DA-8164

**DA-8164** is the primary active metabolite of udenafil, a phosphodiesterase type 5 (PDE5) inhibitor. Udenafil is used primarily for the treatment of erectile dysfunction. DA-8164 is formed in vivo following administration of udenafil and has pharmacological activity similar to its parent compound. The metabolite exhibits a similar pharmacokinetic profile to udenafil, with a terminal half-life of approximately 12–15 hours. Mechanistically, both udenafil and its metabolite DA-8164 act by selectively inhibiting the phosphodiesterase type 5 enzyme, leading to vasodilation and increased blood flow in certain tissues, such as the corpus cavernosum. DA-8164's development and study to date have focused on its exposure and metabolism as a component of udenafil pharmacokinetics in clinical studies of erectile dysfunction and related cardiovascular indications[1][2][3].