Influence of cytochrome P450 3A5 (CYP3A5) genetic polymorphism on dose-adjusted plasma levels of carbamazepine in epileptic patients in South Indian population.

AIM

The aim of the study was to compare the dose-adjusted plasma levels of carbamazepine (CBZ) among expressers and nonexpressers of cytochrome P450 3A5 genotypes.

SUBJECTS AND METHODS

The study was carried out in 100 epileptic patients who were on CBZ monotherapy. Steady-state plasma CBZ levels were measured using reverse-phase high-performance liquid chromatography method, and genotyping of was done using real-time polymerase chain reaction method.

RESULTS

Patients inheriting variant (nonexpressers) had an increased plasma concentration of CBZ (4.86 μg/ml) when compared to patients inheriting either or (expressers) (4.3 μg/ml, = 0.004). Nonexpressers had significantly increased plasma concentrations of CBZ when adjusted for dose and weight when compared to expressers ( < 0.002 and < 0.001, respectively). The frequency of adverse reactions in expressers and nonexpressers was 12% and 9%, respectively.

CONCLUSION

There is a significant influence of genetic polymorphism (6986A>G) on dose-adjusted plasma levels of CBZ in epileptic patients in the South Indian population.