Buy Udenafil online for ED TreatmentUdenafil is the active ingredient in Zudena. Read everything about Udenafil and where to buy Udenafil online for ED treatment. Udenafil was developed by the pharma company called "Dong-A Pharmaceutical'. It has fairly rapid onset of action (peak plasma concentration after 1 to 1.5 hours) and has long duration of action of around 11 to 13 hours. Udenafil allows once-daily dosage and typical doses are 100 and 200 mg, similar as with Viagra (sildenafil citrate). Udenafil ( sold under the brand-names Zudena and Zydena) is available in Korea, Russia and the Philippines.