The Food and Drug Administration is investigating reports of liver damage in patients taking diet pills containing the chemical orlistat, an ingredient in the popular over-the-counter drug Alli and its prescription version Xenical.
While the FDA has not sent out a public warning about the drug, it is looking at reports that 32 cases of serious liver damage have been identified from 1999 to 2008, including six cases of liver failure. All but two of the injuries occurred outside the United States.
"We estimate that since 1999, more than 11 million prescriptions have been dispensed, and we see 32 adverse events around the world. It's a fairly unusual occurrence [for a] very popular drug," an FDA spokeswoman said.
Orlistat blocks the intestines from absorbing fat when taken up to three times a day with meals. The FDA approved Xenical in 1999 for weight management in conjunction with a reduced-calorie diet. Alli, which contains half the dose of orlistat, was cleared for nonprescription use in 2007.
Both drugs are marketed by British drugmaker GlaxoSmithKline, though Xenical is manufactured by Swiss firm Roche.
Consumers taking the diet pills should continue to use as directed, the FDA said, although they should discontinue use if they experience weakness, fever, jaundice or other symptoms of liver injury. With wire reports