Vardenafil (generic Levitra) promotes the development of an erection by relaxing particular muscles in the genital area, which in turn allows the genital tract to become more filled with blood. The PDE-5 enzyme is inhibited by vardenafil, which is known as a PDE-5 inhibitor. It achieves its effect by inhibiting PDE-5, a protein that is naturally present in your body and is responsible for preventing erections from occurring. When it prevents it from working.