ABSTRACT
Objective: To optimize andrographolide pellet by using a quality by design (QbD) approach. Methods: Usingthe cumulative in vitro release as evaluation index, the single-factor investigation and hazard analysis were used to study the core and coating process of andrographolide colon-targeting pellets, and the central composite design-response surface method was used to optimize and predict the three key factors of plasticizer dosage, aging time, and coating weight gain. Results: The optimum coating process parameters were as following: plasticizer dosage of 3 g, coating weight gain of 20%, and aging time of 1 h. The process had been verified that the optimal formulation process had a cumulative in vitro release of 6.9% in the acid phase (0.1 mol/L HCl)-buffered salt phase (pH 6.0) and a cumulative in vitro release of more than 90% in the pH 7.2 buffered salt phase. Conclusion: It is feasible to apply the QbD concept optimization in the study of andrographolide colon-targeting pellets.