The influence of commonly prescribed synthetic drugs for peptic ulcer on the pharmacokinetic fate of glycyrrhizin from Shaoyao-Gancao-Tang

The influence of synthetic drugs prescribed for peptic ulcer on the pharmac okinetic fate of glycyrrhizin (GL) from Shaoyao-Gancao-tang (SGT, a traditi onal Chinese formulation, Shakuyaku-Kanzo-to in Japanese) was investigated in rats. Co-administration of histamine H-2-receptor antagonist (cimetidine ) and anticholinergic drug (scopolamine butyl bromide) with SGT didn't infl uence the area under the plasma concentration-time curves (AUC) of glycyrrh etic acid (GA), an active metabolite derived from GL in SGT. The AUC of GA from SGT were significantly reduced by co-administration of synthetic drugs commonly used for peptic ulcer in a triple therapy (OAM), a combination of a proton pump inhibitor (omeprazole) and two antibiotics (amoxicillin and metronidazole). We found that the reduction of AUC in OAM treatment was due to the antibacterial effect of amoxicillin and metronidazole on intestinal bacteria in rat which lead to the decrease of GL-hydrolysis activity. The present study suggests that it may not be a proper way to use triple therap y containing antibiotics simultaneously with SGT for healing of chronic ulc ers.