WASHINGTON, DC — The fatalities ranged from the oldest man, an 80-year-old who collapsed suddenly in the middle of having sex, to the youngest, a 48-year-old, who experienced chest pains while having sex and later died in a hospital emergency room.

The Food and Drug Administration, aware of growing public attention to reports of men dying after using the popular impotence drug Viagra, released details of the known 16 cases Tuesday but continued to stress that there is no known direct link thus far between the drug and the deaths.

Seven of the 16 men died after having sex, and most of the men who died had been suffering from some underlying disease, including heart disease, high blood pressure or diabetes, the FDA said.

Nine men died during the clinical trials of Viagra.

Many of the deaths were attributed to heart disease, although some of the men were taking — or had been administered — other medications known to be dangerous when used with Viagra.

The agency put out the brief descriptions in response to a Freedom of Information request, and said that the deaths at this time do not represent newly identified dangers related to the drug.

"We continue to believe the drug is safe, and people should talk to their health care providers about using it," agency spokeswoman Lorrie McHugh said. "We expect we will continue to get ongoing reports, and we will monitor them." Viagra, sold by prescription and made by New York-based Pfizer Pharmaceuticals, has become wildly popular since receiving FDA approval in March.

Many seeking Viagra are middle-aged or older, whose impotence often results from heart disease and diabetes.

At least 1.7 million prescriptions have been written for the drug, which works by relaxing muscles and allowing increased blood flow to certain areas of the penis, leading to an erection. But Viagra can have life-threatening interactions with other drugs, specifically heart medications containing nitrates, such as nitroglycerin. Nine men died during the clinical trials of the drug.

Physicians and others repeatedly have pointed out that many of the men seeking Viagra are middle-aged or older, whose impotence is often the result of such ailments as heart disease and diabetes. Some doctors have complained that men seeking Viagra have failed to reveal to them that they are taking other medications. Experts also have pointed out that the physical exertion involved in sex can put a considerable strain on the heart, especially for men who have not regularly engaged in it.

The FDA, emphasizing that in many instances the information was incomplete, released the following details:

The agency described the remaining four cases as coming from media reports.

WASHINGTON, DC — At least 69 Americans who took the erection-enhancing drug Viagra died in the first four months it was on the market, the Food and Drug Administration (FDA) said in a new report.

But the deaths, which have been mounting steadily over the months, may not indicate any special danger from the Pfizer Inc. drug, given the age, health and large number of men who are taking it, specialists said.

"How many people die during the act anyway?"

Doctors have written out 3.6 million prescriptions and millions of men have taken the drug, which was hailed on its release in March as the long-awaited wonder drug for many men who had difficulty getting an erection.

"If there is a one in 100,000 chance of something happening that's pretty low ... What I tell my patients is that there is uncertainty. I think it's a safe drug but I think long-term studies are going to tell us how this works out," James Barada, a urologist in Albany, New York, told Reuters Wednesday.

The FDA, collating voluntary accounts from many sources, said 18 of the patients died during or immediately after sexual intercourse. Within a further five hours of taking the drug, seven others had begun to show whatever symptoms eventually led to death, said the the report that was posted Monday on the agency's Internet site.

Dr. David Flockhart, an expert in drug interactions at Georgetown University in Washington, said in a recent interview that it would be very hard to blame such deaths on Viagra.

"I wonder what the baseline death rate is without Viagra," he said. "How many people die during the act anyway?"

"If you age-index it for how many medical problems the individuals have and you take out those who took it inappropriately, I don't know of any huge disasters," William Steers of the University of Virginia said of earlier figures.

The FDA noted that the link with Viagra was circumstantial and it did not know how comprehensive its data was.

"An accumulation of adverse event reports does not necessarily indicate that the adverse event was caused by the drug. The event may be due to an underlying disease or some other factor or factors," the report said.

"It may be playing Russian roulette with a little blue pill."

"As with all approved medications, the FDA will continue to monitor the ... safety of Viagra by carefully reviewing reports of death and other serious adverse events and will continue to evaluate the need for regulatory action," it added.

The FDA received reports of 123 patients dying after being prescribed Viagra, including 12 foreigners. In the case of 30, the reports were from unverifiable sources and another 12 people may not have taken the drug, despite having the prescription.

Of the remaining 69 U.S. patients—66 identified as men and three of unidentified gender—two had strokes and 46 had cardiovascular events. The cause of death was unknown or not mentioned in the other 21 cases.

Reports to the FDA gave ages for 55 of the dead. They ranged from 29 to 87, with a median of 64, it said.

Fifty-one of the 69 patients had one or more of the factors associated with cardiovascular diseases or cerebrovascular disease, such as hypertension, smoking or obesity.

Twelve of the men who died had taken nitroglycerin or a nitrate medication, which can be fatal if taken in conjunction with Viagra.

Viagra acts by enhancing the muscle relaxant effects of nitric oxide, a chemical that is normally released in response to sexual stimulation. This allows increased blood flow into certain areas of the penis, leading to an erection.

The labeling warns patients not to mix it with nitrate-based heart drugs and advises a thorough medical examination before the drug is prescribed.

"There is a degree of cardiac risk associated with sexual activity; therefore, physicians may wish to consider the cardiovascular status of their patients prior to initiating any treatments for erectile dysfunction," the labeling adds.

But one consumer group, Public Citizen, said last week that the labeling was not strong enough.

"The FDA, in their rush to approve this drug, never put this drug before an advisory committee," said Dr. Sidney Wolfe, director of Public Citizen's health research group.

"There are a number of studies in different species showing damaged blood vessels with long-term use. This is not terribly surprising but there is no mention in the labeling," he added.

The American College of Cardiology and the American Heart Association have expressed concern about the use of Viagra by patients with any kind of heart disease.

Barada, who helped draw up erectile dysfunction guidelines for the American Urological Association, said he was concerned about the deaths because some people may have a special sensitivity to the drug and some doctors might be prescribing it to the wrong people.

"There may be a population that is more sensitive to these drugs than we were able to pick up in the trials. It may be playing Russian roulette with a little blue pill," he said.