(market name or ) is a kind of PDE5 inhibitor used for the treatment of erectile dysfunction, benign prostatic hypertrophy and pulmonary arterial hypertension. The effect of is relaxing the blood vessels muscles and increasing the blood flow into the corpus cavernosum. The mechanism of action of is through inhibiting the activity of the cGMP specific phosphodiesterase type 5 (PDE5). PDE5 degrades cGMP in the corpus cavernosum located around the penis. Therefore, leads to the increased concentration of cGMP which further causes the smooth muscle relaxation and increased blood flow into the corpus cavernosum. Some clinical studies also implied that could improve endothelia function in men with increased cardiovascular risk and lower the urinary tract symptoms secondary to benign prostatic hyperplasia.is different in structure from both and. It is rapidly absorbed and peaks in concentration (378 μg/L after a 20-mg dose) after 2 hours, displaying a long half-life of 17.5 hours. It also is metabolized by the liver (CYP3A4). Notably, its pharmacokinetics is not clinically influenced by alcohol or food intake or by factors such as diabetes or impaired hepatic or renal function.analgesic, uptake blocker, mu-opiod receptor agonist. A phosphodiesterase 5 inhibitor. is used for the treatment of erectile dysfunction.