Optimization of Formulation Process of Ginkgo Folium Bi-layer Osmotic Pump Controlled-release Tablets by Central Composite Design-response Surface Methodology

Objective: To optimize formulation of Ginkgo Folium bi-layer osmotic pump controlledrelease tablets. Method: With accumulative release rate of total flavonol glycosides as index,single-factor tests were adopted to screen formulations of drug-layer, push-layer and coating solution, drug release behavior was evaluated by similarity factor method. Taking the amount of PEG4000 in coating solution,coating weight and the amount of polyoxyethylene in push-layer as independent variables,linearity of release curve and accumulative drug release in 16 h as dependent variables, central composite design-response surface methodology was applied to optimize formulation. Result: Optimum formula was as follows: polyoxyethylene amount of 120 mg,the amount of PEG4000 of 1. 5 g,coating weight of 11%; accumulative release of total flavonol glycosides in 16 h was above90%. Conclusion: Release curve of this preparation meets requirements with correlation coefficient of 0. 9964. This optimized formulation is stable and suitable for industrial production of Ginkgo Folium bi-layer osmotic pump controlled-release tablets.