CYP3A5 and epilepsy: In this study, the population clearance estimates for carbamazepine indicated that there was an 8% increase in the serum concentration in patients with CYP3A5*3/*3 compared to those with CYP3A5*1/*1 or *1/*3, suggesting that the CYP3A5*3 genotypes may not be as important in the pharmacokinetics of carbamazepine in Japanese patients with epilepsy.