Electrocardiographic and Hemodynamic Effects of a Multicomponent Dietary Supplement Containing Ephedra and Caffeine: A Randomized Controlled Trial

CONTEXT Metabolife 356, a multicomponent dietary supplement containing ephedra and caffeine (DSEC) in addition to several other components, is the top-selling dietary weight loss supplement. Given its common use, anecdotal reports of cardiovascular and cerebrovascular adverse events, and paucity of safety data, further research with this DSEC was warranted. OBJECTIVE To determine the impact of the DSEC on corrected QT (QTc) interval duration and systolic blood pressure (SBP). DESIGN Randomized, double-blind, placebo-controlled, crossover study conducted from January to May 2003. SETTING AND PARTICIPANTS Fifteen healthy volunteers (mean [SD] age, 26.7 [2.52] years; weight, 72.7 [14.93] kg), 6 (40%) of whom were women, recruited from the University of Connecticut, Storrs campus. INTERVENTION A single dose of the DSEC (containing 19 ingredients including ephedra [12 mg] and caffeine [40 mg]) or matching placebo were administered in a crossover fashion with a 7-day washout period between treatments. MAIN OUTCOME MEASURES Maximal QTc interval and SBP assessed at 1, 3, and 5 hours after dosing for the DSEC relative to placebo. RESULTS Individuals receiving the DSEC had a longer maximal QTc interval (mean [SD], 419.4 [11.8] vs 396.1 [15.7] milliseconds; P