title: Repetitive administration of Shaoyao-Gancao-tang to rats restores the bioavailability of glycyrrhizin reduced by antibiotic treatment.
abstract: Shaoyao-Gancao-tang (SGT), a traditional Chinese formulation, is often used together with antibiotics such as amoxicillin and metronidazole (AMPC-MET) for the treatment of peptic ulcers in Japan. However, the bioavailability of glycyrrhizin (GL) in SGT is severely reduced by a single administration of AMPC-MET, and the reducing effect continues for 12 days. GL is one of the major pharmacologically important glycosides in SGT and is transformed into the active metabolite 18beta-glycyrrhetic acid (GA) by intestinal bacteria in the gut, followed by absorption of the latter into the blood. In order to reduce the negative effect of AMPC-MET on the bioavailability of GL, the optimum scheduling of the medications was examined. We found that the reduction in the plasma GA concentration and the GL-metabolizing activity in faeces caused by a single dose of AMPC-MET could be sharply attenuated by the repetitive administration of SGT for 4 days. The GA concentration and the GL-metabolizing activity were strongly enhanced by further continuous administration of SGT. These findings suggest that repetitive administration of SGT starting 1 or 2 days after the administration of AMPC-MET speeds the recovery of the bioavailability of GL in SGT. Similar strategies for administering medications may also be useful for combination therapy of antibiotics with other traditional Chinese formulations containing bioactive glycosides.
authors.affiliation: Division of Pharmacognosy, Institute of Natural Medicine, Toyama Medical and Pharmaceutical University, 2630 Sugitani, Toyama 930-0194, Japan.
authors.forename: Ju-Xiu
authors.initials: JX
authors.lastname: He
authors.forename: Teruaki
authors.initials: T
authors.lastname: Akao
authors.forename: Tadato
authors.initials: T
authors.lastname: Tani
mesh_terms: D000658:Amoxicillin / Q000008:administration & dosage / Q000009:adverse effects; D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000009:adverse effects*; D000890:Anti-Infective Agents / Q000097:blood / Q000493:pharmacokinetics*; D019540:Area Under Curve; D001682:Biological Availability; D004334:Drug Administration Schedule; D004338:Drug Combinations; D004365:Drugs, Chinese Herbal / Q000008:administration & dosage / Q000494:pharmacology*; D019695:Glycyrrhizic Acid / Q000097:blood / Q000493:pharmacokinetics*; D006207:Half-Life; D008297:Male; D008795:Metronidazole / Q000008:administration & dosage / Q000009:adverse effects; D051381:Rats; D017208:Rats, Wistar
chemical_list: D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D004338:Drug Combinations; D004365:Drugs, Chinese Herbal; D008795:Metronidazole; D019695:Glycyrrhizic Acid; D000658:Amoxicillin