India, a main source of inexpensive AIDS drugs, is in the midst of a patent quandary. Patent wrangles have become almost de rigueur since the country passed the 2005 Patents Amendment Act. A New Delhi high court judgment, expected soon, has the potential to change the rules of the game. Similar to Switzerland's Novartis "Gleevec" battle, a new case promises to become the second test case in less than a year to tackle the way the Indian judiciary balance public health issues and patents owned by multinational pharmaceutical manufacturers.

In a first, Mumbai-headquartered Cipla launched in January a generic version of a drug with the full knowledge that the original has been patented in India. The patented product is a lung cancer drug marketed by Switzerland's F. Hoffmann-La Roche under the brand name "Tarceva" (erlotinib). (Roche received an Indian patent for "Tarceva" in July 2007.) Roche India has claimed patent infringement and asked the New Delhi high court to restrain Cipla from selling its generic version. Cipla's generic, erlocip, costs $42 per tablet, versus $125 for the Roche version.

Because the Indian patent law allows pre-grant as well as postgrant opposition, Roche's patent is not the only one being challenged. In the case of pregrant opposition, Torrent Pharmaceuticals (Ahmedabad) is opposing AstraZeneca's (United Kingdom) cholesterol reducer "Crestor" and Mumbai's Ajanta Pharma is opposing Eli Lilly's (Indiana) "Cialis." New Delhi's Ranbaxy Laboratories is challenging Pfizer's (New York) antifungal "Vfend."

The patent fight is not limited to multinationals. Domestic companies are also suing each other to gain access to a population of over 1 billion in India. Cipla and Hetero (Hyderabad), for example, have opposed Wockhardt's patent application on the antibacterial drug "Nadifloxacin." India's leading drug firms, Ranbaxy Laboratories and Cipla, are believed to have filed as many as 70 oppositions (Ranbaxy–55; Cipla–15), some against each other and some against other domestic companies.

"Cipla's case for 'Erlotinib' is undoubtedly a legally risky move," says Ranga Iyer, president of the Organization of Pharmaceutical Producers of India, a body of multinational drug firms operating in the country. "Launching a generic version of a patent product is an infringement of the patent and it amounts to violation of the country's law."

Gopakumar Nair, a patent consultant based in Mumbai, holds a different view. "Erlotinib is a derivative of another known cancer drug, 'Gefitinib,'a pre-1995 invention of European drugmaker AstraZeneca. Since the Delhi patent office had denied a patent for this (AstraZeneca) drug, a patent for its derivative will not be strong, and the generic company can get the patent revoked through a post-grant opposition."

Be that as it may, Cipla started a new trend in the HIV/AIDS drug market a few years ago by offering generic versions at one-tenth the cost of prevailing brand drug prices. Cipla contends that Roche's "original invention date does not justify the claim for patent," according to Amar Lulla, managing director of Cipla in an interview before the litigation case commenced.

On its part, Roche is not ready to buckle. "If any company launches this product in India, it is an infringement of the patent and we will be forced to take necessary action immediately," Roche India managing director Girish Telang said before filing the patent infringement case.