Influence of hydroxypropyl-β-cyclodextrin on stability of potassium dehydroandrographolidi succinas

Abstract

OBJECTIVE: To investigate the effect of hydroxypropyl-β- cyclodextrin(HP-β-CD) on the stability of potassium dehydroandrographolidi succinas(DAS-K) in aqueous solution. METHODS: The degradation kinetics of DAS-K in aqueous solution were investigated at different pH, different HP-β-CD concentration and various temperatures. The rate constant(kc) for the degradation of DAS-K in inclusion complex and equilibrium constant(K A) were calculated by the curve-fitting method. RESULTS: The hydrolytic degradation of DAS-K followed first-order kinetics in different HP-β-CD concentration. The apparent rate contant(kobs) for the hydrolysis of the drug was not a linear function of HP-β-CD concentration and asymptotically approached a minimum value with increasing HP-β-CD concentration. The stabilizing effect of HP-β-CD on DAS-K was more significant at low temperature. CONCLUSION: HP-β-CD represents a visible means of stabilization of DAS-K solution in the study.