This study constructed and optimized the design space of the spray drying process for Xiaochengqi granules based on the concept of quality by design(QbD).The powder yield,moisture content,contents of naringin,neohesperidin,honokiol,magnolol,emodin and chrysophanol were taken as critical quality attributes(CQAs).The comprehensive weight coefficient of each CQA was determined by the analytic hierarchy process combined with entropy method,then the comprehensive scores of evaluation were calculated.According to the results of Plackett-Burman design,the relative density of the liquid medicine and the feeding speed were identified as the critical process parameters(CPPs)for the spray drying process of Xiaochengqi granules.Then,the central composite design was used to optimize the ranges of the selected CPPs.The design space was obtained through model fitting,and based on a 95%confidence interval,the relative density of the liquid medicine was determined to be 1.03-1.06,and the feeding speed was 6-12 mL/min.The verification results showed that the process parameters within the design space could ensure the stability of the spray drying process and product quality of Xiaochengqi granules.
quality by designXiaochengqi granulespray dryinganalytic hierarchy processentropy methodPlackett-Burman designcentral composite designdesign space