A 35-year-old woman has severe irritable bowel syndrome characterized by frequent and profuse diarrhea. She is being treated with alosetron because she has not responded to other forms of antidiarrheal therapy. The physician treating this patient must diligently monitor for
congestive heart failure.
Answer is a. Alosetron is a 5-HT3 receptor antagonist that reduces GI contractility with decreased colonic transit and increased fluid absorption. The drug was withdrawn from the US market (then reapproved by the FDA) because of an unusually high incidence of ischemic colitis (up to 3 per 1000 patients). The cause is not fully established but may result from the drug’s ability to suppress intestinal relaxation.