In revised product labeling for Viagra (sildenafil), the U.S. FDA and Pfizer Inc. are advising doctors about postmarketing reports of serious adverse events. The new information augments the original drug labeling which warned against the concomitant use of Viagra and nitrates. The FDA typically requires manufacturers to update their labeling with such information, even though in this case, postmarketing reports involving Viagra constitute only a small fraction of the more than six million prescriptions written for the drug.

The labeling notes that it is not possible at present to determine whether the cardiovascular events are directly related to Viagra, to sexual activity, to the patient's underlying disease, or to a combination of these factors.

Information added to the labeling includes:
*Cardiovascular events: The revised labeling addresses postmarketing reports of heart attacks, sudden cardiac deaths, and hypertension.
*Risk of sexual activity: Sexual activity in patients with preexisting cardiovascular disease carries a potential cardiac risk. Pfizer, therefore, advises doctors that treatments for impotence, including Viagra, generally should not be used in men for whom sexual activity is inadvisable because of their underlying cardiovascular status.
*Vasodilatory effects (effects on blood pressure): Physicians should consider whether their patients with heart disease could be affected by transient decreases in blood pressure, especially in combination with sexual activity.
*Patients who were not studied in clinical trials: Several groups of patients were not studied in the clinical trials for Viagra. The new labeling notes that if Viagra is prescribed for these patients, it should be done with caution.
These include patients who:

• suffered a heart attack, stroke, or life-threatening arrhythmia within the previous six months,
• had significant hypotension (lowered blood pressure) or hypertension (uncontrolled high blood pressure of greater than 170/110),
• had a history of cardiac failure or coronary artery disease causing unstable angina, and
• had retinitis pigmentosa, an eye disorder.

*Prolonged erections or priapism: The labeling now includes a warning about the rare occurrence of painful, prolonged erections. This is a serious condition that requires immediate medical attention. The labeling advises patients to seek prompt medical attention if their erection last longer than four hours.