Avanafil metabolite M4 is a major active metabolite of the phosphodiesterase 5 (PDE5) inhibitor avanafil . Avanafil is metabolized by the cytochrome P450 (CYP450) isoforms CYP3A4 and CYP2C to the major metabolites avanafil metabolite M4 and avanafil metabolite M16 , as well as minor metabolites. Avanafil metabolite M4 inhibits PDE5 with 18% of the potency of avanafil.
