Viagra: things you should know

1. The history of Viagra

In the early 1980s, medical science realized it was possible to artificially induce an erection by means of an injection. The breakthrough came with the development of a muscle relaxant called Phentolamine. The problem, however, was that the erection resulted from the injection no matter what the man was doing. This could be extremely inconvenient but, at that time, there was no way to mimic the natural process which allows the erection to come and go in response to sexual stimulation.

The story now shifts to Pfizer which was doing research into drugs to treat angina — chest pain related to a heart disorder. Early research had shown a relationship between nitric oxide and the ability of arteries to dilate. While putting the prototype drug through clinical trials, the company found that the effect on the coronary arteries was limited, but the effect on the primary artery leading into the penis was powerful. The rest, as they say, is history. Viagra was launched in 1998 and has become one of the more recognized brand names in the world — primarily because it works so well.

2. How does it work?

The physical and psychological processes for producing an erection are well-understood. Looked at objectively, there is actually very little that can go wrong. When a man is sexually stimulated, the brain responds by releasing a trigger chemical, nitric oxide, into the bloodstream to dilate the artery leading into the penis. As more blood flows into the penis, it is absorbed by a sponge-like area called the corpus cavernosum. The corpus expands and presses against the vein that would drain the blood out of the penis. Because the blood is trapped, an erection is formed. When the sexual activity is ended, the brain releases a second chemical to reverse the process. This chemical is called phosphodiesterase type 5 (PDE5). If there is PDE5 present in the muscle walls of the arterial system, there will be no dilation and no erection. If PDE5 is released too early in the cycle of sexual activity, the erection is lost. Viagra is a PDE5 inhibitor. It stops the action of PDE5. This allows the body to go through its natural cycle of responding to sexual stimulation and normal performance is restored. It is a simple and effective solution to the problem.

3. Viagra and grapefruit juice

In 2002, there was a definitive clinical test carried out in Köln, Germany to confirm whether the increasingly common myth about grapefruit juice was real. The way mouth-to-mouth passes information can be spreading truth or lies. People mishear or decide that what they heard was boring and, with just a little exaggeration, it could be more interesting. There had been a suspicion that men who had grapefruit juice for their breakfast did not respond to Viagra. The German researchers decided to put it to the test. They found twenty-four otherwise healthy men, gave them juice to drink followed by Viagra. Blood samples were then taken over the next 24 hours to determine how rapidly the drug was absorbed into the bloodstream and how long it stayed active. The test was repeated one week later except that the tablets were swallowed with water.

The results confirmed that the juice did significantly affect the rate at which Viagra was absorbed. In approximately one quarter of the participants, the effect of the drug was delayed. Under normal circumstances, men are advised to allow about one hour to pass before attempting sexual intimacy. When mixed with grapefruit juice, 25% of men were likely to be disappointed with the results. As a result of this and other studies, men are therefore advised not to drink the juice or eat the fruit while taking Viagra. If you are hooked on juice, stick with oranges.