Pfizer Inc., the world's largest drug company, has filed a patent infringement suit against Teva Pharmaceutical Industries Ltd. and Sandoz Inc over their azithromycin products, the generic versions of Pfizer's antibiotic, Zithromax, used for the treatment of respiratory infections. Pfizer also petitioned the US Food & Drug Association (FDA) to recall the products sold by Teva and Sandoz, saying the drugs have been misbranded because their labels do not accurately describe the drugs' active ingredients. "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," said Hank McKinnell, Chairman and CEO of US-based Pfizer. "We want to ensure that patients do not receive generic products that fail to meet FDA standards." Teva said, in response, that it believes the allegations are baseless and without merit. "Pfizer's efforts are a thinly veiled attempt to discredit Teva and the entire generic drug industry, which have been providing affordable, safe pharmaceutical products to patients for decades," Teva said. "We have substantial defenses to Pfizer's enforcement of the sesquihydrate patent." Teva and Sandoz launched their versions of the Zithromax drug in November 2005 after Pfizer's US patent expired. The branded product has annual sales of approximately $1.6 billion. In its law suit, Pfizer is claiming that the Teva and Sandoz products violate a recently-issued patent covering azithromycin sesquihydrate and is therefore requesting that the court impose preliminary and permanent injunctions against further sales of the drugs. It alleges that the drugs contain significant amounts of azithromycin sesquihydrate rather than the azithromycin monohydrate that Teva and Sandoz claim in their labels. In addition to asking the FDA to force a product recall, Pfizer requested that the FDA 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." Teva said its azithromycin active pharmaceutical ingredient is manufactured by its own API division and that "the final product contains azithromycin monohydrate as stated on the label and as approved by the FDA."