Impotence in men is treated with Levitra. I purchased Levitra online from a reliable source. Vardenafil, one of its components, increases blood flow to the penis. It is a PDE-5 inhibitor that enhances blood flow to the penis by relaxing the muscles in blood vessel walls. The arteries get constricted due to an enzyme called PDE 5, which impairs healthy blood flow. cGMP manufacturing is required for the occurrence of an erection. Blood is transported to and from the penis via cGMP. PDE 5 prevents erection from happening correctly and degrades cGMP.