Which enzyme is NOT listed among the metabolizing enzymes/transporters for brexpiprazole?

• A. CYP1A2
• B. CYP2B6
• C. CYP3A4
• D. CYP2D6

Answer: (B)

Brexpiprazole is cleared mainly by liver enzymes in the cytochrome P450 family, with CYP3A4 and CYP2D6 doing most of the metabolism. These two enzymes metabolize brexpiprazole into inactive forms, shaping how much drug is present in the body over time. CYP2B6 does not play a meaningful role in brexpiprazole metabolism, so it would not be listed among the enzymes metabolizing or transporting the drug. That’s why this enzyme is the best answer.

In practical terms, factors that inhibit or induce CYP3A4 or CYP2D6 can alter brexpiprazole levels and effects, whereas changes in CYP2B6 are unlikely to have a clinically relevant impact. The other enzymes mentioned are consistent with brexpiprazole’s known metabolic pathways, reinforcing why the inactive-in-this-context enzyme is chosen.