Delhi High Court Upholds Rejection Of Esteve Pharma's Tramadol-Celecoxib Co-Crystal Patent

The Delhi High Court on 7 August dismissed an appeal filed by Esteve Pharmaceuticals S.A. against the rejection of its patent application for a co-crystal of tramadol and coxibs.

Justice Tushar Rao Gedela held that the claimed invention lacked inventive step under Section 2(1)(ja) of the Patents Act, 1970, as the prior art documents, when read together, rendered the invention obvious. He held:

“Therefore, reading of the prior art…which discloses the combination of tramadol and celecoxib as a method of treating pain, along with the disclosure under prior art D7, would render the present invention obvious.”

Esteve had filed a national phase patent application in India in February 2012, claiming priority from 2009, for an invention titled “Co-crystals of Tramadol and Coxibs.”

The amended application claimed a co-crystal combining tramadol with celecoxib, a drug belonging to the coxib class of pain relievers. Esteve contended that combining the two known painkillers in co-crystal form produced a novel solid form with better bioavailability, higher solubility and a synergistic pain relief effect compared to either drug used alone.

The Assistant Controller of Patents rejected the application in February 2020, holding that the claimed invention lacked inventive step and therefore did not constitute a patentable invention. Esteve challenged the rejection before the High Court.

The Court undertook a side by side comparison of the claims in the application with the disclosures in the prior art. It found that one of the prior art documents expressly disclosed combining tramadol with celecoxib and stated that “some of these combination products also have the advantage of producing a synergistic analgesic effect.”

Further, the Bench observed that the specific improvements claimed by Esteve, including increased bioavailability, better dose response and improved stability, were already disclosed as general advantages of co-crystals in prior art D7. It held:

“The aforesaid comparison would amply suggest that the disclosure in D7 also specifies... increased bioavailability in the co-crystals compared to the individual APIs; dose response of the co-crystal is increased as compared to an API; increase in stability of the co-crystal. These parameters are also claimed in the present invention.”

Bringing its analysis together, the Court concluded that “...the invention claimed under the subject application lacks inventive step and therefore, barred under Section 2(1)(ja) of the Act.”

Accordingly, the High Court dismissed the appeal and upheld the Controller's rejection of Esteve's patent application, with no order as to costs.