Investigation Of Pharmacokinetics And Chiral Metabolism Of Nebivolol

Objective:This study combines the genetic polymorphisms of CYP2D6, a main metabolizing enzyme of nebivolol, to study its pharmacokinetic characteristics and chiral metabolic characteristics and mechanism in chinese population.Methods:The plasma concentrations of nebivolol racemate was determined by LC-MS/MS method, the concentration of enantiomers was separated using a chiral column and measured by LC-MS/MS method. Drug and metabolite concentrations in microsomal incubation system were measured by high performance liquid chromatography. Using PCR-RFLP method for genotyping.In pharmacokinetic studies,16subjects was screened, including8cases of CYP2D6*10homozygous mutation,3cases of homozygous wild type,5cases of mutant heterozygotes. Using self-control test method, a single dose of5mg,10mg. Repeated administration is administered once a day,5mg for each,7consecutive days. Sampling at different times, determined blood concentrationand pharmacokinetic parameters.In vitro metabolism mechanism studies was conducted with recombinant enzyme and microsomal enzyme method, investigated the catalytic mechanism of the enzyme catalytic mechanism of the enzyme and its enantiomers of the racemate of metabolism.In chiral pharmacokinetic studies,8subjects comply with the requirements of genotype were screened (screening genotype by CYP2D6*10mutation and CYP2C19*2mutation). Genotype of subjects were CCAA, CCGG, TTAA, TTGG, each two cases. After a single oral administration of10mg nebivolol, blood samples were collected to measure the concentration of the drug and the pharmacokinetic parameters.The results:LC-MS/MS method for the determination of drug concentration in plasma methodology is feasible, in line with the biological sample testing requirements. Using a chiral column can be efficiently separated plasma nebivolol enantiomers, the separation liquid can be collected by LC-MS/MS method for measuring the concentration of nebivolol enantiomers.In the Chinese population, Nebivolol in the range of5mg～10mg dose conform linear pharmacokinetic processes, and5mg multiple doses also conform accumulation of liner kinetics, and pharmacokinetic parameters consistent with the foreign literature. The CYP2D6*10mutant subjects witnessed a significant increasing trend of drug exposure, showed no significant difference owing to the effect of the number of subjects and individual differences.In vitro tests confirmed that CYP2D6, CYP2C19, CYP3A4has a catalytic effect on metabolism of nebivolol, CYP2D6and CYP2C19is the main catalysis enzyme, in which CYP2D6catalyze the metabolism of of L-nebivolol and CYP2C19catalyze D-nebivolol.Invivo chiral metabolism studies display, CYP2D6*10mutant TT genotype have higher racemic drug exposure and L-drug exposure, and CYP2C19*2mutation GG and AA racemic haven’t obvious drug exposure difference, but AA type higner GG genotype in the D-drug exposure.Conclusion:In the Chinese population, the pharmacokinetic of Nebivolol affected by CYP2D6gene polymorphism. People with CYP2D6*10homozygous mutation have a higher drug exposure, while CYP2C19gene mutations less affect the pharmacokinetics of nebivolol. The Nebivolol enantiomers are subject to different degrees of CYP2D6and CYP2C19metabolism.