ABCB1 c.3435C>T and EPHX1 c.416A>G polymorphisms influence plasma carbamazepine concentration, metabolism and pharmacoresistance in epileptic patients

Background: ABCB1, EPHX1 and SCN1A gene polymorphisms have been reported play important roles in individual variability carbamazepine (CBZ) metabolism and resistance, but the result of that association still remains controversial. Objective: To clarify the associations among ABCB1, EPHX1 and SCN1A gene polymorphisms and CBZ metabolism and resistance. Methods: The PubMed, EMBASE, Cochrane library, Chinese National Knowledge Infrastructure, Chinese Science and Technique Journals Database, China Biology medicine disc and Wan Fang Database were searched for appropriate studies up to April 2020. Results: A total of 18 studies involving 3293 related epilepsy patients were included. ABCB1 c.3435C>T polymorphism was significantly associated with adjusted concentrations of CBZ (CC vs. CT, P=0.004), and EPHX c.416A>G polymorphism was significantly associated with carbamazepine-10, 11-trans dihydrodiol (CBZD) (AA vs. GG, P=0.045; AG vs. GG, P=0.010). Furthermore, ABCB1 c.3435C>T polymorphism was also observed to be significantly influenced CBZ resistance (CT vs TT, P=0.01; CC+CT vs TT, P=0.006). Conclusion: ABCB1 c.3435C>T polymorphism may affect the CBZ metabolism and resistance, EPHX1 c.416A>G polymorphism may only affect CBZ metabolism. These findings provided further evidence for individualized therapy of epilepsy patients in clinics. Nevertheless further large studies are still warranted to provide conclusive evidences.