Loperamide

Loperamide, usually as hydrochloride, is a drug effective against diarrhea resulting from gastroenteritis or inflammatory bowel disease. In most countries it is available generically under brand names such as Lopex®, Imodium®, and Pepto® Diarrhea Control.

Mode of action

It is an opioid and acts on the opioid receptors in the large intestines; it does not affect the central nervous system like other opioids.

It works by increasing the tone of the large intestine causing contents to move more slowly through. As a result, feces remains for an extended period of time in the intestine. This produces a lessening of stool volume, increased stool viscosity, and decreased fluid loss.

Contraindications

Treatment should be avoided in the presence of fever or if the stool is bloody. Treatment is not recommended for patients who could suffer detrimental effects from rebound constipation. If there is a suspicion of diarrhea associated with organisms that can penetrate the intestinal walls, such as E. coli O157:H7 or salmonella, loperamide is contraindicated.

Side-effects

Side effects can include the following: drowsiness, constipation, abdominal pain or discomfort, dry mouth, fatigue, and in rare cases toxic megacolon.