Abstract:JBPOS0101 is a new antiepileptic drug and is a substrate of UDP‐glucuronosyltransferases (UGTs) in in vitro test. In vitro experiments showed different results regarding whether JBPOS0101 induces (EC50 136 μM) or inhibits (IC50 95.4–386.5 μM) cytochrome P450 (CYP) 3A4. As co‐medication of JBPOS0101 and carbamazepine (CBZ) is expected in clinical settings, drug–drug interactions (DDIs) between them should be determined. This study aimed to investigate pharmacokinetic (PK) interactions of JBPOS0101 influenced by CYP3A4 and UGTs using midazolam (MDZ) and CBZ. A two‐cohort, open‐label, fixed‐sequence study was conducted in healthy Koreans. In cohort A, subjects received MDZ IV alone, and then JBPOS0101 were co‐administered with MDZ after oral doses of JBPOS0101 for 7 days. In cohort B, multiple doses of JBPOS0101 and CBZ were administered respectively, and subjects received both together for 7 days. Serial blood samples were collected for PK analysis. When MDZ and JBPOS0101 were co‐administered, the systemic exposure of MDZ decreased by 30%. Meanwhile, JBPOS0101 did not significantly changed the PK of CBZ. CBZ decreased the systemic exposure of JBPOS0101 at steady state by 40%, respectively. With IV administration of MDZ, JBPOS0101 acted as a weak inducer of hepatic CYP3A4 and decreased systemic exposure of MDZ. The ability of JBPOS0101 to similarly modulate gut CYP3A4 activity will require further evaluation. Co‐administration of multiple doses of JBPOS0101 and CBZ did not significantly alter CBZ pharmacokinetics, but the clinical impact of decreased systemic exposure of JBPOS0101 by CBZ should be further considered.