ABSTRACT
Objective To use the inclusion technology for improving the solubility and dissolution rate of baicalein from monolithic osmotic pump tablet containing inclusion complex of baicalein by observing the effects of the core and coating on in vitro drug release. Methods Baicalein-inclusion complex was prepared by the inclusion technique, and its solubility and dissolution rate were determined. The percent of cumulative release was used to evaluate the drug release profile in vitro. Single factor analysis was used to study the effects of NaCl and PEO amounts, coating weight and plasticizer amount on drug release. Then orthogonal design was used to select the optimal formulation of monolithic osmotic pump tablet containing baicalein-inclusion complex. Results The solubility and dissolution rate of baicalein were greatly enhanced when prepared into inclusion complex. Orthogonal design results indicated that PEO content in the tablet core and plasticizer PEG 400 in the coating had significant effects on the drug release, and the optimum formulation was: baicalein-inclusion complex 180 mg, NaCl 100 mg, PEO 80 mg, coating weight 4% and plasticizer 9%. The tablets with optimized formula achieved the desired zero-order release profile (r=0.997 8) within 12 hours and the cumulative release was higher than 88%. Conclusion Monolithic osmotic pump tablet of baicalein has been successfully prepared using inclusion complex as the intermediate, and the release behavior accords with zero-order kinetics equation.