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A Swiss type of claim is generally used as a means to claim a new use of a known substance. Swiss type claims can be for medicaments as well as non-medicaments. For example, a Swiss type claim for medicaments is normally in the form:Use of compound X in the manufacture of a medicament for the treatment of disorder Y”.

New use of known medicament

In India, traditionally claims relating to the second use of a known substance have been barred from patentability. The position in India therefore, was much the same as the English position before the Patents Act of 1977 (discussed later in this post).

The amendments to the Indian Patents Act, effective from January 1, 2005 have made brought in some changes in this matter.. Section 3 of the Indian Patent Act states what are not inventions within the meaning of the Indian Patent Act.

Before the amendment of 2005, clause 3(d) read as: 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

The above clause effectively made all Swiss type claims in respect of medicaments un-patentable. This was the English position too before the judgment in Wyeth (John & Brother Ltd’s Application) [1985] RPC 545.

However, in 2005, clause 3(d), has been amended in 2005 and now reads as:“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:  “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.

It would be noted that the first part of the above clause is worded negatively, viz. “which does not result in the ………” This part of the clause read with the opening words of section 3 (which too is negatively worded) therefore mandates that a new form of a known substance which results in enhancement of efficacy would be patentable. The remaining part of the clause deals with exclusions from patentability. Clearly, these exclusions would apply only to new forms of known substances that do not pass the test of enhancement of efficacy. The “Explanation” to the clause is consistent with the first part of the clause. The Explanation excludes certain new forms of known substances from patentability in case they do not pass the test of “enhancement of efficacy”. It is clear from the above, that a new form a known medicine (such as polymorph, salt etc.) would be patentable in case there is enhancement of efficacy.

In this context it would be noted that the second part of clause 3(d) still incorporates the prohibition of clause 3(d) prior to its amendment. This would suggest that the use of an existing substance, without change of form, in the manufacture of a medicament for the treatment of a different therapeutic indication not be patentable.

In relation to the second use of medicaments, it would further be noted that there is the problem of “inherency” which too needs to be overcome. The Court of Appeals  Bristol-Myers Squibb v Baker Norton [2001] RPC 1 referred to the House of Lords decision in Merrell Dow Pharmaceuticals Inc. and Another v. H.N. Norton & Co. Ltd. and Others, [1996] RPC 76 as follows:

The House of Lords held that the claim lacked novelty. Lord Hoffmann said at page 89 line 12:

“My Lords, I think that on this point the Patents Act 1977 is perfectly clear. Section 2(2) does not purport to confine the state of the art about products to knowledge of their chemical composition. It is the invention which must be new and which must therefore not be part of the state of the art. It is therefore part of the state of the art if the information which has been disclosed enables the public to know the products under its description sufficient to work the invention.”

He went on at page 90 line 40 to conclude:

“In this case, knowledge of the acid metabolite was in my view made available to the public by the terfenadine specification under the description ‘a part of the chemical reaction in the human body produced by the ingestion of terfenadine and having an anti-histamine effect’. Was this description sufficient to make the product part of the state of the art? For many purposes, obviously not. It would not enable anyone to work the invention in the form of isolating or synthesising the acid metabolite. But for the purpose of working the invention by making the acid metabolite in the body by ingesting terfenadine, I think it plainly was. It enabled the public to work the invention by making the acid metabolite in their livers. The fact that they would not have been able to describe the chemical reaction in these terms does mean that they were not working the invention. Whether or not a person is working a product invention is an objective fact independent of what he knows or thinks he knows about what he is doing.”

Having rejected the argument that the invention had been made available by use of the terfenadine, he said page 91 line 26:

“Anticipation by disclosure, on the other hand, relies upon the communication to the public of information which enables it to do an act having the inevitable consequence of making the acid metabolite. The terfenadine specification teaches that the ingestion of terfenadine will produce a chemical reaction in the body and for the purposes of working the invention in this form, this is a sufficient description of the making of the acid metabolite. Under the description the acid metabolite was part of the state of the art.”

The Indian Patents Act too provides that prior public use of the invention is novelty destroying. It is therefore likely that the position in the English law would also apply in India i.e. in case the known substance has been administered as a medicament earlier, it is unlikely that its new therapeutic use would be patentable unless the prior use did not result in the same chemical effect within the body.

It would therefore appear that the use of a known medicament in the manufacture of a medicament for a different therapeutic indication may not be patentable. A new form of a known substance may however be patentable in case there is enhancement of efficacy.

Method of treatment

At this stage it would be useful to refer to clause (i) of Section 3 of the Indian Patents Act, which provides as: “any process for the medicinal, surgical, curative, prophylactic, diagnostic, therapeutic or other treatment of human beings or any process for a similar treatment of animals to render them free of disease or to increase their economic value or that of their products”

Hence, clause 3(i) absolutely bars patenting of the process for the medicinal treatment of human beings and animals. The line between “the use of a substance in the preparation of a medicine for the treatment of a disease” and “the process for treating a disease using a substance” is thin. It is therefore necessary to draft Swiss claims carefully. There is likely to be controversy in India as to whether a claim is a Swiss claim or a method of treatment claim. This controversy will be resolved only through the judiciary.

It would follow from the above that Swiss type claims in India are likely to be possible only if the following conditions are satisfied:

  1. A new therapeutic use is found for a known substance;
  2. The Swiss type claim is not for the new substance itself but for an hitherto unknown form (such as salt, polymorph etc.) of the substance;
  3. The new form is substantially different in property with regard to efficacy.

Further, under Indian law no claim relating to a method of treatment is patentable.

Please note that the above does not amount to legal advice (as usual). Please get in touch with a Legal Counsel before taking any action which may affect your patent application.