Pfizer Inc has filed patent infringement suit against three Indian companies, namely Sun Pharma, Wockhardt Ltd and Lupin Ltd to block marketing generic equivalents to its blockbuster neuropathic pain management drug, Lyrica, in US.

The law suit against Lupin pharma is on the allegation that the company has infringed US Patent No 6,001,876 for isobutylgaba and its derivatives for the treatment of pain issued in December 1999, Patent No 6,197,819 for gamma amino butyric acid analogs and optical isomers, issued in March 2001, and Patent No 5,563,175 GABA and L-glutamic acid analogs for anti-seizure treatment, issued in October 1996.

The petition against Sun Pharma and Wockhardt alleges that the abbreviated new drug applications (ANDAs) of these companies to market generic pregabalin (active ingredient of Lyrica) is an infringement of its 819 patent and has sought the District Court of Delaware to restrict the companies from selling the product prior to the patent expiry of the main ingredient. The case is against the US-based subsidiary of these companies and the parent companies based in India.

Simultaneously, Pfizer has also filed similar law suit in the District Court of Delaware against Actavis Elizabeth LLC and Sandoz Inc to block the marketing of generic Lyrica. According to available information, Lyrica has patent protection through various patent claims at least till December 2018.

Lyrica, a prescription medication used to treat fibromyalgia (muscle and connective tissue pain) and certain types of nerve pain and epileptic seizures, is one of Pfizer's most successful pharmaceutical launches in the recent years and sales improved as it continues to be approved to treat other conditions such as central nerve pain and generalized anxiety disorder.

The product, which entered the US market in 2005, recorded USD 1.8 billion global sales in the year 2007, according to reports. Further, the market research report of Datamonitor Healthcare forecasts that the product will reach almost USD 3 billion in sales by 2017, out of the expected global size of USD 6.3 billion neuropathic pain drug market by the time.

Besides, the company has also extended its research pipeline to identify additional uses of the pain killer. The company claims that the product not only relieves neuropathic pain but also manages co-morbid conditions like sleep disturbance, anxiety and depression.

The company, which launched Lyrica in India in the first quarter of 2006, also claims that the product is the first pregabalin molecule to be approved by Indian regulatory authorities, based on results from clinical trials conducted abroad as well as in Indian patients. In the Indian markets, both 'Caduet' and 'Lyrica' (both launched in February 2006) have together contributed around one per cent of Pfizer India's pharma revenues, according to market research reports.