MUMBAI, Dec 11 (Reuters) - India has revoked a patent granted to an asthma drug made by Schering Corp, later bought by U.S.-based Merck & Co, citing lack of invention, after Indian drugmaker Cipla Ltd challenged an earlier decision.
The move is the latest in a series of patent cancellations by India, where generic medicines account for more than 90 percent of drug sales by value and whose huge potential to western drugmakers is undermined by intellectual property issues.
Earlier this year, India revoked Pfizer Inc's patent on cancer drug Sutent, while an Indian patents appeal board overturned Roche Holding AG's patent on hepatitis C drug Pegasys.
The aerosol suspension formulation of the asthma drug, which won an Indian patent last year, combines three molecules: mometasone furoate, formoterol and heptaflouropropane. It was not immediately clear if Merck markets this drug under a specific brand name in India.
T.V. Madhusudhan, India's assistant controller of patents and design, said the patent-holder did not show an "inventive step" for the drug, either on individual parameters or in its entirety.
The ruling was posted on Tuesday on the website of the Indian patents office.
A similar asthma treatment, Dulera, lost its Indian patent held by Novartis AG in 2010.
Officials at Merck could not immediately be reached for comment by Reuters.