Vardenafil is a selective and orally active inhibitor of phosphodiesterase-5 ( PDE5 ), with an IC 50 of 0.7 nM. Vardenafil shows inhibitory towards PDE1 , PDE6 with IC 50 s of 180 nM, and 11 nM, while IC 50 s are >1000 nM for PDE3 and PDE4. Vardenafil competitively inhibits cyclic guanosine monophosphate (cGMP) hydrolysis and thus increases cGMP levels. Vardenafil can be used for the research of erectile dysfunction, hepatitis, diabetes.