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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