Udenafil Impurities

The drug udenafil is marketed under the trade name Zydena. It is within the PDE₅ inhibitor class. Like other PDE₅ inhibitors, it is used to treat erectile dysfunction. Udenafil was developed by Dong-A Pharmaceutical. It has fairly rapid onset of action, a Tmax typically within 0.5 to 1.5 hours and an elimination half-life in the range of about 10 to 13 hours, allowing therapeutic effect to persist into the 8 to 12 hour window in many subjects. Chemically, udenafil is a small molecule inhibitor selective for phosphodiesterase type 5 with higher affinity for PDE₅ than for PDE₆ and PDE₃ in vitro; it increases cGMP in corpus cavernosum smooth muscle leading to vasodilation in response to sexual stimulation. Udenafil is administered orally and undergoes hepatic metabolism predominantly via CYP3A4 with minor contribution from other CYP isoforms; common pharmacokinetic characteristics include moderate oral bioavailability, dose-proportional exposure over the therapeutic range, and renal excretion of metabolites. Standard clinical and pharmacodynamic assessments report improved erectile function scores versus baseline in controlled trials, and concomitant use with nitrates is contraindicated due to risk of clinically significant hypotension.