The US firm said that it had invented ‘Sitagliptin’ salt that is used in its anti-diabetes drugs and holds the patent for the molecule. However, Glenmark retorted that it has used ‘sitagliptin phosphate’ in its anti-diabetes drugs, Zita and Zita-Met and said that MSD had no patent right over this salt. Hearing the case, India’s Delhi High Court reserved its verdict on the appeal filed by MSD against the single judge bench order, refusing to restrain Indian firm Glenmark from manufacturing and selling the anti-diabetes drugs Zita and Zita-Met. Sitagliptin phosphate, which has been used by Glenmark in its anti-diabetes drug, is a distinct product from Sitagliptin and due to this the firm had obtained separate patent for Sitagliptin Phosphate in the US. Glenmark further said that MSD first applied for a separate patent for sitagliptin phosphate in India and later abandoned it.
The MSD victory comes against a backdrop of defeats for Western pharmaceutical companies trying to defend their intellectual property in India.
Earlier this year Novartis failed in a bid to secure protection for its Glivec (imatinib) cancer drug in India’s Supreme Court, and there have also been knockbacks in recent months regarding Roche’s Pegasys (peginterferon alfa-2a), Merck & Co’s Singulair (montelukast), Gilead Sciences’ Viread (tenofovir), Pfizer’s Sutent (sunitinib) and Bayer’s Nexavar (sorafenib tosylate).
In essence, because the phosphate salt form was a derivative of sitagliptin it should have been ineligible for protection under section 3(d) of India’s patent regime. Glenmark however launched generics containing the phosphate salt and argues that as a result it does not infringe Merck’s IP in India.
Merck has been selling Januvia on the Indian market since 2008, and also allows domestic drugmaker Sun Pharmaceutical to sell it under licence as Istavel. Januvia is the company’s top-selling product with sales of around $4.1bn last year, with Janumet adding another $1.6bn to the tally.