Objective: To establish determination of in vitro release of alkaline substances from Wutou binary-released granules by the method of area under absorbance-wavelength curve (AUAWC). Method: The studies on in vitro release for Wutou ordinary granules and Wutou polyacrylic acid resin coated granules were researched.Release medium containing drug was obtained at different time points

the individual sample solutions were obtained through chloroform extraction after pH adjusting.The AUAWC were calculated by Origin 8.0 software

and the mixed concentration of different alkaline substances in sample solutions was obtained.Then

the cumulative release curve of Wutou binary-released granules was drawn and the drug release trends of these two granules were compared. Result: This established AUAWC was stable

feasible and accurate with the linear equation of Y=0.145 4X+3.240 4(r=0.999 3) and the average recovery of 106.25% (RSD 6.2%).The cumulative release curve of in vitro release showed that alkaline substances from ordinary granules in the acidic medium was rapid release

which was 54.55% at the 10th min and 94.51% at the 45th min.While the release of those from Wutou polyacrylic acid resin coated granules in acid medium was only a little release

but it released significantly in the simulated intestinal fluid with cumulative release rate of 90.26% at the 210th min. Conclusion: The chloroform extraction shows a good release trend of the alkaline substances in different granules.AUAWC can be used for the determination of in vitro release of Wutou binary-released granules

it will provide a good instruction for the study of release of alkaline substances in other Chinese materia medica preparations and their in vitro and in vivo researches.