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

Inhibition and Induction by Poziotinib of Different Rat Cytochrome P450 Enzymes In Vivo and in an In Vitro Cocktail Method

Poziotinib is an orally active, irreversible, pan-HER tyrosine kinase inhibitor used to treat non-small cell lung cancer, breast cancer, and gastric cancer. Poziotinib is currently under clinical investigation, and understanding its drug-drug interactions is extremely important for its future development and clinical application. The cocktail method is most suitable for evaluating the activity of cytochrome P450 enzymes (CYPs). As poziotinib is partially metabolized by CYPs, cocktail probes are used to study the interaction between drugs metabolized by each CYP subtype. Midazolam, bupropion, dextromethorphan, tolbutamide, chlorzoxazone, phenacetin, and their metabolites were used to examine the effects of poziotinib on the activity of cyp1a2, 2b1, 2d1, 2c11, 2e1, and 3a1/2, respectively. The in vitro experiment was carried out by using rat liver microsomes (RLMs), whereas the in vivo experiment involved the comparison of the pharmacokinetic parameters of the probes after co-administration with poziotinib to rats to those of control rats treated with only probes. UPLC-MS/MS was used to detect the probes and their metabolites in rat plasma and rat liver microsomes. The in vitro results revealed that the half-maximal inhibitory concentration values of bupropion and tolbutamide in RLMs were 8.79 and 20.17 μM, respectively, indicating that poziotinib showed varying degrees of inhibition toward cyp2b1 and cyp2c11. Poziotinib was a competitive inhibitor of cyp2b1 and cyp2c11, with Ki values of 16.18 and 17.66 μM, respectively. No time- or concentration-dependence of inhibition by poziotinib was observed toward cyp2b1 and cyp2c11 in RLMs. Additionally, no obvious inhibitory effects were observed on the activity of cyp1a2, cyp2d1, cyp2e1, and cyp3a1/2. In vivo analysis revealed that bupropion, tolbutamide, phenacetin, and chlorzoxazone showed significantly different pharmacokinetic parameters after administration (p < 0.05); there was no significant difference in the pharmacokinetic parameters of dextromethorphan and midazolam. These results show that poziotinib inhibited cyp2b1 and cyp2c11, but induced cyp1a2 and cyp2e1 in rats. Thus, poziotinib inhibited cyp2b1 and cyp2c11 activity in rats, suggesting the possibility of interactions between poziotinib and these CYP substrates and the need for caution when combining them in clinical settings.

Effects of mongolian medicine Terminalia chebula Retz. on 6 CYP450 enzymes in rats

Terminalia chebula Retz. (TCR) is a medicinal material commonly used in Mongolian medicine. After consulting the literature at home and abroad, current research on TCR focuses on chemical composition, pharmacodynamics, and fingerprints. The pharmacokinetics of TCR has not been reported. Cytochrome P450 (CYP450) is the main drug-metabolizing enzyme, and its activity may be induced or inhibited by certain drugs, resulting in drug interactions in clinical applications. The objective of this study was to establish a high performance liquid chromatography (HPLC) method that can simultaneously detect multiple probe drugs to determine the effect of TCR on the activities of CYP450 enzymes CYP2C19, CYP2E1, CYP2D6, CYP2C9, CYP3A4, and CYP1A2. Wistar rats (male) were divided into 5 groups according to the randomization principle, namely the control group, the positive group, and the high, medium and low dose group. After 15 days of continuous administration, the mixed probe drug was injected into the vein, and then a small amount of blood was collected from the orbital vein at different time points. After the samples were processed, the blood concentration of each probe drug was measured by the established HPLC method. The pharmacokinetic parameters of each probe drug were calculated using DAS software. Compared with the control group, the plasma clearance (CL) of chlorzoxazone and omeprazole decreased, and the maximum plasma concentration (C_max) and area under the curve (AUC) increased in the TCR group. The pharmacokinetic parameters of theophylline, midazolam, metoprolol, and tolbutamide did not differ significantly. The results indicated that TCR mainly inhibited the activities of CYP2E1 and CYP2C19, but had no effect on the activities of CYP1A2, CYP2C9, CYP3A4 and CYP2D6. Extra care should be taken when drugs metabolized by CYP2C19 and CYP2E1 enzymes are used in combination with TCR, as drug-herb interactions may occur. These results can guide the clinical application of related drugs and provide valuable information for drug interactions. The main component that affects enzyme activity may be tannins in the water extract.

Effects of Digeda-4 Decoction on the CYP450 Activities in Rats Using a Cocktail Method by HPLC

Digeda-4 decoction is a traditional Mongolian medicine; its effects on cytochrome (CYP) enzymes are still unclear. CYP450 isoenzymes are the main drug metabolic enzymes, and their activities may be induced or inhibited by certain drugs, which lead to drug interactions in clinical use. Effects of Digeda-4 decoction on the activities of CYP450 subtype enzymes CYP1A2, CYP2C9, CYP2E1, CYP2C19, and CYP3A4 in rats were studied by cocktail method, and the pharmacokinetic parameters of five specific probe drugs (theophylline, tolbutamide, chlorzoxazone, omeprazole, and midazolam) were calculated by DAS software; changes of parameters can be used to evaluate the effects of Digeda-4 decoction on enzyme activities. The experimental rats were divided into three groups: control group, Digeda group, and positive group. Rats in Digeda group were given Digeda-4 decoction through continuous gavage for 14 days. After fasting for 12 hours, the mixed probes drug solution was injected into the tail vein; the blood samples were collected through the orbital vein at different time points. The concentrations of probe drugs in rat plasma were measured by HPLC. Compared with the control group, the half-life time (t_1/2) of the pharmacokinetic parameters of theophylline, tolbutamide, omeprazole, and midazolam was prolonged, the area under the curve (AUC) increased, and the plasma clearance (CL) decreased in the Digeda group. Continuous gavage administration for 14 days may inhibit the activities of CYP450 subtype enzymes CYP1A2, CYP2C9, CYP2C19, and CYP3A4 of rats. Herb-drug interaction should be noted between Digeda-4 decoction and the drugs metabolized by CYP1A2, CYP2C9, CYP2C19, and CYP3A4.