Sildenafil Citrate, the active ingredient in Cenforce 50 mg, belongs to a class of medications known as PDE5 inhibitors (phosphodiesterase type 5 inhibitors). It works by blocking the enzyme PDE5, which normally breaks down cyclic GMP, a compound responsible for relaxing the smooth muscle and dilating blood vessels in the penis. When PDE5 is inhibited, cyclic GMP levels remain higher, leading to the relaxation of blood vessels in the penis and increased blood flow.