ABSTRACT
Objective: In order to provide an effective reference to the study on its preparation, the stability in vitro of andrographolide was investigated. Methods: Andrographolide was dissolved in phosphate buffer solutions of different pH values; classical isothermal method was employed; the content of andrographolide was determined by RP HPLC; then the stability of the drug in different biological media and organic solvents at 37?C was investigated. Results: The stability of andrographolide was different at different pH values and was best in the condition of pH=3～5. In biological media, it was most stable in bovine serum and the next was in mice homogenate. Conclusion: In different conditions, the stability of andrographolide was different. It provided a reference to the study on andrographolide and its preparation.