Antihipertensi Drugs

Antihypertensive Agents

PRADITA DIAH PERMATASARI

Hypertension

High blood pressure Normal: Systolic < 130 mm

Hg Diastolic < 85 mm Hg

Classification of Blood PressureCategory Systemic BP (mm Hg) Diastolic BP (mm Hg)

Normal <120 <80

prehipertensi 120-139 80-89

HypertensionStage 1 140-159 90-99Stage 2 160 100

Classification of Blood PressurePrimary Hypertension Specific cause unknown 90% of the cases Also known as essential or idiopathic

hypertensionSecondary Hypertension Cause is known (such as eclampsia of

pregnancy, renal artery disease, pheochromocytoma)

10% of the cases

Blood Pressure = CO x SVR CO = Cardiac output SVR = Systemic vascular resistance


Medications used to treat hypertension

Antihypertensive Agents: Categories Adrenergic agents Angiotensin-converting enzyme inhibitors Angiotensin II receptor blockers Calcium channel blockers Diuretics Vasodilators

Antihypertensive Agents: Categories

Adrenergic Agents Alpha1 blockers Beta blockers (cardioselective and nonselective) Centrally acting alpha blockers Combined alpha-beta blockers Peripheral-acting adrenergic agents

Antihypertensive Agents: Mechanism of Action

Adrenergic AgentsAlpha1 Blockers (peripherally acting) Block the alpha1-adrenergic receptors The SNS is not stimulated

Result: DECREASED blood pressure

Stimulation of alpha1-adrenergic receptors causes HYPERtension

Blocking alpha1-adrenergic receptors causes decreased blood pressure

Antihypertensive Agents:

Adrenergic AgentsAlpha1 Blockers doxazosin (Cardura) prazosin (Minipress) terazosin (Hytrin)

Antihypertensive Agents: Mechanism of ActionAdrenergic AgentsCentral-Acting Adrenergics Stimulate alpha2-adrenergic

receptors Sympathetic outflow from the CNS is

decreased

Result: decreased blood pressure


Adrenergic AgentsCentral-Acting Adrenergics clonidine (Catapres) methyldopa (Aldomet)

(drug of choice for hypertension in pregnancy)

Antihypertensive Agents: Mechanism of ActionAdrenergic AgentsAdrenergic Neuronal Blockers

(peripherally acting) Inhibit release of norepinephrine Also deplete norepinephrine stores SNS (peripheral adrenergic nerves) is

not stimulated



Adrenergic AgentsAdrenergic Neuronal Blockers

(peripherally acting) reserpine guanadrel (Hylorel) guanethidine (Ismelin)

Antihypertensive Agents: Adrenergic Agents

Therapeutic Uses Alpha1 blockers (peripherally acting)

Treatment of hypertension Relief of symptoms of BPH Management of of severe CHF when used

with cardiac glycosides and diuretics

Antihypertensive Agents: Adrenergic Agents

Therapeutic Uses Central-Acting Adrenergics

Treatment of hypertension, either alone or with other agents

Usually used after other agents have failed due to side effects

Also may be used for treatment of severe dysmenorrhea, menopausal flushing, glaucoma

Clonidine is useful in the management of withdrawal symptoms in opioid- or nicotine-dependent persons

Antihypertensive Agents: Adrenergic AgentsTherapeutic Uses Adrenergic neuronal blockers

(peripherally acting) Treatment of hypertension, either alone or with

other agents Seldom used because of frequent side effects

Antihypertensive Agents: Adrenergic AgentsSide EffectsMost common: dry mouthdrowsinesssedation constipationOther: headaches sleep disturbances nausearashcardiac disturbances (palpitations)

HIGH INCIDENCE OF ORTHOSTATIC HYPOTENSION

Antihypertensive Agents: CategoriesAngiotensin-Converting Enzyme Inhibitors(ACE Inhibitors) Large group of safe and effective

drugs Often used as first-line agents for CHF

and hypertension May be combined with a thiazide

diuretic or calcium channel blocker


ACE Inhibitors

RAAS: Renin Angiotensin-Aldosterone System

When the enzyme angiotensin I is converted to angiotensin II, the result is potent vasoconstriction and stimulation of aldosterone

Result of vasoconstriction: increased systemic vascular resistance and increased afterload

Therefore, increased BP

Antihypertensive Agents: Mechanism of ActionACE Inhibitors Aldosterone stimulates water and

sodium resorption. Result: increased blood volume,

increased preload, and increased B

Antihypertensive Agents: Mechanism of ActionACE Inhibitors ACE Inhibitors block the angiotensin-

converting enzyme, thus preventing the formation of angiotensin II.

Also prevent the breakdown of the vasodilating substance, bradykinin

Result: decreased systemic vascular resistance (afterload), vasodilation, and therefore, decreased blood pressure

Antihypertensive AgentsACE Inhibitors captopril (Capoten) Short half-life, must be dosed more frequently

than others enalapril (Vasotec) The only ACE inhibitor available in oral and

parenteral forms lisinopril (Prinivil and Zestril) and quinapril

(Accupril) Newer agents, long half-lives, once-a-day

dosing Several other agents available

Antihypertensive Agents: Therapeutic UsesACE Inhibitors Hypertension CHF (either alone or in combination with

diuretics or other agents)

Slows progression of left ventricular hypertrophy after an MI

Renal protective effects in patients with diabetes

Drugs of choice in hypertensive patients with CHF

Antihypertensive Agents: Side EffectsACE Inhibitors Fatigue Dizziness Headache Mood changes Impaired taste

Dry, nonproductive cough, reverses when therapy is stopped

NOTE: first-dose hypotensive effect may occur!!

Antihypertensive Agents: CategoriesAngiotensin II Receptor Blockers (A II Blockers or

ARBs) Newer class Well-tolerated Do not cause coughing

Antihypertensive Agents: Mechanism of ActionAngiotensin II Receptor Blockers Allow angiotensin I to be converted to

angiotensin II, but block the receptors that receive angiotensin II

Block vasoconstriction and release of aldosterone


Angiotensin II Receptor Blockers losartan (Cozaar) eposartan (Teveten) valsartan (Diovan) irbesartan (Avapro) candesartan (Atacand) telmisartan (Micardis)

Antihypertensive Agents: Therapeutic UsesAngiotensin II Receptor Blockers Hypertension Adjunctive agents for the treatment

of CHF May be used alone or with other

agents such as diuretics

Antihypertensive Agents: Side EffectsAngiotensin II Receptor Blockers Upper respiratory infections Headache May cause occasional dizziness,

inability to sleep, diarrhea, dyspnea, heartburn, nasal congestion, back pain, fatigue

Antihypertensive Agents: CategoriesCalcium Channel Blockers Benzothiazepines Dihydropyridines Phenylalkylamines

Antihypertensive Agents: Mechanism of ActionCalcium Channel Blockers Cause smooth muscle relaxation by

blocking the binding of calcium to its receptors, preventing muscle contraction

This causes decreased peripheral smooth muscle tone, decreased systemic vascular resistance



Calcium Channel Blockers Benzothiazepines:

diltiazem (Cardizem, Dilacor) Phenylalkamines:

verapamil (Calan, Isoptin) Dihydropyridines:

amlodipine (Norvasc), bepridil (Vascor), nicardipine (Cardene)

nifedipine (Procardia), nimodipine (Nimotop)

Antihypertensive Agents: Therapeutic UsesCalcium Channel Blockers Angina Hypertension Dysrhythmias Migraine headaches

Antihypertensive Agents: Side EffectsCalcium Channel Blockers Cardiovascular

hypotension, palpitations, tachycardia Gastrointestinal

constipation, nausea Other

rash, flushing, peripheral edema, dermatitis

Antihypertensive Agents: DiureticsDecrease the plasma and extracellular fluid

volumesResults: decreased preload

decreased cardiac output decreased total peripheral resistance

Overall effect: decreased workload of the heart, and decreased blood pressure


Vasodilators

Directly relaxes arteriolar smooth muscle Result: decreased systemic vascular

response, decreased afterload, andPERIPHERAL VASODILATION


Vasodilators diazoxide (Hyperstat) hydralazine HCl (Apresoline) minoxidil (Loniten, Rogaine) sodium nitroprusside (Nipride,

Nitropress)

Antihypertensive Agents: Therapeutic UsesVasodilators Treatment of hypertension May be used in combination with

other agents Sodium nitroprusside and diazoxide

IV are reserved for the management of hypertensive emergencies

Antihypertensive Agents: Side EffectsVasodilators Hydralazine:

dizziness, headache, anxiety, tachycardia, nausea and vomiting, diarrhea, anemia, dyspnea, edema, nasal congestion

Sodium nitroprusside: bradycardia, hypotension, possible

cyanide toxicity

Antihypertensive Agents: Nursing Implications Before beginning therapy, obtain a thorough

health history and head-to-toe physical examination.

Assess for contraindications to specific antihypertensive agents.

Assess for conditions that require cautious use of these agents.

Antihypertensive Agents: Nursing Implications Educate patients about the importance of

not missing a dose and taking the medications exactly as prescribed.

Patients should never double up on doses if a dose is missed; check with physician for instructions on what to do if a dose is missed.

Monitor BP during therapy. Instruct patients to keep a journal of regular BP checks.

Antihypertensive Agents: Nursing Implications Instruct patients that these drugs should not

be stopped abruptly, as this may cause a rebound hypertensive crisis, and perhaps lead to CVA.

Oral forms should be given with meals so that absorption is more gradual and effective.

Administer IV forms with extreme caution and use an IV pump.

Antihypertensive Agents: Nursing Implications Remind patients that medications is

only part of therapy. Encourage patients to watch their diet, stress level, weight, and alcohol intake.

Patients should avoid smoking and eating foods high in sodium.

Encourage supervised exercise.

Antihypertensive Agents: Nursing Implications Instruct patients to change positions

slowly to avoid syncope from postural hypotension.

Patients should report unusual shortness of breath; difficulty breathing; swelling of the feet, ankles, face, or around the eyes; weight gain or loss; chest pain; palpitations; or excessive fatigue.

Antihypertensive Agents: Nursing Implications Men taking these agents may not be

aware that impotence is an expected effect. This may influence compliance with drug therapy.

If patients are experiencing serious side effects, or believe that the dose or medication needs to be changed, they should contact their physician immediately.

Antihypertensive Agents: Nursing Implications Hot tubs, showers, or baths; hot

weather; prolonged sitting or standing; physical exercise; and alcohol ingestion may aggravate low blood pressure, leading to fainting and injury. Patients should sit or lie down until symptoms subside.

Patients should not take any other medications, including OTC drugs, without first getting the approval of their physician.

Antihypertensive Agents: Nursing Implications Monitor for side/adverse effects

(dizziness, orthostatic hypotension, fatigue) and for toxic effects.

Monitor for therapeutic effects

Blood pressure should be maintained at less than 140/90 mm Hg

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Antihipertensi Drugs

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