Pharmaceutical Polymorphism

Abstract

An explanation is given of crystalline solids and polymorphism in general. The crystal structure/chemical and physical properties relation is illustrated for the element carbon. The FDA’s definition of polymorphism is given. The polymorphism of phenacetin (para-acetylaminophenol) is shown and some figures are given on the existence of polymorphism in medicinal active principles. Solubility differences are the most important consequence of pharmaceutical polymorphs, and affect properties like bioavailability and bioactivity, among others. The difficulty of making pharmaceutical preparations from specific polymorphs is illustrated by means of the emblematic case of the drug Ritonavir. The economic and public health consequences in Latin America are shown using the experience of neighboring countries like Brazil and Argentina, and a resolution of the Public Health Institute (ISP) of Chile in relation to the polymorphism is reported.