30-70% of people with cirrhosis. The burden of this distur-bance depends on the demands made on the individu-al. Diminished performance may be of particularimportance in manual work (e.g. operating conveyerbelt) and driving a car. Reduction in the quality of lifeand personal safety may be associated even with HEgrade 0 (see section 3.2).

Typical symptoms and signs of HE grades I-IV are pre-sented in Table 2.1. The degree of severity of hepaticencephalopathy can progress very quickly.Neuropsychiatric symptoms of overt hepatic encepha-lopathy are extremely variable. The first clinical indica-tions are, for example, sleep disturbances, loss of driveand mood swings as well as loss of fine motor func-tions. Poor attention span, lack of concentration andreduced mental agility can be taken as signs of dimin-ished cognitive function. As these are non-specific, theyare often not recognized as signs of hepatic encepha-lopathy. With HE grade II, symptoms of psychomotorretardation with disorientation and memory defectsappear. Characteristic flapping tremor (asterixis) is asign of neuromuscular disorder, as are ataxia, dysarthriaand increased reflexes. Occasionally, hallucinations anddelusions occur.Changes in personality – often the intensification of apreviously existing characteristic – may be pronounced.In the later stages of hepatic encephalopathy, alter-ations in the level of consciousness determine theclinical picture. HE grade IV is characterised by deepcoma with response only to painful stimuli.

Overt hepatic encephalopathy

divisions are based largely on the mental state of thepatient; they range from HE grade 0 with no distur-bance of consciousness to deep coma with HE gradeIV.

In the stage of minimal (subclinical or latent) hepaticencephalopathy – HE grade 0 – the patient has nocomplaints and on direct questioning has no symptomsbelonging to grade I. Sleep, concentration, fine motorfunctions, general performance and mood are notaffected. Even so, results of psychometric and neuro-psychological tests show subtle abnormalities, provid-ing evidence of cerebral disturbance in the sense ofretardation of psychomotor functions.

Minimal hepatic encephalopathy

HE grade State of conciousness/ Behaviour Neuromuscularintellect symptoms

Minimal clinically normal but clinically normal but disturbance of finesubclinical abnormal pathological abnormal pathological motor function

and psychometric tests and psychometric testsI reduced concentration and personality changes disturbance of fine

prolonged reaction time, motor functionsleep disorders, fatigue(reduced alertness)

II retardation, lethargy marked personality asterixis, slurredchanges, temporal speechdisorientation

III disorientation, somnolence, bizarre behaviour, hypo- and hyperreflexia,stupor delusions asterixis, convulsions

IV coma ceased areflexia, loss of tone

Tab. 2.1: Degrees of severity of hepatic encephalopathy: Classification of the mental state accordingto West Haven criteria (modified after Conn and Bircher 1994)


2726

2.2 Precipitating factors in hepatic encephalopathy

A great variety of factors can precipitate or exacerbatehepatic encephalopathy (Figure 2.1). Often there isinterplay of several factors. The severity of the cirrhosisand the extent of collateral circulation do not necessar-ily determine the likelihood of encephalopathy. Hepaticencephalopathy may be induced by a certain combina-tion of precipitating factors even in patients withoutrecognizable impairment of liver function and no mark-ed portosystemic shunt volume.

The majority of precipitating factors is associated withincreased nitrogen or an increased number of nitro-genous metabolites in the blood.

Many precipitatingfactors

Hepatic encephalopathy may also occur in acute liverfailure, e.g. with fulminating hepatitis (see section 1.2).This is basically indistinguishable from the symptomsseen with chronic liver disease; however, the distur-bances of cerebral function appear more abruptly andprogress more rapidly. States of delirium, restlessnessand seizure tendency are more common than withother forms of hepatic encephalopathy.

Hepatic encephalopathy inacute liver failure

Increased ammonia in the brain• Increased ammonia production:

Protein-rich dietGI bleedingHypokalaemiaConstipationInfection

• Increased passage of ammoniainto the brain:

Metabolic alkalosis(esp. diuretics)Vomiting

Volume deficiency• Diuretics

(in forced mobilization of ascites)• Vomiting• Diarrhoea• Bleeding

Drugs

Transjugular intrahepatic porto-systemic stent shunt (TIPS)

Hypoxia

Figure 2.1: Precipitating factors in hepatic encephalopathy (after Caspary 2001)

Summary: The definition of hepatic encephalopathy encompasses the liver diseaseand the cerebral dysfunction. Assessment of the severity of the conditionis made clinically on the basis of the mental state (HE grade in accordancewith West Haven criteria). With the minimal or subclinical form (HE grade0) there are no obvious clinical deficiencies but the results of psychomet-ric tests are abnormal. Increasing deterioration of the level of conscious-ness becomes apparent with HE grades I-IV, reaching deep coma by HEgrade IV.


2928

Hepatic encephalopathy may also be precipitatedfollowing the creation of a transjugular intrahepatic portosystemic shunt (TIPS) as a therapeutic measure.Encephalopathy becomes overt in about a quarter ofTIPS patients. The main indications for a TIPS are haemodynamic problems, especially prophylaxis ofrecurrent bleeding from oesophageal or abdominal varices. If there is not already severe hepatic encephalop-athy (grade II-IV), the risk of encephalopathy has to beaccepted, since these haemodynamic complications aredifficult to treat and potentially fatal. Elderly patients(>60 years of age) are particularly at risk. The patho-physiological changes responsible for the manifestationof hepatic encephalopathy in patients with shunts aredescribed in section 1.2.

TIPS and hepaticencephalopathy

The common precipitating factors of azotaemia, bleed-ing from shunt varices, infections and protein-rich diet,lead to increased nitrogenous compounds that are bro-ken down to ammonia which cannot be sufficientlydetoxified because of impaired liver function. At thesame time there is decompensation of ammonia detox-ification.Hypovolaemia, aspiration of ascites, diuresis, hypoka-laemia or hyponatraemia may lead to disturbances offluid balance, acid-base balance and electrolyte con-centrations. As a result, more ammonia may be produc-ed in the kidneys, hepatic and renal blood flow bereduced and detoxification in the liver impaired. Di-uretics also directly inhibit urea synthesis in the liver.Metabolic acidosis also adversely affects urea synthe-sis.

Other factors that commonly precipitate overt hepaticencephalopathy are sedatives and tranquillisers, espe-cially benzodiazepines. These substances have a neu-rodepressant action and in this way may promote hepat-ic encephalopathy. Since these drugs are metabolizedin the liver, impaired hepatic function prolongs their half-lives; this means that a relative overdose may occureven when normal dosages are taken. Sedative drugsshould therefore be prescribed for patients with cirrho-sis only in special circumstances.

Alcohol induces hepatic encephalopathy not only bycausing cirrhosis of the liver; it may also act as a precip-itating factor through its neurodepressant effects.

Summary: All conditions that increase the ammonia concentration in the blood – byincreasing ammonia production or disrupting detoxification – are pos-sible precipitating factors in the manifestation of hepatic encephalopa-thy. Neurodepressant agents (e.g. benzodiazepines, alcohol) may like-wise precipitate hepatic encephalopathy. When a TIPS is created as atherapeutic measure, the risk of hepatic encephalopathy must also beaccepted. Elderly patients (>60 years of age) are particularly at risk.


3130

chromatin. These pathological changes indicate a keyrole for the astrocytes in the pathogenesis of enceph-alopathy (Figure 2.2).

The astrocytes are important components of the blood-brain barrier. The uptake of substances from the bloodinto the brain requires the transastrocyte transportmechanism. Astrocytes are in close contact with neuro-nal cells and are involved in the metabolic processes ofneurotransmitters and regulation of ion concentrationsin the brain.

Swelling of astrocytes

2.3 Pathogenesis of hepaticencephalopathy

Explanation of the pathogenesis of hepatic encepha-lopathy requires investigation of the relationship be-tween liver function and cerebral function, two highlycomplex systems. Results are frequently not easy tointerpret and give rise to further questions. The manysymptoms and signs and their variability with respectto the degree of severity and progression make it dif-ficult to find a common pathomechanism that explainsall the forms of encephalopathy.Despite intensive scientific research, it has not yetbeen possible to completely elucidate the pathophys-iological mechanisms of hepatic encephalopathy.However, it is certain that increased ammonia con-centration in the blood contributes to the pathogene-sis. There is probably synergy with other pathome-chanisms.

2.3.1 Neuropathological changes

Hepatic encephalopathy is basically a reversible dis-turbance of cerebral function. Damage to neuronalcells is not seen. In neuropathological studies, how-ever, changes can be identified in the morphology ofthe astrocytes. In acute liver failure, the astrocytes areswollen. In cirrhosis of the liver, neuropathologicalchanges can be seen, which are described as Alzhei-mer type II astrocytosis. These astrocytes are charac-terized by large swollen nuclei and margination of the

Figure 2.2: Alzheimer type II astrocytesAlz: Alzheimer astrocyte, N: normal astrocyte


3332

The mechanism of neurotoxicity of ammonia in the brainhas not yet been completely explained. There is experi-mental evidence of disturbances of the cerebral energymetabolism and neurotransmission, direct modulationof neuronal activity and an indirect effect on the neu-rones via the astrocytes. On the basis of recent studies,functional disturbance of the astroglia with resultingdysfunction of the neuronal cells is possibly the mostimportant neurotoxic mechanism of action of ammonia.

Accumulation of glutamine (a product of ammoniadetoxification) in the cells is the main cause of the astro-cyte swelling. Only these cells contain glutamine syn-thetase, an enzyme capable of detoxifying ammonia inthe brain (Figure 2.3).

Neurotoxicity of ammonia

2.3.2 Ammonia and the glial hypothesis

An increased ammonia concentration in the blood cer-tainly contributes to the manifestation of hepatic en-cephalopathy. There is no pathogenetic concept inwhich ammonia does not play a key role. The followingpoints in particular support this:

• In most patients with hepatic encephalopathy, theammonia concentration in the blood is raised.Only 10% of patients have normal levels.

• In cases of hyperammonaemia, lowering theammonia concentration leads to improvement inthe symptoms.

• Hepatic encephalopathy occurs far and awaymost commonly in patients with cirrhosis of theliver and portosystemic collateral circulations, inwhom insufficiently detoxified blood – especiallywith respect to ammonia – reaches the brain.

• There is a certain correlation between ammoniaconcentration and the severity of the hepaticencephalopathy.

• Conditions where the ammonia is raised can pre-cipitate or exacerbate hepatic encephalopathy,while a fall in ammonia concentration improvesthe clinical symptoms and signs.

In animal experiments hyperammonaemia induceschanges that are also seen in liver patients (e.g. cerebraloedema and raised intracranial pressure) as well asnumerous neurochemical changes similar to thosefound in humans.

Pathogenetic significance of ammonia

Glu

GluGlu

GlnGln

Gln

NH3 NH3

SYNAPSE ASTROCYTE

NORMAL

GLU-RECEPTOR

NH3

Glu

GluGlu

GlnGlnGln

NH3 NH3

SYNAPSE ASTROCYTE

HYPERAMMONAEMIA

GLU-RECEPTOR

NH3

Figure 2.3: Diagrammatic representation of glutamate-glutamine cycle in the glutamatergic synapseand the influence of hyperammonaemia(Gln = glutamine; Glu =glutamate; (1) = glutaminase; (2) = glutamine synthetase)

Ammonia and glial swelling


3534

may arise. There may be changes in the permeability ofthe blood-brain barrier with symptoms of raised intra-cranial pressure. In addition, effects on the activity of ionchannels, disturbances of neurotransmitter and recep-tor functions, and damage to the neuronal energy sup-ply are to be expected. The glutamatergic neurotrans-mitter system that controls cognitive function isprobably involved in the process; due to the increasedconsumption of glutamate needed to detoxify ammo-nia, glutamate deficiency results in the glutamatergicneurones. Frequently it cannot be determined howmuch the functional changes in neuronal activity aredue to direct toxic effects of ammonia and how muchto indirect effects of the glial swelling.

2.3.3 Additional pathologicalmechanisms

Besides the role of ammonia and the concept of glialswelling, there are indications that additional patho-mechanisms exist. These may be synergistic or mayeven determine the manifestation of hepatic encepha-lopathy.

There is evidence for considering the neurotoxic effectsof other endogenous substances – for example, mer-captans which are formed during the breakdown ofsulphur-containing amino acids (e.g. methionine) bybacteria. These substances are responsible for thecharacteristic foetor hepaticus. They inhibit Na+/K+

ATPase and potentiate the neurotoxicity of ammonia.

Other substances such as cytokines and benzodiaze-pines or conditions such as hyponatraemia may besynergistic to the ammonia effects and thus contributeto the astrocyte swelling, or may even be the maincause of this change.

Figure 2.4 gives an overview of the different factorscontributing to the pathogenesis of hepatic encepha-lopathy.

In acute liver failure, glial swelling occurs with clinicallyovert cerebral oedema. Findings from recent studieshave shown that there is also a disturbance of cell vol-ume homeostasis with glial swelling in chronic liver dis-eases and hepatic encephalopathy (Häussinger et al,2000).

Many potential functional disturbances of the glial cellsthemselves and of the glial-neuronal communications

Changes in post-synaptic receptors

Changes in neurotransmitters

Swelling and functional disturbance of the astroglia

Neurotoxin ammonia/amino acid imbalance

Impaired liver function

Changes in theblood-brain barrier

Figure 2.4: Interplay of various pathogenetic factors in hepatic encephalopathy

Other endogenousneurotoxins


3736

that the concentrations of aromatic amino acids in thebrain also increase while the branched-chain aminoacid concentrations are reduced (Figure 2.5).

The aromatic amino acids are substrates for neuro-transmitter synthesis – tyrosine and phenyl alanine fordopamine, and tryptophan for serotonin. The excesssupply of substrates may mean that substances suchas tyramine, octopamine and phenyl ethanola-mine are formed via secondary metabolic pathways.These act as “false neurotransmitters” by competingwith the normal transmitters for the same receptors andthereby disrupting neuronal activity.

Phenols are also neurotoxins; they lead to coma in ani-mal experiments. They are derivatives of the aminoacids phenyl alanine and tyrosine, and are formed in thegastrointestinal tract.

Short and medium chain fatty acids are producedby the physiological intestinal flora during the break-down of fatty acids, and can also be formed in the liveritself. They inhibit Na+/K+ ATPase and urea synthesis inthe liver. In addition, there is some evidence that thesecompounds increase the tryptophan uptake into thebrain and thus affect transmitter metabolism.

The blood-brain barrier is a complex physiologicalfunctional unit which protects the brain from metabolicdisturbances in the rest of the body. In acute liver failure, the permeability of the blood-brain barrier isincreased in a non-specific manner. Certain changes inthe blood-brain barrier are also seen in chronic liver fail-ure. The transport capacity for neutral amino acids isincreased but reduced for basic amino acids, ketonebodies and glucose. At the same time, the ammonia-dependent rise in intracerebral glutamine formationincreases the uptake of neutral amino acids into thebrain. The selective changes in permeability that can beobserved are possibly related to the glial swelling.

In chronic liver disease, the blood shows a typicalamino acid distribution profile. The quantitative rela-tionship between aromatic (tyrosine, phenyl alanine,tryptophan) and branched-chain amino acids (valine,leucine, isoleucine) shifts towards the aromatic aminoacids. On the basis of this observation, it is assumed

Increased permeability of the blood-brain barrier

Amino acid imbalanceand “false neurotrans-

mitters”

NH3

Glutamine

Glutamine

Glutamate Glutamine

Glutamine

Glutamate

Figure 2.5: Diagrammatic representation of ammonia and amino acids exchange. Ammonia taken upinto the brain is converted to glutamine, which is exchanged for the branched-chain amino acids(BCAA) and aromatic amino acids (AAA) present in the plasma, which use the same transport system.In the case of portosystemic encephalopathy, increased levels of ammonia in the blood lead to raisedconcentrations of glutamine in the brain. The higher AAA to BCAA concentration ratio in the blood promotes the entry of AAAs into the brain through exchange with glutamine (after Conn, 1994)

Neurotoxicity of ammonia


3938

On the basis of the therapeutic neurodepressant effectsof benzodiazepines, which are notable precipitating fac-tors for hepatic encephalopathy, the hypothesis hasbeen proposed that so-called endogenous benzodiaze-pines and related substances (endozepines) which canbe found in the blood and brain as well as in plant prep-arations and foodstuffs, contribute to the pathogenesisof hepatic encephalopathy by their agonistic actions onthe GABA receptors. Gamma-aminobutyric acid(GABA) is an important inhibitory neurotransmitter in thebrain and GABA receptors are to be found on neuronesand astrocytes. Activation of the GABA-ergic systemhas a neurodepressant effect.

The increased uptake of tryptophan into the brain leadsto an increased formation of serotonin. The density ofserotonin receptors decreases while their affinityincreases. Changes regarding the neurotransmitternoradrenaline are also seen in hepatic encephalopathy,which may possibly have pathogenetic significance.

Results of recent studies have suggested an associa-tion between hepatic encephalopathy and the traceelements zinc and manganese. It has been shownthat the activity of enzymes in the urea cycle is reducedwhen there is zinc deficiency.

NMR studies in patients with hepatic encephalopathyhave indicated deposits of manganese in the basal ganglia.

The question of how relevant these findings are topathogenesis remains open.

GABA-ergic transmission

Serotonin,noradrenaline

Zinc, manganese

Summary: Every last detail of the pathogenesis of hepatic encephalopathy has notyet been fully elucidated. Ammonia certainly plays a key role. The asso-ciated glial hypothesis, which assumes an underlying mechanism of dis-rupted interaction between the altered astrocytes and other cellular ele-ments of the brain, brings the various findings together in acomprehensive manner. The concept of synergistic mechanisms be-tween the observed influencing factors is plausible and correlates withthe variable symptoms and signs to be seen in hepatic encephalopathy.


41

In alcoholics with cirrhosis of the liver, Wernicke-Korsakovsyndrome and delirium tremens from alcohol withdraw-al must in particular be included in the differential diag-nosis of hepatic encephalopathy. Subdural haematomaand other vascular processes, space-occupyinglesions, intoxication, encephalitis, hypothyroidism andmetabolic disorders such as hypo- or hyperglycaemia,uraemia and hyponatraemia have all to be consideredas well.

With hepatic encephalopathy, changes in the EEG arevisible as abnormal slowing of the baseline activity although this is not pathognomic. Similar changes canbe seen with uraemia, CO2 poisoning, vitamin B12 defi-ciency, hypoxia or hypoglycaemia. In addition, it is dif-ficult to evaluate changes because a reference EEG isnot usually available for the patient. It is often the casethat no clear boundary can be drawn between normaland pathological. Similar restrictions exist in respect toinvestigations with evoked potentials (VEP, P300). Andthese methods are also relatively time consuming andexpensive. Electrophysiological methods are thereforenot of prime importance in the diagnostic work-up ofovert symptoms.

The main indication for imaging procedures in the differential diagnosis of hepatic encephalopathy is theexclusion of other cerebral processes, especially cerebral haemorrhage. If symptoms corresponding tobleeding etc. are present, these imaging techniquesare first-line investigations.

Differential diagnosis

Electrophysiologicalinvestigations

Imaging techniques (CT, MRI etc.)

3.1 Diagnostic procedures

The diagnosis of hepatic encephalopathy is made onthe basis of the clinical picture (see West Haven criteria)and must be considered in every patient with neuro-psychiatric disturbances and liver disease. The diagno-sis is easy in known cases of cirrhosis of the liver or ful-minating hepatitis but presents difficulties when the liverdisease has not yet been diagnosed.Clinico-chemical blood tests may be worthwhile in re-vealing a hitherto unsuspected liver disease or hyper-ammonaemia syndrome, but have only limited rele-vance in the diagnosis of hepatic encephalopathy.

The following summary proposed by Gerber and Schomerus indicates the relevant laboratory tests thatmay be useful in this context (Table 3.1).

Diagnosis of hepaticencephalopathy on

the basis of theclinical picture

3 DIAGNOSIS OF HEPATIC ENCEPHALOPATHY

40

Liver function tests• Transaminases (GOT, GPT)• Cholestasis parameters

(AP, γ−GT)• Bilirubin• Total proteins with

electrophoresis/albumin• Prothrombin time

Blood glucose

Electrolytes (with calcium and phosphate)

Creatinine, urea

Drug screening (urine and blood)

Alcohol levels

Blood gas analysis

Fasting ammonia concentration

Cultures(blood, urine, sputum, faeces)

Hepatitis and HIV

Ascites (cells and culture)

Blood picture, C-reactive protein,erythrocyte sedimentation rate

Table 3.1: Laboratory tests in hepatic encephalopathy (after Gerber and Schomerus, 2000)


42

Using specific test procedures and a standardized testdrive, a study conducted recently by a research groupat the University of Hamburg, in collaboration with theFöhrenkamp clinic of the Mölln BfA rehabilitation centre,showed that patients with cirrhosis of the liver and sub-clinical hepatic encephalopathy were not completely fitto drive. Not only was their ability to drive a car severe-ly restricted but also the ability to adapt their drivingbehaviour to the general rules of the road, as can beseen in Figure 3.1 (Wein et al., 2002).

Diminished function in minimal hepatic encephalopathyis best identified with the aid of psychometric tests.Moreover, these tests are relatively easy and cheap toadminister (see section 3.3).

Reduced fitness todrive in patients withsubclinical hepaticencephalopathy

Psychometric procedures in subclinical hepaticencephalopathy

43

3.2 Early diagnosis

Early recognition of hepatic encephalopathy is of partic-ular clinical relevance, i.e. diagnosis in HE grade 0.Disturbances of consciousness are not yet noticeablewith minimal or subclinical hepatic encephalopathy butimpairment of intellectual function already exists. This isimportant to the patient for two reasons:

• Recognition of incipient hepatic encephalopathy is anindication of the decompensation of the underlyingcirrhosis and the necessity of treatment.

• Even the existing limitations represent a risk to thepatient at work (especially manual occupations) ordriving a car.

Reductions in performance such as slower reactiontimes, inaccurate perception of geometric shapes andreduced visual selection abilities, which are at first bare-ly noticeable, are important at work or driving a car. Inaddition, there are personality changes such as reduc-ed emotional stability, loss of self-control and self-criti-cism as well as a tendency to dissimulate (Häussingerand Maier, 1996). The risks of a road traffic accident oran accident during manual work are thereby increased.

Diminished performance in

subclinical hepaticencephalopathy 5

4

3

2

1

BF SI GEB BH RB BL ZF GEA OW VB ABH SH EP SE AB BEA

MarksBF observing pedestriansSI checking safe to proceedGEB observing speed

restrictions BH observing obstacles RB observing rulesBL signallingZF rapid mergingGEA adaptation of speedOW orientation by signpostsVB observing right of wayABH maintaining distanceSP keeping in laneEP parkingSE getting into the correct

laneAB hill startsBEA obeying traffic lights

SHE Group of patients with cirrhosis of the liverwithout subclinical hepatic encephalopathy

SHE+ Group of patients with cirrhosis of the liverwith subclinical hepatic encephalopathy

KK Clinical control subjects

Figure 3.1: Test drive: Marks gained in driving categories (after Wein et al., 2002)Note: Marks in school reports etc. in Germany are scored with 1 being the highest

Summary: Hepatic encephalopathy is diagnosed on the basis of the clinical picture.The necessary investigations for the differential diagnosis of this condi-tion include laboratory tests, imaging procedures and occasionally elec-trophysiological examinations.


45

3.3 Criteria for assessing degreeof severity and monitoring the course of disease

Estimating the degree of severity of hepaticencephalopathy depends in the first line on the mentalstate. This is evaluated on the basis of the patient’sclinical symptoms, in accordance with the HE grades ofConn and co-workers described above (see Table 2.1).

HE grade andmental state

In certain cases, minimal hepatic encephalopathy inpatients with cirrhosis of the liver can also be recognizedin the EEG. Evoked potential tests (especially P 300) like-wise show a certain diagnostic sensitivity for the earlydiagnosis of hepatic encephalopathy. However, becausethe procedure has relatively high technical requirements, itis not generally used for routine diagnostic investigation.

A procedure that has recently become established in thediagnostic investigation of hepatic encephalopathy is thedetermination of the critical flicker frequency (CFF). In thistest, the patient is shown a light that flickers with increas-ing or decreasing frequency. With ascending frequency,the patient sees the light become constant (= fusion fre-quency). In the reverse procedure, the stable light startsto flicker as the frequency descends. The CFF is clearlyaltered in patients with subclinical hepatic encephalopa-thy compared with healthy people. As the severity of thecondition increases, the CFF falls (Figure 3.2), and risesagain with improvement in the HE episode (Figure 3.3)(Kircheis et al., 2002).

Critical flickerfrequency

44

50

45

40

35

30

25

Controls HE 0 SHE HE I HE II

CF

F (

Hz)

ns.ns.

p < 0,01

p < 0,001p < 0,001

p < 0,001p < 0,01

p < 0,001

Figure 3.2: CFF in patients with cirrhosis of the liver (Kircheis etal., 2002)

42

40

38

36

34

0 1 3 5 7 9

HE I

HE I

SHE

SHE SHE

HE 0

CF

F (

Hz)

Days

Figure 3.3: CFF in patients with cirrhosis during and after recoveryfrom an episode of hepatic encephalopathy (Kircheis et al., 2002)

Summary: The early diagnosis of hepatic encephalopathy in HE grade 0 is particu-larly important for the patient. Hitherto unrecognized diminution of per-formance increases the risk of accidents at work or in road traffic.Psychometric tests are simple to administer and appropriate for theearly diagnosis of reduced intellectual function in hepatic encephalopa-thy. The determination of CFF is also very promising.


As a rule, in patients with hepatic encephalopathy,abnormal slowing of baseline activity and an increase inamplitude can be seen in parallel with the degree ofseverity. Table 3.3 shows a semiquantitative classifica-tion of frequency for the PSE index.

Many psychometric tests are used to establish and quantify deterioration of intellectual function. Thisincludes slowing down of the psychomotor perfor-mance speed as well as restriction of both visual spatialorientation and visual constructive ability. Validated andquantifiable psychometric test procedures whichdetermine these deficits are the number connectiontest (NCT) versions A and B, the digit symbol test(DST) and the line tracing test (LTT).

From the practical point of view, a test should be sim-ple to explain and quick to perform as well as quick andeasy to evaluate. Taking these points into consideration,the number connection test (NCT) has proved itself tobe a valuable tool (Conn and Bircher, 1994). Table 3.4shows the standard forms used for versions A and B ofthis test.

EEG

Psychometric test procedures

47

The PSE index represents an extension developed byConn and co-workers (Conn and Bircher, 1994). Inaddition to the mental state (c.f. Table 2.1), this indexincludes the semiquantative assessment of the symp-tom of asterixis (Table 3.2), the time taken to completethe number connection test (Table 3.4), the EEG (Table3.3) and the ammonia concentration (Table 3.5). Grad-ing of each variable is weighted (mental state x3, eachof the others x1) and added together to give a maxi-mum PSE score of 28 points. The ratio of the individu-al score obtained to the maximum score gives the PSEindex. The PSE index is more complex than the HEgrading and is suitable for monitoring progress.

Even though asterixis (flapping tremor) as a sign of neu-romuscular disturbance is frequently present and isconsidered to be characteristic of hepatic encephalop-athy, it is not actually specific to this condition. It alsoappears with other disorders (e.g. intoxication, hypo-magnesaemia etc.). From the clinical point of view,however, it is suitable for diagnosing, evaluating theseverity of the condition, and monitoring its progress.Table 3.2 shows a semiquantitative classification for thePSE index.

Asterixis

46

PSE index for monitoring progress

Grade 0 No tremor

Grade 1 Rare tremor (1–2 per 30 seconds)

Grade 2 Occasional, irregular tremor

(3–4 per 30 seconds)

Grade 3 Frequent tremor (5–30 per 30 seconds)

Grade 4 Virtually uninterrupted tremor present

Table 3.2: Semiquantitative grading of asterixis (flapping tremor)(after Conn and Bircher, 1994)

Grade 0 Alpha-frequency, 8.5–12 cycles per second (cps)

Grade 1 7–8 cps

Grade 2 5–7 cps

Grade 3 3–5 cps

Grade 4 maximum 3 cps

Table 3.3: Semiquantitative grading of the EEG (after Conn and Bircher, 1994)


4948

Table 3.4 shows a semiquantitative grading of the timetaken to perform the number connection test A for thePSE index. Figures 3.5 and 3.6 show the line tracing testand digit symbol tests. These are also evaluated accord-ing to the time required to complete the sequences.

As most forms of hepatic encephalopathy are associat-ed with an increased nitrogen load and/or reduceddetoxification of ammonia, the determination of theammonia concentration in the blood provides diagnos-tic evidence as well as an indication of the severity ofthe condition. Although the ammonia concentration inarterial blood does not rise in strict proportion to theseverity of the hepatic encephalopathy, there is a posi-tive linear correlation between these two parameters(Conn and Bircher, 1994). Poor correlation may partlybe attributed to difficulties with the analytical methodsused.

Ammonia concentration

Figure 3.4: Number connection test, Versions A (NCT-A) and B (NCT-B). In NCT-A the numbers have to bejoined consecutively in numerical order (1,2,3…) as quickly as possible. In the more complicated NCT-B,the numbers and letters must be connected alternately numerically and alphabetically (1,A,2,B…). Evalu-ation of both tests is based on the time required to complete the test (Conn 1977)

Grade 0 15–30 seconds




Grade 4 >120 (test cannot be carried out)

Table 3.4: Semiquantitative grading of the number connection testA (after Conn and Bircher, 1994)

Figure 3.5: (left) The line tracing test shows a complicated trace. Using a pencil, the patient has to rapidly fol-low the original 5 mm wide track from beginning to end without going over the edges – at the same time, thisis one way of testing “fitness to drive”. Evaluation considers both the time taken to complete the test and thenumber of errors (Schomerus et al., 1981)Figure 3.6: (right) In the digit symbol test, the blanks should be filled in as quickly as possible with the sym-bols corresponding to the numbers given at the beginning. Evaluation depends on the total number of cor-rectly inserted symbols within 90 seconds


50

The management of hepatic encephalopathy dependsmainly on the severity of the clinical picture. Intensivemedical care will be required as first line therapy in thecase of fulminating hepatic failure, while prophylacticmeasures to prevent progression and avoidance of pre-cipitating factors need to be considered in the treat-ment of subclinical encephalopathy.

4.1 General therapeutic concepts

The search for precipitating factors of hepatic encepha-lopathy is of prime importance in both treatment of theacute case and prevention. Such factors play a role in70-80% of patients (see section 2.2). Successfully elim-inating the most common precipitating factors –gastrointestinal bleeding, azotaemia, sedatives, infec-tions and excessive protein consumption – may preventprogression and overt symptoms in many cases. Themost important measures that have to be consideredstem from the need to eliminate these factors (Häussingerand Meier, 1996):

• Stop bleeding

• Treat anaemia (aim: haematocrit = 30%)

• Treat acidosis with bicarbonate

• Correct electrolytes to within normal range

• Discontinue diuretics

• Treat infections with antibiotics

• Discontinue sedatives

• Reduce protein intake

• Make every effort to obtain abstinence

from alcohol

Eliminating precipitating factors

4 TREATMENT OF HEPATIC ENCEPHALOPATHY

51

In a recent study, it has been shown that a method notcustomarily used (partial pressure measurement ofgaseous or “free” ammonia, which passes more easilyinto the brain) gives a closer correlation with the HEgrade than conventional measurements of the totalconcentration of arterial ammonia (Kramer et al., 2000).

Table 3.5 shows a semiquantitative grading of the arte-rial ammonia concentration for the PSE index.

Grade 0 Within normal range (<60 µmol/l)

Grade 1 1–1.33 x upper limit of normal

Grade 2 1.33–1.67 x upper limit of normal

Grade 3 1.67–2.0 x upper limit of normal

Grade 4 >2 x upper limit of normal

Table 3.5: Semiquantitative grading of the arterial ammonia concentration (after Conn and Bircher, 1994)

Summary:Suitable means of classifying and monitoring the degree of severity ofhepatic encephalopathy include the HE grading of the mental state andthe PSE index, which also takes into account the semiquantitative grad-ing of other factors – asterixis, EEG, number connection test and ammo-nia concentration.


4.3 Drug therapy

Although not yet elucidated in every detail, theneurotoxin ammonia plays an undisputed key role in thepathogenesis of hepatic encephalopathy. As in thepast, the therapeutic objective is still the reduction ofpathologically elevated levels of ammonia in the blood(see section 2.3).

The active substances used are selected principally inan effort to reduce ammonia production, promoteammonia detoxification, correct the amino acid imbal-ance and have a positive effect on neurodepression.

Reduction of intestinal ammonia productionCleaning out the intestinal tract should eliminate nitro-genous substances from which ammonia is produced.Non-absorbable disaccharides (e.g. lactulose) aremainly used for this purpose. Apart from their laxativeactions, disaccharides also affect ammonia productionin the intestinal flora. In bacterial metabolism, theirbreakdown products increase the incorporation of nitro-gen into bacterial proteins, so that less ammonia is re-leased; this in turn reduces the ammonia concentrationin the portal vein blood. Non-absorbable antibiotics(e.g. neomycin) are used to reduce the physiologicalflora in the large intestine and thus also to reduce theproduction of ammonia.

Increase in extra-intestinal ammonia detoxification An important therapeutic means of increasing ammoniadetoxification is stimulation of the urea cycle activity inthe periportal hepatocytes and stimulation of glutamine

Pharmacotherapeuticprinciples in hepaticencephalopathy

53

Knowledge of the precipitating factors is also very rele-vant to prophylaxis against recurrence. By avoidingsuch factors (e.g. sedatives, alcohol, and excessiveprotein consumption) and early treatment (e.g. infec-tions) the progression of hepatic encephalopathy canbe positively influenced.

4.2 Dietary therapy

An adequate diet is extremely important for patientswith hepatic encephalopathy and/or predisposing liverdisease. These patients often suffer from loss of appe-tite and do not consume enough calories. This poor dietfavours protein catabolism which is associated with theincreased formation of ammonia. Reduction in musclemass disrupts extrahepatic ammonia detoxificationsince muscle tissue contributes to detoxifying ammonia(see section 1.1). Resistance to infection also falls withinadequate nutrition. Active dietary therapy has a corre-spondingly favourable effect on the prognosis.

With acute hepatic encephalopathy, the temporaryreduction of protein intake to 20-30 g/day is indicated.The protein intake can then gradually be increased untila daily intake of 1 g/kg body weight is reached. Long-term protein restriction which was previously mandato-ry is now considered obsolete. Such protein restrictioncan only be justified in special cases of marked proteinintolerance. In the majority of cases an adequate balanc-ed diet improves the patent’s prognosis.

Regulation of protein intake

52


5554

Effects on neurodepressionInhibition of the GABA-ergic system with the group ofsubstances known as benzodiazepine antagonists(e.g. flumazenil) counteracts the neurodepressanteffects of the GABA-ergic activation.

With the exception of silymarin, the active substancesmentioned above are currently used in clinical practicefor the treatment of hepatic encephalopathy. Informa-tion on the efficacy of these substances has in the pastbeen widely based on empirical findings and on theresults of studies where the methods used no longermeet current research standards.

In the meantime, criteria for the demonstration of treat-ment efficacy have been drawn up for clinical trials.Apart from general criteria (such as randomization,double-blinding, testing against placebo controls orstandard drug therapy, and the inclusion of a sufficientnumber of cases), the definition of efficacy criteria is ofparticular relevance in studies on hepatic encephalopa-thy. End points for demonstrating efficacy are basicallyclinical outcome measures such as the mental state (HEgrade) and the PSE index which includes criteria suchas psychometric tests and ammonia concentration (seesection 3.3).

Conducting such studies is made particularly difficult bythe great variability of symptoms and the spontaneousprogression of hepatic encephalopathy. Even so, thenecessary evidence of efficacy has in the meantimebeen provided for some of the active substances in usetoday – forming the basis of “evidence-based medicine”.

Pharmacotherapeuticefficacy

synthetase in the perivenous hepatocytes (also knownas scavenger cells). L-ornithine-L-aspartate im-proves the detoxification of ammonia by supplying aspar-tate for glutamine synthesis in the perivenous scaven-ger cells. Ornithine promotes the urea cycle in theperiportal hepatocytes. Both oral (6 g three times a day)and parenteral (20 g/day) administration of L-ornithine-L-aspartate leads to a demonstrable reduction in hyper-ammoniaemia as well as improvements in the impairedmental functions of hepatic encephalopathy.

The use of benzoate is based on a different principle.This substance increases the excretion of ammonia.

Zinc is a co-factor of all the enzymes in the urea cycle.Administration of zinc supplements should thereforestimulate urea synthesis.

A plant pharmaceutical, silymarin (an extract of milkthistle seeds), is used to protect the liver. Studies on thisextract have shown that it prevents the entry of toxinsinto liver cells, supports protein synthesis and stimu-lates regeneration of damaged hepatocytes. Lowering ofthe blood ammonia concentration is not to be expectedwith silymarin.

Correcting the amino acid imbalance The administration of branched-chain amino acids(BCAA), i.e. leucine, isoleucine and valine, redresses theamino acid imbalance which adversely affects neuro-transmitter metabolism in the brain and peripheral pro-tein metabolism.


57

An evidence-based medicine review of the pharmaco-therapy of hepatic encephalopathy has been publishedrecently. Studies with adequate methodology havebeen carried out for some of the substances (Table 4.1).

This review shows that positive results from placebo-controlled trails are already available for some drugs.

At the present time, the following recommendations aremade for the treatment of acute and chronic hepaticencephalopathy (Table 4.2; after Caspary, 2001)

Evidence-based effectiveness of

drug therapy

56

Therapeutic principle Active substance Results of placebo-controlled trials

Reduction of intestinal Lactulose enema better than placeboammonia production

Oral lactulose not definitively better than placebo (number of cases too small)

Neomycin not better than placebo

Increasing extra-intestinal L-ornithine-L-aspartate better than placeboammonia detoxification

Correcting amino acid Branched-chain amino better than placebo imbalance acids (BCAA)

Benzodiazepine receptor Flumazenil better than placeboantagonists

Table 4.1: Drug therapy of hepatic encephalopathy. Evidence of efficacy from placebo-controlled trials (after Ferenci and Müller, 1999)

Acute HE:

• Elimination of precipitating factors:GI bleeding, azotaemia, diuretics, sedatives, infections, increased dietary proteins, hypokalaemia and/or metabolic acidosis, hypo-volaemia, hypoxia, spontaneous bacterial peritonitis (SBP)

• Measures to reduce ammonia concentration:Endoscopic control of bleeding, nasogastric lavage; oral lactulose (20-50 ml x 3) or lactulose enema (300 ml in 1200 ml H2O)

• Protein restriction:0-30 g for max three days, then increase by 10 g/day to reach 1g/kgbody weight with sufficient calorie intake.

• Oral neomycin:50-100 mg/kg body weight/day in 3-4 divided doses if inadequateresponse to lactulose

• Flumazenil:If the patient has previously been treated with benzodiazepines

• L-ornithine-L-aspartate (Hepa-Merz®):60 g/day i.v. (max. 5 g/h) if the above measures have been un-successful

• Branched-chain amino acids (BCAA):By infusion, if the above measures have been unsuccessful

• Paramomycin:4 g/day in 2-4 divided doses or vancomycin (250 mg x 4) or metronidazole (400 mg x 2)

• If the above are unsuccessful or the HE deteriorates, liver transplantation should be considered

Chronic persistent HE

• Lactulose: 20-50 ml x 3

• Protein restriction – only if lactulose is ineffective:1 g protein/kg body weight/day. If not tolerated, vegetable proteins orbranched-chain amino acids (BCAA) oral 0.25 g/kg body weight/day

• L-ornithine-L-aspartate (Hepa-Merz®): 6-9 g/day x 3

• Prevention of precipitating factors (see above)

• Consider indications for liver transplantation!

Table 4.2: Treatment recommendations for acute and chronichepatic encephalopathy (after Caspary, 2001)


58

5.1 Mechanism of action

Detoxification of ammonia takes place predominantly inthe liver in the periportal and perivenous hepatocytes (seesection 1.1). Ammonia is converted to urea in the ureacycle; ammonia reacts with glutamate to form glutamine(see Figure 1.2).L-ornithine-L-aspartate is able to promote the detoxifica-tion of ammonia by stimulating disrupted urea and gluta-mine synthesis (Figure 5.1)

Urea synthesis is an irreversible liver-specific process,which takes place primarily in the periportal hepato-cytes. Ornithine activates the enzyme carbamyl phos-phate synthetase necessary for this process. Since orni-

Stimulation of the urea cycle andglutamine productionin the liver

5 MECHANISM OF ACTION AND PHARMACODYNAMICS OF HEPA-MERZ®

59

MitochondrionMitochondrion

Periportal hepatocytes

CytosolCytosol

Glutamine synthetase

Ornithine

Perivenous hepatocytes

Glutamine

Glutamine Glutamine

Glutamine

α-Keto-glutarate

Urea

Urea

Glutaminase

Malate

α-Ketoglutarate, Aspartate

Carbamyl-phosphatesynthetase

Figure 5.1: Effects of L-ornithine-L-aspartate on urea and glutamine synthesis

Summary:Treatment of hepatic encephalopathy includes intervening in the knownpathomechanisms. This includes the exclusion of precipitating factorsand correction of the dietary deficiencies that frequently exist. Pharma-cotherapy aims principally to reduce the ammonia production, promoteammonia detoxification, correct amino acid imbalance and counteractneurodepression. In recent years – for reasons of quality assurance andcost reduction – the requirements of evidence-based medicine havecome to the forefront of medical practice. Such evidence of efficacydefinitely exists for L-ornithine-L-aspartate.

Further studies are in the planning stage and will be carried out with the aim of meeting the criteria of evi-dence-based medicine for the treatment of hepaticencephalopathy.


61

Through increased glutamine formation, the therapeuticadministration of L-ornithine-L-aspartate (Hepa-Merz®)also leads to an increase in ammonia detoxification inthe brain and muscles. This mechanism is of particularimportance where there is a marked collateral circula-tion or acute liver failure, when detoxification in the liveris reduced or temporarily ceases.

thine also acts as a substrate in urea synthesis, it isinvolved in the activation of the urea cycle in severalways and thus in the irreversible (final) ammonia detoxi-fication.

Aspartate and ornithine likewise support glutamine syn-thesis. Glutamine synthesis (addition of ammonia toglutamate) is localized to the perivenous hepatocytes.The prerequisite for this reaction is a sufficiently largesupply of glutamate. As has recently been shown,aspartate (via α-ketoglutarate), glutamate and otherdicarboxylates are taken up almost exclusively by peri-venous cells. By making aspartate available (after itsconversion into dicarboxylates) L-ornithine-L-aspartatesupplies the perivenous cells with substrates for thesynthesis of glutamine. In this way, ammonia detoxifica-tion is increased through the formation of glutamine bythe action of glutamine synthetase (Häussinger, 1990;Stoll and Häussinger, 1989; Häussinger et al., 1990;Stoll et al., 1991; Stoll and Häussinger, 1991).

Reversible detoxification of ammonia via glutamine syn-thesis in the liver, brain and muscles (see section 1.1) isalso increased by L-ornithine-L-aspartate.

Stimulation of ammo-nia detoxification byglutamine synthesis

60

Effects of ornithine on the urea cycle:- substrate for urea synthesis- activator of carbamyl phosphate synthetase

Summary:The therapeutic administration of L-ornithine-L-aspartate (Hepa-Merz®)increases ammonia detoxification in two ways:• Activation of the urea cycle in the liver by making available the meta-

bolic substrates ornithine and aspartate. • The substrates ornithine and aspartate promote the formation of

glutamate and thus stimulate ammonia detoxification via glutaminesynthesis in the liver, brain and muscles.

Ammonia detoxification via glutamine synthesis in the brain and muscletissue makes an additional contribution to the ammonia reducing effectsof L-ornithine-L-aspartate in cases of hyperammonaemia when detoxifi-cation in the liver is by-passed or temporarily ceases.

Effects of aspartate on glutamine synthesis:- substrate for glutamine formation


The administration of L-ornithine-L-aspartate signifi-cantly increased the activity of these two enzymes by30% and 40% respectively, reaching almost normallevels. At the same time, there was a significant increasein the urea concentration of about 34%. The fall in theammonia concentration was also significant (Figure 5.2).

Examination of hepatocyte cultures from the twogroups showed a higher urea production in the hepato-cytes from L-ornithine-L-aspartate-treated rats in com-parison with the untreated cirrhotic rats. It can be con-cluded from these results that treatment of cirrhotic ratswith L-ornithine-L-aspartate increases urea synthesisand thus the capacity to detoxify ammonia.

63

5.2 Pharmacodynamic effects inanimal experiments

5.2.1 Effects of Hepa-Merz® onammonia metabolism

The effects of L-ornithine-L-aspartate on ammoniametabolism have been investigated in many experimen-tal animal studies. Parameters such as the protectiveeffect against liver damage (induced by carbon tetra-chloride, ammonium acetate or ammonium chloride),reduction in ammonia levels and increase in urea syn-thesis have been tested in various animal models(mouse, rat, rabbit, dog) (Greenstein et al, 1956; Salva-tore et al., 1959; Salvatore and Bocchini, 1961; Shioyaet al., 1964; Salvatore et al., 1964; Grossi et al., 1967;Zicha and Zicha, 1968; Hermann, 1972; Zieve et al.,1986). As well as L-ornithine-L-aspartate, the individualcomponents and other amino acids have sometimesbeen tested to compare their effects. In these studies,ammonia metabolism tended towards normal and therewas a reduction in the ammonia toxicity on treatmentwith L-ornithine-L-aspartate.

In a more recent study, the effects of L-ornithine-L-aspartate on hyperammonaemia and urea metabo-lism in cirrhotic rats were investigated (Gebhardt et al.,1997). Cirrhosis was induced by carbon tetrachloride(CCl4). In cirrhotic animals, the activities of carbamylphosphate synthetase and arginase were lowered, indi-cating reduced functioning of the urea cycle.

Experimental animalstudies on ammonia

metabolism

Activation of ureacycle enzymes by

L-ornithine-L-aspartate

62

8

7

6

5

4

3C OA C

Urea Ammonia

Urea

(µM

)

Amm

onia (µM)

OA

800

600

400

200

0

∗∗

∗

Figure 5.2: Serum concentrations of urea and ammonia in cirrhoticrats without (pink column) and with L-ornithine-L-aspartate (redcolumn). Mean ± SEM given for each group; differences betweentest animals and untreated controls are significant at *p<0.03 and**p<0.004 (after Gebhardt et al., 1997)


effects of L-ornithine-L-aspartate on cerebral metabo-lism (in-vivo measurement of ammonia). In-vivo mea-surements were carried out by proton magnetic reso-nance spectroscopy (proton MRS) with specialapplication and analysis procedures. This methoddemonstrated a reduction in the ammonia with theadministration of L-ornithine-L-aspartate, as well as asmaller rise in lactate and a slower increase in glutaminein comparison with controls. All changes were statisti-cally significant. Even though the increase in glutamineand lactate in the brain in hyperammonaemia is well-known, it was not previously possible to investigate thisin vivo. For the first time, these results demonstrated invivo metabolic changes in the brain providing evidenceof the protective effects of L-ornithine-L-aspartate inhyperammonaemia.

The uptake of radioactively-labelled ornithine andaspartate into the brain was investigated in a differentanimal model (Albrecht et al., 1994). Acute hepaticencephalopathy was induced in rats by hepatotoxicthioacetamide. Substance uptake was given by the brainuptake index (BUI) calculated from the radioactivitymeasured and administered. The BUI was investigatedin three stages: a coma stage (3 administrations ofthioacetamide) a milder stage (2 administrations) and agroup with induced hyperammonaemia (ammoniumacetate) without liver damage. In the coma group, theBUI for ornithine increased after 24 hours to 275% ofcontrol levels and milder stages, to 220% of controllevels after 7 days and 442% after 21 days (each sig-nificant at p<0.05).

In-vivo measurementof ammonia in the

brain

Transport of ornithineinto the brain

65

5.2.2 Effects of Hepa-Merz® onmetabolism in the brain

To elucidate its mechanism of action, L-ornithine-L-aspartate was administered to rats with portocavalshunts and hyperammonaemia induced by ammoniumacetate infusion (Vogels et al., 1995). This is a valid ani-mal model of hepatic encephalopathy in subacute liverfailure. In comparison with controls, significantly lowerammonia concentrations were measured in the blood(322 ± 40 vs 500 ± 32 mM, p<0.01) and in the brain(2.06 ± 0.2 vs 2.73 mM, p<0.05) following administra-tion of L-ornithine-L-aspartate. Lowering of serumammonia levels could be attributed to the significantlyhigher urea synthesis in animals treated with L-ornithine-L-aspartate. In this group, glutamine and glutamate inthe blood (signs of increased glutamine synthesis) weresignificantly higher than in the control group. In thecerebral dialysate, glutamate was significantly increasedwhile glutamine showed a trend towards higher levels.Both in the blood and brain the ratio between branched-chain amino acids and aromatic amino acids(BCAA/AAA) tended towards normal, mainly due to thereduction of aromatic amino acids. With respect to thecriteria for encephalopathy (EEG, clinical grading) thesewere less pronounced on treatment with L-ornithine-L-aspartate, although the differences did not reach sta-tistical significance.

A further study carried out by Slotboom et al. (1994) inthe same animal model reported on the additional

Reduced NH3- con-centration and over-

coming amino acidimbalance in the brain

64


relevant changes for lysine. From these study results,the authors concluded that the transport system acrossthe blood-brain barrier is modified by as yet unidentifiedfactors, possibly released by the damaged liver. The g+transporter which normally gives preference to argininemay change in structure or conformation to preferen-tially transport ornithine, or a normally latent ornithine-specific transport system is activated.

The protective effects of L-ornithine-L-aspartate andthe possible mechanism of action were investigated inrats with portocaval shunts and hyperammonaemiainduced by ammonium acetate infusion (Rose et al.,1998). It was shown that L-ornithine-L-aspartate infu-sions could prevent ammonium acetate-induced comain all animals. None of the rats treated with L-ornithine-L-aspartate showed any deterioration of neurologicalstatus under these conditions although all the non-treated animals did.

These protective effects of L-ornithine-L-aspartate wereassociated with a smaller rise in ammonia levels in theblood and an increase in the urea concentration(p<0.01 and p<0.05 vs controls). In both plasma andcerebrospinal fluid (CSF), concentrations of glutamateand glutamine were significantly higher than in the con-trol animals. The branched-chain amino acids were higher in the plasma than in the control group, but onlyleucine was higher in the CSF.

These results show the protective effects of L-ornithine-L-aspartate with respect to hyperammonaemia-inducedcoma. The mechanism of action consists on the one hand

Coma-protectiveeffects through stimulation of centraland peripheral ammo-nia detoxification

67

Induced hyperammonaemia did not lead to increaseduptake of ornithine into the brain.

Aspartate is not normally transported across the blood-brain barrier. The BUI for L-aspartate did not increase inany of the three stages, an indication that the blood-brain barrier remains intact in this animal model.

It can be concluded from the results of this study thatornithine administered therapeutically in the form of L-ornithine-L-aspartate is taken up into the brain in casesof hepatic encephalopathy, probably through activationof the transport system across the blood-brain barrier.

Using the same animal model (hepatic encephalopathyinduced by 2 doses of thioacetamide), this researchgroup conducted a further study to investigate thetransport system for ornithine across the blood-brainbarrier in more detail (Albrecht et al., 1996). Ornithinepasses across the blood-brain barrier in the same wayas the other two dibasic amino acids, arginine and ly-sine, via a common saturatable transport system (g+transporter). The objective of the study was to deter-mine whether the BUIs of radioactively-labelled orni-thine, arginine and lysine were different in this model of hepatic encephalopathy.

The BUI for ornithine increased to 186% after 7 daysand to 345% after 21 days in comparison with theuntreated controls (p<0.05 vs controls in both cases).The corresponding values for arginine were 30% and42%, respectively (p<0.05 vs controls in both cases),i.e. transport into the brain decreased. There were no

Transport system forornithine and arginine

across the blood-brain barrier

66


69

Coma appeared in the control groups after about 11hours but not until 15 hours with L-ornithine-L-aspartateinfusions (p<0.02). The water content of brain tissuewas significantly less in the L-ornithine-L-aspartate-treated animals than those given saline infusions andapproached levels in the control animals (Figure 5.4).

The observed protective effects of L-ornithine-L-aspar-tate were accompanied by increased plasma concen-trations of glutamate, γ−aminobutyric acid (GABA), tau-rine and alanine as well as the branched-chain aminoacids leucine, isoleucine and valine. Increased gluta-mate concentrations deliver the substrate for ammoniadetoxification via glutamine synthesis. In agreement

of peripheral stimulation of urea and glutamine synthesisand increased central glutamine synthesis on the other.

In acute liver failure (ALF) the development of cerebraloedema with raised intracranial pressure and cerebralherniation are the most important causes of death. Theeffects of L-ornithine-L-aspartate were tested in an ani-mal model of acute liver failure, induced by hepaticdevascularisation (Rose et al., 1999). In this model,treatment with L-ornithine-L-aspartate infusions led toplasma ammonia concentrations approaching normal incomparison with controls (Figure 5.3). The appearanceof signs of severe encephalopathy – defined as pre-coma and coma, in accordance with the degree ofseverity – were significantly delayed.

Protective effects of Hepa-Merz® incerebral oedema

68

700

600

500

400

300

200

100

0Baseline +6 hours Pre-coma Coma

Amm

onia

con

cent

ratio

n in

pla

sma

(µg/

dl)

*

* ** *

Administration of OAor saline

L-ornithine-L-aspartate infusionSaline infusion

83,0

82,5

82,0

81,5

81,0

80,5

80,0

79,5

79,0Controls ALF

salineinfusion

ALFOA

infusion

% w

ater

in b

rain

tiss

ue

p < 0.05

p < 0.001 p < 0.001

Figure 5.3: Effects of L-ornithine-L-aspartate infusions on the plas-ma ammonia concentration in comparison with controls given sa-line infusions in a model of acute liver failure with encephalopathy.The first measurement after baseline was taken 6 hours after liga-tion of the hepatic artery. The stages of pre-coma and coma weredefined on the basis of the neurological status. The means ± SE areshown for each group. Differences between the groups are statisti-cally significant at *p<0.05 and **p<0.01 (after Rose et al., 1999)

Figure 5.4: Effects of L-ornithine-L-aspartate (OA) infusions on thewater content of the brain tissue in comparison with normal controlsand animals given saline infusions in a model of acute liver failure(ALF) with encephalopathy. The individual values are shown withmeans (horizontal lines) for each group as well as the differencesbetween the groups (p<0.01, p<0.05) (after Rose et al. 1999)


7170

with this, glutamine in the plasma was significantly rais-ed (p<0.02), indicating increased glutamine synthesis inthe muscles. Also in agreement, direct measurement ofglutamine synthetase in the muscle showed that theactivity of this enzyme was doubled in animals treatedwith L-ornithine-L-aspartate. In this animal model ofacute liver failure, increased glutamate concentrationscan regularly be demonstrated in the extracellular fluidof the brain. It is therefore assumed that this contributesto the development of cerebral oedema in acute liverfailure. Lowering of the CSF glutamate levels by 60% asseen in this experiment and the concurrent reduction inwater content support this hypothesis. Glutamine in theCSF remains virtually unchanged.

Results in animal models of acute liver failure with en-cephalopathy show the ammonia-lowering effects of L-ornithine-L-aspartate together with a protective effectagainst the development of cerebral oedema and ence-phalopathy. Lowering of the ammonia can be attributedto increased ammonia detoxification through stimula-tion of glutamine synthesis in the muscles.

Summary: Results of animal experiments carried out in models of the various formsof encephalopathy in hyperammonaemia and acute liver failure show theprotective effects of L-ornithine-L-aspartate with respect to hyperam-monaemia and encephalopathy. Various methods have shown themechanisms of action to be the lowering of the ammonia concentrationsin the blood and brain. The reasons for this are increased urea synthesisin the liver and stimulation of glutamine synthesis which has beendemonstrated in the muscle and sometimes also in the brain. Transportof ornithine across the blood-brain barrier has been demonstrated. Orni-thine contributes to the observed therapeutic effects possibly by thepromotion of glutamate formation in the brain.


7372

6 CLINICAL RESULTS WITH HEPA-MERZ®

Experimental cl in ical studies

Authors Study design Duration- No. of Aetiology of Test drug/placebo Efficacy of L-ornithine-L-aspartateof study patients hyperammonaemia or control

Henglein-Ottermann 1976

Leweling et al. 1991

Reynolds et al. 1999

Rees et al. 2000

Delcker et al. 2002

Rd pc crossover,intra-individualRd db pc crossoverdesignRd pc

Rd pc

Open

90 min

8 h

7 days

60 min

24 h

20

10

16

8

15

Cirrhosis; administration of anNH4Cl infusion

Cirrhosis; induction of hyperammonaemia by protein consumptionCirrhosis

Cirrhosis, oral glutamine load (20 g)

CirrhosisHE I, II

OA i.v. (5 g/h) vs 10% sorbitol(placebo)

OA i.v. (5, 20, 40 g/day) vs 0.9% NaCl (placebo)

OA i.v. (40 g/8h) vs placebo

OA i.v. (5 g/h) vs placebo

OA i.v. (40 g/8h)

- ammonia-lowering effect

- dose-dependent reduction of ammonia in blood, increase in BCAA/AAA ratio

- increased rate of protein synthesis in muscle after meals- inhibition of catabolic metabolism in muscles

- suppression of expected rise in ammonia - stabilization of psychometric functions

- decrease in arterial NH3 concentration and in glutamate + glutamine/creatine ratios

- close correlation of both parameters

Cl inical Tr ia ls with intravenous L-orni thine-L-aspartate


Kircheis et al. 1997

Feher et al. 1997

Rd db pc

Rd pc db

7 days

7 days

126

80

Cirrhosis

Cirrhosis

OA i.v. (20 g/day) vs 5% fructose (placebo)

OA i.v. (20 g/4h) vs placebo

- improvement of mental function- reduction in time required for NCT - ammonia-lowering effect- reduction in ammonia levels

Cl inical Tr ia ls with oral L-orni thine-L-aspartate


Stauch et al. 1998

Liehr et al. 1992

Rd db pc

Rd controlled

14 days

14 days

66

42

Cirrhosis

Cirrhosis

OA oral (3x 6 g/day)vs placebo

OA oral (3x 9 g/day)vs lactulose oral (3x 30 ml)

- improvement of mental function- reduction in time required for NCT - ammonia-lowering effect- effects of OA and lactulose with respect to improvement

of mental function- reduction in time required for NCT and lowering of ammonia

Table 6.1: Controlled clinical trials with Hepa-Merz®(L-ornithine-L-aspartate, OA) in patients with Rd: randomised; db: double-blind; pc: placebo-controlled hyperammonaemia and hepatic encephalopathy


74

clinical practice (GCP) etc. In this way the requirementsfor evidence-based medicine (see section 4.3) are alsoclearly met for treatment with Hepa-Merz® (L-ornithine-L-aspartate).

6.2 Experimental clinical studieswith Hepa-Merz®

6.2.1 Effects of Hepa-Merz® onammonia concentration

From a very early stage, measurement of the ammoniaconcentration has been included in clinical studies as akey feature of the mechanism of action. Changes in theammonia concentrations on treatment with L-ornithine-L-aspartate were closely related to the clinical thera-peutic efficacy (Schmitt and Ziegler, 1970; Leonhardtand Bungert, 1972; Müting and Reikowski, 1980,Müting et al., 1992). In the majority of the more recentclinical studies, the ammonia concentration was alsodetermined, that is to say, was one of the main out-come measures. In the following controlled experimen-tal clinical studies, various aspects of the effects of L-ornithine-L-aspartate on hyperammonaemia wereinvestigated.

In a controlled clinical study, ammonia concentrations invenous blood were investigated after hyperammon-aemia had been experimentally induced in patients withcirrhosis and in healthy volunteers, with and without theadministration of L-ornithine-L-aspartate (Henglein-Ottermann, 1976). For this purpose, hyperammon-aemia was induced in 10 patients with cirrhosis and 10

Ammonia concentrations in clinical studies with Hepa-Merz®

75

6.1 Clinical research with Hepa-Merz®

The clinical efficacy of Hepa-Merz® (L-ornithine-L-aspartate) in liver diseases has already been compre-hensively investigated and reported in therapeuticobservations and clinical trials (Kalk, 1958; Kosozu1966; Schäfer, 1968; Aschke,1969; Melzer et al., 1969;Vorberg, 1969; Baumann, 1970; Schmitt and Ziegler,1970; Wotzka and Weber, 1972; Leonhardt and Bun-gert, 1972; Hunold, 1973; Schmidt, 1974; Müting andReikowski, 1980; Hendricks and Hellweg, 1984; Müller-Kengelbach, 1986; Müting et al., 1988; Handschuh,1990; Müting et al., 1992; Podymova and Nadinskaya,1998). In these studies the use of Hepa-Merz®, as infu-sion, oral administration or a combination of the two,was documented in patients with mild to severe liverinsufficiency. The underlying cause of hepatic dysfunc-tion was most often cirrhosis, although patients withother liver diseases were also treated. The documentedduration of the studies ranged from a few days to sev-eral years.

In the past few years, clinical trials on the efficacy andtolerability of Hepa-Merz® (L-ornithine-L-aspartate)have been conducted in accordance with generalmethodological advances in clinical research and evi-dence-based medicine (see sections 6.3 and 6.4).These include, in particular, criteria such as placebocontrols, double blind conditions, randomized alloca-tion to treatment arms, sufficient numbers of patientsaccording to estimates of the number of cases requir-ed, conduction of the trial in accordance with good

Clinical research withHepa-Merz® and evidence-based

medicine

Controlled clinicalstudies with experimental hyperammonaemia


7776

study with a four-way crossover design (Lewling et al,1991, Staedt et al., 1993). Ten patients with cirrhosis ofthe liver and hyperammonaemia (postprandial >120µg/dl) each underwent four test procedures in varyingorder. An 8-hour infusion containing 5 g, 20 g or 40 g ofL-ornithine-L-aspartate or placebo was given duringeach treatment unit, so that, by the end of the study,data were available for analysis from each patient ateach of the four doses. Two protein loads were given oneach study day, similar to normal dietary habits: 0.25g/kg body weight in the mornings and 0.5 g/kg bodyweight at lunchtime.

healthy volunteers by giving them ammonium chlorideinfusions (40 mg/kg body weight over 60 minutes) andload-response curves were plotted from the blood sam-ples taken over a total of 2 hours. As expected, theconcentrations in cirrhotic patients were statistically sig-nificantly higher at all times than in the healthy test sub-jects (peak levels in each case were reached 60 mi-nutes after the start of the infusion). The infusion wasrepeated on another day in the study, but this time withthe additional administration of 5 mg L-ornithine-L-aspartate (randomized test sequence). This showedthat the higher peak ammonia concentrations mea-sured in the cirrhotic patients after 60 minutes could besignificantly reduced by the administration of L-ornithine-L-aspartate (p≤0.05) so that the overall load-responsecurve was flatter. As expected, administration of L-ornithine-L-aspartate made no difference to theammonia concentrations in people with healthy livers(Figure 6.1).

Ammonia loading demonstrated the reduced detoxifica-tion ability of the cirrhotic liver though an – in contrast tothe healthy liver – overall higher concentration of am-monia in the blood with a more prolonged duration,which could be significantly lowered by the administra-tion of L-ornithine-L-aspartate, especially the peakvalues.

The dose-effect relationships of L-ornithine-L-aspartateto the physiological postprandial hyperammonaemiaand the amino acid profile in the plasma were investi-gated in a randomized double-blind, placebo-controlled

800

600

400

200

0

NH4 (µg/dl) ✱ p < 0.05 x ± SEM

✱

0 30 50 60 70 90 120

Time (min) after the NH4CI infusion

L-ornithine-L-aspartate (5 g/h)NH4CI infusion (40 mg/kg BW)

NH4CI NH4CI + OA

+

Figure 6.1: Effects of Hepa-Merz® on the hyperammonaemia induc-ed by ammonium chloride infusion (40 mg NH4Cl/kg BW) inpatients with cirrhosis of the liver

Lowering of ammonia in patients with

cirrhosis

Dose-dependenteffects on postprandi-al hyperammonaemia


7978

with L-ornithine-L-aspartate than with placebo; with adose of 40 g, the difference in peak levels at 11 o’ clockwas statistically significant. The analysis also showedthat, compared with placebo, L-ornithine-L-aspartatecaused a significant rise in serum urea, a sign of increas-ed ammonia detoxification.

The amino acids alanine, arginine, glutamate, glutamineand proline which are metabolically linked to the met-abolism of ornithine and aspartate, increased markedlyunder the administration of L-ornithine-L-aspartate,sometimes in a statistically significant manner whencompared with placebo. On the other hand, the aminoacids methionine, phenylalanine, tyrosine, threonine,serine and glycine were reduced in a dose-dependentmanner. The reduction in these amino acids, which arenot metabolically closely associated with L-ornithine-L-aspartate, may be interpreted as peripheral retention(decreased release or increased uptake in the periphery).The authors discuss the effects as an indication of theimprovement in protein equilibrium and an anticataboliceffect of L-ornithine-L-aspartate in muscle tissue as acontribution to the observed lowering of ammonia.A supplementary evaluation of the study data (Staedt etal., 1993) quantified the relationship of branched-chainamino acids (BCAA) to aromatic amino acids (AAA). Inpatients with cirrhosis, there is often a shift in the equilib-rium between these two groups, in favour of the aro-matic amino acids (see section 2.2.3). After protein load-ing, the mean BCAA/AAA quotient under placebo clearlyfell from 1.6 to 1.2. With the administration of L-ornithine-L-aspartate (40 g), however, the quotientwas increased from 1.4 to 1.5. This result is a sign that

Analysis of the ammonia concentration from venousblood showed that, in comparison with placebo, post-prandial hyperammonaemia was lowered by the admin-istration of L-ornithine-L-aspartate in a dose-dependentmanner, and with the highest dose it was almost pre-vented (Figure 6.2). All postprandial values were lower

400

350

300

250

200

150

100

✱ p < at 9:00

NH4 (µg/dl) ✱ ✱ p < at 9:00

➨

9 11 13 hours

400

350

300

250

200

150

100

✱ p < at 13:00

NH4 (µg/dl) ✱ ✱ p < at 13:00

➨

13 15 17 hours

✱

✱

Placebo OA (40g)OA (20g)OA (5g)

+ +

✱ ✱

✱ ✱

✱

✱ ✱

Protein load (0,25 g/kg BW)

Protein load (0,5 g/kg BW)

Figure 6.2: Venous ammonia concentrations (median ± SEM) with infusions of Hepa-Merz® at doses of5 g, 20 g and 40 g and placebo, with protein loading at 9:00 and 13:00 hours. Postprandial hyperam-monaemia (significant increases at 11:00 and 15:00 on placebo) were prevented at 15:00 with 20 gand at 11:00 and 15:00 with 40g L-ornithine-L-aspartate. Peak values measured at 11:00 with 40 g OAwere significantly lower than with placebo (after Staedt et al., 1993)

Amino acid profile andperipheral metabolism


8180

However the increase seen on treatment with L-ornithine-L-aspartate was significantly less than with placebo(Figure 6.3).

Parallel to the inhibition of the ammonia increase afterprotein loading, the administration of L-ornithine-L-aspartate stabilized psychometric functions. Whilethe reaction time to a visual stimulus (choice reactiontime, CRT) was significantly prolonged after a proteinload and placebo, there was no prolongation of reactiontime when L-ornithine-L-aspartate was administered(Figure 6.4).

The results of these controlled clinical studies show thatthe administration of L-ornithine-L-aspartate counter-acts metabolic disturbance after a protein meal inpatients with cirrhosis and, in parallel to this, thepsychometric functions remain stable.

Increase in ammoniaand reaction times

after protein loading,compared with

placebo

the amino acid imbalance tends towards normal ontreatment with L-ornithine-L-aspartate.

The results of these controlled studies demonstratedthat the effects L-ornithine-L-aspartate on postprandialhyperammonaemia are dose-dependent. In addition,they showed that L-ornithine-L-aspartate causes chang-es in the amino acid profile that can be interpreted asanticatabolic actions, as well as having a positive effecton the preexisting imbalance between branched-chainand aromatic amino acids found in patients with cir-rhosis.

With hepatic insufficiency, the ammonia concentrationin the blood rises to unphysiological levels after a pro-tein meal. A controlled clinical study was carried out toinvestigate whether, due to its specific effects, theadministration of L-ornithine-L-aspartate protectedagainst a rise in ammonia after protein loading and, asa result, had a positive effect on psychometricallymeasurable functional deficiencies (Rees et al., 2000).Eight patients with cirrhosis of the liver were each subjected to two loading tests with 20 g glutamine. Inrandomized sequence, either 5 g L-ornithine-L-aspartateor placebo was infused concurrently. Ammonia concentrations in the blood were determined beforeand after the glutamine load and psychometric testsperformed at the same time.

As expected, the glutamine load caused an increase invenous ammonia, the baseline being 27 ± 5 µmol(mean ± SEM).

100

80

60

40

20

0

L-ornithin-L-aspartate Placebo

36 µmol/l

62 µmol/l

Amm

onia

µm

ol/l

Figure 6.3: Venous ammonia concentration after protein loading (20 g glutamine) on treatment with Hepa-Merz® (left) and placebo(right) in patients with cirrhosis of the liver. Figures shown are themean values (after Rees et al., 2000)


8382

the start of treatment and 7 days afterwards, the proteinsynthesis rate in muscle was tested both in a fastingstate and after the ingestion of food, using a specialprocedure (leucine incorporation). The results of thestudy showed a return to the normal response on L-ornithine-L-aspartate, with a significant increase inthe protein synthesis rate in muscle after the ingestionof food from 0.044 ± 0.009 to 0.071 ± 0.022% per hour(mean ± SEM, p=0.06). In contrast, there were nochanges on placebo treatment. Under fasting condi-tions, the protein synthesis rate in muscle was furtherreduced on placebo while it stabilized on L-ornithine-L-aspartate (Figure 6.5 and Table 6.2).

6.2.2 Effects of Hepa-Merz® onprotein synthesis in muscle

Muscle wasting is a characteristic symptom in cirrhosisof the liver and is, as a rule, associated with an unfa-vourable prognosis. In people with healthy livers, therate of protein synthesis in muscle tissue rises after theintake of food, whereas this increase is lacking orreduced in cirrhotic patients. A controlled clinical study (Reynolds et al., 1999) was carried out to investigatewhether, because of its favourable effects on the metab-olism of ammonia and amino acid equilibrium, L-orni-thine-L-aspartate also beneficially influenced proteinmetabolism. Sixteen patients with cirrhosis of the liverand muscle wasting were randomized to infusions of 40 g L-ornithine-L-aspartate or placebo for 7 days. Prior to

450

400

350

300before after before

L-ornithine-L-aspartate Placebo

glutamine load glutamine load

Reac

tiont

ime

in m

s

after

406 404390

416

Figure 6.4: Reaction time in choice reaction test (CRT) before andafter protein loading (20 g glutamine) on Hepa-Merz® (left) or pla-cebo (right) in patients with cirrhosis of the liver. Figures shown arethe mean values (after Rees et al., 2000)

Protein synthesis rate in muscle in comparison with

placebo

Tab. 6.2: Protein synthesis rate (%/h) in muscle of cirrhotic patients;means (SEM) *p=0,06

Fig. 6.5: Representation of the values from Tab. 6.2 as the differencebetween day 1 and day 7

% / h

0,03

0,025

0,02

0,015

0,1

0,005

0

-0,005

-0,01

-0,015

L-ornithine-L-aspartate Placebo

fasting posprandial fasting posprandial

OA (fasting)OA (posprandial)Placebo (fasting)Placebo (posprandial)

-0,004

0,027

-0,012

0,003

Prot

ein

synt

hesi

s

OA group Placebo groupfasting after food fasting after food

Day 1 0.051 (0.015) 0.044 (0.009)* 0.047 (0.016) 0.046 (0.016)

Day 7 0.047 (0.015) 0.071 (0.022)* 0.035 (0.012) 0.049 (0.023)


85

given an infusion of 40 g L-ornithine-L-aspartate. Imme-diately before and 6 hours after the start of the infusion,MRS investigations were carried out in the parietalregion and at the same time, the arterial ammonia con-centration was determined.

It was shown that the ammonia concentration in arteri-al blood and the Glut+Gln/Cr ratio in the brain correlat-ed in a statistically significant manner (r = 0.72,p<0.001). Both parameters decreased with the infusionof L-ornithine-L-aspartate, and the extent of thesechanges also correlated in a statistically significantmanner (r = 0.54, p<0.04). Figure 6.7 shows NMRspectra before and after the infusion of Hepa-Merz®.

These results confirm that, in parallel to the reduction inammonia concentration, L-ornithine-L-aspartate has aneffect in reducing the glutamine and glutamate concen-trations in the brain. At the same time, this investigationpresents a new parameter for clinical studies on hepatic

The results can be interpreted as the inhibition of catabolicmuscle metabolism and stimulation of protein synthesis inthe muscle due to L-ornithine-L-aspartate.

6.2.3 Effects of Hepa-Merz® onneurometabolites

Neurometabolites in the brain can be demonstrated in vivousing proton magnetic resonance spectroscopy (protonMRS) (Delcker et al., 2002). The typical changes seen inhepatic encephalopathy relate in particular to the concen-tration of glutamine which is increased in the brain – possi-bly as a result of the increased ammonia in the blood andthe stimulation of glutamine synthesis in the astrocytes(Figure 6.6).

In an open study, it was investigated whether the ratioof glutamine + glutamate in relation to creatine(Glut+Gln/Cr) changed when L-ornithine-L-aspartatewas given, and whether this ratio correlated with thelowering of the ammonia concentration seen with L-ornithine-L-aspartate. With these objectives, fifteenpatients with grade I/II hepatic encephalopathy were

Ammonia and neurometabolites

in the brain

84

4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0

Glu Gln

Figure 6.6: Characteristic neurometabolite concentrations inpatients with hepatic encephalopathy

4.0 3.8 3.6 3.4 3.2 3.0 2.8 2.6 2.4 2.2 2.0 1.8 1.6 1.4 1.2 1.0

Glu + Gln

prior to ornithine aspartate infusion after ornithine aspartate infusion

Glu + Gln

4.0 3.8 3.6 3.4 3.2 3.0 2.8 2.6

ppmppm

2.4 2.2 2.0 1.8 1.6 1.4 1.2 1.0

Figure 6.7: Nuclear magnetic resonance spectra before and after Hepa-Merz® infusion. On the right a clearlowering of the glutamate and glutamine concentrations in the brain can be seen following the infusion


8786

parameters were the HE grade, the PSE index and thevenous ammonia concentration under fasting condi-tions.

The results of venous ammonia concentrations showedstatistically significant differences in favour of L-ornithine-L-aspartate (Figure 6.8). The mean values under fastingconditions before the start of treatment were 81 ± 38µmol/l in the L-ornithine-L-aspartate group and 83 ± 43µmol/l in the placebo group. After seven days they haddecreased on average by 17 ±37 µmol/l and 6 ± 32µmol/l, respectively (before/after comparison). Thegroup differences in favour of L-ornithine-L-aspartatetherapy were statistically significant after 4 and 7 days(p=0.0155 and p=0.0188). The mean postprandialammonia concentration of 83 ± 37 µmol/l initially mea-sured in the L-ornithine-L-aspartate group was lowerthan that of 91 ± 48 µmol/l in the placebo group. After7 days’ treatment the mean postprandial ammonia con-centrations had decreased by 16 ± 40 µmol/l and by 10± 36 µmol/l, respectively. The group differences infavour of L-ornithine-L-aspartate treatment were signifi-cant on days 2 and 4 (p<0.013) and showed a tenden-cy towards significance on day 7 (p=0.078).

Statistically significant group differences in the timerequired for the NCT-A were also seen in favour of L-ornithine-L-aspartate treatment (Figure 6.9).A sub-evaluation of the degree of severity of the hepat-ic encephalopathy showed that the group differenceswith grade II were the most pronounced, but were alsosignificant with subacute hepatic encephalopathy (SHE)and grade I. The mental state recorded on the basis of

Placebo-controlleddouble-blind trial on

126 patients with cirrhosis of the liver

and HE grade 0 (subclinical) to II

encephalopathy which can be used in vivo to deter-mine quantitative changes in neuro-metabolites in thebrain.

6.3 Clinical results with intra-venous Hepa-Merz® therapy

6.3.1 Hepa-Merz® infusion in comparison with placebo

A multicentre randomized double-blind placebo-con-trolled trial was carried out to demonstrate the efficacyand tolerability of L-ornithine-L-aspartate infusion con-centrate (Kircheis et al., 1997). One hundred and twen-ty-six patients with cirrhosis of the liver and chronic(persistent) overt hepatic encephalopathy (grades I/II,West Haven criteria) or subclinical hepatic encephalop-athy (SHE and performance time for number connec-tion test A >30 seconds) were enrolled. In addition, allpatients had to have demonstrable hyperammonaemia(venous ammonia concentration >50 µmol/l).

The patients were given daily in-patient treatment forseven days, receiving an infusion of 20 g L-ornithine-L-aspartate (4 ampoules infusion concentrate) dissolv-ed in 250 carrier solution over 4 hours (N=63), or a cor-responding placebo infusion (N=63). At the same timethey were given a diet containing 1 g protein/kg bodyweight per day divided into three meals. Investigationswere carried out before the start of treatment (time 0)and after 2, 4 and 7 days. The main efficacy parameterswere the postprandial venous ammonia concentrationand the time required for NCT-A. Further efficacy

Fasting and postprandial ammonia concentrations

Performance time for the number connection test

HE grading and PSE index


8988

the changes in the HE grade after 7 days’ treatmentwith L-ornithine-L-aspartate. With HE grade 0, a reduc-tion in the NCT performance time from the baselinevalue to <30 s was taken as evidence of improvement.L-ornithine-L-aspartate was clearly superior to placebo.

In addition, changes in the modified PSE index wereevaluated. HE grade, venous ammonia concentrationand NCT performance time were taken into account inthe calculation. The mean of the PSE index at the startof treatment was 0.28 ± 0.12 in both the L-ornithine-L-aspartate and the placebo groups. By the end oftreatment (day 7), it had fallen to 0.135 ± 0.10 in the L-ornithine-L-aspartate group and to 0.22 ± 0.14 onplacebo. Both the comparison of treatments on day 7

clinical criteria (HE grade) improved more clearly after 7days’ treatment with L-ornithine-L-aspartate (frommean 0.97 ± 0.53 to 0.42 ± 0.33) than on placebo (0.91± 0.48 to 0.72 ± 0.52). Statistical analysis showed sig-nificant differences between the groups (p<0.001) infavour of L-ornithine-L-aspartate. Figure 6.10 shows

160

140

120

100

80

60

40

20

0

Duration of treatment (in days)

0 2 4 0 2 4 77

Fast

ing

amm

onia

(µm

ol/l)

*** *****

***

*

*p < 0.05, **p > 0.01, ***p < 0.001

160

140

120

100

80

60

40

20

0


0 2 4 0 2 4 77

Post

pran

dial

am

mon

ia (µ

mol

/l)

**

*****

*p < 0.05, **p > 0.01, ***p < 0.001

Mean ± SD OA (P25 to P75)

Median Placebo (P25 to P75)

P 75

Mittelwert

Median

P 25

P 75Mittelwert

MedianP 25

Figure 6.8: Reduction in ammonia levels (µmol/l) over a period of 7days on treatment with L-ornithine-L-aspartate (left) versus placebo(right). Figures given are the mean (black square) and standard devia-tion, median (white square), 25th and 75th percentiles and the groupdifferences between the two treatments (after Kircheis et al., 1997)

100

80

60

40

20

0


0 2 4 0 2 4 77

NCT-

A (s

econ

ds)

*p < 0.05, **p > 0.01, ***p < 0.001

Mean ±SD OA (P25 bis P75)

Median Placebo (P25 bis P75)

P 75

Mittelwert

Median

P 25

***

**

*Figure 6.9: Effects of L-ornithine-L-aspartate (left) versus placebo(right) on the time required to perform the number connection test.Figures given are the mean (black square) and standard deviation,median (white square), 25th and 75th percentiles and the group dif-ferences between the two treatments (after Kircheis et al., 1997)


9190

• 1 patient was excluded before the start of the trialbecause of non-cooperation

Placebo group:• 1 patient with advancing cardiac failure

In the three patients (5%) with gastrointestinal symp-toms or nausea/vomiting, a causal relationship with theL-ornithine-L-aspartate infusion cannot be ruled out.

The results of the double-blind trial show the efficacy ofL-ornithine-L-aspartate in comparison with placebowith respect to the mental state, the ammonia concen-tration and the performance time for the NCT-A. Theproduct was predominantly well tolerated without caus-ing any serious adverse reactions.

A further multicentre, randomized double-blind trial hasalso been carried out with placebo control (Feher et al.,1997). In this study, 80 patients with alcohol-inducedcirrhosis of the liver and established hyperammon-aemia (defined as >50 µmol/l) were enrolled. Over 7days, the patients received either a four-hour infusionof 20 g L-ornithine-L-aspartate in 250 ml saline solu-tion (N=40) or physiological saline (N=40). Investiga-tions were carried out after 3, 5 and 7 days. Theammonia concentration was measured in the morn-ings, in the fasting state. Clinical symptoms and signswere also recorded.

At the start of the study, mean venous ammonia con-centrations were comparable, at 77 µmol/l in the L-ornithine-L-aspartate group and 82 µmol/l in the pla-cebo group. During the course of treatment, the mean

and the before/after comparison between the groupsshowed statistically significant differences in favour of L-ornithine-L-aspartate (p=0.0011 and p=0.0003,respectively).

Infusion therapy was well tolerated by 88% of thepatients in the L-ornithine-L-aspartate groups and100% of the patients given placebo. Adverse eventswith shortened duration of treatment occurred in 7patients:

L-ornithine-L-aspartate group:• 3 patients with gastrointestinal symptoms (nausea/

vomiting)• 1 patient with an acute abdomen due to a

perforated ulcer• 1 patient who developed hepatorenal syndrome

N

40

35

30

25

20

15

10

5

0


Placebo

Patie

nts

with

impr

ovem

ent i

n HE

gra

de

Overall HEgrade II

HEgrade I

SHE

37

20

9

2

19

129

6

Figure 6.10: Number of patients with improvement in the HE gradeafter 7 days’ treatment with L-ornithine-L-aspartate or placebo inthe various subgroups (SHE = subclinical hepatic encephalopathy)(after Kircheis et al., 1997)

Safety and tolerability

Placebo-controlleddouble-blind trial on 80 patients with cirrhosis of the liverand hyperammonaemia


93

L-aspartate group and 28 in the placebo group. Thenumber of patients who showed no improvement wasclearly higher in the placebo group (12 vs 7). The over-all assessment of tolerability showed that L-ornithine-L-aspartate was predominantly well or satisfactorilytolerated, and poorly tolerated in only 3 cases. Noadverse effects were seen in either treatment group. The results of this placebo-controlled trial once againconfirm the efficacy of Hepa-Merz® in patients with cir-rhosis of the liver and raised ammonia concentrations,as well as its good tolerability

6.3.2 Meta-analysis of placebo-controlled trials

In the context of a meta-analysis, a quantitative system-ic overview of randomized placebo-controlled clinicaltrials with L-ornithine-L-aspartate infusion concentratewas carried out to investigate treatment effects (Delcker et al., 2000). The data analysis was conduct-ed in accordance with the QUORUM statement on thequality of reports for meta-analyses (Moher et al.,1999). Blinded individual data on 246 patients from fiverandomized controlled clinical trials formed the basis ofthe evaluation. Two of these trials had already beenpublished and biometric final reports were available forthe other three.

In all five trials, patients with hepatic encephalopathy asa complication of cirrhosis of the liver were treated witheither L-ornithine-L-aspartate infusion concentrate orplacebo over a period of 7 days. The mental state (HE

values sank by 32% (to 52 µmol/l after 7 days) on L-ornithine-L-aspartate and by 15% (to 70 µmol/l after 7days) on placebo. On treatment with L-ornithine-L-aspar-tate, the mean ammonia concentration fell almost to theupper limit of normal. The difference between the testgroup and placebo was statistically significant (p<0.05).

Evaluation of relevant clinical symptoms showed adecrease for all criteria in both treatment groups. Al-though this was more pronounced in the OA group, itdid not reach statistical significance because of theincreased number of cases. There was, however, atrend towards a clear reduction in the patient numbersin the L-ornithine-L-aspartate (LOLA) group in compari-son with placebo (Table 6.3).

At the end of treatment, an overall assessment of ther-apeutic success was made by the physician. Clinicalimprovements were seen in 33 patients in the L-ornithine-

92

LOLA LOLA Placebo Placebobefore after before after

Fatigue 21 10 27 17

Feeling of fullness 19 14 22 16

Gastrointestinal 16 6 17 6

symptoms

Nausea 15 4 7 5

Loss of appetite 22 11 22 13

Jaundice 21 14 25 19

Foetor hepaticus 9 5 11 9

Ascites 21 20 21 18

Pruritus 4 2 7 5

Table 6.3: Number of patients with clinical symptoms or signs be-fore and after 7 days’ treatment with Hepa-Merz® or placebo (afterFeher et al., 1997)

Overall assessment oftherapeutic success

Meta-analysis of randomized placebo-controlled clinical trials with L-ornithine-L-aspartate infusionconcentrate


9594

ence between treatments after 7 days was statisticallysignificant with p=0.015.

L-ornithine-L-aspartate was predominantly well tolerat-ed. Documented adverse effects were restricted tonausea, vomiting and fatigue.

grade), the number connection test A (NCT-A) perfor-mance time and the venous ammonia concentrationswere used for the analysis of efficacy.

With respect to the mental state of the patients, therewas a significant improvement on L-ornithine-L-aspar-tate in comparison with placebo after 7 days’ treatment.The odds ratio was 3.22 with a 95% confidence inter-val of 1.38 to 7.55 (p<0.01).

The performance time for the number connection testwas more clearly reduced on L-ornithine-L-aspartatetreatment than with placebo (Figure 6.11). The differ-ence between treatments after 7 days was statistically significant at p<0.001.

The venous postprandial ammonia concentration alsoshowed a significantly greater reduction on L-ornithine-L-aspartate than on placebo (Figure 6.12). The differ-

Figure 6.11: Performance time for the number connection test(NCT-A) before the start of treatment (Day 0) as well as after 2 and7 days’ treatment with L-ornithine-L-aspartate or placebo. Figuresgiven are the mean ± SEM, database 246 patients (after Delcker etal., 2000)

80

70

60

50

40

30

20Day 0

p<0.001

431 5 6 after7 days

after2 days

Seco

nds

L-ornithine-L-aspartate infusionPlacebo

Figure 6.12: Venous postprandial ammonia concentrations beforethe start of treatment (Day 0) as well as after 2 and 7 days’ treat-ment with L-ornithine-L-aspartate or placebo. Figures given are themean ± SEM, database 246 patients (after Delcker et al., 2000)

100

90

80

70

60

50

40Day 0

p<0.015

431 5 6 after7 days

after2 days

Amm

onia

(µm

ol/l)

L-ornithine-L-aspartate infusionPlacebo

Summary: In summary, this meta-analysis based on the individual data of 246patients from randomized placebo-controlled clinical trials shows that 7days’ treatment with Hepa-Merz® infusion concentrate leads to improve-ment of the mental state, reduction in the time needed to complete thenumber connection test and lowering of the ammonia concentration inthe blood, while generally being well tolerated. The treatment differ-ences in comparison to placebo were always statistically significant infavour of Hepa-Merz® infusion concentrate.


97

At the same time all participants were given a diet con-taining 1 g protein/kg body weight/day in three dividedmeals. Examinations were carried out prior to the start oftreatment (day 0) and after 7 and 14 days. The main out-come measures were postprandial venous ammoniaconcentration (1 hour after the morning protein meal) andthe performance time for the NCT-A carried out at thesame time. Further parameters of efficacy included themental state (HE grade), the PSE index and the venousammonia concentrations under fasting conditions.

The results of venous postprandial ammonia concen-tration showed statistically significant differences infavour of L-ornithine-L-aspartate in both the before/after comparison and in the group comparison (Figure6.13).

6.4 Clinical results with oral Hepa-Merz® therapy

In the long-term treatment of associated conditions andsequelae of diseases with impaired detoxification func-tion of the liver (e.g. cirrhosis), it is important that aneffective oral form of the medicinal product is also avail-able. L-ornithine-L-aspartate can be used long-term inthe form of Hepa-Merz® Granules 6000 (1 sachet with10 g granules contains 6 g L-ornithine-L-aspartate) orHepa-Merz® Granules 3000 (1 sachet with 5 g granulescontains 3 g L-ornithine-L-aspartate). The efficacy ofthis pharmaceutical form has also been studied in clini-cal trials.

6.4.1 Hepa-Merz® Granules in comparison with placebo

The efficacy of L-ornithine-L-aspartate granules com-pared with placebo was tested in a multicentre randomized double-blind trial in 66 patients with cirrhosisof the liver and stable chronic overt (HE grade I/II) orsubclinical hepatic encephalopathy (HE grade 0)(Stauch et al., 1998). Further inclusion criteria werehyperammonaemia (fasting venous ammonia concen-tration >50 µmol/l) and a performance time >30 s in thenumber connection test (NCT-A).The patients were given 2 sachets of Hepa-Merz®

Granules 3000 (each containing 3 g L-ornithine-L-aspartate) dissolved in water, three times a day (totaldaily dose: 18 g) for 14 days (N = 34) or a correspond-ing placebo (N = 32).

96

Placebo-controlleddouble-blind trial

in 66 patients with cirrhosis of the liver

and HE grade 0 (subclinical) to II

Figure 6.13: Effects of L-ornithine-L-aspartate (left) and placebo (right)on the postprandial venous ammonia concentration. Figures given arethe mean (black square) and standard deviation, median (whitesquare), 25th and 75th percentiles (after Stauch et al., 1998)

180

160

140

120

100

80

60

40

20

0


0 7 14 0 7 14

Posp

rand

ial a

mm

onia

leve

l mea

sure

d (µ

mol

/l)

**

**

**p < 0.01




9998

change was seen with placebo (1.16 ± 0.65 vs 0.93 ±0.63, p>0.05).

With the baseline clinical assessment of HE 0, a reduc-tion in the NCT-A performance time to <30 secondswas taken as evidence of improvement. The clinicalrelevance of the treatment difference between L-ornithine-L-aspartate and placebo is particularly obvious whenconsidering the number and proportion of patients withimprovement of the HE grade. More than twice as manypatients improved on L-ornithine-L-aspartate as did onplacebo.

Calculation of the modified PSE index included the HEgrade, the postprandial venous ammonia concentrationand the NCT performance time. In accordance with thestatistically significant group differences in favour of L-ornithine-L-aspartate found in these three parame-ters, the difference in the PSE index was also statisti-cally significant at p<0.01. The mean PSE index in theL-ornithine-L-aspartate group was 0.29 ± 0.11 at thestart of treatment, improving to 0.20 ± 0.14 after 14days (p<0.01). The corresponding values for the place-bo group were 0.32 ± 0.12 vs 0.28 ± 0.15 (n.s.).

Treatment was predominantly well tolerated in bothgroups (L-ornithine-L-aspartate 94% and placebo81%). Two patients in the L-ornithine-L-aspartate groupand 6 patients in the placebo group rated the tolerabili-ty as moderate. No patients showed any adverse reac-tions to the medication. One patient in each group wasexcluded from the trial prematurely because of poorcompliance.

A similar result was seen in the venous ammonia con-centrations measured under fasting conditions. Herethe group difference was clearly in favour of L-ornithine-L-aspartate.

With respect to the second main outcome measure, theperformance time for the NCT-A, there was a statisti-cally significant group difference in favour of L-ornithine-L-aspartate after 14 days (p<0.05). While the timerequired for the test stayed more or less constant in theplacebo group, it was progressively shortened on treat-ment with L-ornithine-L-aspartate (Figure 6.14).

The HE grade established clinically showed a statisti-cally significant improvement, from a mean of 1.04 ±0.54 to 0.68 ± 0.47, after 14 days’ treatment with L-ornithine-L-aspartate (p<0.05) while no significant

Figure 6.14: Effects of L-ornithine-L-aspartate (left) and placebo(right) on performance time in the number connection test. Figuresgiven are the mean (black square) and standard deviation, median(white square), 25th and 75th percentiles (after Stauch et al., 1998)

120

100

80

60

40

20

0


0 7 14 0 7 14

NCT-

A (s

ec)

****

**p < 0.01




100

hol misuse (71%); viral infections, medicines, industrialchemicals and other aetiological factors were also men-tioned. The most frequent diagnosis was that of fattyliver (55.5%), followed by cirrhosis of the liver (32.4%)and chronic hepatitis (21.7%). Other diagnoses were oflesser importance (multiple entries were possible).

It was planned that parameters routinely used by thephysician to monitor the course of the disease – aspar-tate aminotransferase (AST), alanine amino-transferase(ALT), gamma-glutamyl transferase (γ−GT), bilirubin andthe prothrombin time – would be measured before andafter treatment. Evaluation of these parameters showedclear reductions in the mean values of AST, ALT, γ−GTand bilirubin with a slight increase in the prothrombintime over the entire patient population. Figure 6.15gives an overview of the three largest diagnostic groups– patients with fatty liver, cirrhosis of the liver and chron-ic hepatitis – and the most frequently measured param-eters AST, ALT and γ−GT.

The results show very clearly that there was a reductionin the clinically relevant parameters in all three diagnos-tic groups, most pronounced in patients with fatty liver.Patients were also subdivided into three groups withrespect to the daily dose (normal dose 9 g L-ornithine-L-aspartate/day, <9 g OA/day and >9 g OA/day) and tothe duration of therapy (<30 days, 31-60 days, 61-90days) in order to investigate the relationship of these cri-teria to the therapeutic effects. There was a positiverelationship between the percentage reduction in theliver enzymes and the daily dosage and duration oftreatment.

101

One further patient on placebo had to be switched toanother therapy because of worsening encephalopathy.

6.4.2 Hepa-Merz® Granules in themedical practice

In order to study the effectiveness and tolerability oftreatment with L-ornithine-L-aspartate granules underconditions of medical practice, observation of use wascarried out in 250 internal and general medical prac-tices (Grüngreiff and Lambert-Baumann, 2001).Records were kept on patients with chronic liver dis-eases who had previously been unsuccessfully treatedwith general non-pharmacological measures and inwhom the physician saw an indication for medicationwith L-ornithine-L-aspartate granules. Besides theusual medical history, data concerning diagnosis, dos-age and duration of treatment, therapeutic monitoring(clinical symptoms and routine laboratory tests) andtolerability were documented. In total, data were collect-ed on 1167 patients. The mean age of these patientswas 53.5 years (18 to 87 years) and the majority weremen (71%). On average, the liver disease had beenknown about for some 4-5 years. The underlying causemost frequently suspected by the physician was alco-

Summary: These placebo-controlled clinical trials show that the oral form of L-orni-thine-L-aspartate is comparable to L-ornithine-L-aspartate infusion con-centrate with respect to efficacy and tolerability.

Observation of use in 1167 patients

with liver diseases

Laboratory tests for therapeutic monitoring


103102

The clinical symptom of “fatigue” which was recordedalso showed a clear improvement during the course oftreatment. In 178 of the patients with cirrhosis of theliver, very marked fatigue was recorded initially; thisimproved in 95% of the patients. The mild to moderatefatigue experienced by 157 patients at the start of treat-ment was no longer present in 53% of these patients atthe final assessment, as can be seen in Figure 6.16.At the end of the observation period, the treating physi-cians made an overall assessment of the effectivenessand tolerability of treatment with L-ornithine-L-aspartate.Analysis of these data showed their positive assess-ment of treatment success (Figure 6.17).

Additional factors which had positive effects on thelevels of the liver enzymes were good compliance anda definite abstinence from alcohol during the period ofobservation. In 348 of the patients with cirrhosis, infor-mation was supplied on hepatic encephalopathy (HE).In 105 (30%) of these patients mild (HE grade I) and in27 (8%) moderate (grade II) hepatic encephalopathywas initially diagnosed. Analysis showed that 78% ofthe patients with moderate hepatic encephalopathyimproved to a lower grade and 49% of the patientswith grade I hepatic encephalopathy regressed tograde 0.

Figure 6.15: Changes in AST, ALT and γ−GT on treatment with Hepa-Merz® Granules in the three largest diagnostic groups. Data onpatient numbers (N) and percentage decrease in transaminases (afterGrüngreiff and Lambert-Baumann, 2001)

%

20

10

0

-10

-20

-30

-40

-50

-60

-70AST ALT γ-GT

n = 963

Perc

enta

ge re

duct

ion

in tr

ansa

min

ases

befo

re a

nd a

fter t

reat

men

t

cirrhosis fatty liverchr. hep.

Figure 6.16: Effects of treatment with Hepa-Merz® Granules on theclinical parameter “fatigue” (after Grüngreiff and Lambert-Baumann,2001)

180

160

140

120

100

80

60

40

20

0

HE I HE II severe fatigue

mildfatigue

n = 348

Impr

ovem

ent i

n HE

/fatig

ue in

pat

ient

s w

ith c

irrho

sis

Num

ber o

f pat

ient

s

before treatmentafter treatment

Improvement in clinical symptoms

on L-ornithine-L-aspartate

Overall assessmentof efficacy and tolerability


105104

6.4.3 Hepa-Merz® Granules in comparison with lactulose

The disaccharide lactulose – which is not cleaved in thegastrointestinal tract – has been used for a long time inthe treatment of hepatic encephalopathy (see section4.3). However, the therapeutic use of lactulose is limitedbecause of its frequently occurring adverse effects(gastrointestinal symptoms, diarrhoea). Because themechanisms of action of L-ornithine-L-aspartate andlactulose are basically different, a direct comparison ofthe efficacy and tolerability of the two substancesseemed to be clinically relevant.

To this end, a monocentre randomized clinical trial inparallel groups was carried out (Liehr et al., 1992;Kircheis et al., 1993; Krüger et al., 1994) in which 48patients with cirrhosis of the liver, hyperammonaemia(>50 µmol/l) and minimal or overt hepatic encephalop-athy were included. The patients were treated for 14days with either L-ornithine-L-aspartate granules (3 x 9 g per day) or lactulose (initial dose 3 x 33 g, followedby individual adjustment of the daily dose). Both groupsshowed a reduction in the mean NCT performancetime: from 58 s to 47 s in the L-ornithine-L-aspartategroups and from 66 s to 53 s in the lactulose group.The mean ammonia concentration was lowered only onL-ornithine-L-aspartate (from 120 µmol/l to 105 µmol/l).Mean values of γ−GT improved in both groups. HEgrading also improved in both groups, whereby 29% ofpatients on L-ornithine-L-aspartate no longer had anydiscernable HE at the end of treatment compared withonly 5% of lactulose patients. Treatment with L-ornithine-

And in only 8 cases did the physician consider thatthere was a possible or probable causal relationshipbetween L-ornithine-L-aspartate and adverse events.These were mild and mainly gastrointestinal symptoms.There were no serious adverse drug reactions.

Figure 6.17: Overall assessment of the efficacy (left) and tolerability(right) of treatment with Hepa-Merz® Granules at the end of treatment,shown as percentages (after Grüngreiff and Lambert-Baumann, 2001)

very goodgoodmoderate/slightnone

Therapeuticefficacy

Tolerability

very goodgoodmoderate/slight

Summary: The results of this observation of use in 1167 patients with chronic liverdisease substantially confirm the efficacy and the good tolerability ofHepa-Merz® Granules shown in controlled clinical trials, under conditionspertaining to the medical practice.

Controlled clinicalstudies in patientswith cirrhosis


107106

of therapeutic use and clinical studies in patients with mildto severe impairment of hepatic function. The majoritywere patients with cirrhosis but patients with other liverdiseases were also treated. The documented duration oftreatment ranged from a few days to several years.

Recent placebo-controlled double-blind trials with L-ornithine-L-aspartate infusion concentrate and L-ornithine-L-aspartate granules have been carried outin accordance with the current requirements of evidence-based medicine. With respect to its efficacy in cirrhosisof the liver and hepatic encephalopathy (subclinical toHE grade II), average and clinically relevant findings ontreatment with L-ornithine-L-aspartate in comparisonwith placebo show that:• the mental state improves (significant reduction in the

HE grade)• the PSE index falls significantly• performance time in the number connection test is

significantly reduced• ammonia concentrations in the fasting and postpran-

dial states are significantly lowered.

The results of experimental clinical studies, many obser-vations of therapeutic use and clinical trials with L-orni-thine-L-aspartate have thus been confirmed in accor-dance with the criteria of evidence-based medicine.The tolerability of L-ornithine-L-aspartate was good;serious adverse reactions did not occur. In a few cases,patients receiving L-ornithine-L-aspartate infusion ther-apy experienced mild gastrointestinal symptoms whichcould be interpreted as evidence of adverse drug reac-tions to L-ornithine-L-aspartate.

L-aspartate was much better tolerated than lactulosetherapy. 45% of the patients treated with lactulosereported adverse reactions, mostly diarrhoea commenc-ing within the first three days.

6.5 Summary of results withHepa-Merz®

Pharmacodynamic effects and dose-effect relationshipswere investigated in experimental clinical studies with L-ornithine-L-aspartate. It has been shown that treat-ment with L-ornithine-L-aspartate:

• lowers the elevated ammonia concentration in theblood and increases the formation of urea

• reduces or prevents pathological postprandialammonia levels in the blood

• counteracts amino acid imbalance (increase of theBCAA/AAA ratio)

• improves protein synthesis in the muscle (evidence of anti-catabolic action)

• stabilized psychometric functions and the mentalstate under protein loading

• reduces pathological glutamine and glutamateconcentrations in the brain in parallel with thelowering of ammonia in the arterial blood

• has dose-dependent effects.

The results of experimental clinical studies are in agree-ment with the findings of experimental animal studies. Theclinical efficacy and tolerability of L-ornithine-L-aspartateas an infusion, with oral administration or a combinationof the two, have been investigated in many observations

Effects of L-ornithine-L-aspartate

Efficacy and tolerability of



With severely impaired hepatic function, the infusionshould be reduced to a rate that the individual can toler-ate.

Because of its mechanism of action, L-ornithine-L-aspartate leads to the increased formation of ureawhich has to be eliminated via the kidneys. L-ornithine-L-aspartate should therefore not be used in caseswhere there is severe impairment of renal function. As ageneral rule, the creatinine level should not be greaterthan 3 mg/dl.

Attention to renalfunction (creatininenot greater than 3 mg/dl)

109

Data on safety and tolerability of Hepa-Merz® from theobservations of therapeutic use, clinical studies andespecially the placebo-controlled double-blind trialshave proven that the tolerability of L-ornithine-L-aspar-tate is very good. There were no cases of serious ad-verse drug reactions.

In the placebo-controlled double-blind trials with largecase numbers, there were three cases (5% of the L-ornithine-L-aspartate treated patients) of mild gastro-intestinal disturbances i.e. nausea/vomiting with infu-sion therapy (Kircheis et al., 1997); there were no casesin the placebo group. In the largest placebo-controlledtrial with L-ornithine-L-aspartate granules, there wereno adverse events at all in either group (Stauch et al.,1998).

It is known from spontaneous notification of suspectedadverse drug reactions and reports from therapeuticpractice that nausea occasionally occurs on infusiontherapy, with vomiting rarely. The symptoms are gener-ally transient and are reversible with a reduction in thedose or the rate of infusion.

In summary it can be said that L-ornithine-L-aspartatetherapy is generally very well tolerated and that adversereactions may occur rarely, in the form of mild gastroin-testinal disturbances. To prevent such reactions, amaximum infusion rate of 5 g L-ornithine-L-aspartateinfusion concentrate per hour is recommended.

Rate of infusionshould not be greaterthan 5 g L-ornithine-L-aspartate per hour

7 SAFETY AND TOLERABILITY

108


110

8.2 Toxicology

Toxicological tests of L-ornithine-L-aspartate on ratsand dogs following single doses and after repeatedadministration of infusions over 4 weeks gave a no-effect level of approx. 1500 mg/kg.

Reproduction studies on mutagenicity found no abnor-malities. There is no need to suspect any carcinogenicpotential.

8.3 Pharmacokinetics

L-ornithine-L-aspartate is rapidly absorbed and cleav-ed into L-ornithine and L-aspartate. The eliminationhalf-life of each the amino acids is short – approx. 40minutes. Some L-aspartate also appears unchanged inthe urine.

The bioavailability is 82.2 ± 28% after either intrave-nous or oral administration.

111

8.1 Chemico-physical data

L-ornithine-L-aspartate, the stable salt of the naturally-occurring amino acids, L-ornithine and L-aspartic acid,is available in the pharmaceutical forms of granules,chewable tablets and infusion concentrate. 1 sachet ofHepa-Merz® Granules 3000 contains 3.0 g of L-ornithine-L-aspartate; 1 sachet of Hepa-Merz® Granules 6000contains 6.0 g of L-ornithine-L-aspartate. Hepa-Merz®

Chewable tablets, containing 3.0 g L-ornithine-L-aspartate, have the great advantage that no water orother fluid is required to take them. Their pleasant fruitflavour aids patient compliance. 10 ml infusion con-centrate contain 5.0 g L-ornithine-L-aspartate in waterfor injection.

8 CHEMISTRY, TOXICOLOGY AND PHARMACOKINETICS OF HEPA-MERZ®

Chemical name (S) - 2,5 – diaminopentanoic acid – (S) 2 amino succinate

INN L-ornithine-L-aspartate

Structural formula

Molecular formula C9 H19 N3 O6

Molecular weight 265.3

Appearance white or colourless crystalline powder

Odour odourless

Taste metallic, salty

Solubility readily soluble in water, poorly soluble in ethyl alcohol

CO C CCH2 CH2 CH2 NH3

NH3O

H

O C CH2 C

HO

C O

O

NH3


ContraindicationsSevere impairment of kidney function (renal failure)Serum creatinine should not be greater than 3 mg/100ml.

Use in pregnancy and lactation:Ornithine-aspartate has no known damaging effectsduring pregnancy and lactation.Contains fructose.When taken according to the dosage recommenda-tions, each dose of the granules supplies 1.13 g fruc-tose per sachet. Due to the possibility of hitherto unde-tected fructose intolerance, this medicinal productshould only be given to babies and young children afterconsultation with the treating physician. It is absolutelyessential that adolescents and adult patients with he-reditary fructose intolerance consult the treating physi-cian before taking this medicinal product.

Adverse reactionsNone known

WarningsThis medicine contains the colouring agent E 110 (Sun-set yellow) which may cause allergic reactions – includ-ing asthma – in people who are particularly sensitive to this substance. Allergy is seen more frequently in people who are allergic to acetyl salicylic acid.

113

Hepa-Merz® Granules

Active substanceL-ornithine-L-aspartate

Composition 1 sachet with 5 g granules contains

Active ingredients L-ornithine-L-aspartate 3.0 g

Other ingredientsCitric acid, anhydrousSaccharin sodiumSodium cyclamateFructosePovidoneFlavourings E 110 colouring

Note for people with diabetes1 sachet with granules contains 1.13 g fructose (corresponding to 0.11 carbohydrate exchanges)

IndicationsTreatment of associated conditions and sequelae ofdiseases with impaired hepatic detoxification (e.g. cirrhosis of the liver), when there are symptoms andsigns of minimal or overt hepatic encephalopathy.

9 BASIC INFORMATION

112


Hepa-Merz® Infusion concentrate

Active substanceL-ornithine-L-aspartate

Composition 1 ampoule with 10 ml contains

Active ingredients L-ornithine-L-aspartate 5.0 g

Other ingredientsWater for injection

IndicationsTreatment of associated conditions and sequelae ofdiseases with impaired hepatic detoxification (e.g. cir-rhosis of the liver), when there are symptoms and signsof minimal or overt hepatic encephalopathy; especiallyfor the treatment of incipient loss of consciousness(pre-coma) and clouding of consciousness (coma)

ContraindicationsSevere impairment of kidney function (renal failure).Serum creatinine should not be greater than 3 mg/100ml.

Use in pregnancy and lactationOrnithine-aspartate has no known damaging effectsduring pregnancy and lactation.

Adverse reactionsOccasionally nausea has been reported and rarelyvomiting. However these are usually transient and do

115

Mode of actionHepa-Merz® contains L-ornithine-L-aspartate, whichstimulates ammonia detoxification by increasing ureasynthesis in the urea cycle. In addition it detoxifies theextrahepatic ammonia in the tissues.

DosageTake the contents of 1-2 sachets Hepa-Merz® Granulesdissolved in water, up to three times a day

Interactions with other medicinesNone known

114


AAA Aromatic amino acids ALF Acute liver failureALT Alanine aminotransferaseAP Alkaline phosphataseAST Aspartate aminotransferaseBCAA branched-chain amino acids BUI Brain uptake indexCAH Chronic active hepatitisCC Clinical control groupCFF Critical flicker frequencyCHE CholinesteraseChT Chewable tabletcps Cycles per secondCRT Choice reaction timeCT Computerised tomographyCr Creatinine dl DecilitreDST Digit symbol testEEG ElectroencephalogramFig FigureGABA Gamma aminobutyric acidGCP Good clinical practiceGOT Glutamic-oxaloacetic transaminaseGDH Glutamate dehydrogenaseGln GlutamineGlu GlutamateGPT Glutamic-pyruvic transaminaseγ-GT Gamma-glutamyl transferaseHE Hepatic encephalopathy INR International normalised ratio (= thromboplastin time)l LitreLD Lethal doseLTT Line tracing test

10 ABBREVIATIONS

117

not require discontinuation of the medicinal product:they disappear with reduction in the dose or the rate ofinfusion.

WarningsNone

Mode of actionStimulation of ammonia detoxification by increasingurea synthesis in the urea cycle. Extrahepatic detoxifi-cation of ammonia in the tissues.

DosageAs long as not otherwise prescribed, up to 4 ampoulesdaily. With incipient loss of consciousness (pre-comaand clouding of consciousness (coma) up to 8 am-poules within 24 hours, depending on the severity of thecondition.

Interactions with other medicinesNone known

116


11.1 General references

Blei AT, Butterworth RF (Eds.). Hepatic Encephalopathy.Seminars in Liver Disease 1996; Vol. 16, No. 3, Thieme,New York, Stuttgart.

Blei AT. Diagnosis and treatment of hepatic encephalop-athy. Bailliere's Clinical Gastroenterology 2000; 14(6):959–974.

Böker K, Heringlake S. Das akute Leberversagen. Kli-nikarzt 1999; 2/28: 54–58.

Conn HO, Bircher J (Eds.). Hepatic Encephalopathy:Syndromes and Therapies. Medi-Ed Press 1994, Bloo-mington, Illinois.

Caspary W.F Hepatische Enzephalopathie. In: CasparyW.F, Leuschner U, Zeuzem S. (Hrsg.). Therapie vonLeber- und Gallekrankheiten. 2. Aufl., Springer-Verlag,2001: 309–325.

Ferenci P, Müller C. Hepatic encephalopathy: treatment.In: McDonald JWD, Burroughs AK, Feagan BG (Eds.).Evidence based gastroenterology and hepatology. BMJBooks 1999, London; 443–455.

Gerber T, Schomerus H. Hepatic encephalopathy inliver cirrhosis, pathogenesis, diagnosis and manage-ment. Drugs 2000; 60(6): 1353–1370.

Gerok W, Blum H.E. (Hrsg). Hepatologie. Urban &Schwarzenberg 1995, München.

11 REFERENCES

119

MRI Magnetic resonance imagingMRS Magnetic resonance spectroscopyµmol Micromolmg MilligramN NumberNASH Non-alcoholic steatohepatitisNCT Number connection testNH3/NH4

+ Ammonia/ammonium ionNMR Nuclear magnetic resonance n.s. not significantOA L-ornithine-L-aspartatePSE Portosystemic encephalopathy QUORUM Quality of reporting of meta-analysiss SecondsSD Standard deviationSEM Standard error of the meanSHE Subacute hepatic encephalopathy Tab TableTIPS Transjugular intrahepatic portosystemic

stent shuntVEP Visual evoked potential

118


Trautwein C, Manns MP. Chronische Hepatitis. DerInternist 1997; 3: 283–295.

Mullen K.D, Dasarathy S. Hepatic Encephalopathy. In:Schiff E.R, Sorrell M.F, Daddrey W.C (Editors). Diseases ofthe Liver, Lippincott Williams & Wilkins Philadelphia 1999.

Wein Ch, Popp B, Koch H. NeuropsychologischeUntersuchungen und Fahrverhalten bei Patienten mitLeberzirrhose, Neurol. Rehabil. 2001; 7(5): 242–262.

Weißenborn K. Hepatische Enzephalopathie. In:Schmidt E., Schmidt FW, Manns MP (Hrsg.). Leberer-krankungen: Pathophysiologie-Diagnostik-Therapie,Wiss. Verl.Ges. Stuttgart, 2000; ISBN 3-8047-1640-7.

11.2 References on Hepa-Merz®

Albrecht J, Hilgier W, Januszewski S, Kapuscinski A,Quack G. Increase of the brain uptake index for L-ornithine in rats with hepatic encephalopathy. Neuro-report 1994; 5: 671–673.

Albrecht J, Hilgier W, Januszewski S, Quack G. Contra-sting effects of toxic liver damage on the brain uptakeindices ornithine, arginine and lysine: modulation bytreatment with ornithine aspartate. Metabolic BrainDiseases 1996; 11: 229–237.

Aschke J. Erfahrungen mit L-Ornithin-L-Aspartat beiLeberkranken. Med. Welt 1969, 20(12): 657–662.

121

Häussinger D, Kircheis G, Fischer R, Schliess F, vomDahl S. Hepatic encephalopathy in chronic liver dis-ease: a clinical manifestation of astrocyte swelling andlow-grade cerebral edema? Journal of Hepatology2000; 32: 1035–1038.

Häussinger D, Maier KP. Hepatische Enzephalopathie.Georg Thieme Verlag 1996, Stuttgart, New York.

Häussinger D. Nitrogen metabolism in liver: structuraland functional organization and phy-siological rele-vance. Biochem. J. 1990; 267: 281–290.

Kaiser S, Gerok W, Häussinger D. Ammonia and gluta-mine metabolism in human liver slices: new aspects onthe pathogenesis of hyperammonaemia in chronic liverdisease. Eur. J. Clin. Invest. 1988; 18(5): 535–542.

Kircheis G, Wettstein M, Timmermann L, Schnitzler A,Häussinger D. Critical flicker frequency for quantificationof low-grade hepatic encephalopathy. Hepatology2002; 35: 357–366.

Kramer L, Tribl B, Gendo A, Zauner C, Schneider B,Ferenci P, Madl C. Partial pressure of ammonia versusammonia in hepatic encephalopathy. Hepatology 2000;31(1): 30–34.

Kuhlbusch R, Enck P, Häussinger D. Hepatische Enze-phalopathie: neuropsychologische und neurophysiolo-gische Diagnostik. Z. Gastroenterol. 1998; 36: 1075–1083.

120


123122

Grossi CE, Prytz B, Rousselot LM. Amino acids mix-tures in prevention of acute ammonia intoxication indogs. Arch Surg 1967; 94: 261–266.

Grüngreiff K, Lambert-Baumann J. Wirksamkeit von L-Ornithin-L-Aspartat-Granulat bei chronischen Leber-erkrankungen. Ergebnisse einer Anwendungsbeobach-tung bei 1167 Patienten. Med Welt 2001; 52: 219–226.

Handschuh H. Ammoniaksenkung als Ziel. FortschrMed 1990; 108(13): 83.

Hendricks R, Hellweg H-R. Therapie von Lebererkran-kungen mit oral verabreichtem Ornithin-aspartat – Ver-laufsbeobachtung über 6 Monate. Med. Welt 1984; 35:596–600.

Henglein-Ottermann D, Der Einfluß von Ornithin-Aspar-tat auf die experimentell erzeugte Hyperammoniämie.Klinisch-experimentelle Studie. Therapie der Gegenwart1976; 115: 9.

Hermann G. Experimentell erzeugte endogene Hyper-ammoniämien durch Narkotika an der Ratte und derenBeinflussung durch L-Ornithin-L-Aspartat. in: Ed.Szam. Ammoniakstoffwechsel. Schattauer Verlag,Stuttgart-New York 1972; 219–223.

Hunold W. Klinische Erfahrungen bei Hepatopathien –insbesondere bei Patienten mit alko-holtoxisch undnutritivtoxisch bedingter Fettleber – unter der Monothe-rapie mit Ornithin-aspartat. Z für Allgemeinmedizin1973; 10 (49. Jahrg.): 469–472.

Baumann M. Klinische Erfahrungen mit Hepa-Merz.Zeitschrift Allgemeinmed. 1970; 46(17): 895–900.

Delcker A, Jalan R, Schumacher M, Comes G. L-orni-thine-L-aspartate vs placebo in the treatment of hepat-ic encephalopathy: A meta-analysis of randomized pla-cebo-controlled trials using individual data. Hepatol2000; 32(4), Pt. 2 of 2, 310 A (Abstract 604).

Delcker A, Turowski B, Mihm U, Raab P., Rusch O, Pila-tus U, Zanella F.E, Proton MR Spectroscopy of Neuro-metabolites in Hepatic Encephalopathy During L-Orni-thine-L-Aspartate Treatment – Results of a Pilot Study.Metabolic Brain Disease 2002, Vol. 17, No. 2 (in press).

Fehér J, Láng I, Gógl A et al. Effect of ornithine-aspar-tate infusion on elevated serum ammonia concentrationin cirrhotic patients - results of a randomized, placebo-controlled double-blind multicentre trial. Med Sci Monit1997; 3(5): 669–673.

Gebhardt R, Beckers G, Gaunitz F et al. Treatment ofcirrhotic rats with L-ornithine-L-aspartate enhancesurea synthesis and lowers serum ammonia levels.J Pharmacol Exp Ther 1997; 283(1): 1–6.

Greenstein JP, Winitz M, Gullino P et al. Studies on themetabolism of amino acids and related compounds invivo. III. Prevention of ammonia toxicity by arginine andrelated compounds. Arch Biochem 1956; 64: 342–254.


125124

Liehr M, Huth M, Kircheis G, Wagner M. A comparisonof l-ornithine-l-aspartate and lactulose in the manage-ment of chronic liver disease and hepatic encephalopa-thy. J Gastroenterol Hepatol 1992; 7 (suppl1): abstract106.

Melzer H, Weber D, Wotzka R. Zur Therapie von Leber-krankheiten mit L-Ornithin-L-Aspartat. Med. Klinik1969; 64(35): 1541–1544.

Müller-Kengelbach P. Behandlung chronischer Leber-schäden mit Ornithin-aspartat. Therapie Woche 1986;36: 3743–3749.

Müting D, Kalk J-F, Fischer R, Wurzel H, Reikowski J.Hepatic detoxification and hepatic function in chronicactive hepatitis with and without cirrhosis. DigestiveDiseases and Sciences 1988; 33 (1): 41–46.

Müting D, Kalk JF, Klein CP. Long-term effectiveness ofhigh-dosed ornithine-aspartate on urea synthesis rateand portal hypertension in human liver cirrhosis. AminoAcids 1992; 3: 147–153.

Müting D, Reikowski J. Controlled study of the effect ofan orally administered ammonia-lowering amino acid(ornithine-aspartate) on liver and pancreas function inliver cirrhosis patients. Therapiewoche 1980; 30:5990–5996.

Podymova SD, Nadinskaya MJ. The treatment of hepat-ic encephalopathy. Digestion 1998; 59 [Suppl. 3]: 348.

Kalk H. Die Klinik der akuten Leberinsuffizienz.Gastroenterologia 1958, 90: 217–290.

Kircheis G, Nilius R, Held C et al. Therapeutic efficacy ofL-ornithine-L-aspartate infusions in patients with cirrho-sis and hepatic encephalopathy: results of a placebo-controlled, double-blind study. Hepatology 1997; 25(6):1351–1360.

Kircheis G, Quack G, Erbler H. L-ornithine-L-aspartatein the treatment of hyperammonemia and hepatic en-cephalopathy. in: Eds. Conn HO, Bircher J. HepaticEncephalopathy: Syn-dromes and Therapies. Medi-EDPress, Bloomington, Illinois 1993: 373–383.

Kosozu K. Clinical study on the effects of L-ornithine-L-aspartate on liver dysfunction. [Article in Japanese].Iryo 1966; 20(4): 339–346.

Krüger B, Held C, Kircheis G. Ornithinaspartat bei hepa-tischer Enzephalopathie : ein alter neuer Therapieansatz.Z. Ärztl.Fortbild (Jena). 1994; 88(9): 673–679.

Leonhardt H, Bungert HJ. Therapie der schweren Hyper-ammoniämie. Med. Klinik 1972; 32/33: 1052–1056.

Leweling H, Kortsik C, Gladisch R, Staedt U, HagmüllerE, Holm E. Effects of ornithine aspartate on plasmaammonia and plasma amino acids in patients with livercirrhosis. A double-blind, randomized study using afour-fold crossover design.In: Bengtsson F: Hepatic Encephalopathy and Metabol-ic Nitrogen Exchange. CRC Press 1991, 377–389.


127126

Salvatore F, Scoppa P, Cozzolino. Protective effect ofornithine and aspartic acid in chronic carbon tetrachlo-ride intoxication. Clin. Chim. Acta 1959; 4: 728–732.

Schäfer W. Die intravenöse Zufuhr von L-Ornithin-L-Aspartat bei Leberkrankheiten. Münch. Med. Wschr.1968, 43: 2521–2525.

Schmidt L. Behandlung alkoholinduzierter Hepatopa-thien. Therapie der Gegenwart 1974; 11 (113. Jahrg.):1940–1972.

Schmitt W und Ziegler KB: Der Einfluss von L-Ornithin-L-Aspartat auf den arteriellen und venösen Blutammo-niakspiegel bei Leberzirrhotikern. Med. Welt 1970, 21:1361.

Shioya, Kuraiski K, Kakimoto M, Tamama Y. Pharma-cological study on L-ornithine-L-aspartate. Jap J Phar-macol 1964; 14: 201–214.

Slotboom J, Vogels BAPM, De Haan JG et al. Protonresonance spectroscopy study of the effects of L-ornithi-ne-L-aspartate on the development of encephalopathy,using localization pulses with reduced specific absorptionrate. J Magnetic Resonance 1994; B105: 147–156.

Staedt U, Leweling H, Gladisch R, Kortsik C, HagmullerE, Holm E. Effects of ornithine aspartate on plasmaammonia and plasma amino acids in patients with cir-rhosis. A double-blind, randomized study using a four-fold crossover design. J Hepatol 1993; 19(3): 424-430.

Rees CJ, Oppong K, Mardinie H Al, Hudson M, Record CO. Effect of L-ornithine-L-asparate on patientswith and without TIPS undergoing glutamine challenge:a double blind, placebo controlled trial. Gut 2000; 47:571–574.

Reynolds N, Downie S, Smith K, Kircheis G, Rennie MJ.Treatment with L-ornithine-L-aspartate (LOLA) infusionrestores muscle protein synthesis responsiveness tofeeding in patients with cirrhosis. Journal of Hepatology1999, (Suppl. 1) Vol. 30.

Rose C, Michalak A, Pannunzio P et al. L-ornithine-L-aspartate in experimental portal-systemic encephalop-athy: Therapeutic efficacy and mechanism of action.Metabolic Brain Disease 1998; 13(2): 147–157.

Rose C, Michalak A, Rao KV, Quack G, Kircheis G, But-terworth RF. L-ornithine-L-aspartate lowers plasma andcerebrospinal fluid ammonia and prevents brain edemain rats with acute liver failure. Hepatology 1999; 30(3):636–640.

Salvatore F, Bocchini V. Prevention of ammonia toxicityby amino acids concerned in the biosynthesis of urea.Nature 1961; 191: 705–706.

Salvatore F, Cimino F, D'Ayella-Caracciolo M, CittadiniD. Mechanism of the protection by L-ornithine-L-aspar-tate mixture and by L-arginine in ammonia intoxication.Arch Biochem Bio-phys 1964; 107: 499–503.


129128

Zieve L, Lyftogt C, Raphael D. Ammonia toxicity: com-parative protective effect of various arginine and orni-thine derivatives, aspartate, benzoate, and carbamylglutamate. Metabolic Brain Disease 1986; 1: 25–35.

Stauch S, Kircheis G, Adler G et al. Orale L-Ornithin-L-Aspartat-Therapie der chronischen hepatischenEnzephalopathie: Ergebnisse einer Placebo-kontrollier-ten Doppelblind-Studie. J Hepatol 1998; 28: 856–864.

Turowski B, Delcker A, Zanella FE. Proton-MR-Spectros-copy of neurometabolites in hepatic encephalopathy.Journal of Imaging 2001; 11(1) Nr. 4 (Abstract).

Vogels BAPM, Slotboom J, de Haan JG, Bovee WMMJ,Quack G, Chamuleau RAFM. The effect of L-ornithine-L-aspartate on mild encephalopathy due to portosystem-ic shunting and hyperammonemia. In: Capocaccia L etal., eds. Advances in Hepatic Encephalopathy andMetabolic Nitrogen Exchange. CRC Press London1995, 423–431.

Vogels BA, Karlsen OT, Mass MA, Bovee WM, Chamu-leau RA. L-ornithine vs. L-ornithine-L-aspartate as atreatment for hyperammonemia-induced encephalopa-thy in rats. J Hepatol 1997; 26(1): 174–182.

Vorberg G. Ambulante Behandlung Leberkranker mitOrnithinasparthat. Ärztliche Praxis 1969; 59 (21.Jahrg.): 3208.

Wotzka R, Weber D. Weitere klinische Erfahrungen mitL-Ornithin-L-Aspartat bei Lebererkrankungen. Ther.Gegenwart 1972; 111: 400–412.

Zicha K, Zicha M. Die Leberschutzwirkung von L-Ornithin-L-Aspartat bei Arzneimittelschäden an Rat-ten. Zeitschrift für Gastroenterologie 1968; 6: 423–429.


Notes

131

Notes

130


Merz Pharmaceuticals GmbHMedical Sciences

Eckenheimer Landstrasse 100D-60318 Frankfurt am Main

Tel: +49 (0)69.15 03-1Fax: +49 (0)69.15 03-4 06

www.merz.com


Liver Diseases And Hepatic Encephalopathy

Health & Medicine

Transcript of Liver Diseases And Hepatic Encephalopathy