Sildenafil works by inhibiting phosphodiesterase-5 (PDE5), a specific enzyme found in the smooth muscle of blood vessels in the lungs and the penis. This inhibition increases the levels of cyclic guanosine monophosphate (cGMP). Increased cGMP leads to relaxation of smooth muscle in the blood vessels, allowing for increased blood flow.
Increased Blood Flow to the Penis
In the context of erectile dysfunction, this enhanced blood flow to the corpus cavernosum (the erectile tissue in the penis) is key. The increased blood flow contributes to penile erection. The effect is triggered by sexual stimulation; sildenafil doesn’t cause an erection without sexual stimulation.
Important Considerations Regarding PDE5 Inhibition
It’s important to note that PDE5 is also found in other parts of the body, including the lungs and the retina. While sildenafil’s impact on PDE5 in the lungs is generally minor at therapeutic doses, individuals with pulmonary hypertension might experience side effects due to this wider impact. Similarly, potential vision changes are linked to the effects of PDE5 inhibition in the retina.
Dosage and Timing
The dose of sildenafil prescribed depends on individual factors and the patient’s medical history. Your doctor will carefully consider these factors before recommending a dosage. Typically, sildenafil is taken approximately one hour before sexual activity, allowing sufficient time for the medication to take effect.
