gi drugs

AGENTS USED TO TREAT GASTROINTESTINAL

DISORDERS

ANTACIDSANTACIDS

HYDROCHLORIC ACID

is constantly secreted by the parietal cells in

the lining of the stomach.

The rate of acid secretion in the

stomach may vary widely throughout the day, but it is generally at its highest level just before or during the ingestion of a meal

ANTACIDS

-are alkaline chemical agents used for relief

of symptoms associated with hyperacidity and

peptic ulcer disease

-primary goal is for relief of pain

The pain-reducing effect of antacids is believed to be due to their:

acid neutralizing capacity

inhibition of the protein-digesting ability of pepsin

action to increase the resistance of the stomach lining

The pain-reducing effect of antacids is believed to be due to their:

Ability to increase the tone of the lower esophageal sphincter

-this is why antacids are effective in reducing pain associated with GERD

SELECTION OF ANTACIDS

An ideal antacid product:

effectively neutralizes large volumes of acid with a reasonably small dose

avoids causing “acid rebound”

has a prolonged action

does not interfere with the digestion or absorption of nutrients or drugs



does not cause constipation or diarrhea

does not release carbon dioxide gas in the stomach



does not interfere with electrolyte and acid base balance at usual therapeutic doses

is palatable

is inexpensive

CLASSIFICATION

SYSTEMIC ANTACIDS

NON-SYSTEMIC ANTACIDS

SYSTEMIC ANTACIDS

- are highly soluble in gastric fluids; once dissolved, they are absorbed

readily-agents this category (sodium

bicarbonate) have a rapid onset and a short duration of action

SYSTEMIC ANTACIDS

- most likely to cause acid-base and electrolyte disturbances

- May cause rebound hyperacidity

NONSYSTEMIC ANTACIDS

- most useful agents for long-term therapy

- although a small proportion of the antacid may be absorbed, most of the

dose remains in the GI tract and will not alter systemic acid base balance or

electrolyte levels


- caution must be used in administering magnesium-containing antacids to clients with impaired renal function

-as magnesium may accumulate and cause toxicity in such clients


- Most non-systemic antacids will cause either constipation or diarrhea

EXAMPLE OF NONSYSTEMIC ANTACIDS

Aluminum carbonate gel (Basaljel)Aluminum hydroxide gel (Amphogel,

Alternagel)Aluminum phosphate gel (Phosphaljel)

Calcium carbonate (Tums, Chooz)Dihydroxy-aluminum sodium carbonate

(Rolaids Antacid)

EXAMPLE OF NONSYSTEMIC ANTACIDS

Magaldrate (Riopan)Magnesium Hydroxide (Milk of

Magnesia, MOM)Magnesium Oxide

EXAMPLE OF SYSTEMIC ANTACIDS

Sodium Bicarbonate (Baking Soda, Soda Mint)

NURSING IMPLICATIONSNURSING IMPLICATIONS

Administration with other drugs or food may reduce the absorption of these

agents

Do not take other oral drugs within 1-2 hours of antacid administration

Monitor quality and consistency of stool during antacid therapy


Shake liquid antacid products well prior to use

Follow administration of antacid with a small amount of water or milk to facilitate passage into stomach

Do not administer within 1-2 hours of any enteric coated products


Assess the client’s response to antacid use

OTHER AGENTS OTHER AGENTS AFFECTING AFFECTING

GASTROINTESTINAL GASTROINTESTINAL FUNCTIONFUNCTION

LAXATIVES

CONSTIPATION is a condition in which passage of feces through the lower GI

tract is slow or nonexistent

This results in a reduction in the frequency and an increase in difficulty

of fecal evacuation

FACTORS THAT CONTRIBUTE TO CONSTIPATION

Ignoring the defecation urge

Environmental changes

Ingestion of a low-residue diet

Decreased physical activity

Emotional stress


Ingestion of constipating foods (e.g. dairy products)

Use of constipating drugs (e.g. calcium-and/or aluminum-containing antacids, anticholinergics, opiates)


Chronic misuse or overuse of stimulant laxatives

Decreased fluid intake

LAXATIVES

are drugs intended to facilitate the passage and elimination of feces from

the colon and rectum

USES OF LAXATIVES

Prepare clients for a lower GI x-ray series or surgery

Reduce the strain of defecation in clients with cardiovascular disease or in

post-operative clients

Diagnose and treat parasitic infestations of the GI tract

USES OF LAXATIVES

Help remove unabsorbed poisons from the GI tract when oral poisonous

substances have been consumed

Prevent or treat constipation

STIMULANT LAXATIVES

-increase the motility of the GI tract by chemical irritation of the intestinal

mucosa

-it may also act by increasing the secretion of water into both the small

and large intestines

They tend to produce a watery, often diarrheal, stool

EXAMPLE OF STIMULANT LAXATIVES

Bisacodyl (Dulcolax, Bisacolax)Cascara Sagrada

Castor OilPhenolphthalein (Alophen)

Senna (Senokot)

NURSING IMPLICATIONS

Contraindicated for use in clients with abdominal pain, nausea, vomiting, or

rectal fissuresShould only be used for short-term

treatmentEvaluate effectiveness of laxative

SALINE LAXATIVES

-draw water through the intestinal wall by osmotic action and thereby increase

the fluidity of the stool and stimulate greater intestinal motility

Saline laxatives are only employed in the rapid evacuation of the bowel (in

preparing a client for endoscopic examination)

EXAMPLE OF SALINE LAXATIVES

Magnesium CitrateMagnesium Hydroxide

Magnesium Sulfate, epsom saltsSodium Phosphate (Fleet enema)


Should only be used for short-term treatment

Contraindicated for use in clients with abdominal pain, nausea, vomiting, or

other symptoms of appendicitisEvaluate the effectiveness of laxative

BULK-FORMING LAXATIVES

-among the safest laxatives available. They are natural or semisynthetic

compounds that absorb fluid and swell in the intestine, thereby stimulating

peristaltic action

-tend to produce normally formed stool


Barley Malt extract (Maltsupex)Methylcellulose (Citrucel)

PolycarbophilPsyllium (Metamucil, Novo-Mucilax)


Laxative effect may not be evident for up to 3 days

Contraindicated for use in clients with abdominal pain, nausea, vomiting or

other symptoms of appendicitisEvaluate effectiveness of laxative

LUBRICANT LAXATIVES

-this are oils that act as lubricants to facilitate the passage of the fecal mass

through the intestine

EXAMPLE: Liquid Petrolatum (Fleet Oil Retention Enema)

Oral form should be administered on an empty stomach because of the drugs ability to impair the absorption of fat-soluble drugs and nutrients

STOOL SOFTENERS

-this are detergent-like drugs that permit easier penetration and mixing of

fats and fluids with the fecal mass

-this agent does not irritate the intestine or stimulate peristaltic action


Docusate calcium (Calax, Surfak)Docusate potassium (Dialose)

Docusate sodium (Colace, Selax)


Liquid dosage form may be given in milk, fruit juice, or formula to mask tasteAction may not be evident for up to 3

daysPrevents development of constipation.

It is not used to treat existing constipation


Avoid use for longer than 1 weekEvaluate client for the effectiveness of

these agents

ANTIDIARRHEAL AGENTS

DIARRHEA is defined as the abnormally frequent passage of watery

stools.

It is generally caused by the failure of the small and large colon to adequately absorb fluid from the intestinal contents

POSSIBLE CAUSES OF DIARRHEA

Allergy

Amebic dysentery

Antibiotics

Cancer of the GI Tract

Food poisoning

POSSIBLE CAUSES OF DIARRHEA

Lactose intolerance

Medication

Radiation

Regional enteritis

Ulcerative colitis

DRUG THERAPY

is generally aimed at REDUCING the MOTILITY of the GI Tract,

thereby permitting normal dehydration of the intestinal contents to take place

DRUGS THAT REDUCE GI MOTILITY

TWO CLASSES:

OPIUM DERIVATIVES

gi drugs

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