5-HT3 receptor antagonists
5-HT3 receptor antagonists
Alosetron is a selective 5-HT3 receptor antagonist used for short-term treatment of women with irritable bowel syndrome (IBS) with severe diarrhea as the main symptom. This drug is available only through a restricted marketing program because of reported serious GI adverse effects. Only prescribers enrolled in the prescribing program for alosetron may write a prescription for it.
Pharmacokinetics
Alosetron is rapidly absorbed after oral administration and is metabolized by the cytochrome P450 pathway.
Pharmacodynamics
Alosetron is thought to block serotonin in the GI system, thereby reducing the abdominal cramping and discomfort, urgency, and diarrhea commonly associated with IBS.
Pharmacotherapeutics
Alosetron is used for the short-term treatment of a woman with IBS whose primary symptom is diarrhea. The drug shouldn’t be taken if the patient is constipated and should be stopped if constipation develops.
Drug interactions
Alosetron produces a 30% inhibition of N-acetyltransferase and CYP1A2. Although studies haven’t been done, the inhibition of N-acetyltransferase may have clinical significance when alosetron is given with such drugs as isoniazid, procainamide, and hydral-azine. Alosetron given with other drugs that decrease GI motility could cause constipation.
Warning!
Adverse reactions to alosetron
Alosetron can cause serious and sometimes fatal adverse reactions, such as ischemic colitis, and complications of constipation, including obstruction, perforation, and toxic megacolon.
Elderly patients
Older adults may have increased sensitivity to alosetron’s effects, thus increasing their risk of developing serious constipation
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