A novel gastric-resident osmotic pump tablet: in vitro and in vivo evaluation.

A novel famotidine gastric-resident osmotic pump tablet was developed. Pharmaceutical iron powder was used as a gas-formation and density-increasing agent. Central composite design-response surface methodology was used to investigate the influence of factors, i.e., polyethylene oxide (Mw 1,000,000) content, NaCl content, iron powder content and weight gain, on the responses including ultimate cumulative release and correlation coefficient of drug release profile. A second-order polynomial equation was fitted to the data and actual response values are in good accordance with the predicted ones. The optimized formulation displays a complete drug delivery and zero-order release rate. Gamma scintigraphy was selected as the method to monitor in vivo gastric residence time of the (99m)Tc-labeled system in Beagle dogs. It was observed that the system can retain in stomach for an extended period of 7h after administration compared with conventional tablets. The present investigation suggests that water-insoluble drug can be delivered from single-layer osmotic pump tablets completely due to the push power of the hydrogen gas generated by the reaction of the iron and gastric fluid. And iron powder can increase the system density which is over 2.5 g cm(-3), making the system resident in stomach to prolong the drug delivery time in absorption zone.