Viagra Mechanism of Action
Before understanding that how Viagra works or what is the mechanism behind the working of Viagra it is very important to understand the erectile function in men.
Penile erection is an important attribute of a sexually healthy man. The erection of a male penis is caused because of the pressure of the blood that flows into the penis, making it engorged with blood and thus giving it some extra length and firmness. Erections can occur both when a man is awake as well as when he is asleep. When a man dreams in his sleep during his REM (rapid eye movement) pattern of sleep, he gets penile erections even then too.
Penile erection has got its own importance in the sexual relationship of a couple. For a successful vaginal penetration a man needs to have an erect penis. It is only then that he can achieve a satisfactory sexual intercourse. Generally in all men, the nerves, arteries and the vascular function are normal and hence an average man achieves erection when he is sexually stimulated. Erections are a result of sexual stimulation. For other men this may not be the case. They may not be able to achieve erections in spite of getting sexually aroused by their respective partners. This is the point where Viagra comes to the rescue of such men. Viagra works in that part of the body where it is required the most. As described earlier, the penis gets erect only when the blood flows to the penis making it engorged with blood. Viagra provides penile erection by increasing the blood flow into the male genital region. With Viagra you need to be sexually aroused or stimulated to achieve the erection. Viagra will not start working on its own. Viagra is not an aphrodisiac or a hormone. Just by popping a Viagra pill it is wrong to assume to achieve erection.
Viagra belongs to the class of PDE5 inhibitor drugs which inhibit or block the chemicals known as phospho diesterase inhibitor drugs. The physiology of erections involves many chemical reactions in the body. The sexual stimulation releases nitric oxide in the corpus cavernosum, the two parallel channels situated at the sides along the length of the penis. The release of nitric oxide activates the enzyme guanylate cyclase which results in the increased levels of cyclic guanosine monophosphate responsible for the penile erections.
Viagra works by inhibiting the chemical phosphodiesterase type 5 which is responsible for the erections turning flaccid. This prolongs the effect of the muscle relaxation in the corpus cavernosum area of the penis allowing the blood to flow into the spongy tissues of the penis causing an erection. Viagra does not have any direct relaxant effect on the corpus cavernosum area in the human penis but enhances the effect of nitric oxide (NO) by inhibiting phosphodiesterase type 5 (PDE5), which is responsible for degradation of cGMP or cyclic guanosine monophosphate in the corpus cavernosum. When sexual stimulation causes local release of nitric oxide the inhibition of PDE5 by Viagra causes increased levels of cGMP or cyclic guanosine monophosphate in the corpus cavernosum, resulting in smooth muscle relaxation and inflow of blood to the corpus cavernosum resulting in the required erections of the penis.