Progress on application of central composite design-response surface methodology in optimization of preparations in China

Central composite design (CCD) is one of the most commonly used design methods in response surface optimization and has been widely applied in the field of pharmaceutics to optimize preparations. On the 20th anniversary of the introduction of CCD into China, the paper reviews its application in domestic pharmaceutical researches. Based on the brief introduction of basic principle and operation steps of CCD, the mistakes emerging in the application of CCD are summarized, including conceptual confusion with Box-Behnken design and face-centered CCD as well as wrong designs. Besides, the issues concerning the selection of factors and responses are discussed. The article is helpful for researchers to comprehensively understand the CCD and facilitates the rational application of this method.