Claims are the technical solutions seeking protection, which should be achieved or generalized from the contents sufficiently disclosed in the description. It is pivotal that claims are well drafted because in the case of inappropriate generalization, such claims would be deemed not supported by the description. In practice, determination on the appropriateness of generalization remains controversial. Medical use is an essential improvement drug invention. In ascertaining whether a claim of medical use invention is supported, it is crucial to reasonably interpret the scope of the claim.

Background

By analyzing an invalidation case of a medical use patent, this article dissects the examination methodology employed by the Re-examination and Invalidation Department of the Patent Office, and may shed some light on patent drafting, granting and affirmation procedure. The invalidation case (Decision No. 38074) relates to a patent for medical use of Levo-ornidazole (L-ornidazole). Claim 1 seeks to protect "Use of L-ornidazole in the preparation of an anti-parasitic infection medicament". L-ornidazole is a single isomer of the marketed drug racemic ornidazole. The inventor of the patent found that L-ornidazole can remarkably reduce CNS toxicity while retaining the effect of ornidazole, and thus has a therapeutic advantage. The working examples of the description provide experimental data on L-ornidazole’s effect of anti-protozoan infections and also its toxicology. In the invalidation proceeding, the petitioner argued that the term “parasite” defines overly broad scope so that the claim cannot be supported by the description. This is because different parasites have distinct habits and metabolic systems, and this patent description only provides data for trichomonas vaginalis and cecal amoeba. Persons skilled in the art cannot predict the efficacy of L-ornidazole against other parasites.

Invalidity decision

The invalidation decision finds that the improvement of this patent lies in the discovery that L-ornidazole has lower CNS toxicity, rather than new pharmacological activities such as activity against a broadened spectrum of parasite. It is known in the prior art that nitroimidazole drugs like ornidazole have anti-parasitic, especially anti-protozoan, effects. Due to the structural similarity between L-ornidazole and racemic ornidazole, it is predictable that their efficacies are similar. Based on the disclosure of the description, those skilled in the art can reasonably determine the protection scope of the claims, rather than arbitrarily extend it to the extreme case, i.e. being effective for all parasites.

Comments

Claims should be reasonably interpreted by taking into account the inventive improvement and the prior art, rather than completely relying on the literal meaning of claim language. In judging whether a claim can be supported by the description, it is vital to identify the substantial contribution made by the invention to the prior art and the specific working examples should not be the sole basis for judging “support” of a claim.

Contributor: Wu Xiaohui