Solubility of solid dispersions of pizotifen malate and povidone

We analyzed the physicochemical characteristics of solid dispersions of piz otifen malate and povidone (Kollidon 12) at different proportions; we used X-ray diffraction, infrared spectrometry, and differential scanning calorim etry (DSC) and tested of the solid dispersions in equilibrium. The results were compared the solubility with findings for physical mixtures with the s ame proportions. A solid dispersion with a drug proportion of 16%-17% forme d a eutectic mixture. Solubility of pizotifen malate increased with the pro portion of drug in the solid dispersion lip to a drug:polymer ratio of 40:6 0. The hydrotropic effect of the polymer also favored solubility: In physic al mixtures, this effect was greatest at a drug:polymer ratio of 10:90; sol ubility at this proportion was equal to that of the solid dispersion at the same proportion.