Influence of CYP2C9 genotype on warfarin dose requirements--a systematic review and meta-analysis.
OBJECTIVE
To quantify the influence of common cytochrome P450 2C9 (CYP2C9) polymorphisms on warfarin dose requirements.


METHODS
A systematic review and a meta-analysis, calculating the warfarin dose reduction associated with the five most common variant CYP2C9 genotypes.


RESULTS
Thirty-nine studies (7,907 patients) were included in the meta-analysis. Compared to the CYP2C9*1/*1 genotype, the CYP2C9*1/*2, CYP2C9*1/*3, CYP2C9*2/*2, CYP2C9*2/*3, and CYP2C9*3/*3 required warfarin doses that were 19.6 (95% confidence interval 17.4, 21.9), 33.7 (29.4, 38.1), 36.0 (29.9, 42.0), 56.7 (49.1, 64.3), and 78.1% (72.0, 84.3) lower, respectively. The impact of CYP2C9 genotype tended to be larger in patients without interacting drugs.


CONCLUSIONS
Previous studies have rarely been powered to determine the quantitative influence of specific CYP2C9 genotypes on warfarin dose requirements. The results from our pooled analysis are likely to be the most accurate to date and the methodology could serve as a model for future pharmacogenetic meta-analyses.
Lindh
Jonatan D
JD
Division of Clinical Pharmacology, Karolinska Institutet, Stockholm, Sweden. jonatan.lindh@ki.se
Holm
Lennart
L
Andersson
Marine L
ML
Rane
Anders
A
D000925:Anticoagulants / Q000008:administration & dosage* / Q000009:adverse effects / Q000378:metabolism* / Q000493:pharmacokinetics; D001189:Aryl Hydrocarbon Hydroxylases / Q000235:genetics*; D065729:Cytochrome P-450 CYP2C9; D004334:Drug Administration Schedule; D004347:Drug Interactions; D005838:Genotype; D006801:Humans; D016014:Linear Models; D010597:Pharmacogenetics; D011110:Polymorphism, Genetic; D014859:Warfarin / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D044465:White People / Q000235:genetics
D000925:Anticoagulants; D014859:Warfarin; C450260:CYP2C9 protein, human; D065729:Cytochrome P-450 CYP2C9; D001189:Aryl Hydrocarbon Hydroxylases