Use of Raman in analysing polymorphism in pharmaceutical drugs

Polymorphs are different structural forms of pharmaceutical solids, which are mostly organic. Their formation is driven by thermodynamic considerations, which can therefore lead to differences in chemical and biological properties of drug candidates that, in turn, impacts on their quality control, licensing and patent protection requirements¹. This article will provide a brief overview of the use of Raman spectroscopy, particularly in the low frequency lattice mode region, to detect and understand polymorphs in pharmaceutical drugs. Examples on acetaminophen from earlier work and recent results on polymorphism with fenofibrate, including in situ temperature-dependent measurements, are discussed.