Delhi High Court Rejects Patent for Novel Drug Formulation

In a significant ruling for the pharmaceutical industry, the Delhi High Court has dismissed an appeal challenging the rejection of a patent application for a sustained-release formulation of exenatide. Presided over by Hon'ble Mr. Justice Tejas Karia, the court affirmed that the proposed invention lacked an "inventive step" as required under Section 2(1)(ja) of the Patents Act, 1970, citing extensive prior art.

The Backdrop: A Dispute Over Innovation

The appellants, Amylin Pharmaceuticals, LLC and Astrazeneca Pharmaceuticals LP, sought patent protection for a "manufactured pre-mixed formulation for injection" using exenatide—a drug primarily used for Type 2 diabetes. The core of their application focused on a formulation containing microspheres suspended in a non-aqueous carrier comprising triglycerides of C6 to C12 fatty acids.

The Assistant Controller of Patents and Designs had previously rejected the application in 2018, arguing that the combination of elements claimed—specifically the use of pre-mixed formulations and specific stabilizers—would have been obvious to a Person Skilled in the Art (PSITA) based on existing literature.

Arguments from the Industry and Regulators

The appellants argued that their invention bridged a critical gap in medical delivery, eliminating the need for daily injections and offering superior stability and patient compliance. They contended that neither the specific non-aqueous carrier nor the precise combination of ingredients was disclosed in the cited prior art (D1-D4). They further emphasized that their formulation provides a "one-component" solution that avoids the complexities and potential risks of standard two-component systems.

Conversely, the Respondent maintained that the claimed formulation was merely a predictable development. The Counsel for the Respondent demonstrated how prior art references—specifically D1 (microsphere systems), D2 (GLP-1 analogues and stabilizers), and D4 (sustained-release polypeptides)—already contained