Six men have died after using Viagra since the popular impotence drug hit the market, federal regulators and the drug's manufacturer said yesterday.
The causes of the deaths are still under investigation, and the drug's maker, Pfizer Inc., declined to elaborate. While the deaths could prove to be unrelated to the drug, the new reports raised concerns that Viagra could be interacting with other medications, or is allowing men with heart conditions to overexert themselves through sexual activity and bring on heart attacks.
Since the Food and Drug Administration approved Viagra in April, more than 900,000 users have gotten prescriptions, according to market research firm IMS America Ltd. -- making Viagra the biggest new drug launch in recent years.
Pfizer this week sent a letter to doctors reiterating some of the health warnings that it had published at the time of the drug's approval. Since "sexual activity generally involves an increase in cardiac work and myocardial oxygen demand," the company stated, physicians should evaluate the heart health of patients before prescribing the drug. Cardiovascular disease is the leading cause of impotence and could create health complications for users.
Pfizer also warned emergency room doctors to ask heart patients if they are taking Viagra before administering drugs that might cause a drop in blood pressure, such as the heart medicine nitroglycerin. Since Viagra also can depress blood pressure, the combination can cause dangerously low levels. The company also advised doctors to look out for complications arising from the use of Viagra with such recreational drugs as amyl nitrate, which also lowers blood pressure.
"Overall, the experience to date is consistent with everything we know about Viagra," said Pfizer spokesman Andy McCormick -- "that is, it's safe and effective medication." Joseph Feczko, Pfizer's top drug safety official, said the complications reported so far are "lower than we'd expect, based on the number of prescriptions," and said that the figures thus far "give us a reassuring feeling."
FDA spokeswoman Lorrie McHugh said that the agency is investigating the deaths, but officials "continue to believe that the drug is safe and effective for its indications and the intended patient population."
Doctors, however, have been prescribing Viagra for users who do not fall within that ideal patient population -- that is, men with impotence problems who have been screened for cardiovascular disease, or who are taking nitrates. Once a drug is approved for one use, doctors are allowed to prescribe it freely.
The risk of heart attack from having sex is generally low -- only about about 20 cases per million, just 2 1/2 times greater than the baseline level of risk in daily life, said James E. Muller, a director of the Gill Heart Institute at the University of Kentucky.
But if a patient's impotence is caused by undiagnosed heart disease and he does not normally exercise, and if the newly regained sexual ability leads him to exert himself strenuously, Muller said, the risk could become significant. "My guess is they'll have a one in a thousand risk of heart attack," Muller said.
Heart attack is "a predictable result" of using Viagra for that class of men, said James Barada, of the Center for Male Sexual Health in Albany, N.Y. Other doctors have told him about prescribing the drug over the phone, Barada said. "I do not give Viagra unless they see me face to face" so that he can discuss the underlying disease issues, he said.
Ron Simon, a Washington attorney who publishes a newsletter dealing with pharmaceutical lawsuits, said "it's almost certain that there'll be litigation about it," but added that "the company is doing a good job putting [the information] out -- you've got to give them credit for that."
The drug, also known as sidenafil citrate, enhances the body's natural system for creating erections, allowing the smooth muscles in the penis to relax and in turn allowing the organ to fill with blood. It has been found effective for 70 percent of men in clinical trials -- somewhat less effective than systems requiring hypodermic injection or insertion in the urethra, but more palatable to many men.
At the time of the drug's release, side effects were generally termed minimal. However, eight men who took the drug during clinical trials died, all from cardiovascular trouble. Only one person who was taking a fake pill as part of the trial died, a suicide.
In the report accompanying the drug's approval, the FDA stated that, of the deaths on Viagra, "most occurred in a setting of risk factors and medical history making the observed events plausibly not related to the study drug." Sidney M. Wolfe, executive director of the Public Citizen Health Research Group, a consumer group, said that the history of heart troubles in many of the cases should have been interpreted as a risk for the drug instead of being used as an excuse to say the drug was "plausibly not related" to the deaths.
Doctors don't prescribe in a vacuum, and patients have been clamoring for the drug -- even when it might not be in their best interests. In online discussions of impotence, one patient who said he was taking nitrates said that he might simply stop taking his heart medication so that he could get erections again; another wrote that "I was willing to have a heart attack as long as I had an erection :-)."
Such sentiments don't surprise Ira Sharlip, a urologist with Pan-Pacific Urology in San Francisco and a member of the impotence guidelines committee of the American Urological Association. "I know a whole lot of men who would say, 'If I go out in the saddle, that's all right with me, but I want to be riding.' "
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