Drug Interactions Of Baicalin With CYP3A And P-gp

Background and ObjectiveBaicalin(BG),the major bioactive compound from Scutellaria baicalensis,is widely applied in traditional Chinese medicine for the treatment of inflammation,hepatitis,various infections,and tumors.In 2005,baicalin capsules(250mg per capsule,approval no.H20158009)were approved by the state food and drug administration of China for the adjuvant therapy of hepatitis(2 capsules 3 times a day).BG is the mainly bioactive constituent and phytochemical marker for the quality control of about 100 kinds of Traditional Chinese Medicine preparations.BG and Traditional Chinese Medicine that containing BG are widely used in clinic.However,several lines of evidence suggest that BG may cause drug-drug interactions in humans.Pharmacokinetic interactions mediated by drug metabolizing enzymes and transporters are the important causes of drug interactions(DDI)in clinic.Many studies have found that baicalin can affect the activity and expression of CYP3 A and p-glycoprotein(P-gp).These results indicate that DDIs may occurs when co-medication with BG.The aim of this study was to explore a potential effect of BG on Cs A exposure in healthy volunteers and to assess possible effects on individual pharmacokinetic processes in detail.Moreover,this article explored the effect of baicalin on the pharmacokinetics of sorafenib in rats and its mechanism of action.1.The effect of baicalin on the pharmacokinetics of cyclosporine A in healthy Chinese volunteersAfter overnight fasting,the participants were administrated 200 mg Cs A orally(8 soft capsules)in the morning on day 1 during the first period.In the second period,after a washout period of two weeks,the same procedure was repeated with Cs A in combination with 500 mg BG(2 capsules).Blood samples(4 m L each)were collected at multiple time points pre-dose,0.5,1.0,1.5,2,2.5,3,4,6,8,10,12,16,24,36,and 48 h after dosing on days 1 and 15,respectively.2.Effect of BG on pharmacokinetics of sorafenib in rats2.1 Establishment of a method for the determination of sorafenib in rat plasma by LC-MS /MSA LC-MS/MS method for the determination of sorafenib in plasma was established.And the specificity,calibration curve,lower limit of quantitation(LLOQ),accuracy,precision,recovery,matrix effect and stability were validated according to US Food and Drug Administration Bioanalytical Method Validation.2.2 Dosing scheduleTwenty-four rats were randomly divided into two groups(9)=12 per group,half male and female): control group and BG co-administration group.Rats in the control group were given normal saline by intragastric administration,while rats in the BG group were given 160 mg/kg BG for one day or seven days by gavage 30 min before administration of sorafenib(50 mg/kg,i.g.).Blood samples(0.20 m L)were obtained into heparinized centrifuge tube before admistation and at 0.25,0.5,1,2,4,6,8,12,24,36,48,and 72 h after administration of sorafenib.2.3 Effect of baicalin on the absorption of sorafenibTo investigate the effect of baicalin on the absorption of sorafenib,the rat single-pass intestinal perfusion model was used.The concentration of sorafenib was determined by LC-MS/MS and the permeability coefficients were calculated.2.4 Effect of BG on Sorafenib metabolism in liver microsomesRats under anesthesia were killed,and liver microsomes were prepared.To investigate the effects of BG on midazolam and sorafenib metabolism,midazolam and sorafenib were incubated with rat liver microsomes in presence of NADPH.LC-MS methods were used to analyze 1'-hydroxymidazolam(1-OH MDZ,the metabolite of the probe substrate midazolam for CYP3A)and Sorafenib N-oxyde(the metabolite of sorafenib mediated by CYP3A).Different concentrations of BG were added to the incubation system to investigate its inhibitory effect on sorafenib metabolism,and the inhibition constant(Ki)or IC50 was calculated.2.5 Effect of baicalin on the expression of intestinal P-gpWestern Blot analyses were used to investigate the effects of BG on the expression of P-gp protein in rat intestinal.2.6 Statistical analysisThe pharmacokinetic parameters of sorafenib in rats were calculated using Win Nonlin 7.0 software,and the data were statistically analyzed using SPSS 23.0 software.Independent-sample t-test or nonparametric test was used to compare the significant differences between the two groups.P<0.05 was considered statistically significant.Result1 The effect of BG on the pharmacokinetics of cyclosporine A in healthy Chinese volunteersIn addition,no significant differences(P > 0.05)were observed in Cmax,AUC0-48,AUC0-?,Tmax,T1/2,MRT0-48,CL/F and Vz/F of Cs A between Cs A administration alone and BG co-treatment grounp,suggesting that BG did not affect the respective pharmacokinetic parameters of Cs A to a clinically relevant extent.2.Effect of BG on pharmacokinetics of sorafenib in rats2.1 Method validationCalibration curves showed good linearity over the range of 5–2000 ng/m L for sorafenib.The specificity,lower limit of quantitation(LLOQ),accuracy,precision,recovery,matrix effect and stability were fully validated.The method was sensitive and reliable,and could be used to determine the concentration of sorafenib in rat plasma.2.2 Effect of baicalin on pharmacokinetics of sorafenib in ratsThe validated analytical method was employed to study the pharmacokinetic profiles of sorafenib in rats.When the rats were pretreated with BG(160 mg/kg,i.g.)for single dose,the Cmax,AUC0-t and AUC0-? of Sorafenib in BG grounp were increased by 1.83,1.67 and 1.63 times,respectively,compared to control group.Meanwhile,BG(160 mg/kg,7 days,i.g.)treatment significant increased the Cmax,AUC0-t,and AUC0-? of Sorafenib.2.3 Effect of baicalin on the absorption of sorafenib in ratsThe results showed that the Ka and Peff of Sorafenib increased significantly after the addition of BG.The results indicated that BG could enhance the absorption of sorafenib in the intestine of rats.2.4.Effects of BG on midazolam and sorafenib metabolismCompared with the control group,there were no significant changes in the enzyme kinetic parameters(Vmax,Km and CLint)of 1-OH MDZ and Sorafenib N-oxyde in the liver microsomes of rats after multiple doses of BG.BG didn't exhibited potency to inhibite sorafenib metabolism in human/rat liver microsomes.2.5 Effect of baicalin on the expression of intestinal P-gpIn line with in vitro metabolism results,baicalin treatment significantly induce the P-gp expression in rat intestine.Conclusion1.Co-administration of a single 500 mg BG dose has no clinically relevant effect on the exposure of Cs A in healthy volunteers.2.Single-dose and multiple doses BG administration could significantly increase the exposure of sorafenib in male and female rats.3.The absorption of sorafenib in the intestinal tract was increased after administration of baicalin.No significant inhibitory potency of BG was found towards sorafenib metabolism in pooled human liver/rat microsomes.