Which area of the penis is primarily affected by sildenafil when treating erectile dysfunction?

Sildenafil acts primarily on the corpora cavernosa of the penis when treating erectile dysfunction. The corpora cavernosa are two columns of erectile tissue that run along the length of the penis and are essential for achieving and maintaining an erection. When sexual stimulation occurs, nitric oxide is released, leading to the production of cyclic guanosine monophosphate (cGMP), which causes relaxation of the smooth muscle in the blood vessels of the corpora cavernosa. This relaxation allows for increased blood flow into the area, resulting in engorgement and the rigidity characteristic of an erection.

Sildenafil inhibits phosphodiesterase type 5 (PDE5), the enzyme responsible for breaking down cGMP. By preventing the degradation of cGMP, sildenafil effectively prolongs its action, facilitating sustained vasodilation and increased blood flow specifically to the corpora cavernosa. This enhanced blood flow is what allows individuals to achieve and maintain an erection in response to sexual stimulation, which is the desired therapeutic effect of sildenafil in the management of erectile dysfunction.