Author(s): Deepali Manish Gangrade, Priyanka Yashwant Kulkarni, Swati Devendra Bakshi
Polymorphism presents a challenge to pharmaceutical industry to produce drugs of consistent quality. Polymorphic conversion occurs due to various sources like change in the temperature, presence of air, mechanical stress, humidity and lead to formation of new polymorph. Their presence can adversely affect the bioavailability, stability, safety and efficacy of the pharmaceutical products. To avoid these adverse effects, detection of polymorphic impurity is needed. Identification of polymorphic impurity can be done by various techniques either alone or in combination. The PXRD technique identifies different crystal phases by their unique diffraction patterns by capturing the three dimensional diffraction patterns in a two dimensional plot. DSC is a thermal method of analysis which is used to study thermal transitions. Infrared and Raman spectra identify a pure crystal form from different crystalline forms of the same organic compound. NMR spectroscopy indicates the presence of configurational or conformational multiplicity present in the solid state. Optical microscopy determines the optical properties and morphological properties of particles. Scanning Electron Microscopy determines surface topography and type of crystals (Polymorphism and crystal habit). HSM is an analytical technique enables the solid state characterization of materials by combining the properties of microscopy and thermal analysis. When single technique fails to identify the polymorphs, then combination techniques are used. DSC-FTIR technique gives spectroscopic and thermodynamic information about a solid or liquid sample undergoing thermal modification. DSC-PXRD allows simultaneous measurements of thermochemical and thermophysical events, while following changes in crystalline structure(polymorphism) during these events. This article briefly reviews, the importance of detection of polymorphism in pharmaceuticals, types of polymorphism and its characterization.