Objective: To optimize composition of compound Gehuang microporous osmotic pump tablets for providing a research model of microporous osmotic pump tablets of Chinese medicine effective components. Method: The content of total alkaloids in Coptidis Rhizoma was determined by ultraviolet spectrophotometry at 346 nm.Taking accumulative release rate of total alkaloids in Coptidis Rhizoma as index

based on single factor tests

central composite design-response surface methodology was adopted to optimize prescription with polyoxyethylene content and polyethylene glycol 400 content and coating weight as factors. Result: The best prescription were:Coptidis Rhizoma extract of 75 mg

Puerariae Lobatae Radix extract of 75 mg

NaCl of 72 mg

polyoxyethylene of 78 mg

microcrystalline cellulose of 15 mg

sodium dodecyl sulfate of 9 mg.In coating solution

concentrations of cellulose acetate

polyethylene glycol and dibutyl phthalate were 30

82

9 g·L-1

coating weight was 8.2%.Accumulative release rate in 12 h of total alkaloids was 81.9%. Conclusion: Release profile of compound Gehuang microporous osmotic pump tablets meets requirements

its zero order equation fitting degree reaches 0.990 9.This optimized preparation processes is stable and reasonable.