The Food and Drug Administration (FDA) is cautioning US consumers about dangers associated with buying prescription drugs over the Internet. This alert is being issued based on information the agency received showing that 24 apparently related web sites may be involved in the distribution of counterfeit prescription drugs.

On three occasions during recent months, FDA received information that counterfeit versions of Xenical 120 mg capsules, a drug manufactured by Hoffmann-La Roche Inc. Roche were obtained by three consumers from two different Web sites. Xenical is an FDA-approved drug used to help obese individuals who meet certain weight and height requirements lose weight and maintain weight loss.

None of the capsules ordered off the Web sites contained orlistat, the active ingredient in authentic Xenical. In fact, laboratory analysis conducted by Roche and submitted to the FDA confirmed that one capsule contained sibutramine, which is the active ingredient in Meridia, an FDA-approved prescription drug manufactured by Abbott Laboratories.

While this product is also used to help people lose weight and maintain that loss, it should not be used in certain patient populations and therefore is not a substitute for other weight loss products. In addition the drug interactions profile is different between Xenical and sibutramine, as is the dosing frequency; sibutramine is administered once daily while Xenical is dosed three times a day.

Other samples of drug product obtained from two of the Internet orders were composed of only talc and starch. According to Roche, these two samples displayed a valid Roche lot number of B2306 and were labelled with an expiration date of April 2007. The correct expiration date for this lot number is actually March 2005. Pictures of the counterfeit Xenical capsules provided