In vitro and in vivo evaluation of a novel push-pull osmotic pump with orifices on both side surfaces

A novel push-pull osmotic pump (PPOP) was developed for delivery of water-insoluble drug gliclazide. Compared to conventional PPOP, which only had orifice(s) on the side of the drug layer, the novel PPOP had orifices of the same diameter on both side surfaces. The in vitro drug-release behavior of both novel PPOP and conventional PPOP were studied and compared; it was found that the drug-release rate of both kinds of PPOP could be influenced by coating level and core hardness whereas orifice size did not have much influence on it, and the study also showed that none of the former factors could influence the similarity of the drug-release profiles of the two kinds of PPOP. Mechanism of drug release from novel PPOP was illustrated using Poiseuille's law of lamina flow, and it was found that under regular formulation, the dissolution profiles of the two kinds of PPOP were similar. In vivo study also showed that the concentration-time profiles of gliclazide in plasma of the two PPOP were comparable and both of them had good in vitro-in vivo correlation. By simply drilled on both side surfaces, the novel PPOP did not need side identification when drilled, so it was more suitable for industrial manufacture than the conventional ones.