Tanning drug may find new life as Viagra alternative

Melanotan darkened the skin of the frog on the right.

IMPOTENCE: description risk symptoms treatment prevention Choose a link above to learn more about impotence. Source: WebMD

DOCTOR Q&A: Read what doctors say about Viagra and impotence or ask your own questions.

June 17, 1999
Web posted at: 2:37 p.m. EDT (1837 GMT)

By Senior Medical Correspondent Dan Rutz

(CNN) -- Last year's U.S. approval of Viagra, the first-ever pill for impotence, has sparked great interest in developing more remedies for sexual dysfunction. One promising lead comes from the University of Arizona, where researchers had been hard at work on a drug to prevent skin cancer.

Melanotan II was being tested as a safe way to get a protective suntan, explains Dr. Norman Levine, a dermatology researcher. "Our goal was to try and induce a tan without exposing them to potentially harmful rays of the sun or tanning booth."

As expected, Melanotan darkened skin pigment, but researchers soon learned that's not all it could do.

"It so happens that one very astute observer who took this drug reported to us that he was developing spontaneous erections," Levine recalls, and with that, the dermatologists brought on the urologists and charted a new course for developing Melanotan II.

Melanotan to the test

Dr. Hunter Wessells alternated doses of Melanotan II with a placebo in 10 men diagnosed with erectile dysfunction. All of them were impressed by the results. Nine out of 10 developed erections when given the real drug.

And, Wessells adds, it happened without any effort on their part. "These men were not looking at erotic video tapes. They weren't engaging in sexual activity. They were just sitting around. And on the placebo, none of them got any erectile activity -- zero."

"Jim," 42, became impotent a year and a half ago. It took him several months to admit the problem, even to himself. "'Cause I figured ... new girlfriend ... maybe it's getting nervous, and this or that. But it never got any better, and it was, like, absolutely nothing. So I went and checked with a doctor."

Injectable medication helped him, but he didn't like giving himself shots. He was relieved when Viagra hit the market, and disappointed when it didn't work for him. But Melanotan did.

"The Melanotan, the first time, was absolutely amazing. I knew something was going on. It was a very large effect." Neither Jim nor the other participants in that trial were exposed to any sexually illicit material. They were sent home after receiving the drug and told to wait around to see what might what happen.

Within 40 minutes responders reported a need to stretch -- a harmless side effect of the drug -- and soon after, spontaneous erections. Although they were instructed not to have sex, "Jim" says it could have taken place under the right circumstances. "This would have been fun. This would have been enough to have intercourse," he said.

Libido booster?

Researchers believe Melanotan II works directly on the brain, where it affects sexual desire as well as physical performance. Viagra, by comparison, appears to have no direct effect on libido. According to Wessells, "with Viagra the man has to initiate sexual activity or Viagra won't work. With this it sort of comes on its own." If further testing confirms the drug to be safe and effective, doctors say it might be useful for treating both psychological and physiological impotence.

Viagra may be one of the most successful new drugs in history, but it has been clear from the start that the first impotence pill approved in the United States isn't for everyone. Depending on the cause of their sexual problems, the little blue pill fails to produce erections for a quarter to half of the men who try it. And men on certain heart medications have been warned not to take Viagra due to the chance of dangerous drug interactions that can even prove fatal.

Melanotan doesn't appear to affect blood pressure adversely, as Viagra can, so its promoters say it should be safe for just about anyone. But the U.S. Food and Drug Administration has advised the Arizona researchers to proceed with caution. New studies, slated to begin this summer, will test Melanotan in the laboratory.

Volunteers who've lost their sexual function after prostate removal surgery, but who have an intact nerve (necessary for erection), will be given the drug under close observation. In addition to measuring sexual response, doctors will conduct blood tests and other measurements to assure the drug is as safe as they think it is. For now, Melanotan must be injected under the skin, but it's probable, doctors say, that a commercial version would be formulated as an eyedrop or nasal spray.

The University of Arizona researchers remain optimistic about their work but are quick to point out that Melanotan II faces years of testing before it might become available to men in need.