Research Area: Metabolic Disease
Biological Activity:
Loperamide is an opioid-receptor agonist with an ED50 of 0.15 mg/kg. It acts on the μ-opioid receptors in the myenteric plexus of the large intestine; by itself it does not affect the central nervous system like other opioids. It works by decreasing the activity of the myenteric plexus, which, like morphine, decreases the tone of the longitudinal smooth muscles but increases tone of circular 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. [1][2]