To establish and validate the design space of the Digeda-4 flavored decoction( DGD-4D) extraction process by using the quality by design( Qb D) concept. With DGD-4D decoction pieces as a model drug,with the transfer rate of aesculin,picroside I,picroside Ⅱ,geniposide and the yield of extract as critical quality attributes( CQAs),the single factor experiment design was used to determine the level of each factor; the Plackett-Burman experiment design was used to select the critical process parameters( CPPs);and the Box-Behnken experiment design was used to optimize the extraction process. The design space of the DGD-4D extraction process was established,and finally,four experimental points were selected to verify the established model. The single factor experiment determined the levels of each factor,including soaking time 60 min and 30 min,water adding volume 12 times and 8 times,extraction time 90 min and 30 min,number of extraction times 3 times and 1 time,as well as extraction temperature 100 ℃ and 90 ℃.By Plackett-Burman experimental design,the DGD-4D water addition,extraction time and number of extraction times were determined to be CPPs. The Box-Behnken experimental variance analysis showed that P of the regression model was less than 0. 01 and the misstated value was more than 0. 01,indicating that the model had good predictive ability,and the operation space of CPPs in the DGD-4D extraction process was determined as follows: the amount of water addition was 10-12 times; extraction time 50-80 min; and number of extraction times was 3 times. The design space of DGD-4D extraction process based on the concept of Qb D is conducive to improving the stability of product quality and laying a foundation for the future development of DGD-4D.
Keywords: DGD-4D; critical process parameters; critical quality attributes; design space; extraction process; quality by design.