title: Effects of CYP2C9 polymorphisms on the pharmacokinetics of R- and S-phenprocoumon in healthy volunteers.
abstract: CYP2C9 catalyses the biotransformation of the oral anticoagulants S-warfarin and R- and S-acenocoumarol. According to data obtained in vitro, phenprocoumon is also metabolized by CYP2C9 but the impact of the CYP2C9 polymorphism on phenprocoumon pharmacokinetics has not been studied. Twenty-six healthy heterozygous and homozygous carriers of the CYP2C9 alleles *1 (wild-type), *2 (Arg144Cys), and *3 (Ile359Leu) received a single oral dose of 12 mg of racemic phenprocoumon. Plasma and 12 h urine concentrations of both enantiomers and their monohydroxylated metabolites were measured by high-performance liquid chromatography with mass spectrometry detection. No significant effect of the CYP2C9 variants *2 and *3 on R-phenprocoumon pharmacokinetic parameters was detected, but S-phenprocoumon clearance tended to decrease with increasing number of CYP2C9*2 and *3 alleles. The ratios of S- to R-phenprocoumon plasma clearances were higher with a median of 0.95 in carriers of *1/*1 versus 0.65 in *3/*3 (P < 0.001 for trend). Plasma and urine concentrations of 4'-, 6- and 7-hydroxyphenprocoumon were significantly lower in homozygous carriers of the CYP2C9*2 and *3 variants compared to CYP2C9*1/*1. Carriers of CYP2C9*3/*3 had a median AUC of (R,S) 7-OH-phenprocoumon of only approximately 25% compared to the wild-type genotype. The AUC of (R,S) 6-OH-phenprocoumon was only approximately 50% in CYP2C9*3/*3 compared to the homozygous wild-type genotype. In conclusion, carriers of CYP2C9*2 and *3 alleles had a lower metabolic capacity regarding phenprocoumon hydroxylation than those with CYP2C9*1/*1. However, regarding phenprocoumon hydroxylation CYP2C9 genotypes had only marginal effects on S- and R-phenprocoumon total clearance in healthy volunteers.
authors.affiliation: Institute of Clinical Pharmacology, Charité, Humboldt University of Berlin, Germany.
authors.forename: Julia
authors.initials: J
authors.lastname: Kirchheiner
authors.forename: Mike
authors.initials: M
authors.lastname: Ufer
authors.forename: Ev-Charlotte
authors.initials: EC
authors.lastname: Walter
authors.forename: Bernd
authors.initials: B
authors.lastname: Kammerer
authors.forename: Rainer
authors.initials: R
authors.lastname: Kahlich
authors.forename: Christian
authors.initials: C
authors.lastname: Meisel
authors.forename: Matthias
authors.initials: M
authors.lastname: Schwab
authors.forename: Christoph H
authors.initials: CH
authors.lastname: Gleiter
authors.forename: Anders
authors.initials: A
authors.lastname: Rane
authors.forename: Ivar
authors.initials: I
authors.lastname: Roots
authors.forename: Jürgen
authors.initials: J
authors.lastname: Brockmöller
mesh_terms: D000483:Alleles; D001189:Aryl Hydrocarbon Hydroxylases / Q000235:genetics*; D002851:Chromatography, High Pressure Liquid; D065729:Cytochrome P-450 CYP2C9; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D013058:Mass Spectrometry; D010644:Phenprocoumon / Q000097:blood / Q000493:pharmacokinetics* / Q000652:urine; D011110:Polymorphism, Genetic; D012016:Reference Values; D013237:Stereoisomerism
chemical_list: C450260:CYP2C9 protein, human; D065729:Cytochrome P-450 CYP2C9; D001189:Aryl Hydrocarbon Hydroxylases; D010644:Phenprocoumon