Retrospection on polymorphism and cocrystallization of anti-retrovirals.

Successful pharmaceutical development of a drug molecule depends not only on its potency and selectivity but also on its solid state. Thus the properties of active pharmaceutical ingrdient depend on the identity of its constituents as well as on their arrangement. It is quite common for a drug molecule to exist in more than one crystalline arrangement leading to polymorphism. The various polymorphs differ from each other in dissolution rate, bioavailability, oral absorption, toxicology and clinical trial results. Ultimately both safety and efficacy are impacted by properties that vary among different solid forms. In the recent years screening of polymorphs is increasingly emphasised in the pharmaceutical industry not only because of the valuable knowledge obtained provides necessary guidance for further development but also because of the issue of intellectual property rights. Cocrystallization is an emerging area of research and provides a unique opportunity to enhance marketed products or to pursue compounds that had otherwise been deemed non developable. This review discusses that how common polymorphism among anti- retroviral and its effect on their efficacy. Prevalence of cocrystallization in improving the bioavailability and efficacy of these pharmaceutically important drugs is also incorporated.