Lupin, Glenmark sued in US on patent infringement

Lupin and Glenmark Pharmaceuticals have been sued by multinational pharmaceutical companies, Schering Corporation and Wyeth in the US in two separate patent infringement cases.

Wyeth Pharmaceuticals sued Lupin in the Maryland district court on March 12 for challenging three patents on Wyeth's Effexor XR capsule (Venlafaxine hydrochloride), a blockbuster anti-depressent drug. Lupin had filed an abbreviated new drug application (ANDA) to obtain US FDA approval for generic versions of venlafaxine hydrochloride extended-release capsules in 37.5mg, 75mg, and 150mg dosage strengths.

"Based on the growth that we have witnessed in the US, Lupin is in the process of building a generics powerhouse. The Para IV strategy is a key part of this where we carefully select products whose patents we believe we do not infringe or are invalid. Lawsuits such as this are really a part of the process," Dr Kamal K Sharma, managing director, Lupin told Business Standard.

Sources said while the patents on Effexor are slated to expire by 2017, the patent on key ingredient venlafaxine will expire in 2008. Effexor, Wyeth's top-selling drug, accounted for about $3.72 billion sales in 2006.

Glenmark Pharmaceuticals has been sued by Schering Corporation and MSP Company Singapore LLC in the New Jersey district court for filing an ANDA with the US FDA seeking regulatory approval for the generic version of the anti-cholestrol drug Ezetimibe, marketed by Schering as 'Zetia'. Glenmark is believed to be the first to file ANDA for Ezetimibe, on October 25, 2006.

As per the US rules, Glenmark will be entitled to a 180-day exclusivity period on expiration of the patent if Glenmark successfully challenges the patent.

Zetia had sales of approximately US $ 1.5 billion in the US market based on IMS sales data for the year ended Jan 2007.

Ranbaxy Laboratories was sued by Pfizer a few weeks ago following Ranbaxy's ANDA submission to the US FDA for marketing approval of generic Caduet, another blockbuster anti-cholesterol drug of Pfizer.

In another patent infringement case, Sun Pharmaceutical's US subsidiary Caraco Pharmaceuticals filed a case this month with the Michigan eastern district court against pharmaceutical majors Forest Laboratories Inc of US and Lundbeck A/S of Denmark, demanding a launch of its generic version of anxiety and depression drug Lexapro, known as escitalopram oxalate.