Sildenafil is primarily used as what type of medication?

Sildenafil is primarily classified as a phosphodiesterase inhibitor, specifically targeting phosphodiesterase type 5 (PDE5). This mechanism is crucial because sildenafil works by blocking the action of PDE5, leading to increased levels of cyclic guanosine monophosphate (cGMP) in the smooth muscle of blood vessels, particularly in the penis. This accumulation of cGMP promotes vasodilation, which facilitates increased blood flow, thus assisting in the treatment of erectile dysfunction.

Moreover, sildenafil is also utilized in the treatment of pulmonary arterial hypertension, where its effect on cGMP contributes to relaxation and dilation of blood vessels, lowering pulmonary artery pressure and improving exercise capacity. This dual functionality reinforces the importance of sildenafil as a phosphodiesterase inhibitor rather than fitting into categories like antidepressants or antihypertensives, which have entirely different mechanisms and therapeutic targets.