DRUGS AFFECTING GASTROINTESTINAL SYSTEM

Antacids
Prototype :
- aluminum/magnesium compounds (Maalox)
- sodium bicarbonate (Alka-Seltzer)
- calcium carbonate (Tums)
- magnesium hydroxide (Milk of Magnesia).
Mechanism of actions :
- neutralize the stomach acidity.
Adverse effects :
- metabolic alkalosis, stone formation
- electrolyte imbalance
- diarrhea (magnesium), constipation (aluminum).
Nursing considerations :
- Give 1 hr after meals.
- Avoid giving medications within 1-2 hrs of antacid administration
(decreases absorption).
- Take fluids to flush after intake of antacid suspensions.
- Monitor for changes of bowel patterns.

Histamine – 2 blockers
Prototype :
- cimetidine (Tagamet), ranitidine (Zantac),
famotidine (Pepcid), nizatidine (Axid).
Mechanism of action:
- blocks H2 receptors in the stomach, reducing
acid secretions.
Nursing considerations :
- Given before or with meals
- Avoid giving other drugs with cimetidine
- Gynecomastia may developed with chronic use of cimetidine.


Proton – Pump Inhibitors (PPI)
Prototype :
- omeprazole (Losec), Lansoprazole (Lanz), pantoprazole (Pantoloc).
Mechanism of action :
- inhibit the proton H+ to combine with Cl- toform hydrochloric acid.
Nursing considerations :
- Given before meals preferably at morning.


Mucosal Barriers
Prototype :
- sucralfate (Carafate), misoprostol (Cytotec).
Mechanism of action :
- coats the mucosa to prevent ulcerations.
Nursing consideration :
- Given before meals.
- Misoprostol is contraindicated for pregnants.
- Sucralfate cause constipation

Anti-diarrheal Agents
Prototype :
- diphenoxylate (Lomotil), loperamide (Imodium), kaolin/pectin mixture (Kaopectate).
Mechanism of actions :
- decrease stomach motility and peristalsis.
Nursing considerations :
- Monitor for rebound constipation.
- Be cautious taking if with infectious diarrhea.
- Monitor atropine toxicity with diphenoxylate.
- Clay, white or pale stool is common with kaopectate.

Laxatives
a. lactulose (Cephulac), Na biphosphate (Fleet
enema) & magnesium salt (Milk of Magnesia)
- retain fluid and distend intestine
b. ducosate (Dialose)
- emulsify fecal fat and water
c. bisacodyl (Dulcolax) & senna (X-prep)
- irritates intestinal mucosa and
stimulate intestinal smooth muscles
d. bulk-forming laxative (Metamucil)
- increase fecal bulk and water content
e. mineral oil
- lubricates & prevent colon absorption

Emetics
Prototype : ipecac syrup, apomorphine
Mechanism of actions :
- induce vomiting through stimulation of vomiting center of medulla.
Indications :
- ingestion of poisonous or toxic substances.
Nursing considerations :
- Consult poison control center before induction of vomiting.
- Administer ipecac syrup with large amount of fluid