Delhi High Court Upholds Rejection Of Patent For Amylin and AstraZeneca's Sustained-Release Diabetes Injection

The Delhi High Court has upheld the Patent Office's refusal to grant Amylin Pharmaceuticals and AstraZeneca Pharmaceuticals a patent for their sustained-release exenatide injection for diabetes, ruling that the formulation was 'obvious' from existing science and lacked the inventive step required for protection.

A single bench of Justice Tejas Karia in an order dated November 24 said that the formulation would be obvious to a skilled person, reading the earlier scientific disclosures, "obvious to PSITA (Person Skilled in the Art) to arrive at the present invention, which was made to utilize pre-mixed formulations comprising active pharmaceutical ingredient Exenatide and stability agent sugar as taught by D2 in microsphere delivery systems taught by Dl.”

The case arose from the companies' 2011 application seeking a patent for a ready-to-inject formulation consisting of drug-loaded microspheres suspended in a non-aqueous oil-based carrier. The design was meant to release exenatide gradually, reducing the need for daily injections and avoiding the “burst release” that can occur immediately after injection.

The firms argued that none of the cited prior-art documents disclosed their specific combination of features, including the use of medium-chain triglycerides as a non-aqueous carrier along with exenatide and sugar in the claimed proportions. They said the Patent Office had failed to consider their detailed submissions and that some prior art even taught away from their approach.

The Patent Office maintained that all the essential elements were already known. It pointed to prior disclosures on microsphere systems, fixed oils, exenatide with sugars, and methods to control release, and said a skilled person could combine these without difficulty. Its position was that the invention was a predictable variation rather than an invention.

The court agreed with that assessment, examining D1 to D4 and finding that the differences the companies relied on would be filled by routine experimentation.

Applying the test for inventive step laid down in Hoffmann-La Roche v Cipla, the court held that the formulation did not represent a technical advance over what was already known. It dismissed the appeal and upheld the Patent Office's 2018 refusal order.

Case Title: Amylin Pharmaceuticals LLC And Anr. v. Assistant Controller Of Patents

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