Systematic reviews of the epidemiology of sexual difficulties, dysfunction, and dissatisfaction indicate that sexual problems are common in men and women in all societies and more frequent in older individuals and among those with chronic medical conditions, including depression. For example, the Global Survey of Sexual Attitudes and Behavior, of over 27,000 men and women aged 40–80 years, found “early ejaculation” (i.e., rapid or premature ejaculation) to be the most common sexual dysfunction, affecting 14% of men, with “erectile difficulties” having a prevalence of 10% all sexual dysfunctions in men being more prevalent in older groups.
Nitric oxide is involved in the physiology of the sexual response, in both men and women. In men, nitric oxide in the corpus cavernosum of the penis binds to guanylate cyclase receptors, which results in increased levels of cyclic guanosine monophosphate (cGMP), leading to smooth muscle relaxation (vasodilation) of the intimal cushions of the helicine arteries, which in turn leads to vasodilation, increased flow of blood into the spongy tissue of the penis, and resulting in erection.
The cGMP acts as a competitive binding agent of PDE5 in the corpus cavernosum, resulting in more cGMP and facilitation of erection. In women, the role of nitric oxide and its interplay with estrogen are less well understood, but phosphodiesterase type 5 inhibitor enhancement of nitric oxide-cGMP in nonadrenergic-noncholinergic signaling for women seems similar to men, and the release of nitric oxide results in vasodilatation in clitoral and vaginal tissues.

References

1.Francesco Lotti and Mario Maggi. Nat Rev Urol. 2018;15(5):287–307.