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Delhi High Court Upholds Rejection Of Esteve Pharma's Tramadol-Celecoxib Co-Crystal Patent For
In a significant patent ruling, the has dismissed an appeal by Esteve Pharmaceuticals S.A. challenging the rejection of its patent application for co-crystals of tramadol and celecoxib, holding that the claimed invention lacked an under .
Justice Tushar Rao Gedela, delivering the judgment on , found that documents, when read together, rendered the claimed invention obvious to a .
A Combination of Known Painkillers
Esteve Pharmaceuticals had filed a national phase patent application in India in
, claiming priority from
, for an invention titled
"Co-crystals of Tramadol and Coxibs."
The amended claims were restricted to a specific co-crystal combining tramadol—a synthetic opioid analgesic—with celecoxib, a selective COX-2 inhibitor from the coxib class of non-steroidal anti-inflammatory drugs.
The company contended that forming a co-crystal of these two known painkillers produced a single, homogeneous crystalline phase with distinct physicochemical characteristics—offering improved bioavailability, higher solubility, and a synergistic pain-relief effect compared to either drug administered alone.
The rejected the application in , raising objections under Sections 2(1)(ja), 3(d), and 3(e) of the Act. Esteve challenged this rejection before the High Court.
The Argument Over Synergy and
Senior counsel for Esteve argued that the objection under was unsustainable since the Controller had effectively conceded by not sustaining the initial objection. He further contended that the claimed co-crystal was not a mere admixture—which would fall foul of —but a distinct crystalline form evidenced by its unique Powder X-Ray Diffraction pattern.
On , Esteve argued that documents listing celecoxib among many possible NSAIDs provided no enabling disclosure or motivation to select tramadol and celecoxib specifically. The company also pointed to efficacy data showing the co-crystal's ED50 value of 2.04, compared to 5.41 for tramadol and 3.03 for celecoxib individually, as evidence of synergy.
The respondent, however, maintained that the cumulatively rendered the invention obvious, emphasizing that one document explicitly disclosed combining tramadol with celecoxib and noted potential synergistic effects.
Tells the Story
The Court undertook a detailed side-by-side comparison of the patent claims with the disclosures in
documents D5 and D7. Document D5, relating to a slow-release tramadol and NSAID combination for treating pain, expressly listed celecoxib among the NSAIDs that could replace naproxen in the combination. Its paragraph [0012] admitted that
"some of these combination products also have the advantage of producing a synergistic analgesic effect."
Document D7, which concerned pharmaceutical co-crystal compositions, disclosed that co-crystals of APIs could improve properties including solubility, bioavailability, dose response, and stability compared to individual APIs. Critically, both tramadol and celecoxib appeared in Table IV of D7, and the document described methods for preparing co-crystals by dissolving components in a solvent and allowing evaporation.
The Court observed that the improvements claimed by Esteve—increased bioavailability, better dose response, and improved stability—were already disclosed as general advantages of co-crystals in D7.
Key Observations
The judgment noted:
"Therefore, reading of the …which discloses the combination of tramadol and celecoxib as a method of treating pain, along with the disclosure under D7, would render the present invention obvious."
The Court further observed that D7's disclosure
"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."
The Court also rejected Esteve's argument that the failed to provide motivation, holding that D5's disclosure of synergistic analgesic effects in combination products would motivate a to apply the co-crystal teachings of D7 for improved results.
Decision and Implications
Concluding that
"the invention claimed under the subject application lacks
and therefore, barred under Section 2(1)(ja) of the Act,"
the High Court dismissed the appeal with no order as to costs. Having upheld the objection on
, the Court declined to examine the separate objections under Sections 3(d) and 3(e), citing the precedent in
.
The ruling reinforces the principle that combining disclosures from multiple references can defeat an claim where the combination of known drugs and known co-crystal technology would be obvious to a . It also underscores the importance of demonstrating genuine innovation beyond merely applying known techniques to known substances, a terrain carefully guarded by Indian patent law.
