Udenafil, the active ingredient present in Zudena, is a potent PDE-5 inhibitor. This drug efficaciously acts to boost blood flow to the penile organ and helps to palliate ED. This inhibitory action prevents the degradation of a vasodilator of cGMP. This substance is then produced in a higher amount that helps to relax the smooth muscles and dilates the blood vessels inside the penile region. Nitric oxide is also produced, which is also a vasodilator. This process helps to augment blood flow to the penile organ within 30 to 60 minutes. Zudena is rapidly absorbed in the bloodstream and helps a man to attain an erection when he is sexually aroused.