In vitro evaluations for pharmacokinetic drug-drug interactions of a novel serotonin-dopamine activity modulator, brexpiprazole.

Brexpiprazole, a serotonin-dopamine activity modulator, is indicated for the treatment of schizophrenia and also adjunctive therapy to antidepressants for the treatment of Major Depressive Disorder. To determine the drug-drug interaction risk for cytochrome P450, and SLC and ABC transporters, brexpiprazole and its metabolite, DM-3411 were assessed in this in vitro investigation.Brexpiprazole exhibited weak inhibitory effects (IC50 >13 µmol/L) on CYP2C9, CYP2C19, CYP2D6 and CYP3A4 activities, but had moderate inhibitor activity on CYP2B6 (IC50 8.19 µmol/L). The ratio of systemic unbound concentration (3.8 nmol/L) to the Ki value was sufficiently low. DM-3411 had comparable inhibitory potentials with brexpiprazole only for CYP2D6 and CYP3A4. The mRNA expressions of CYP1A2, CYP2B6 and CYP3A4 were not changed by the exposure of brexpiprazole to human hepatocytes.Brexpiprazole and DM-3411 exhibited weak or no inhibitory effects for hepatic and renal transporters (OATPs, OATs, OCTs, MATE1, and BSEP), except for MATE-2K (0.156 µmol/L of DM-3411), even for which the ratio to systemic unbound concentration (5.3 nmol/L) was sufficiently low.Brexpiprazole effected the functions of P-gp and BCRP with IC50 values of 6.31 and 1.16 µmol/L, respectively, however, the pharmacokinetic alteration was not observed in the clinical concomitant study on P-gp and BCRP substrates.These in vitro data suggest that brexpiprazole is unlikely to cause clinically relevant drug interactions resulting from the effects on CYPs or transporters mediating the absorption, metabolism, and/or disposition of co-administered drugs.