Expression of Hepatic Cytochrome P450s in Rats Administered with Guibi-tang, a Traditional Herbal Formula

The aim of this study was to investigate the possible herb-drug interactions between the traditional herbal formula Guibi-tang (GBT; Guipi-tang, Kihi-to) and conventional drugs.

GBT was orally administered to either male or female Sprague Dawley (SD) rats once daily at doses of 1000, 2000, or 5000 mg/kg/day for 13 weeks. The messenger ribonucleic acid (mRNA) expression of drug-metabolizing enzyme cytochrome P450 isozymes (cytochrome P450s; CYP1A1, 1A2, 2B1/2, 2C11, 2E1, 3A1, 3A2, and 4A1) was analyzed in hepatic tissues by reverse transcription-polymerase chain reaction.

Repeated oral administration of GBT did not significantly influence the mRNA expression of hepatic CYP1A1, 1A2, 2B1/2, 2C11, 2E1, 3A1, 3A2, and 4A1 in male rats. By contrast, in female rats, the mRNA expression of hepatic CYP1A2 and 2B1/2 was significantly increased by repeated GBT treatment.

Our findings indicate that caution is required in females when GBT is taken concomitantly with conventional drugs metabolized by CYP1A2 or 2B1/2. Our results provide information regarding the safety and effectiveness of GBT for clinical use.

Repeated oral administration of Guibi-tang (GBT) for 13 weeks did not affect the messenger ribonucleic acid (mRNA) expression of hepatic CYP1A1, 1A2, 2B1/2, 2C11, 2E1, 3A1, 3A2, and 4A1 in male ratsRepeated oral administration of GBT for 13 weeks induced mRNA expression of hepatic CYP1A2 and 2B1/2 but not for CYP1A1, 2C11, 2E1, 3A1, 3A2, and 4A1 in female rats. Abbreviations used: CYP450: Cytochrome P450s, GBT: Guibi-tang, SD: Sprague Dawley, HPLC: High-performance liquid chromatography, OECD: Organization for Economic Cooperation and Development, RNA: Ribonucleic acid, RT-PCR: Reverse transcription-polymerase chain reaction, GADPH: Glyceraldehyde-3-phosphate dehydrogenase.