Metabolism Based Herb-drug Interaction-jiangzhi Herbs And Atorvastatin In Vitro

Background: Co-medication with HMG-CoA inhibitors such as Atovastatin(AVT) and herb medicines has been used in treatment and/or prevention of coronary disease, especially in prevention of inflammatory reaction and loss of systemic endothelial function which leads to the damage of myocardial and major adverse cardiac events(MACE). The metabolism based herb-drug interaction will be one of key elements for affecting clinical efficacy and safety. Objective: This research program was to study the metabolism based herb-drug interaction between AVT and Jiangzhi Herb Medicine(Fang-2) by using in vitro technologies. Method:(1) The test articles of herbs and it’s six individual herbs(Rhizoma Et Radix Polygoni Cuspidati, Rhizoma Alismatis, Rhizoma Atractylodis, Radix Et Rhizoma Glycyrrhizae, Cortex Magnoliae Officinalis, and Spica Prunellae) were prepared by a standard procedure using liquid extraction.(2) CYP3A4 inhibition study: Human and rat liver microsomes were incubated with extract of Fang-2 or those of it’s individual herbs at 37℃ for 15 minutes, and then with testosterone, probe substrate of CYP3A4 in the presence of β-NADPH. Enzyme activity of CYP3A4, 6β-hydroxylation of testosterone was quantified by using LC-MS/MS.(3) Herb-Drug interaction study: Liver microsomes were preincubated with extract of Fang-2 or those of it’s individual herbs at 37℃ for 15 minutes, and then with AVT in the presence of β-NADPH. Parent depletion of AVT was quantified by using developed LCMSMS methods. Results:(1) CYP3A4 inhibition: Fang-2 showed inhibitive potential on CYP3A4 activity with IC50 of 9.884 mg/mL. Rhizoma Et Radix Polygoni Cuspidati prevented parent depletion of AVT most potentially among 6 individual herb, one individual herb in Fang-2 showed strongest inhibition on CYP3A4 with IC50 of 0.5491 mg/mL. Other individual herb in Fang-2 inhibited the activity of this isoforms with IC50 value of 15.78 mg/mL(Rhizoma Alismatis), 28.13 mg/mL(Rhizoma Atractylodis), >100 mg/mL(Radix Et Rhizoma Glycyrrhizae), 9.02 mg/mL(Cortex Magnoliae Officinali)and 14.28 mg/mL(Spica Prunellae).(2) AVT was extensively depleted by the 1st pass metabolism with intrinsic clearance rate(Clint) of 41.10 ml/mg/min and T1/2 of 60.43 min in liver microsomal incubation. The parent depletion of AVT was affected by preincubation with Fang-2, characterized by an decreased Clint of <21 ml/mg/min and increased T1/2 of >120min, suggesting that Fang-2 prevent parent depletion of AVT from 1st pass metabolism in liver microsomal incubation. Other individual herbs also showed lower intrinsic clearance rates, e.g. 24.91ml/mg/min for Radix Et Rhizoma Glycyrrhizae, 19.34 ml/mg/min for Rhizoma Atractylodis, 13.28 ml/mg/min for Spica Prunellae and longer T1/2 values compared with AVT, e.g. 99.70 min for Radix Et Rhizoma Glycyrrhizae, 128.4 min for Rhizoma Atractylodis, 187.0 min for Spica Prunellae. The inhibition of CYP3A4 by Fang-2 and its herbs was correlated with their preventing AVT from 1st pass metabolism by Fang-2 and its element positively. Conclusions:(1) Fang-2, and its herbs inhibited CYP3A4, key enzyme to metabolize Fang-2 in human and rat liver microsomes. Rhizoma Et Radix Polygoni Cuspidati was the most potential inhibitor for inhibiting CYP3A4.(2) Fang-2 and its individual herbs prevented AVT from 1st pass metabolism by inhibiting CYP3A4 enzyme activity, and the prevention of AVT depletion was correlated with CYP3A4 inhibition positively and significantly.Furth investigation for metabolism based Herb-Drug interaction between Fang-2 and Atorvastatin will have significant clinical benefits in cardiovascular clinical pharmacology.