Pfizer Inc has filed a citizen petition alerting the FDA that generic azithromycin products sold by Teva Pharmaceuticals USA and Sandoz Inc. appear to be misbranded because their labels do not accurately describe the drugs' active ingredients.

Pfizer also has brought patent infringement actions against the two companies claiming that these products violate a recently-issued Pfizer patent. The Teva and Sandoz drugs are generic versions of Pfizer's antibiotic, Zithromax, informs the company release.

Pfizer's petition asks the FDA to initiate a recall of the Teva and Sandoz medicines to correct their misbranding. Pfizer also asks the agency to review the product approval applications filed by the two companies to ensure the information contained within them is accurate and complete and, if not, to take appropriate remedial action.

"Patients and physicians must be able to trust that the medicine in the bottle is the same as that which is described in the label. Pfizer wants to ensure that patients do not receive generic products that fail to meet FDA standards," said Hank McKinnell, Pfizer chairman and chief executive officer.

In its patent infringement actions, Pfizer is claiming that the Teva and Sandoz products violate a recently-issued Pfizer patent covering azithromycin sesquihydrate. Pfizer is requesting that the court impose preliminary and permanent injunctions against further sales of the drugs.

Pfizer alleges that the drugs contain significant amounts of azithromycin sesquihydrate rather than the azithromycin monohydrate that they claim in their labels. Both Pfizer's Zithromax and a generic azithromycin launched by the company's Greenstone subsidiary contain azithromycin dihydrate, which is the product approved in Pfizer's NDA. Zithromax's composition-of-matter patent in the US expired in November 2005, added the release.

Teva and Sandoz each launched their generic products in November, 2005. In response to those launches, Greenstone introduced its generic azithromycin in the same month. Pfizer will continue to market its generic azithromycin through Greenstone.