Medecins Sans Frontieres has criticised Swiss drugmaker Novartis for a lawsuit - due to get underway in India today - which it claims could have a "devastating impact" on access to medicines in the developing world.

Novartis is challenging a part of India’s patent law - Section 3(d) - which along with other provisions of the patent law says that a new form of a known medicine can only be patented if it is not obvious and shows significantly improved therapeutic efficacy over existing medicines, notes MSF.

Effectively this means that new therapeutic applications for older compounds, for example, can secure patent protection. Section 3(d) presumes a modification of a known chemical composition is non-patentable, for example, and moreover shifts the burden of rebutting this to patent applicants.

Novartis legal action stems from its attempt to obtain an Indian patent on Gleevec/Glivec (imatinib mesylate), its drug for chronic myeloid leukaemia and other cancers, which was denied by India's Patent Office in 2006.

The long-running legal actions continue their course in India's Supreme Court today, following defeat in the initial case in 2007 and a subsequent appeal in 2009.

"If Novartis succeeds in weakening the interpretation of Section 3(d) for the purpose of obtaining a patent on a specific salt of the anticancer drug imatinib, it would force India to grant far more patents than it currently does or is required to under international trade rules," claims MSF.

"This could lead to generic competition on many essential drugs ending entirely and prices for these in both India and developing countries remaining very high."

In past comments on the case, Novartis has insisted that its actions are related to access to medicines - given that Gleevec is indicated for a tiny patient population - but rather about are aimed at clarifying the intellectual property rights environment in India.

Current safeguards give the Indian government a number of options to ensure public access lifesaving drugs, it said.