Objective:To prepare single-chamber and single-layer osmotic pump-controlled release tablets of bergenin with high drug loading

which was a poorly water-soluble drug. Method: Solid dispersion was prepared with common excipients of osmotic pump tablets as mixed carrier material

prescription of tablets core was optimized by isoosmotic principle;With cumulative release of bergenin as index

coating formulation was selected by central composite design-response surface methodology. Result: When the mass fraction of PEG 1500 was 1.30% and coating gain was 9.5%

cumulative release of prepared osmotic pump tablets of bergenin with high drug loading was nearly 80%

it fitted zero-order release profile. Conclusion: It could effectively increase drug loading of osmotic pump tablets by giving full play to functions of excipients;Methods of optimizing formulation of tablet core and coating could significantly shorten experiment cycle

and this study could provide a new approaches of prescription design of osmotic pump preparation.