Sildenafil works by inhibiting a specific enzyme called phosphodiesterase-5 (PDE5).
This inhibition leads to increased levels of cyclic guanosine monophosphate (cGMP) in the smooth muscle cells of the corpus cavernosum, a crucial tissue in the penis.
- Higher cGMP levels relax these muscles. Relaxation increases blood flow into the penis. This increased blood flow facilitates penile erection.
The process is triggered by sexual stimulation, which initiates the release of nitric oxide (NO).
NO activates guanylate cyclase. Guanylate cyclase produces cGMP. PDE5 normally breaks down cGMP, but sildenafil blocks this action.
Therefore, the sustained elevated cGMP levels maintain the relaxed state of the smooth muscles, enabling a sustained erection until sexual stimulation ceases and cGMP levels naturally decline.
It’s important to note that sildenafil requires sexual stimulation to be effective; it doesn’t cause erections spontaneously.
