Singapore: In what looked like a patent suit that could stir further controversy about patenting in the life sciences industry, US drug major Merck Sharp and Dohme (MSD) filed a patent against Indian firm Glenmark.

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.