Monday, October 23, 2006

Study Suggests Viagra Safe for Men Not Taking Nitrates

Taking a single dose of the popular impotence drug Viagra (sildenafil) caused no cardiovascular problems in 14 men who had severely clogged arteries, researchers report in the June 1, 2000, New England Journal of Medicine. Instead, Viagra decreased blood pressure slightly and boosted blood flow in coronary arteries, which is good for the heart.

"Viagra should be safe for many cardiovascular patients who are not on nitrates and who are capable of moderate activity," Dr. Howard C. Herrmann of the University of Pennsylvania in Philadelphia told HeartInfo/Mediconsult. Patients may want a stress test to make sure their heart can handle the exertion of intercourse, he said. Nitrates, a common heart medication taken for chest pain, are dangerous if used in combination with Viagra, studies have shown.

During the past couple of years, the Food and Drug Administration has raised concerns about Viagra by reporting that a significant number of men had heart attacks and cardiac arrests soon after taking the drug and before having intercourse. Researchers wondered if this was because many impotent men also have heart disease or if Viagra was dangerous to the heart.

Viagra works by inhibiting a type of enzyme in the penis, and similar enzymes are also found in the heart muscle. Researchers wondered if inhibiting the enzyme posed a cardiac risk, Dr. Herrmann explained.

As part of the open-label, non-blinded study, he and his colleagues gave 100 milligrams of the drug to 14 heart patients and then monitored their lung and heart function. All were
in their 50s and 60s and had at least one artery that was more than 70 percent blocked.

The men were on a variety of medications, but none were on nitrates. Almost half of the group had hypertension or diabetes, or were smokers. Before and 45 minutes after taking Viagra, the participants had their blood pressure, heart rate, and blood flow measured. The men did not have intercourse during the study, so it was not a test of the effects of Viagra on the heart during exertion.

On most measures of blood pressure and blood flow, Viagra did not appear to have any significant effect, the researchers report, "and it had no effect on pulmonary-capillary wedge pressure, right atrial pressure, heart rate, or cardiac output." There were no adverse effects on coronary blood flow. And none of the men in the study experienced any serious side effects, like low blood pressure or chest pain, that could be linked to Viagra, according to the authors.

"Our data support the consensus position of the American College of Cardiology and the American Heart Association that sildenafil is safe for patients with stable coronary artery disease who are not taking medications containing nitrates," the authors conclude.

Pfizer Inc, which makes Viagra, funded the study.

The American College of Cardiology and the American Heart Association recommend that patients with stable coronary disease who are not taking nitrates should consult their physician about the risks and benefits of taking Viagra. Those taking a combination of blood pressure-lowering drugs may be at increased risk for drug interactions, they note.

In addition, Dr. Andrew P. Levy, Medical Advisor for HeartInfo, cautions that "It is difficult to make many conclusions from such a small study. Men with heart disease should consult their doctor before taking Viagra. We don't yet understand why the drug may cause death, and this study is not definitive."

Erectile dysfunction affects up to 30 million men in the United States, and shares certain risk factors with heart disease, including age, diabetes, hypertension, hypercholesterolemia, and smoking.

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