Drugmaker Bayer has said that it is challenging an order from the patents office that allowed Hyderabad-based Natco Pharma to sell a cheap generic version of the German firm's drug Nexavar in India. Nexavar is used in the treatment of cancer of the kidney and liver.
The patents office had stripped Bayer of its exclusive rights to sell Nexavar, saying most Indians could not afford it.
Bayer said it had appealed against the ruling.
"We will rigorously continue to defend our intellectual property rights, which are a prerequisite for bringing innovative medicines to patients," a company spokesman said.
India's decision on Nexavar was seen as a precedent that could extend to other treatments, including modern HIV/AIDS drugs, in a major blow to global pharmaceutical firms.
Separately, Bayer is suing another Indian drugmaker, Cipla, for patent infringement over Nexavar. Cipla has been selling generic Nexavar in India and it has slashed the price of the drug by 75% to Rs 6,840 a month.