Prescription Obesity Drug Linked to Colon Cancer; Petition Filed Today with FDA

WASHINGTON, D.C. – Public Citizen today petitioned the U.S. Food and Drug Administration (FDA) to immediately remove from the market the prescription version of Xenical (orlistat, made by Roche Pharmaceuticals) because the obesity treatment has been known to cause a significant increase in aberrant crypt foci (ACF), which are widely believed to be a precursor to colon cancer. Last week, the FDA sent an “approvable” letter concerning the over-the-counter (OTC) version of orlistat to GlaxoSmithKline, which has applied to market this version. Despite safety concerns, if GlaxoSmithKline meets the conditions set by the FDA – conditions that have not been made public – this would make the drug eligible for final approval for OTC sales.

Public Citizen’s petition is based on findings from the pharmacology review of Roche’s own data and a recent independent confirmation that orlistat causes ACF in the colon of rats. There is a large amount of scientific literature that acknowledges the importance of ACF as the earliest identifiable neoplastic colonic lesion and a putative precursor of colon cancer. The FDA’s own 1997 review of orlistat indicated a concern with colonic cell proliferation, and the drug was not initially approved by the FDA because of clinical trials that found a four- to seven-fold increased risk of getting breast cancer while taking orlistat.

In addition to cancer concerns, adverse events for patients taking orlistat include a cluster of gastrointestinal symptoms and a loss of fat-soluble vitamins, including beta-carotene and vitamins A, D, E and K. Orlistat’s efficacy has also been called into question because of two recently published clinical trials that showed only a 2.8 percent difference in weight loss after four years between patients taking orlistat and those on placebo.

“The failure to ban the prescription version of this drug or, worse, to make it much more widely available by allowing OTC sales, is a decision that is likely to increase cancer incidence,” said Dr. Sidney Wolfe, director of Public Citizen’s Health Research Group. Public Citizen is joined in the petition by two professors of pathology at Case Western Reserve School of Medicine, Dr. Theresa Pretlow and Dr. Thomas Pretlow, who are both experts on ACF’s link to colorectal cancer. Their work on this topic has been largely funded by the National Cancer Institute, whose director is now acting FDA commissioner.

“The FDA should not allow a drug … to remain on the market for the long-term treatment of a non-lethal condition when it combines so little efficacy coupled with a still unresolved potential to cause breast and colon cancer,” says the 12-page petition. “[The] FDA is now considering increasing the number of people exposed to the drug by allowing OTC use. There is no scientific justification for this decision.”

Public Citizen has a strong track record of identifying dangerous drugs well before federal regulators take action to ban or put warnings on these drugs. For example, Public Citizen warned consumers about the dangers of Vioxx, ephedra, Bextra, Rezulin, Baycol, Propulsid and many other drugs years before the drugs were pulled from the market. 

The petition can be viewed at www.WorstPills.org.