Pharmacokinetic Difference between Licorice and Honey-processed Licoricein Rabbits

Abstract

Objectives. Licorice and honey-processed licorice are widely used in clinical Chinese medicine for a variety of conditions and ailments. In this study, we investigated the difference in pharmacokinetics between unprocessed licorice and honey-processed licorice. Methods. Six rabbits were given decoctions of unprocessed licorice and honey-processed licorice in a crossover design. The concentrations of glycyrrhizin and glycyrrhetic acid in serum as well as glycyrrhetic acid in feces suspension were determined by HPLC methods. The pharmacokinetic parameters were calculated by a noncompartment model and statistical comparison was made by paired Student's t test. Results. No significant difference in pharmacokinetics of glycyrrhizin was found between the two treatments; however, licorice processed with honey increased the AUC of glycyrrhetic acid by 48%. The hydrolysis of glycyrrhizin to glycyrrhetic acid in feces suspension was greatly enhanced by the addition of honey. Conclusions. Honey processing of licorice affected the presystemic metabolism of glycyrrhizin and resulted in the elevation of blood levels of glycyrrhetic acid, which indicates that honey might increase the efficacy and toxicity of licorice. ( Mid Taiwan J Med 2004;9:73-9 )