History of Viagra

On March 27, 1998, the U.S. Food and Drug Administration (FDA) approved the first pill shown to be effective against male impotence. In clinical trials, Pfizer Inc.’s Viagra was found to help between 70% and 80% of impotent men achieve erections.

Viagra

Medical industry analysts predicted that the drug could become one of the top-selling pharmaceuticals of all time, with sales approaching $3 billion a year. An estimated 30 million men in the United States are afflicted with impotence, an inability to achieve an erection. Impotence can be caused by diabetes, cardiovascular disease, aging, spinal cord injuries, prostate surgery, and other conditions. Impotence is medically known as erectile dysfunction (ED).

While about 50% of all men between the ages of 40 and 70 report having trouble getting and keeping erections, the initial rush for the drug suggests the percentage may be even higher. Sexual dysfunction is a touchy subject, and may be under-reported.

Shortly after Viagra became available, men of all ages flocked to doctors’ offices seeking the pills. By mid-April 1998, doctors were writing an estimated 40,000 prescriptions a day. By contrast, the antidepressant Prozac, one of the best-selling drugs in the world, is prescribed 70,000 times a day. Viagra pills are taken an hour before men plan to have sex. Each pill costs about $10.

Of the 30 million men in the United States who suffer from ED, only 2.76 million sought treatment in 1997. This reluctance on the part of men with ED may be explained by the drawbacks of traditional therapies. Prior to Viagra, treatments for impotence included penile implant surgery, genital suppositories and injections of erection-producing drugs. Besides being painful and expensive, these treatments detracted from the spontaneity most people appreciate about sex. Pharmacia & Upjohn Inc.’s Caverject injections also had the unfortunate side effect of sometimes producing 18-hour erections.

Accidental effects

Pfizer researchers discovered Viagra’s effects by accident. The drug was originally intended as a treatment for angina, chest pains caused by inadequate blood flow to the heart. Initial trials of the drug in 1991 and 1992 were disappointing. However, some of the men in the trials reported an unusual side effect: increased and prolonged erections.

Investigating the drug further, researchers uncovered its erection-aiding mechanisms. Rather than increasing blood flow to the heart, it increases blood flow to the penis.

Normally, when a man becomes sexually aroused, his body releases a chemical called cyclic GMP. This chemical widens arteries that carry blood into the penis. As these blood vessels widen, they squeeze shut veins that carry blood out of the penis. Blood builds up in the penis and an erection occurs. Men with ED do not produce enough cyclic GMP. Therefore, the arteries never expand enough to close off the veins. Blood continues to flow out of the penis and an erection cannot occur.

Viagra blocks a second chemical, known as PDE5. This chemical breaks down cyclic GMP. With PDE5 disabled, enough cyclic GMP can build up to expand the arteries fully. For men involved in the latest round of clinical trials, Viagra produced erections 67% of the time.

Given Viagra’s effectiveness and the seemingly huge demand for it, critics worried about the potential for abuse. Shortly after its release, urologists reported that between 5% and 10% of patients asking for the drug were not impotent.

Both doctors and Pfizer officials warned that Viagra should be used only by men with clinical ED. Viagra, they argued, would not make a person sexually aroused, and would not cause erections in men lacking sexual desire. Likewise, they claimed, the drug would not improve the sexual performance of men who did not suffer from ED.

Clinical trials showed that Viagra has only mild side effects. These include headaches, indigestion and an occasional blue tinge to the user’s vision. Nonetheless, some doctors feared more dangerous complications would result if the drug was used improperly.

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