Section 3(d) of the Indian Patents Act states:
“The following are not inventions within the meaning of this Act,—
[…] (d) the mere discovery of a new form of a known substance which does not result in the enhancement of the known efficacy of that substance or the mere discovery of any new property or new use for a known substance or of the mere use of a known process, machine or apparatus unless such known process results in a new product or employs at least one new reactant.
Explanation.— For the purposes of this clause, salts, esters, ethers, polymorphs, metabolites, pure form, particle size, isomers, mixtures of isomers, complexes, combinations and other derivatives of known substance shall be considered to be the same substance, unless they differ significantly in properties with regard to efficacy;[…]”
So, under section 3(d) a new form of a known substance may not be patentable. The explanation to section 3(d) states that various derivatives of a known substance shall be considered to be the same as the known substance, unless they differ significantly in properties with regard to efficacy.
Especially given that many pharmaceuticals are developed from earlier compounds (so called “lead compounds”), when is a new compound a “known substance” and when is it a new substance?
This issue was considered by the Indian Supreme Court in 2013 in Novartis AG v Union of India & Others. This case dealt with a patent to the beta crystalline form of Imatinib Mesylate. Imatinib Mesylate itself was held to be previously known, as was the pharmacological properties of Imatinib Mesylate. However, the Court concluded that the beta crystalline form of Imatinib Mesylate may be accepted to be new. Crucially, in the decision it was held that “No material has been offered to indicate that the beta crystalline form of Imatinib Mesylate will produce an enhanced or superior efficacy (therapeutic) on molecular basis than what could be achieved with Imatinib free base in vivo animal model.” Therefore, the beta crystalline form of Imatinib Mesylate failed the test of section 3(d) and was not patentable.
If we put aside issues of efficacy however, some conclusions can be drawn about the ambit of the definition of the term “known substance” in section 3(d) by considering paragraph 191 of the Novartis decision:
“We have held that the subject product, the beta crystalline form of Imatinib Mesylate, does not qualify the test of Section 3(d) of the Act but that is not to say that Section 3(d) bars patent protection for all incremental inventions of chemical and pharmaceutical substances. It will be a grave mistake to read this judgment to mean that section 3(d) was amended with the intent to undo the fundamental change brought in the patent regime by deletion of section 5 from the Parent Act. That is not said in this judgment.”
By way of background, section 5 of the Indian Patents Act was deleted with effect from 1 January 2005 following international pressure on the patentability of pharmaceutical inventions in India. Section 5 stated:
“Section 5. Inventions where only methods or processes of manufacture patentable.—
In the case of inventions—
(a) claiming substances intended for the use, or capable of being used, as food or as medicine or drug, or
(b) relating to substances prepared or produced by chemical processes (including alloys, optical glass, semi-conductors and inter-metallic compounds), no patent shall be granted in respect of claims for the substances themselves, but claims for the methods of processes of manufacture shall be patentable.”
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