Ephedra Found To Change Heart Rhythm
Supplement raises risk threefold, JAMA study findsJan 14, 2004 | San Diego Union Tribune
A single Metabolife 356 pill can alter electrical pulses that control the heart, increasing a person's risk by threefold of developing a potentially fatal irregular heart beat, according to a study in today's issue of the Journal of the American Medical Association.
The small study underscores concerns that led the Food and Drug Administration last month to announce plans to ban products that contain the herbal stimulant ephedra, including the popular diet pill made by San Diego's Metabolife International.
The ephedra ban is expected to take effect 60 days after the FDA publishes a final regulation, which is expected in coming days.
In the JAMA study, researchers tested 15 healthy volunteers to determine the effect of ephedra. When given the nation's leading ephedra diet pill, Metabolife 356, 53 percent of those tested had a noticeable change in their heart rhythm, called QT interval.
Prolonged QT intervals are linked with heart arrhythmias, and the FDA has either banned or refused to approve several drugs that stretched QT intervals past 13 milliseconds, said C. Michael White, the study's lead author and an associate professor at the University of Connecticut School of Pharmacy.
In comparison, White said Metabolife 356 increased the QT interval by 24 milliseconds, similar to medicines such as Seldane, a prescription allergy drug taken off the market in 1997 because of reports of fatal cardiac arrhythmias.
Metabolife said in a written statement yesterday that its products are safe and effective when used as directed. The company suspended sales of its ephedra products in November but continues to market an ephedra-free pill.
"Today's article seems to be nothing more than a case of researchers making questionable data leaps to jump on the anti-ephedra bandwagon," Metabolife said.
Last year, the Rand Corp. reviewed several clinical studies on ephedra, many sponsored by the ephedra industry. The Santa Monica think-tank concluded that the available scientific evidence suggested a link between ephedra products and serious side effects, but said the quantity and quality of the research fell short of scientific proof.
There have been about 16,000 consumer complaints and 155 deaths linked to patients who took ephedra supplements, White said.
White said his study was modeled on the single-dose safety studies required by the FDA for prescription drugs. He said such studies, which are relatively inexpensive and of short duration, should be done on herbal supplements to provide initial safety information.
"There are herbals touted as doing this or that, but if they increase the QT interval and blood pressure, that is probably information that patients should know," said White.
White said his research group will soon launch another safety study to test Metabolife's ephedra-free diet pill, with results expected in November.
Some consumer advocates and medical experts warn that the new generation of ephedra-free diet pills offered by supplement companies have not been properly tested for safety or benefit, and could pose problems similar to ephedra.
Under federal law, supplement companies are not required to test their products before they market them or to report suspected incidents of deaths or side-effects to government regulators.