In a petition, Public Citizen also asked the U.S. Food and Drug Administration to reject making the weight-loss pill widely available over the counter. On Friday, the FDA said it granted GlaxoSmithKline Plc. conditional approval to sell the drug without a prescription if it first meets certain undisclosed criteria. Glaxo owns U.S. rights for nonprescription sales of Xenical.
The group said a December 2005 study confirmed earlier company data showing Xenical, known generically as orlistat, can cause abnormal cell growth in the lining of the colon. Experts widely recognize the lesions as an early indicator of cancer, the advocacy group added.
The study, published in the journal Cancer Letters, found "a significant increase" of colon lesions in rats given Xenical regardless of whether they were on high-fat or standard diets.
Xenical comes in 120-milligram capsules to be taken three times a day with meals. The proposed nonprescription version, called Alli, comes in 60 mg tablets with 1-2 taken with meals.
It works by preventing fat from being absorbed by the body but can cause excess gas, oily discharge and other gastrointestinal problems.
