Avanafil (Zepeed) was approved by the Korean Health Ministry for the treatment of erectile dysfunction (ED) in August 2011. Avanafil is a highly selective type 5 phosphodiesterase (PDE5) inhibitor. Avanafil is reported to be the most selective PDE5 inhibitor on the market. The onset of Tmax and half-life also varies among the marketed PDE5 inhibitors. Sildenafil has a T_max at 1 h and a half-life of 3–5 h. Vardenafil is somewhat similar with a T_max of 0.6 h and a half-life of 4–6 h. Tadalafil has the longest half-life among the marketed drugs with a half-life of 17 h. Avanafil has a fast onset of action reaching T_max in 0.6 h with a half-life of 1.2 h. A synthesis of avanafil (TA-1790) is described in the patent literature. The main elimination route of avanafil is through the bile and feces. Avanafil was also found to be reabsorbed through enterohepatic recirculation.