Small molecule
PubChem CID 3955
Loperamide
Imodium
- Mechanism of action
- Peripheral mu-opioid receptor agonist
- In plain language
- Binds to opioid receptors in the gut wall to slow down intestinal movement, without reaching the brain, so it calms diarrhea without producing typical opioid effects elsewhere in the body.
- How it works
- Loperamide acts as an agonist at mu-opioid receptors in the myenteric plexus of the intestinal wall. Receptor activation inhibits acetylcholine and prostaglandin release, which slows peristaltic contractions and prolongs intestinal transit time. The extended transit time allows greater reabsorption of water and electrolytes, reducing stool volume and increasing fecal viscosity, while increased anal sphincter tone reduces incontinence and urgency. Because loperamide undergoes extensive first-pass metabolism and is actively effluxed by P-glycoprotein at the blood-brain barrier, it produces negligible central opioid activity at therapeutic doses.
- Therapeutic applications
- Indicated for the control and symptomatic relief of acute nonspecific diarrhea and of chronic diarrhea associated with inflammatory bowel disease, and to reduce the volume of discharge from ileostomies. OTC-labeled formulations are indicated for control of symptoms of diarrhea, including travelers' diarrhea.
- Class
- Small molecule
- Therapeutic area
- Gastrointestinal
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