PT  - JOURNAL ARTICLE
AU  - Xiao-Mei Zhuang
AU  - Guo-Lin Shen
AU  - Wei-Bin Xiao
AU  - Yan Tan
AU  - Chuang Lu
AU  - Hua Li
TI  - Assessment of the Roles of P-glycoprotein and Cytochrome P450 in Triptolide-induced Liver Toxicity in Sandwich-Cultured Rat Hepatocyte Model
AID  - 10.1124/dmd.113.054056
DP  - 2013 Dec 01
TA  - Drug Metabolism and Disposition
PG  - 2158--2165
VI  - 41
IP  - 12
4099  - http://dmd.aspetjournals.org/content/41/12/2158.short
4100  - http://dmd.aspetjournals.org/content/41/12/2158.full
SO  - Drug Metab Dispos2013 Dec 01; 41
AB  - Triptolide (TP), a main bioactive component of Tripterygium wilfordii Hook F., is a promising agent for treatment of autoimmune diseases. However, a high incidence of dose-limiting hepatotoxicity was observed in the clinic. Sandwich-cultured rat hepatocyte model was used in this study to identify the involvement of P-glycoprotein (P-gp) in TP disposition and to evaluate TP-induced hepatotoxicity after modulation of P-gp by the known inhibitors, ritonavir and tariquidar, and known inducers, phenobarbital, quercetin, and H2O2. Our data showed that biliary clearance of TP reduced 73.7% and 84.2% upon treatment of ritonavir (25 µM) and tariquidar (5 µM), respectively. In contrast, increases of 346%, 280%, and 273% in biliary clearance of TP were observed with treatment of phenobarbital (1.0 mM), quercetin (20 µM), and H2O2 (0.5 mM), respectively. The TP-induced hepatotoxicity increased by twofold when CYP activity was blocked by 1-aminobenzotriazole, suggesting that CYP and P-gp may both contribute to the detoxification of TP in the SCRH model. In addition, hepatotoxicity and the expression of apoptosis proteins Bax and Bcl-2 were correlated qualitatively with the TP exposure duration and its intracellular concentration, which, in turn, can be modulated by P-gp inhibitors or inducers. Our results for the first time demonstrated that in addition to CYP-mediated metabolism, P-gp also plays an important role in the disposition of TP and TP-induced hepatotoxicity. Thus, the modulation of canalicular P-gp has a potential to cause drug-drug interaction between TP and the coadministered P-gp inhibitors or inducers in the clinic.