Lappaconitine is a water-insoluble drug, which was used as model drug in this study. Currently, two osmotically controlled delivery systems that are widely used for water-insoluble drug are monolithic osmotic tablet （MOT） and push-pull osmotic pump （PPOP）. In the present study, lappaconitine solid dispersion monolithic osmotic tablet （lappaconitine-SD-MOT） and lappaconitine-PPOP were developed. The prepared lappaconitine-PPOP was able to delivery drug at the rate of approximate zero-order （r = 0.9931）, and the cumulative release was above 95.0%. The lappaconitine-SD-MOT showed a comparatively poor linearity when the data were plotted according to the zero-order equation （r = 0.9798）, and the cumulative release was 84.69%. Lappaconitine-PPOP exhibited better controlled drug release （higher regression value） compared with lappaconitine-SD-MOT. The similarity index （f2） between lappaconitine-PPOP and lappaconitine-SD-MOT was 49.1 （〈50）. A clear difference of drug release characteristics between the lappaconitine-SD-MOT and lappaconitine-PPOP was revealed. It indicated that the drug release performance of lappaconitine-PPOP could gain favorable zero-order kinetics and higher cumulative release compared with lappaconitine-SD-MOT. Therefore, these results suggested that PPOP was still a very effective device for the delivery of poorly water-soluble drug with zero-order pattern.
