The active ingredient of Cenforce 200 , which is used to treat erectile dysfunction (ED), is sildenafil citrate. The mechanism of action of sildenafil citrate is the inhibition of the phosphodiesterase type 5 (PDE5) enzyme, which is essential for controlling blood flow to the penis. PDE5 is hyperactive in men with ED, inhibiting the dilation of the blood vessels in the penis and enabling enough blood to flow in to support a hard erection. Cenforce 200 and other drugs inhibit PDE5, which raises levels of the chemical cGMP and relaxes the smooth muscles in the penile blood vessels, improving blood flow. When coupled with sexual pleasure, this increased blood flow can produce an erection that is both stronger and more durable.