Doctors who hailed the drug Viagra as a breakthrough for impotent men are predicting that it could have unexpected benefits for women suffering sexual difficulties.
Physicians are basing their hopes on evidence that the drug works upon chemical pathways and tissues that are remarkably similar in men and women. That doesn't mean the drug will have the same dramatic benefits in women, but researchers are eager to find out.
Pfizer Inc., a pharmaceutical giant that is expected to reap huge profits from sales to men, has been testing the drug for two
years among European women who have sexual dysfunction. Recently, a urologist at the University of Maryland Medical Center won a grant to test the drug among women in the United States.
The Johns Hopkins School of Medicine anticipates starting a female-dysfunction trial of its own. Even if Viagra fails these tests, researchers say the drug has sparked interest in a women's health issue that -- like many others in medicine -- has long been neglected.
"All the things that cause dysfunction in men cause dysfunction in women," said Dr. Jennifer Berman, the UM urologist who plans begin a clinical trial in September at Boston University. "But nobody addressed these things before or even asked."
Until recently, she said, "The whole concept has brought about snickers from peers and colleagues."
Three weeks ago, the U.S. Food and Drug Administration approved Viagra for the treatment of male impotence, the inability to achieve or maintain an erection. The first shipments arrived in the nation's pharmacies last week, but men who had been following the advance publicity began calling their doctors and pharmacists as soon as the government acted.
"We've been getting a lot of calls from people who are interested -- along the lines of what's happened with the obesity drugs," said William Popomaronis, owner of the Epic Pharmacy on Harford Road.
'10 new calls a day'
"It's been unbelievable," said Berman. "We've probably been getting 10 new calls a day." Although the calls are coming from men, Berman said she can imagine the day when Viagra and products like it will be used to treat couples -- not just the man or woman.
"The talk is that this is the sex drug of the '90s," she said. "If the man gets fixed and the woman still has problems, it's not going to do them any good."
Pfizer estimates that there are 30 million men in the United States who suffer from the problem known clinically as erectile dysfunction. Many analysts say Viagra could become one of the most popular medications in the United States, challenging such top sellers as ulcer drugs and anti-depressants.
In a nationwide clinical trial, Viagra helped 70 percent of male volunteers whose problems ranged from mild to complete impotence. Their impotence was attributed to a range of medical conditions, including hypertension, high cholesterol, diabetes and nerve damage from prostate surgery.
The results have also re-inforced the growing recognition that impotence is usually a physical, not a psychological, problem.
"Twenty years ago, we used to think that impotence in men was 80 percent psychological and 20 percent physical," said Thomas Bruckman, executive director of the Baltimore-based American Foundation for Urologic Disease, which is funding Berman's study. "Now, we're saying it's 80 percent physical."
Viagra's emergence as an impotence drug is a story of medical serendipity.
Pfizer had developed the drug as a treatment for angina, the chest pains that often accompany a heart condition. The compound didn't work as hoped, but it had an unexpected side effect. In tests performed about a decade ago, many of the men taking the drug became more sexually potent.
Soon after, two scientists at the Johns Hopkins School of Medicine published a groundbreaking study that showed the physiological basis for male erections. Dr. Solomon Snyder, a renowned neuroscientist, and Dr. Arthur L. Burnett, a young urologist, reported that erections result from a "chemical cascade" that begins when nerve endings in the penis release the gas nitric oxide.
The chemical reactions cause smooth muscles in the penis to relax -- a condition that allows the penis to become engorged with blood during sexual arousal. When Pfizer saw the study, company scientists wondered whether their failed heart drug might have had the unintended effect of enhancing male potency by raising nitric oxide levels.
In 1994, Pfizer launched a clinical trial that proved the hypothesis. The three-year experiment involved 4,000 men whose average age was 55. The most common side effects were headache, facial flushing and indigestion.
Viagra is taken about an hour before anticipated sexual activity. It works only with sexual stimulation and, thus, brings about a more natural reaction than do injections, suction devices or implants that produce erections regardless of whether the man is aroused. The pills cost about $10 each and are taken only as needed.
"This pill is a step up," Burnett said. "This is something you can take an hour or two prior to planned sexual activity and hopefully have a response."
Researchers believe the drug may help women, too, based on studies showing that female sexual arousal also depends on nitric oxide. In women, the chemical causes the relaxation and subsequent engorgement of the clitoris -- a response that is a major part of sexual arousal.
"It's the same tissue," Berman said. "The vascular tissue, the smooth muscle and the composition of the clitoris are exactly the same."
Many women, she said, suffer from sexual dysfunction for the same reasons men do: high blood pressure, diabetes and diseased arteries. Less clear is whether the drug will have any effect on women -- or men -- whose sexual problems are rooted in depression or other emotional illnesses.
Neglected subject of study
Berman's two-year grant, totaling $88,000, is small in the high-dollar world of medical research. But it represents the first time the urologic foundation has backed a study of female sexual response.
Sex researchers say the subject has been neglected for many reasons. One is the belief that male potency is more central to reproduction. Another is that scientists feel uncomfortable talking about it, researchers say.
Although Pfizer will not comment on its all-female studies, Berman said she has heard anecdotal reports that the drug has helped many of the women involved. Participants, she said, have reported increased arousal and easier and more frequent orgasms.
Like many researchers, Burnett says Viagra will not help people who lack sexual desire and those who cannot get physically aroused to any degree.
"The people who have partial responses are the ones who most likely will be the beneficiaries," Burnett said. "They just need something that will kick the system into a little higher octane."
Pub Date: 4/22/98