Sildenafil citrate works by inhibiting the enzyme phosphodiesterase type 5 (PDE5), which is responsible for the degradation of cyclic guanosine monophosphate (cGMP) in the smooth muscle cells of the penis and pulmonary arteries. By inhibiting PDE5, sildenafil increases the levels of cGMP, leading to relaxation of smooth muscle cells and vasodilation, which enhances blood flow. This mechanism helps to facilitate erections in men with erectile dysfunction and improve exercise capacity in individuals with pulmonary arterial hypertension. https://www.genericday.com/p-force-fort-150-mg.html