Major factors influencing in vitro drug release from suppositories

The authors studied several important factors which influence in vitro drug release from suppositories. The biopharmaceutical aspect makes it essentia l to know these factors. The suppositories contained antirheumatic piroxica m, which was used as the model substance. Fourteen lipophilic and hydrophil ic suppository bases with various hydroxyl numbers were tested experimental ly. beta-cyclodextrin was used to increase solubility, while tensides with different hydrophilic/lipophilic balance values sewed to increase moistenin g and pharmacon liberation. The best results were obtained with suppositori es prepared with the Witepsol H 15 vehicle, when this base was used no prob lems of production technology were encountered, the physical parameters of the suppositories (solidity, disintegration time) were adequate and the in vitro pharmacon liberation was also optimal. Acceptor phases with different pH values were used during the membrane diffusion studies, and the best re sult was obtained with a pH of 7.5.