Frequency of cytochrome P450 CYP2C9 variants in a Turkish population and functional relevance for phenytoin

Abstract

Frequency of the two CYP2C9 variants in Turkish subjects was in a similar range as in other Caucasian populations. A significant proportion of the interindividual variability in phenytoin trough levels is explained by the genotypes. The 12 h serum concentrations after a single phenytoin dose may be used for routine phenotyping of CYP2C9 mediated metabolic clearance and the p-HPPH/P ratios may be even more sensitive indicators of CYP2C9 activity.