Effects of paeoniflorin on the activities and mRNA expression of rat CYP1A2, CYP2C11 and CYP3A1 enzymes in vivo

Paeoniflorin is the major constituent in extracts of the paeony root, the purpose of the present study was to assess the effects of paeoniflorin on the activities and mRNA expression of the rat hepatic drug-metabolizing enzymes cytochrome P450 (CYP1A2), CYP2C11 and CYP3A1 in vivo.Sprague-Dawley (SD) male rats were treated with paeoniflorin at the dosage of 25, 50 and 100 mg/kg or 0.9% sodium chloride solution by intragastric administration for 7 days, then were given probe drugs phenacetin (CYP1A2), tolbutamide (CYP2C11), or midazolam (CYP3A1) orally on the eighth day. Blood samples were collected at various times, and the plasma concentrations of the probe drugs were estimated with ultra-high-performance liquid chromatography. The mRNA expression levels of rat hepatic CYP1A2, CYP2C11 and CYP3A1 were analysed with real-time PCR.The pharmacokinetic results indicated that paeoniflorin inhibits the activities of CYP1A2, CYP2C11 and CYP3A1 in vivo. The effect was most pronounced on CYP3A1, according to the United States Food and Drug Administration classification of inhibitors of CYP3A, it reached the category of moderate inhibition. The mRNA expression levels of 3 CYP enzymes were also tended to be inhibited.We conclude that paeoniflorin can inhibit the activities of CYP1A2, CYP2C11 and CYP3A1 in vivo, which may affect the metabolism of drugs that are primarily dependent on these pathways.

Hepatic Cytochrome P450 Profiles in Hemorrhagic Shock Model Rats After Transfusion With Stored Red Blood Cells

Red cell transfusions, which deteriorate in quality during storage, triggers several negative biological responses. However, little is known regarding the effects of stored red cell transfusion on cytochrome P450 (P450) profiles. To clarify this issue, we investigated hepatic P450 profiles in hemorrhagic shock model rats after resuscitation with stored packed red cells (PRC). The pharmacokinetics data for P450-metabolizing substrates showed that the clearance of substrates for Cyp1A2 and Cyp3A2 in the stored PRC resuscitation group were decreased compared to sham group. The protein expression, metabolic activity and mRNA expression of the P450 isoforms in the stored PRC resuscitation group were lower than the corresponding values for the sham group. However, these changes would be expected to have weak effects on the in vivo pharmacokinetics of the concomitant drugs based on the criteria stated in the guideline on drug interactions. In contrast, the results of these P450 profiles in the stored PRC and fresh PRC resuscitation group exhibited a similar trend. These results suggest that the stored PRC transfusion has an influence on the hepatic P450 profiles, but is of little clinical significance, not by the deterioration of the quality of red cells but pathophysiological alterations following the hemorrhage and transfusion.

Evaluation of cytochrome P450-based drug metabolism in hemorrhagic shock rats that were transfused with native and an artificial red blood cell preparation, Hemoglobin-vesicles

Hemoglobin-vesicles (Hb-V) are being developed as red blood cell (RBC) substitutes. In this study, we report on quantitative and qualitative alterations of hepatic cytochrome P450 (CYPs) and the pharmacokinetics of CYP-metabolizing drugs, with a focus on four CYP isoforms (CYP1A2, CYP2C11, CYP2E1 and CYP3A2), after Hb-V resuscitation from a massive hemorrhage. The results of proteome analysis and western blot data indicate that resuscitation with both Hb-V and packed RBC (PRBC) resulted in a decrease in the protein levels of CYPs. Along with a decrease in the protein expression of CYPs, pharmacokinetic studies showed that the elimination of CYP-metabolizing drugs was prolonged in the Hb-V and PRBC resuscitation groups. It is also noteworthy that the CYP-metabolizing drugs in the Hb-V resuscitation group was retained for a longer period compared to the PRBC resuscitation group, and this is attributed to the CYP isoforms having a lower metabolic activity in the Hb-V resuscitation group than that for the PRBC resuscitation group. These findings suggest that resuscitation with Hb-V after a massive hemorrhage has a slight but not clinically significant effect on drug metabolism via CYPs in the liver due to decreased protein levels and the metabolic activity with respect to the CYPs.

Assessing cytochrome P450-based drug-drug interactions with hemoglobin-vesicles, an artificial red blood cell preparation, in healthy rats

Hemoglobin-vesicles (Hb-V), hemoglobin encapsulated within a liposome, were developed as an artificial red blood cell (RBC). When Hb-V becomes clinically available in the future, patients would presumably be co-administered with one or more drugs. Since drug-drug interactions can cause serious adverse effects and impede overall curative effects, evidence regarding the risk associated with drug-drug interactions between Hb-V and such simultaneously administered drugs is needed. Therefore, we report on cytochrome P450 (CYP)-based drug interactions with Hb-V in healthy rats. At 1 day after the saline, Hb-V or packed RBC (PRBC) administration, the blood retention of CYP-metabolizing drugs (caffeine, chlorzoxazone, tolbutamide and midazolam) were moderately prolonged in the case of the Hb-V group, but not the PRBC group, compared to saline group. The results of a proteome analysis revealed that the Hb-V administration had only negligible effects on the protein expression of CYPs in the liver. Hb-V administration, however, clearly suppressed the CYP metabolic activity of the four target CYP isoforms compared with the saline and PRBC group. However, these alterations were nearly recovered at 7 day after the Hb-V administration. Taken together, these results suggest that the administration of Hb-V slightly and transiently affects the CYP-based metabolism of the above drugs.

Metabolic interactions of rosmarinic acid with human cytochrome P450 monooxygenases and uridine diphosphate glucuronosyltransferases

In light of the widespread use of herbal medicines containing rosmarinic acid (RA) and limited literature available thereon, we investigated the metabolic interactions of RA with human cytochrome P450 monooxygenases (CYPs) and uridine diphosphate glucuronosyltransferases (UGTs). The involvement of selected enzymes (CYP1A2, CYP2C19, CYP2E1, CYP3 A4, UGT1A1, UGT1A6, and UGT2B7) in the metabolism of RA and the inhibitory effect of RA on the enzyme activity were comprehensively evaluated using human recombinant isozyme system. Additionally, concentration-dependent RA metabolism mediated by phase I enzymes (including CYPs) or UGT was investigated in human liver microsome (HLM) system. A significant disappearance of RA was observed in the seven CYP and UGT isoforms studied, indicating their possible involvement in the metabolism of RA. Based on Michaelis-Menten kinetics, the metabolism study using HLM suggests that the UGT system may have a higher capacity and lower affinity for the metabolism of RA than phase I enzyme (including CYP) systems. Moreover, RA weakly inhibited CYP2C9 and 2E1 activities with IC50 values of 39.6 and 61.0 μM, respectively, while moderately inhibiting UGT1A1, 1A6, and 2B7 with IC50 values of 9.24, 19.1, and 23.4 μM, respectively. By constructing Line weaver-Burk plots, the type of inhibition exhibited by RA on CYP and UGT activities was determined as follows: CYP2C19, mixed inhibition; CYP2E1, UGT1A1, UGT1A6, and UGT2B7, competitive inhibition. Based on the comparison of the IC50 and Ki values obtained in the current study with the previously reported plasma concentrations of RA after oral dosing in humans, it is suggested that RA may significantly inhibit the activities of the tested UGTs, rather than CYPs, in clinical settings. Thus, the present study could provide a basis for further studies on clinically significant interactions between UGT substrate drugs and herbal medicines containing RA.

Effects of Alismatis rhizome on rat cytochrome P450 enzymes

CONTEXT

Alismatis rhizome (RA) (Water Plantain Family, also called "Zexie" in Chinese), one of the commonly used components of traditional Chinese medicines, is derived from the dried rhizomes of Alisma orientalis (Sam.) Juzep. (Alismataceae).

OBJECTIVE

This study explores the RA influences on rat cytochrome P450 (CYP) enzymes (CYP1A2, CYP2C9, CYP2E1 and CYP3A4) by using cocktail probe drugs in vivo.

MATERIALS AND METHODS

A cocktail solution at a dose of 5 mL/kg, which contained phenacetin (20 mg/kg), tolbutamide (5 mg/kg), chlorzoxazone (20 mg/kg) and midazolam (10 mg/kg), was orally administration to rats treated twice daily with RA (10, 20 and 40 g/kg) for consecutive 14 days. Blood samples (0.2 mL) were collected at a series of time-points and the concentrations of probe drugs in plasma were determined by HPLC-MS/MS. The corresponding pharmacokinetic parameters were calculated by the software of DAS 2.0 (Wenzhou Medical College, Zhejiang, China).

RESULTS

In the experiment, there was a statistically significant difference in the t1/2, Cmax, AUC(0-∞) and CL for phenacetin and midazolam, while there was no statistical pharmacokinetics difference for tolbutamide and chlorzoxazone. Our study showed that treatment with multiple doses of RA had an inductive effect on rat CYP1A2 and an inhibitory effect on rat CYP3A4 enzyme activity. However, RA has no inductive or inhibitory effect on the activities of CYP2C9 and CYP2E1.

CONCLUSIONS

Caution is needed when RA is co-administration with some CYP1A2 or CYP3A4 substrates in clinic, because it may result in treatment failure and herb-drug interactions.

Effect of Repeated Wuniu Early Tea Administration on the CYP450 Activity Using a Cocktail Method

Wuniu early tea (Camellia sinensis) is an important beverage consumed in China. Up to date, a lot of methods for identifying and chemical analysing have been done. However, there is no report on the effects of Wuniu early tea on cytochrome P450 isozymes. Therefore, the present objective of our study was to evaluate the potential effects of Wuniu early tea on cytochrome P450 isozymes P2C9, P1A2, P2C19 and P2B6 in rats with a cocktail approach including, matching probe drugs of tolbutamide, phenacetin, omeprazole and bupropion. These four probe drugs were simultaneously administered to rats after repeated Wuniu early tea administration. The pharmacokinetics of the probes in the plasma was simultaneous determined by high-performance liquid chromatography-mass spectrometry. The t_1/2 and AUC_(0-∞) of tolbutamide increased significantly and CL_z decreased remarkably in test rats after repeated Wuniu early tea administration. However, the main pharmacokinetic parameters of the other three probe drugs were not significantly different between control and test rats. The findings in this study suggested that Wuniu early tea could inhibit cytochrome P2C9 while did not influence on cytochrome P1A2, cytochrome P2C19 and cytochrome P2B6.

Assessment of effects of IR and IPC on activities of cytochrome P450 isozymes in rats by a five-drug cocktail approach

BACKGROUND AND OBJECTIVE

To evaluate the effects of ischemia and reperfusion (IR) and ischemic preconditioning (IPC) on the metabolic activities of cytochrome P450 (CYP) isozymes in rats by a five-drug cocktail approach.

METHODS

Cocktail approach was used to evaluate the influence of IR and IPC on the activities of CYP1A2, CYP2C9, CYP2E1, CYP2D6 and CYP3A4, which were reflected by the changes of pharmacokinetic parameters of five specific probe drugs: caffeine, chlorzoxazone, tolbutamide, metoprolol and midazolam, respectively. Rats were randomly divided into IR, IPC and sham groups, and then injected the mixture of five probe drugs. Blood samples were collected at a series of time-points and the concentrations of probe drugs in plasma were determined by a HPLC method with UV detection. The pharmacokinetic parameters were calculated by the software of DAS 2.0.

RESULTS

The parameters including t(1/2β), CLs, AUC, MRT and K10 exhibited a similar tendency for both IR and IPC groups. Compared with sham group, CLs and K10 of five probe drugs were significantly lower (p < 0.05), AUC and t(1/2β) of five or some probe drugs were significantly increased in IR and IPC groups (p < 0.05). Compared with IPC group, CLs of five probe drugs were decreased and AUC were significantly increased in the IR group (p < 0.05).

CONCLUSION

IR can variably decrease the activities of CYP isozymes in rats and this decrease can be attenuated by IPC.

Evaluation of impact of Herba Erigerontis injection, a Chinese herbal prescription, on rat hepatic cytochrome P450 enzymes by cocktail probe drugs

ETHNOPHARMACOLOGICAL RELEVANCE

Herba Erigerontis injection (HEI), one of the most popular herbal prescription in China, is made from the aqueous extracts of Erigeron breviscapus whole plant. Now HEI is widely used for the treatment of cardiovascular diseases and cerebrovascular diseases such as coronary heart disease, anginapectoris and paralysis.

AIM OF THE STUDY

The purpose of this study was to investigate the in vivo effect of HEI on rat cytochrome P450 enzymes (CYP1A2, CYP2C11, CYP2D4, CYP2E1 and CYP3A2) to assess its safety through its potential to interact with co-administered drugs.

MATERIALS AND METHODS

Rats were randomly divided into five groups. Rats were intravenous administrated with HEI via the caudal vein at the dosage of 1.8ml/kg or 7.2ml/kg once daily for consecutive 3 days or 14 days. On the fourth or the fifteenth day, a cocktail solution at a dose of 5ml/kg, which contained caffeine (2.5mg/kg), tolbutamide (2.5mg/kg), chlorzoxazone (5mg/kg), midazolam (5mg/kg) and metoprolol (10mg/kg), was injected via the lingual vein to all rats. Then 0.8ml blood samples were collected at a set of time-points. The plasma concentrations of probe drugs were simultaneously determined by HPLC. Pharmacokinetic parameters simulated by DAS software were used for the evaluation of HEI on the activities of rat CYP1A2, CYP2C11, CYP2D4, CYP2E1 and CYP3A2 enzymes. ANOVA and Dunnett's test was used for data analysis.

RESULTS

There were no significant influence of pharmacokinetic parameters of caffeine, tolbutamide and chlorzoxazone in HEI pretreated rats. But many pharmacokinetic parameters of metoprolol and midazolam in HEI pretreated rats were affected significantly (P<0.05), which indicated that metabolism of metoprolol and midazolam in these treatment groups was evidently slowed down.

CONCLUSIONS

The results from the present in vivo study suggested that HEI showed no effects on rat CYP1A2, CYP2C11 and CYP2E1, however, it demonstrated potential inhibitory effects on rat CYP2D4 and CYP3A2. Therefore, caution is needed when HEI is co-administered with drugs metabolized by human CYP2D6 or CYP3A4 in clinic, which may result in increased concentrations of these drugs and relevant herb-drug interactions.