antimotility

Antimotility is a pharmacological property characterized by the reduction of muscular contractions of the gastrointestinal tract, thereby slowing intestinal transit. In medicine, antimotility agents are used primarily to treat diarrhea by increasing fluid and electrolyte absorption from the stool and by decreasing stool frequency and urgency. Antimotility is the opposite of prokinetic activity, which enhances GI motility.

Most antimotility effects are produced by opioids acting on the enteric nervous system, such as loperamide and diphenoxylate, which activate mu-opioid receptors to diminish propulsive peristalsis while increasing segmental contractions. Some agents also slow motility through anticholinergic (antimuscarinic) action, as seen with hyoscine derivatives. Diphenoxylate is often combined with atropine to discourage misuse. Loperamide is notable for minimal central nervous system penetration, which limits central opioid effects.

Antimotility therapy is generally indicated for short-term management of acute nonspecific diarrhea and for chronic diarrheal syndromes where rapid transit worsens symptoms. Caution is advised in infectious diarrhea with fever or bloody stools, suspected perforation, inflammatory bowel disease with risk of toxic megacolon, or in children. Common adverse effects include constipation, abdominal cramps, and, rarely, ileus. Prolonged use or misuse carries risks of bowel obstruction and, in rare cases, dependence on opioids.