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www.expresspharmaonline.com FORTNIGHTLY INSIGHT FOR PHARMA PROFESSIONALS
1 - 15 November 2005  
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Patent Posts

"Evergreening" - An evergreen issue

Dr Gopakumar Nair takes us through the complexities of patent rights and "evergreening" of expiring patents via the case of Paroxetine—a landmark in the field of patent law.

While the review of TRIPs within 4 years (from 1995) proposed / promised in Art. 27 (3) (b) of TRIPs remains uninitiated, the SPLT (Substantive Patent Law Treaty) proposals are knocking on the Indian doors, offering assistance to have a single patentability criteria for all countries leading to a "Single Global Patent", writes Dr Gopakumar Nair, from Gopakumar Nair Associates.

The proposal of single global patent seems enticing. However, lack of sovereignity to provide for national priorities is a drawback of SPLT option. Also under consideration is the "evergreening" of expiring patents, the slowing down or drying of the New Chemical Entities (NCE) pipelines and the shift of new drug discoveries to New Biological entities (more popularly known as New Molecular Entities).

Evergreening!

The finding that the hemihydrate is anticipated in the light of earlier "anhydrate" strengthens the Indian Patent Act provisions for not granting patentability status

The impact of "evergreening" on the Indian pharma scenario is of great concern to Indian lawmakers. The Parliament undertook the need to amend Section 3(d) of the Patent Act, 1970. As per the final amendment proposed and passed in 2005, the Section 3(d) reads as follows:

"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.]

It is expected that "evergreening" of NCEs and (may be also on NMEs) will be restricted in view of negative coverage against patent extensions. India did not honor product patents till 1995 and which disqualifies pre-1995 molecules for product patent grants post-1995. The provisions of S. 3(d) effectively blocks "salts, esters, ethers, polymorphs, metabolites, pure form, particle size, isomers, mixtures of isomers, complexes, combinations and other derivatives of known substance" from patentability. Most of the simple improvements are "physical" and not "therapeutic", which makes them all the more ineligible for product patents and process patents due to lack of inventiveness.

The Case of Paroxetine

A recent judgement on Paroxetine exemplifies judicial support to "anticipation" and "anti-evergreening". The original inventor of Paroxetine is Ferrosan. The rights to the molecule were acquired by Glaxo SmithKline (GSK) and successfully marketed for a $ four billion plus revenue. GSK applied and obtained hundreds of similar patents in many countries across the world.

Generic companies like Teva and Apotex filed patent applications on processes, dosage forms and Novel Drug Delivery Systems (NDDS). While the 1970 patent for 'anhydrous' Paroxetine expired in 1992, the 'hemihydrate' patent obtained by GSK became listed for marketing permission of "Paxil".

The Paroxetine litigation is famous for the number of times the judgement was appealed. The litigation took off when Apotex filed the Abbreviated New Drug Application (ANDA) based on 'anhydrous'. Apotex challenged the hemihydrate patent in counterclaim. The case thus moved from District Court to Federal Circuit and to the En Banc (full bench) of the Federal Circuit. Every judgement was a landmark decision in the field of patent law.

Same case different judgements!

The 'hemihydrate' patent (US 4,721,723) was invalidated in the seventh Circuit Judge Richard A Posner's Court. Posner opined that patents are for public use after expiry and presence of minor "impurities" of subsequently patented material should not prevent commercial use of patent-expired materials.

The decision was appealed to Federal Circuit (FC) by GSK. The FC did not agree with J.Posner. It said that even if a single crystal of a patented molecule is present in the prior art material, it could infringe. However, from this the question of experimental use [S.102(b) of 35 USC], before one year of application, arose. GSK (SmithKline Beecham at the time) conducted clinical trials on the hemihydrate more than a year before filing patent application for the '723 patent. Public use (unless in-house or with confidentiality - nondisclosure agreement) outside the one year grace period invalidates the patent under 35 USC [S. 1029b)]. GSK argued that the clinical study was for "experimental use" which was not accepted by the Federal Circuit in 2004. Hence the '723 patent was invalidated.

This decision was appealed by GSK on En Banc (full bench) Federal Circuit Hearing. The En Banc CAFC judgement was delivered on April 8, 2005. CAFC in its latest judgement, invalidated the later '723 (hemihydrate) patent for anticipation by the earlier '196 (Ferrosan patent for Anhydrous) under S. 102(a) of USC 35. While doing so the CAFC avoided the issue of "experimental or public use" completely.

While the Paroxetine litigation was going on in USA, the parallel litigation in UK led to a judgement of non-infringement in favour of Apotex invalidating GSK's UK Patent 2,297,550 by Justice Pumfrey.

The judgement opened up valid support for India's S. 3(d) provision. The finding that the hemihydrate is anticipated in the light of earlier "anhydrate" strengthens the Indian Patent Act provisions for not granting patentability status to "salts, esters, ethers, polymorphs, metabolites, pure form, particle size, isomers, mixture of isomers, complexes etc."

The Paroxetine case has touched significant issues in its trial:

  • Anticipation and invalidation (non-patentable) for a new form in the wake of an earlier patent in prior art for the same entity.
  • Definitions, physical and chemical characterisations of anhydrates and hydrates.
  • Stability issues and trivialities involved such as influence of moisture, seeding, pressure, and temperature in different forms
  • Seeding for crystallisation and its impact on patentability
  • Compositions of mixture of crystalline forms and the impact of analytical methods in determining transient differences impacting patentability adversely.

The case laws in USA and UK greatly contribute to the study and analysis of technolegal issues in patentability or subsequent invalidation in patent challenges.

Gopakumar Nair, is the CEO Gopakumar Nair Associates, the IPR consulting firm. Ex-president of the IDMA, Nair was Chairman of Intellectual Property Rights Sub-committee.

 


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