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Electrocardiographic Effects of a Dietary Supplement Containing Ephedra and Caffeine
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To the Editor: Controlled studies of the toxicity of over-the-counter drugs are uncommon, so the study by Dr McBride and colleagues1 of a dietary supplement containing ephedra and caffeine (DSEC) was an important addition to the literature. However, some additional data from that study would be helpful.
Dr McBride and colleagues reported that participants taking DSEC had a significantly increased electrocardiographic (ECG) QTc interval, compared with placebo, when it was calculated by either the Bazett or Framingham formulas. Unfortunately, the source article for the Framingham calculation2 quoted an incorrect formula. One of the participants in the DSEC study had a heart rate of 120/min while taking DSEC. A healthy participant with a heart rate of 120/min who had a QTc interval of 380 milliseconds by the correct Framingham formula would have a QTc interval of 429 milliseconds by the Bazett formula and 1073 milliseconds by the incorrect Framingham formula.2 The . . . [Full Text of this Article]
Milos Milic, MD, PhD;
Demetri Rizos, DO;
Michael G. Ziegler, MD
mziegler@ucsd.edu
Department of Medicine
University of California, San Diego
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ABSTRACT
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