Sildenafil acts by blocking phosphodiesterase 5 (PDE5), an enzyme that promotes breakdown of cGMP, which regulates blood flow in the penis. It requires sexual arousal to work, and does not by itself cause or increase sexual arousal. It also results in dilation of the blood vessels in the lungs.
Sildenafil acts by blocking phosphodiesterase 5 (PDE5), an enzyme that promotes breakdown of cGMP which regulates blood flow in the penis. It requires sexual arousal to work, and does not by itself cause or increase sexual arousal. It also results in dilation of the b,lood vessels in the lungs.