Evergreening is the term used for legal and technological alternatives adopted by Pharmaceutical companies to extend their exclusivity of over production and sale of patented medicines beyond the prescribed statutory timeline of 20 years. The said alternatives enable Pharma companies to retain royalties from patented medicines by either taking out new patents over minor incremental innovation, for example, associated delivery systems, or new pharmaceutical mixtures with a hidden motive of extended exclusivity over the main patented medicine beyond the prescribed time.

The main purpose of research and development for a pharma company is to invent an entirely new medicine or a 'blockbuster' drug, which would disrupt the market in a therapeutic domain. This blockbuster drug is aggressively patented for varied compositions. Strictest of patent monopoly is enforced by the company to prevent and more than often killing the competition in such therapeutic domain. Hence, the innovator company gains hugely from the said patented compositions.

To maintain the innovation, and consequently the market dominance, the innovator company needs to again undertake the entire cycle of research, discovery, clinical trials, marketing and distribution, replete with the risk of failure at every step. Also, majority of new drugs developed by the R&D never make it to the market. Therefore, to retain the market dominance a more certain alternative is to somehow extend the said 20 years period for which the company keeps filing applications for patents over minor variants of the parent compound, called secondary patents. This practice of continued patent protection or prolonged monopoly over the parent compound arising out of minor variants is known as evergreening. To address evergreening, different countries have come up with different standards of qualification of patent grant and protection.

India has been at the forefront of developing an alternative model of patent law which many developing countries have since emulated. To address the issue of evergreening, the Indian Parliament introduced Section 3(d) by way of 2005 Amendment to the Patents Act, 1970. Section 3(d) categorically excludes the derivatives, salts (trivial tweaks) to the known compound as not being inventions under the Act. The Supreme Court of India, in 2013, held Section 3(d) to be constitutionally valid and clarified that in order to get a patent over derivatives of a known compound, the applicant shall show that the said derivative results in enhanced therapeutic efficacy as compared to the known compound.

Subsequent to the said Supreme Court decision, to overcome Section 3(d) provisions, the applicants had to establish therapeutic efficacy by way of sufficient clinical evidence.

It has been seen in a recent study titled 'Pharmaceutical Patent Grants in India' that the Indian Patent Office has allowed nearly 72% for secondary patents in the pharmaceutical field which could have been checked under Section 3(d) of the Act. The said study states that the secondary patents granted by the Patent Office were in contravention of the anti-evergreening provisions contained in the Patent Act, which also included Sections 3(e) and 3(i), apart from Section 3(d).

On further evaluation of the cases in question, the study reports that patent applicants repeatedly blunted the effect of Section 3(d) by claiming incorrect application of Section 3(d) by the Patent Office. The applicants would often divert the attention of the Patent Office to Section 3(e) which stipulates that a mere admixture resulting only in aggregation of the properties of the components thereof is not considered as invention under the Act. To overcome Section 3(e), the applicant had to simply show synergistic effect of the components forming the compound which was much easier in comparison to the requirement of Section 3(d), i.e. to establish the enhanced therapeutic efficacy of the new compound. Accordingly, by showing the synergistic effect (a relatively much easier standard), applicants would steer the argument away from the evidential requirements that a Section 3(d) citation would warrant. Therefore, patent applicants easily overcome the requirement of exhaustive clinical data to establish enhanced therapeutic efficacy and directed their legal arguments towards the application of Section 3(e) thereby switching to simpler test of synergistic effect.

The big pharma companies have been criticizing India's Section 3(d) as being too oppressive on them and against the TRIPS principles. They have been arguing that Section 3(d) is a discouragement to the inventors towards incremental innovations in the pharmaceutical field. The Indian Government counters that patent exclusivity is to incentivize innovation and not for tweaking known compounds without any advancement in efficacy.

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