A 35-year-old woman with irritable bowel syndrome comes to the physician because of increased diarrhea. She has not had any fever, bloody stools, nausea, or vomiting. The increase in stool frequency began when she started a new job. She is started on loperamide, and her symptoms improve. Which of the following is the primary mechanism of action of this drug?

Question

Quizplus · Accepted Answer

Eductional Objective: Loperamide is an antidiarrheal drug that acts directly on M-opioid receptors in the GI tract to inhibit propulsive peristalsis and intestinal fluid secretion, and increase anal sphincter tone. Unlike other M-opioid receptor agonists, loperamide has poor CNS penetration and therefore lacks analgesic properties.

A 35-Year-Old Woman with Irritable Bowel Syndrome Comes to the Physician