NEW YORK -- As Pfizer Inc. plans a national television advertising campaign for its impotence pill Viagra, new safety warnings required by federal regulators could make it difficult to reinvigorate the drug's slowing sales.
After all, discussing impotence on television is a sensitive enough topic without having to disclose potential side effects like heart problems, analysts note.
"It's difficult to incentivize patients and at the same time tell them to use this drug carefully," said Hemant Shah, a drug industry analyst in Warren, N.J.
"(Viagra's) prescription sales have been flat, and this does not help it," Shah said.
The Viagra label changes, ordered Tuesday by the Food and Drug Administration, warn patients to be careful about taking Viagra if they have a history of heart disease, blood pressure problems or certain eye disorders
The agency confirmed that 130 Americans who took Viagra have died since the drug began selling last spring, the majority from heart attacks. No direct link between the drug and the deaths has been established, but regulations require all drug advertising to mention potential side effects.
Pfizer plans to focus its ads on the disease, not the drug itself, said spokesman Andrew McCormick. He said it is too early to determine the effects of the new labels on sales.
Doctors say they and their patients have become much more cautious toward Viagra in recent months as reports of patient deaths and other complications have drawn national attention.
"We see more and more men who have tried Viagra for whom it has been effective, and they decide they no longer want to take it because of the side effects they have heard about," said Dr. Geoffrey Sklar, assistant professor of urology at the University of Maryland Medical Center in Baltimore.
He said the new labels probably won't influence doctors' prescribing habits because most are already aware of potential problems.
Viagra's label already stressed that anyone who takes nitrate-containing medicines, such as the heart drug nitroglycerin, should never take Viagra. The mix can cause a deadly drop in blood pressure.
Among the new warnings required Tuesday:
-- The FDA has received reports of heart attacks, sudden cardiac deaths and hypertension among Viagra users.
-- Sexual activity itself is risky for certain men with cardiovascular disease; and for those men, Viagra is inadvisable.
-- Doctors should consider whether temporary drops in blood pressure caused by Viagra, especially during sexual activity, could harm a heart patient.
-- The FDA has received reports of men suffering painful, prolonged erections after taking Viagra. An erection that lasts longer than four hours requires prompt medical attention.
Sklar said the national television blitz will probably send more men to the doctor's office seeking prescriptions for Viagra.
Television advertising has fueled record sales of a number of prescription drugs, most notably the allergy drug Claritin made by Schering Plough Corp.
Viagra is the most successful introduction of a new prescription drug in history, but its sales have not kept up the early pace. While Pfizer sold $400 million worth in the second quarter, sales fell to $141 million in the third.
Since its introduction in April, 6.1 million Viagra prescriptions have been written, according to IMS Health, a research firm.
In addition to concerns about side effects, sales have waned as a number of large health maintenance organizations have eliminated or cut back on coverage of the $8 pills to save money.
While new U.S. prescriptions for Viagra have fallen from 278,000 a week in May to about 74,000 this month, demand for refills remain healthy, said Mariola Haggar, an analyst with Deutsche Bank Securities. She expects overall Viagra sales to rebound in the months ahead, albeit not to the levels seen last spring. In the short term, she said Pfizer will have to weather "a few more aftershocks" related to the FDA labeling requirements.