Irritable Bowel Syndrome Message Boards | FDA revisions to safety labeling for Lotronex (alosetron )

The U.S. Food and Drug Administration approved in February revisions to safety labeling to advise that use of alosetron HCl has been associated rarely with serious gastrointestinal tract adverse events and concomitant administration of alosetron HCl and fluvoxamine is contraindicated; caspofungin acetate should be administered concomitantly with cyclosporine only in those patients for whom the potential benefit outweighs the potential risk of elevated liver enzyme levels; the atenolol component of atenolol-chlorthalidone tablets is associated with a risk of clinically significant bradycardia in neonates born to mothers receiving the fixed-dose combination drug at parturition or while breast-feeding.

Alosetron (Lotronex) Associated Rarely With Serious Gastrointestinal Adverse Events

On Feb. 18, the FDA approved revisions to the safety labeling for alosetron HCl tablets (Lotronex, made by GlaxoSmithKline) to advise of contraindications and warnings associated with its use.

Concomitant use of alosetron with fluvoxamine is contraindicated. Fluvoxamine is a known strong inhibitor of CYP1A2 that has been shown in clinical studies to increase mean alosetron plasma concentrations by approximately sixfold and prolong its half-life by approximately threefold.

The FDA warns that use of alosetron has been associated with infrequent reports of serious gastrointestinal tract adverse events such as ischemic colitis and complications of constipation. Some of these events have occurred without warning and have resulted in hospitalization, but rarely have resulted in blood transfusion, surgery, or death.

Serious complications of constipation, including obstruction, ileus, impaction, toxic megacolon, and secondary bowel ischemia, have been reported in alosetron clinical trials and during postapproval use. Intestinal surgery, including colectomy, has been required in some cases. Postmarketing reports have also included rare incidences of perforation and death.

In clinical trials, constipation-related adverse events resulted in a discontinuation rate of approximately 10% among alosetron recipients (overall incidence rate for patients is about 0.1%; 1 per 1,000 patients).

The FDA notes that the risk of serious complications of constipation may be increased in patients who are elderly, debilitated, or concurrently receiving medications that reduce gastrointestinal motility.

Alosetron therapy has also been associated with rare reports of ischemic colitis in clinical trials and during postapproval use.

In clinical trials, the cumulative incidence of ischemic colitis was 0.2% in women receiving alosetron for three months (2 per 1,000 patients; 95% confidence interval [CI], 1 - 3) and 0.3% after six months of therapy (3 per 1,000 patients; 95% CI, 1 - 4). According to the FDA, these data from controlled studies are insufficient to estimate the incidence of ischemic colitis in patients receiving alosetron therapy for longer than six months.

Alosetron is indicated for the treatment of chronic, severe, diarrhea-predominant irritable bowel syndrome in women who have not responded adequately to conventional therapy.

http://www.medscape.com/viewarticle/504287

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Heather is the Administrator of the IBS Message Boards. She is the author of Eating for IBS and The First Year: IBS, and the CEO of Heather's Tummy Care. Join her IBS Newsletter. Meet Heather on Facebook!

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