Solid phases of delavirdine mesylate

Delavirdine mesylate was recrystallized from solution under a variety of conditions. Seven crystal forms and a stable amorphous phase were isolated from solution. Two of these crystal forms were polymorphic anhydrates: from XI (U-90152T) and form VIII (U-90152S). Two hydrates (forms VI and XIV), an ethanol solvate (form VII), an acetonitrile solvate (form XIII), and a solvate from methanol/acetone (from XII) were also identified. Six additional phases were identified as the products of solid-state transformations of the hydrated and solvated phases. The solid phases were differentiated by infrared spectroscopy and X-ray powder diffraction. Several of the solid-state phase transformations were mediated by atmospheric moisture. These transformations were studied as a function of relative humidity with dynamic moisture sorption gravimetry (DMSG). DMSG also provided useful measurements of hygroscopicity.