Sulfa drugs as model cocrystal formers

A review of several aspects of cocrystallization involving sulfonamide drugs is presented, with a focus on other drug molecules as cocrystallization partners. Some earlier exploratory studies outlined here led to more recent systematic investigation of processes such as cocrystal preparation by solid-state cogrinding of individual components, selective cocrystal formation in competition experiments, and exchange reactions. These are discussed with reference to the drug sulfadimidine, which featured prominently as a model cocrystal former. Apart from their potential as medicinal agents, cocrystals and salts of sulfa drugs frequently display multiple related physicochemical phenomena including polymorphism, crystal isostructurality, and solvate formation, justifying past and current interest in their solid-state chemistry.