World’s largest drug maker Pfizer has moved the court against Dr Reddy’s Laboratories seeking a delay in launching the Indian drug maker’s low-cost version of atorvastatin, the world’s best-selling medicine, in the US market.

Pfizer said in its filing before a American local court in Delaware last Monday that Dr Reddy’s plan to launch a generic version of atorvastatin sold under the Lipitor brand will infringe upon its patent.

The drug maker, which rakes in over $12 billion in global sales from Lipitor, has asked the court to withhold approval of the drug until one of its patents for Lipitor expires in January 2017.

Media reports quoted Dr Reddy’s spokesman as saying that Pfizer had already sued it for filings for other strengths of atorvastatin while it expected that the US company would file a suit on Dr Reddy’s 80 mg ANDA (abbreviated new drug application) filing.

Earlier, Pfizer had blocked another Indian drug maker Ranbaxy Laboratories from launching a generic version of Lipitor in the US. However in June 2008, it had settled for an out-of-court settlement with Ranbaxy allowing it to sell a low-priced version of the medicine from November 2011, when one of its key patents on the same drug expires.

Ranbaxy now holds a six-month marketing exclusivity for its low-cost version of the product, as it was the first generic drug maker to challenge Pfizer’s patent for Lipitor. The Daiichi Sankyo-owned Ranbaxy will now benefit due to the delay in launch of Dr Reddy’s product.

Hyderabad-based Dr Reddy’s will be allowed to launch its low-priced drug by May 2012 if it wins the case against Pfizer which could bring significant revenue given that there would be a few generic players launching their products after November 2011.

Pfizer initiated legal action after Dr Reddy’s notified that it had filed an ANDA with the American drug regulator to sell atorvastatin calcium tablets in 80 mg dosage forms.

Earlier, the US company had sued Dr Reddy’s for alleged infringement of the same patent when the Indian drug maker sought the US Food and Drugs Administration nod to sell generic versions of atorvastatin calcium tablets in 10 mg, 20 mg, and 40 mg dosage forms. The case is still pending with the same US court.