Sildenafil selectively inhibits phosphodiesterase type 5 (PDE5), an enzyme that breaks down cyclic guanosine monophosphate (cGMP). This leads to increased cGMP levels, producing distinct effects in different tissues.
Erectile Dysfunction
In the penis, increased cGMP relaxes smooth muscle in the corpora cavernosa, allowing increased blood flow. This engorgement facilitates erection. The effect is specific to sexual stimulation; sildenafil doesn’t cause spontaneous erections.
- Optimal sildenafil dosage for erectile dysfunction varies, usually between 25-100mg. Factors influencing dosage include individual response and potential drug interactions. Always consult a physician for appropriate dosage and treatment plan.
Pulmonary Hypertension
In the lungs, elevated cGMP levels resulting from PDE5 inhibition cause pulmonary vasodilation, lowering pulmonary vascular resistance. This improves blood flow and reduces strain on the right ventricle.
Sildenafil’s efficacy in pulmonary hypertension is established, particularly in pulmonary arterial hypertension (PAH). Treatment protocols often involve a different dosage regimen compared to erectile dysfunction, typically starting at lower doses and gradually increasing under medical supervision. Careful monitoring of blood pressure and other vital signs is critical during sildenafil treatment for pulmonary hypertension.
Important Considerations
While sildenafil offers significant benefits, potential side effects exist, including headache, flushing, visual disturbances, and nasal congestion. Patients should discuss these and other possible risks with their healthcare provider. Regular monitoring is essential, especially for those with pre-existing conditions like cardiovascular disease.
