Wilmington, Delaware: Drug maker Pfizer Inc. sued Dr Reddy’s Laboratories Ltd, asking a judge to prohibit sales of generic versions of its best-selling anti-cholesterol medicine Lipitor until 2017.

Hyderabad-based Dr Reddy’s had notified Pfizer in October that it was seeking US Food and Drug Administration permission to sell copies of Lipitor, and that the patent wasn’t infringed, according to the lawsuit.

“Pfizer will be irreparably harmed if Dr Reddy’s is allowed to sell the drug in the US market,” Pfizer lawyers said in the complaint, filed on Tuesday in federal court in Wilmington, Delaware. New York-based Pfizer, with $48.2 billion (Rs2.3 trillion now) in total sales last year, had $12.4 billion in 2008 Lipitor sales, $7.7 billion of which were in the US.

A Dr Reddy’s spokesperson said, “We are confident of our position and are working to resolve the matter as quickly as possible.”

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Mint’s Radhieka Pandeya in New Delhi contributed to this story