The FDA said it has received 32 reports of serious liver injury -- including six cases of liver failure -- among users of diet drug orlistat, which is sold as a prescription drug under the trade name Xenical and as an over-the-counter diet aid under the name Alli.
As a result of those reports, the FDA said it had initiated a safety review of the product, which works by blocking the absorption of ingested dietary fats.
Orlistat 120 mg (Xenical) was approved in 1999 for weight loss in conjunction with a reduced caloric diet and for prevention of rebound weight gain after weight loss. The OTC version, orlistat 60 mg, was approved in 2007 for use by overweight adults ages 18 and older.
The FDA said that in addition to the 32 reported cases, orlistat safety "was discussed at the CDER Drug Safety Oversight Board in April 2009, and the FDA is reviewing other data on suspected cases of liver injury submitted by the manufacturers of orlistat. FDA's analysis of these data is ongoing and no definite association between liver injury and orlistat has been established at this time."