Dissolution kinetics for coprecipitates of diflunisal with PVP K30.

Diflunisal is a nonsteroidal anti-inflammatory drug that is poorly soluble in water. The present study describes the formulation of solid dispersions of the drug designed to increase its solubility. X-ray diffraction and DSC were used to examine the physico-chemical characteristics of solid dispersions of diflunisal and polyvinylpyrrolidone (PVP) prepared by the solvent method, using percentage proportional compositions ranging from 20:80 to 50:50. X-ray diffraction analysis detected that diflunisal is present in solid dispersions in crystalline or amorphous state depending on the PVP content. The thermal behavior of diflunisal observed in the DSC curves of solid dispersion systems, was attributed to a solid-state interaction. The increased release of the PVP-drug dispersion as compared to the PVP-drug physical mixture was attributed to the formation of a complex resulting from the interaction of the drug and the polymer.