Meaning of Real Viagra!

Sildenafil citrate, sold under the names Viagra, Revatio and under various other names, is a drug used to treat male erectile dysfunction (impotence) and pulmonary arterial hypertension (PAH), developed by the pharmaceutical company Pfizer. Its primary competitors on the market are tadalafil (Cialis), and vardenafil (Levitra).

History of Viagra...

Sildenafil (compound UK-92,480) was synthesized by a group of pharmaceutical chemists working at Pfizer's Sandwich, Kent research facility. It was initially studied for use in hypertension (high blood pressure) and angina pectoris (a form of ischaemic cardiovascular disease). Phase I clinical trials under the direction of Ian Osterloh suggested that the drug had little effect on angina, but that it could induce marked penile erections. Pfizer therefore decided to market it for erectile dysfunction, rather than for angina. The drug was patented in 1996, approved for use in erectile dysfunction by the Food and Drug Administration on March 27, 1998, becoming the first pill approved to treat erectile dysfunction in the United States, and offered for sale in the United States later that year.It soon became a great success: annual sales of Viagra in the period 1999–2001 exceeded $1 billion.

Hows it Works?

The Male Anatomy

For many people, talking about the penis is tough. This area of the body is considered private and is usually not discussed publicly. However, the penis is simply a part of the male anatomy designed to accomplish a task, and we'll treat it that way here.

In the case of the penis, there are actually two tasks that it handles:

1. releasing urine from the bladder, known as urination
2. releasing sperm and seminal fluid from the prostate gland, known as ejaculation

Viagra® helps with the second task: ejaculation.

When things are working properly, ejaculation is a three-step process:

1. The man becomes sexually aroused.
2. The penis responds by becoming erect.
3. Stimulation of the penis causes ejaculation.

That sounds simple enough, but in many cases, step two does not happen, making step three difficult or impossible. Although the man is stimulated, the penis does not become erect. To understand why, you need to understand the technology of an erection.

When you want to move nearly any part of your body, you do it using muscles. Whether you are moving your fingers, toes, arms or legs, muscles do the work. Even when you stick your tongue out, you do it using muscles:

• You think about moving some part of your body
• The appropriate muscles contract
• That part of the body moves

Muscles let you move your body voluntarily with precise control.

The penis, on the other hand, is completely different. There are no muscle contractions involved in making the penis erect. To become erect, the penis instead uses pressure.

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Side Effects of Viagra®

Very few drugs work perfectly, and Viagra® is no exception. Just about every drug has side effects that arise because the drug is flowing throughout the body and may affect parts of the body unintentionally. For example, aspirin is a drug that relieves pain, but this same drug can also erode the stomach lining and thin the blood. Those are side effects of aspirin.

Viagra® has several side effects of which patients need to be aware.

The first problem comes because Viagra® happens to have a spillover effect. It blocks PDE5, but it also has an effect on PDE6. It turns out that PDE6 is used in the cone cells in the retina, so Viagra® can have an effect on color vision. Many people who take Viagra® notice a change in the way they perceive green and blue colors, or they see the world with a bluish tinge for several hours. For this reason, pilots cannot take Viagra® within 12 hours of a flight.

The second problem comes for people who are taking drugs like nitroglycerin for angina. Nitroglycerin works by increasing nitric oxide, and it helps with angina by opening up the arteries that supply the heart with oxygen. If you take nitroglycerin and Viagra® together, the increased nitric oxide plus the blocking of PDE5 can lead to problems.

Other problems with Viagra® can include little things like headaches (the drug, as a side effect in some men, opens up arteries in the brain's lining and causes excess pressure) and big things like heart attacks. The possibility of heart attacks is one reason why Viagra® is a prescription drug rather than an over-the-counter drug like aspirin. A doctor needs to understand your medical history and make sure that Viagra® won't cause a heart attack. Occasional patients who take Viagra® get painful, long-lasting erections and have to see a doctor to solve the problem.

Finally, there is some concern that some men, especially younger men who take Viagra® recreationally and who don't really need it for physical reasons, may end up with a dependency on the drug. That is, they may become unable to maintain an erection without taking Viagra®.

For more information about side effects, see RxList: Viagra® Side Effects.

What about Cialis® and Levitra®?
Viagra® is a hugely successful drug, and other drug companies wanted a piece of the action. They developed different chemicals to block the PDE5 enzyme and created two new drugs: Cialis® (tadalafil) and Levitra® (vardenafil).

Because Cialis® and Levitra® block the PDE5 enzyme, they work exactly the same way as Viagra®. They help men who have trouble maintaining an erection because of blood flow problems, and they only work when the man is sexually aroused.

Because they block PDE5 with different chemicals, however, there are some important differences between the three drugs. For example:

• Only Viagra® causes color-vision problems.
• Cialis® causes muscle aches in about 5 percent of patients.
• Viagra® and Levitra® last about four hours in the bloodstream. Cialis® stays in the bloodstream much longer (it has a 17.5-hour half life) and can therefore be effective for more than a day.

For lots more information about Viagra, other drugs that treat erectile dysfunction and related topics, check out the links on the next page.