A private group asked health officials to ban the prescription version of the fat-blocking drug orlistat, citing a link to what some scientists believe are precancerous lesions in the large intestine.
A petition Public Citizen filed with the Food and Drug Administration came just days after the regulatory agency gave conditional approval to GlaxoSmithKline to sell a nonprescription version of the drug.
However, the petition asks only to have the prescription version of orlistat, sold by Roche since 1999 under the brand name Xenical, removed from the market. The group previously opposed allowing orlistat to be sold over the counter.
Dr. Sidney Wolfe, director of Public Citizen’s Health Research Group, said scientific studies in rats linked orlistat to increased numbers in the colon of aberrant crypt foci, or microscopic lesions that some experts think are precancerous.
“To date, the overwhelming body of evidence indicates Xenical is safe and consumers should continue to feel confident in the product,” said Roche spokesman Terence Hurley. He added that more than 22 million patients in 145 countries have used the drug.
Studies in rats and mice given the equivalent of dozens of times the human dose of orlistat found no evidence of the drug causing cancer, according to its FDA-approved labeling information.
Orlistat works when taken with meals by blocking the absorption of about one-quarter of any fat consumed. That fat is passed out of the body in stools, which can be loose as a result.