Polymorph patents; how strong they are really?

摘要

Pharmaceuticals can exist in various solid forms include 'true polymorphs', solvates, desolvates and amorphous solids. Screening of Pharmaceuticals early on in drug discovery to find out all possible solid forms has significant connotations. Any inadvertent production of the 'wrong' polymorph at the crystallisation stage or any transformations of one form to another during dosage form processing, storage and scale-up can result in pharmaceutical dosage forms, which are either ineffective or toxic. The second-generation patent filed by pioneer companies generally claim newer crystal forms as an important aspect in maintaining favourable intellectual property position thereby delaying the generic entry. There are numerous instances where innovator companies have acquired patents on particular polymorphic form, which extend beyond the expiry of basic molecule's patent. In such instances, allows filing of ANDA with paragraph IV certification, provided the solid form discovered by the generic manufacturer bypasses innovator's patent. Successful paragraph IV filing provides exclusive marketing rights for 180 days to the generic manufacturer, and a healthy market share. This article provides in depth analysis of polymorph patents with case examples evaluating that whether these polymorphic patents are really important in qualitative terms or just a ploy to stifle the generic entry.