Viagra, or sildenafil, primarily works by inhibiting phosphodiesterase-5 (PDE5). PDE5 is an enzyme that breaks down cyclic guanosine monophosphate (cGMP), a crucial molecule for achieving and maintaining an erection. By blocking PDE5, Viagra increases cGMP levels.
Increased cGMP: The Key to Erection
Higher cGMP levels relax the smooth muscles in the blood vessels of the penis. This relaxation allows increased blood flow into the penis, leading to an erection. The effect is specific to the penis because the concentration of PDE5 is significantly higher there than in other parts of the body. This targeted action minimizes side effects in other organs.
Sexual stimulation is still necessary to trigger the release of nitric oxide, which initiates the cGMP pathway. Viagra enhances the effect of this naturally occurring process; it doesn’t create erections spontaneously. The drug’s effectiveness depends on the presence of nitric oxide and adequate blood flow to the penis.
