NEW YORK — Pfizer Inc. said it is warning paramedics and emergency room physicians not to treat patients taking its impotence pill Viagra with nitroglycerin and related drugs for heart conditions, a caution that has been on the drug's label since its approval in March.
Using the two drugs together may cause a sudden drop in blood pressure and can be lethal. More than 1 million prescriptions have been written for Viagra since it went on the market two months ago.
Pfizer reported six deaths among Viagra patients to the Food and Drug Administration on Thursday. It's too early to say if Viagra played any role--the FDA hasn't yet had time to ascertain if the men were taking heart medication. But companies are required to reveal any possible adverse reactions to their drugs.
"We'll be looking into these reports" to see if additional warnings are needed, said FDA spokeswoman Lorrie McHugh. She said the agency "continues to believe the drug is safe and effective" when used in the appropriate patients, McHugh said.
But the agency has asked Pfizer to provide additional information to consumers to make sure they use Viagra safely.
Paramedics could administer nitroglycerin to patients suffering from chest pains without knowing the patient may have taken the potency pill.
Eight patients died during the Viagra trials. None of those deaths were attributed to the drug itself, said Pfizer spokeswoman Mariann Caprino.
She noted that men who suffer from impotence often have serious underlying health conditions such as diabetes, cardiovascular disease or prostate cancer.
Pfizer didn't issue the release because of any reported problem, Caprino said.
"We hit around the million prescription mark over the last week," she said. "We just wanted to set the record straight."
Pfizer shares fell $3.69 to close at $109.13 on the New York Stock Exchange.