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Alosetron Dosage

Applies to the following strength(s): 0.5 mg ; 1 mg

The information at is not a substitute for medical advice. ALWAYS consult your doctor or pharmacist.

Usual Adult Dose for:

Additional dosage information:

Usual Adult Dose for Irritable Bowel Syndrome

For women with severe diarrhea-predominant irritable bowel syndrome (IBS) who have failed to respond to conventional therapy:

Initial: 0.5 mg twice a day

Usual Adult Dose for Diarrhea

Study (n=27) - Carcinoid diarrhea
0.5 to 2 mg orally twice daily

Renal Dose Adjustments

Renal impairment (creatinine clearance 4 to 56 mL/min) has no effect on the renal elimination of alosetron due to the minor contribution of this pathway to elimination.

Liver Dose Adjustments

Mild-to-moderate hepatic impairment: use with caution
Severe hepatic impairment: not recommended

Dose Adjustments

The dosage can be increased to up to 1 mg orally twice a day, if, after 4 weeks on the initial recommended dosage, the drug has been well tolerated but does not adequately control IBS symptoms.

Alosetron should be discontinued if adequate control of IBS symptoms has not been achieved after 4 weeks of treatment with 1 mg twice a day.


Alosetron was reapproved on June 7, 2002 after it was voluntarily withdrawn from the market on November 28, 2000, due to fatal ischemic colitis reported with its use. It is available only through a risk management program called the Prometheus Prescribing Program for LOTRONEX, which is administered by Prometheus ( or 1-888-423-5227). Only physicians who have enrolled in the Prometheus Prescribing Program for LOTRONEX, based on their understanding of the benefits and risks, should prescribe alosetron.

Alosetron is indicated only for women with severe diarrhea-predominant irritable bowel syndrome (IBS) who have failed to respond to conventional therapy. All patients must read and sign the Patient-Physician Agreement for LOTRONEX before receiving the initial prescription for alosetron.

Alosetron is contraindicated in patients with constipation, and in patients with a medical history of chronic or severe constipation, or sequelae from constipation, intestinal obstruction, stricture, toxic megacolon, gastrointestinal perforation, and/or adhesions, ischemic colitis, impaired intestinal circulation, thrombophlebitis, or hypercoagulable state, Crohn's disease or ulcerative colitis, and diverticulitis. Alosetron should not be used in patients who are unable to understand or comply with the Patient-Physician Agreement for LOTRONEX.

Infrequent but serious gastrointestinal adverse events have been reported with the use of alosetron. These events, including ischemic colitis and serious complications of constipation, have resulted in hospitalization, and rarely, blood transfusion, surgery, and death. Some patients have experienced serious complications of constipation or ischemic colitis without warning. Ischemic colitis has been reported in patients receiving alosetron in clinical trials as well as during marketed use of the drug. Ischemic colitis has been reported with use of 1 mg twice daily and with lower doses. A dose-response relationship has not been established. Physicians should instruct patients to immediately report constipation or symptoms of ischemic colitis. Alosetron treatment should be discontinued immediately in patients who develop constipation or symptoms of ischemic colitis (such as rectal bleeding, bloody diarrhea, or new or worsening abdominal pain). Treatment should not be restarted in patients who develop ischemic colitis. Patients who are elderly, debilitated, or taking additional drugs that decrease gastrointestinal motility may be at a greater risk of complications of constipation.

Physicians should instruct their patients to read the medication guide before starting alosetron and each time they refill their prescription, not start taking alosetron if they are constipated, to immediately discontinue alosetron and contact them if they become constipated, or have symptoms of ischemic colitis such as new or worsening abdominal pain, bloody diarrhea, or blood in the stool. Contact their physician again if their constipation does not resolve after discontinuation of alosetron. Resume alosetron only if their constipation has resolved and after discussion with and the agreement of their treating physician, stop taking alosetron and contact their physician if alosetron does not adequately control IBS symptoms after 4 weeks of taking 1 mg twice a day.

Safety and effectiveness in pediatric patients have not been determined.


Data not available

Other Comments

The US FDA requires a Risk Evaluation and Mitigation Strategy (REMS) for alosetron. This includes a medication guide, elements to assure safe use, and an implementation system. Additional information is available at

Food will decrease absorption of alosetron by approximately 25%.