The Indian pharmaceutical companies are fighting in more than one-fourth of the patent infringement cases registered in the United States. It is learnt that the total market value of the products over which the Indian companies are fighting, is more than Rs 4000 crore.

According to the available data, there are more than 100 patent cases relating to pharmaceutical products registered in the US and market value of the products is nearly Rs 8500 crore in total. Out of these 100 cases, Indian firms are fighting 30 cases, in which most of the Paragraph IV infringement cases are on major drugs like Aciphex, Allegra, Biaxin XL, Eloxatin and Nexium.

The list of the Indian companies, which involved in the patent litigation cases in the US, includes Dr Reddy's, Ranbaxy, Lupin, Sun Pharma, Dabur Pharma, Glenmark, Orchid Chemicals and Pharmaceuticals and Wockhardt. Dr Reddy's leads the list of the Indian companies, involved in the patent litigation with 10 cases, following Ranbaxy with eight, Sun Pharma six and Lupin four.

Others like Delhi based Dabur Pharma, Chennai based Orchid Chemicals and Pharmaceuticals and Mumbai based Wockhardt involved in one case each. The other Mumbai based pharma major Glenmark is fighting in two cases. The latest instances in the patent litigation row are Novartis charge against Dr Reddy's over Lotrel and US based Sepracor Inc, jointly with University of Massachusetts against Mumbai based Glenmark Pharmaceuticals over anti-allergic drug Clarinex.

The market of Zyprexa over which Eli Lilly is fighting against Dr Reddy's is Rs 400 crore and those of Eloxatin, a drug for cancer treatment, over which sanofi aventis is fighting against Dabur Pharma is Rs 200 crore. The Mumbai based Lupin is fighting a patent litigation with pharma major Wyeth over Effexor XR, which has a market of Rs 250 crore.

Commenting on the patent rows, in which the company has involved, the spokesperson of Ranbaxy, said, "It is part and parcel of each generic company to have access to the to market. The generic version always is strategy of the company to enter the market".

The recent past has also witnessed patent litigation settlements between Ranbaxy and GlaxoSmithKline (GSK) over valtrex and Lupin Ltd with US pharma major Abbott over Abbott's blockbuster antibiotic drug Omnicef, known under the generic name as cefdinir.