Optimization of bi-layer osmotic pump controlled release tablets of total flavonoids from Ginkgo Folium by central composite design-response surface methodology

Objective To prepare bi-layer osmotic pump controlled release tablet of total flavonoids from Ginkgo Folium(BOPCRTTFGF), and to optimize its formulation by central composite design response surface methodology(CCD RSM). Methods Single-factor test was desigined by screening the formulations of tablet core and coating film. The independent variables comprised of amount of polyethylene glycol in coating solution and coating weight gain, and the dependent variables included the percentages cumulative release of BOPCRT-TFGF after 2 and 14 h and multiple correlation coefficient of druge release profile in 1—12 h. The formulation was optimized by CCD RSM and the optimized formulation was also verified. Results The optimized formulation was as follows: The tablet weight gain in coating was 7.58%, and PEG 4000 was 3.41 g. There was no significant difference between the measured and the predicted values. The cumulative release of the optimal osmotic pump tablets after 2 h did not appear sudden release, and the cumulative release within 14 h was over 85%. The drug release profile in 1—12 h exhibited a zero order character. Conclusion A reliable model is established using response surface methodology and the formulation of BOPCRT-TFGF could be optimized. The BOPCRT-TFGF for administration once daily is prepared.