Thermoanalytical and Spectroscopic Characterization of Solid State Dipyridamole

A physico-chemical characterization of dipyridamole (C24H40N8O4), a widely used anti-aggregating agent, has been performed by using a combination of thermoanalytical (DSC) and spectroscopic (XRPD and FT-IR/PAS) techniques. A solid state transition, already reported in literature, has been ascribed to the breaking of an intramolecular H-bonds network. The rupture of a network of intermolecular H-bonds is thought to accompany the fusion. The solid state transition has been shown to be reversible provided the sample has not undergone melting. Mechanical milling and thermal annealing have been shown to decrease melting temperature and enthalpy. The effect brought about by mechanical and thermal treatment on the solid state transition is different. In the milled samples the transition peak shifts towards lower temperatures and its enthalpy suggests that all intramolecular H-bonds have been transformed into intermolecular H-bonds.