SOLUBILIZATION AND INTERACTION OF SULINDAC WITH POLYVINYLPYRROLIDONE K30 IN THE SOLID-STATE AND IN AQUEOUS-SOLUTION

In this report the interactions of sulindac with polyvinylpyrrolidone K30 (PVP K30), both in the solid state and in aqueous solution, have b een investigated. Solid dispersions of sulindac with PVP K30 were prep ared by the solvent method in ethanol from various drug-to-polymer wei ght ratios. X-ray powder diffraction and differential scanning calorim etry have shown that PVP inhibits the crystallization of sulindac. The stabilization of the noncrystalline state of sulindac was shown by x- ray diffractometry after a 1-year storage. There was a considerable in crease in the release rate of the drug when the polymer content was in creased and the intrinsic dissolution rate values of these systems wer e calculated. From the UV spectra a bathochromic shift and a well-defi ned isosbestic point were observed at pH 2 and 6, which confirmed an i nteraction between the drug and the polymer in solution. Moreover, the apparent solubility of sulindac has been modified as a function of th e polymer concentrations. The binding process between the drug and PVP was exothermic from the stability constant values at 25, 30, and 37 d egrees C at pH 2.