Overcome side identification in PPOP by making orifices on both layers

The original purpose of this research was to build a database for an expert system. Unexpectedly, it was found that the color-identifying device in push–pull osmotic pump (PPOP) manufacturing process could be unnecessary. Water-insoluble drug indapamide, gliclazide and dipyridamole were employed as model drugs. Bunches of conventional formulations were designed; and traditional preparation procedures were used. In vitro drug release was studied; and the similarity between the conditions of orifice only on the side of the drug layer and orifices of the same diameter on both sides was evaluated. It was found that the drug release from PPOP could be influenced by formulation and core hardness while it could hardly be influenced by orifice size. No significant difference was observed between the dissolution profiles of orifice only on the side of the drug layer and orifices of the same diameter on both sides. Mechanism of drug release was discussed. The conclusion was that the disadvantage of side identification in PPOP manufacturing process could be overcome by drilling orifices on both sides.