It belongs to a class of medications called phosphodiesterase type 5 (PDE5) inhibitors. Vardenafil works by inhibiting the enzyme PDE5, which is responsible for the degradation of cyclic guanosine monophosphate (cGMP) in the corpus cavernosum of the penis. By inhibiting PDE5, vardenafil helps to increase the levels of cGMP, leading to smooth muscle relaxation and increased blood flow to the penis, resulting in an erection.