Vilitra, which contains the active ingredient Vardenafil, is a phosphodiesterase type 5 (PDE5) inhibitor used to treat erectile dysfunction (ED). It works by increasing blood flow to the penis, but it does not initiate an erection on its own. Sexual stimulation is required because Vilitra enhances the natural erectile response to stimulation by supporting the release of nitric oxide in the corpus cavernosum. This nitric oxide activates an enzyme called guanylate cyclase, increasing levels of cyclic GMP, which relaxes smooth muscle and promotes blood flow. Without sexual arousal, this chain reaction doesn’t begin, rendering the medication ineffective.