This article was originally published by IAM, and has been republished with permission.

Since 2003 it has been possible to extend the duration or term of a Russian patent for a drug, pesticide or agricultural chemical by up to five years. Upon the patent holder's request, an extension to a patent term may be obtained based on the product's first marketing authorisation.

It used to be possible to extend patent claims related to a substance, antibody or pharmaceutical formulation, which included all possible alternatives covered in the corresponding patent claim. However, in 2015 the regulations were tightened and it is now possible to extend patent claims that covered a commercial product whose use was permitted by a marketing authorisation only.

According to the new legislation, an additional patent with restricted claims is issued instead of an extension. The additional patent's claims do not contain alternative features – they are directly related to the product whose use was permitted by the authorisation. Claims directed to use, process, expression vectors and cells, among others (ie, that do not cover the commercial product) are not subject to extensions.

An additional patent for a drug, pesticide or agricultural chemical may be issued if more than five years have passed from the application filing date to the date when the marketing authorisation was obtained. The term of the additional patent cannot exceed five years and is calculated by using the date when the marketing authorisation was obtained, minus the submission date and then minus five years. In order to obtain an additional patent, the patent holder must submit a request to the Russia Patent and Trademark Office (Rospatent) along with a notarised copy of the marketing authorisation and the amended claims that constitute the claims limited to a specific product. For example, if a patent has a Markush claim, then the values of all substitutes will be limited by a single value in the additional patent, in such a way that the Markush claim covers one compound only.

A patent-term extension request is usually reviewed by the same branch department that examined the initial patent application and by the same examiner. If the examiner decides that the amended claims do not comply with the legislative requirements, they can issue an office action. Generally, this happens if amended claims are insufficiently limited and have covered alternatives (eg, more than one compound in the case of a Markush claim). The time for responding to the office action, as well as the extension of time for responding, are the same as those for an application for an invention (ie, three months from the date of the office action issuance).

Rospatent has a fairly strict policy on patent-term extensions and tries to minimise the scope of legal protection provided by an additional patent. For example, when extending the patent term for a pharmaceutical composition, the examiner will try to narrow down the additional patent claims in such a way that the active ingredient content is limited not by a value range, but instead by one or several isolated values that correspond with the values specified in the marketing authorisation. Further, the examiner will try to limit the claims by specifying the excipients in the marketing authorisation and isolating the values of their composition. However, practice has shown that examiners are willing to meet patent holders halfway and ultimately keep an active ingredient composition range in additional patent claims, albeit narrowed down in comparison with the patent.

If the patent claims to a compound have the "pharmaceutically acceptable salt" feature, and the drug authorised for the market contains an active ingredient in the form of a salt only, the examiner will most likely keep the substance and the pharmaceutically acceptable salt feature in the additional patent claims. However, features such as solvates or hydrates will be excluded from additional patent claims if the drug's active ingredient is not one of these.

Therefore, in order to achieve the maximum scope of protection provided by an additional patent, the patent holder is required to provide convincing arguments that each feature kept in the changed claims is related to the drug authorised for the market. In other words, compulsory documents sent to Rospatent should be supplemented with an accompanying letter, which describes in detail how certain features of the claims are related to the commercial product. In this case, the arguments provided in the accompanying letter should be documented.

For example, proving the structure of a substance or antibody requires a copy from a World Health Organisation bulletin, in which the structure of the substance or antibody is given as well as its international non-proprietary name. If the patent claims include isomers, the patent holder should provide copies of the technical documents with regard to the production or qualitative analysis of the drug composition, which show that the composition has, at the very least, trace amounts of such isomers.

If the patent claims do not specify a defined crystalline form, one should provide relevant parts of the dossier with a description of the properties of this form. That said, there may be situations when patent claims use units (eg, cm-1) different from those in the dossier (eg, 2θ). In this case, the units from the dossier must be converted into the units from the claims in such a way that the values of these units coincide and the conversion algorithm must be shown in an accompanying letter.

If an original patent covers several compounds that are present in commercial products and each product has a separate marketing authorisation, it may be possible to obtain an additional patent for each of the compounds.

If one of the patent claims has both a compound and its active metabolite as alternatives, or if the active ingredient is an active metabolite and the patent claims protect a pro-drug, then the claims of an additional patent retain both compounds.

If the patent holder has two patents for different salts of the same substance, an additional patent will be granted to the salt contained in the drug only. The same approach will be adopted for different crystalline forms – an additional patent will be granted for the crystalline form that is present in the drug only.

After agreeing on the scope of claims, the patent holder will receive an additional patent with new claims, the corresponding record will be entered in the state registry and the additional patent claims will be published. Further, the patent will keep its previous number. The term of the additional patent is calculated from the day after the original patent expiry date.

The decision to reject a patent extension as well as the decision to extend a patent term can be challenged before the IP Court within three months.