Spironolactone Crystal Forms

Abstract

Spironolactone was obtained in three polymorphic and five solvated crystalline forms which differed in initial dissolution rate in water by about a factor of 12, the most rapidly dissolving form achieving concentrations about twice the equilibrium solubility; on prolonged contact with water transformation to an hydrated phase occurred. It is suggested that the facility with which spironolactone adopts different crystal forms may be utilised to enhance its dissolution-related oral bioavailability.