loperamide

Loperamide is a commonly used over-the-counter (OTC) and prescription medicine that is approved to help control symptoms of diarrhea, including Travelers’ Diarrhea. The maximum approved daily dose for adults is 8 mg per day for OTC use and 16 mg per day for prescription use. It is sold under the OTC brand name Imodium A-D, as store brands, and as generics. In vitro and animal studies show that IMODIUM® (loperamide hydrochloride) acts by slowing intestinal motility and by affecting water and electrolyte movement through the bowel. Loperamide binds to the opiate receptor in the gut wall. Consequently, it inhibits the release of acetylcholine and prostaglandins, thereby reducing propulsive peristalsis, and increasing intestinal transit time. Loperamide increases the tone of the anal sphincter, thereby reducing incontinence and urgency. Loperamide is also indicated for reducing the volume of discharge from ileostomies. In man, Loperamide prolongs the transit time of the intestinal contents. It reduces the daily fecal volume, increases the viscosity and bulk density, and diminishes the loss of fluid and electrolytes. Tolerance to the antidiarrheal effect has not been observed. Loperamide is an opioid receptor agonist and acts on the mu opioid receptors in the myenteric plexus large intestines; it does not affect the central nervous system like other opioids. It works specifically by decreasing the activity of the myenteric plexus which decreases the motility of the circular and longitudinal smooth muscles of the intestinal wall. This increases the amount of time substances stay in the intestine, allowing for more water to be absorbed out of the fecal matter. Loperamide also decreases colonic mass movements and suppresses the gastrocolic reflex. — NCATS