WEDNESDAY, Feb. 11, 2009 (HealthDay News) -- A new drug for a common heartbeat abnormality produced promising results in its latest trial.
The drug, dronedarone, is being tested for atrial fibrillation, which affects an estimated 2.2 million Americans. The upper chambers of their hearts quiver, rather than beating vigorously, allowing the formation of blood clots that can block a brain artery and cause a stroke.
In an international trial that included 2,301 people with atrial fibrillation, dronedarone (Multaq) reduced the incidence of hospitalization due to stroke, heart attacks and other problems by 24 percent, compared to placebo, according to a report in the Feb. 12 issue of the New England Journal of Medicine.
About 30 percent of those who started the trial discontinued use of the drug -- at an average of about 21 months -- roughly the same percentage as those receiving the placebo.
The U.S. Food and Drug Administration has assigned priority review status to dronedarone, and an FDA advisory committee will meet March 19 to discuss its possible approval.
"I believe this will be approved favorably," said Dr. Richard L. Page, head of the division of cardiology at the University of Washington School of Medicine, who took part in the study. "The overall literature on this drug shows both efficacy and safety."
Atrial fibrillation affects one in 20 Americans by the age of 65, and one in 10 by 85, Page said. Current drug treatments include beta blockers and calcium channel blockers.
Dronedarone is a chemical relative of amiodarone, a drug that has severe side effects but still is widely used in atrial fibrillation. Amiodarone includes iodine, which can cause thyroid problems, and "it takes a while to have an effect," Page said. "You must give relatively high doses early to saturate the body before it has an effect. It is stored in fat tissue and doesn't reach a steady state for a month or longer."
By contrast, "dronedarone has been shown to be quite effective in patients with atrial fibrillation," Page said. "There are two studies published previously that demonstrate a very consistent effect in controlling the time to atrial fibrillation recurrence. It prolonged the time to recurrence better than twofold compared to other treatment, from 53 days to 116 days."
All the trials of dronedarone have been sponsored by the drug's maker, Sanofi-Aventis. One of those studies showed increased mortality in people who had both atrial fibrillation and heart failure.
"We definitely need more treatments for atrial fibrillation," said Dr. Sana Al Khatib, director of electrophysiology at Duke University. "A lot of these medications are not safe, especially for those with structural heart disease. We definitely need more drugs that have a favorable safety profile."
But it's difficult to determine the safety of dronedarone from the newly published study, she said. "The percentage of patients who had to stop the drug was close to 30 percent, which is a high rate," Al Khatib said. "We really don't have a very good idea of the safety profile of the drug. We are not clear about its long-term safety."
The one certainty is that dronedarone should not be prescribed for anyone with heart failure, Al Khatib said. But considering that "we certainly need more medications, it would seem to be a reasonable medication for those who do not have advanced heart failure," she said.
Atrial fibrillation and its treatment are described by the American Heart Association.