• Bokyung Min, Brian F McBride, Michael J Kardas, Agron Ismali, Vinnita Sinha, Jeffrey Kluger, and C Michael White.
• School of Pharmacy, University of Connecticut, Storrs, 06102, USA.
• Pharmacotherapy. 2005 May 1; 25 (5): 654-9.

Study ObjectiveMetabolife 356, an ephedra-containing weight-loss product, substantially increases the corrected QT (QTc) interval. Metabolife Ephedra Free, a similar supplement, contains caffeine and extracts of green tea, garcinia cambogia, and yerba mate. Its electrocardiographic (ECG) effects are not known. Therefore, we sought to determine the effect of this supplement on the QTc interval.DesignRandomized, double-blind, placebo-controlled, crossover study.SettingUniversity of Connecticut, Storrs Campus.SubjectsTwenty healthy volunteers. Intervention. A single capsule containing half the normal recommended dose of Metabolife Ephedra Free or matching placebo was administered in crossover fashion, with a 7-day washout period between treatments.Measurements And Main ResultsBaseline and three postdose ECG measurements were obtained, and QTc intervals were measured over a 5-hour study period. No significant differences in the QTc interval or other ECG variables were observed between the Metabolife Ephedra Free and placebo groups.ConclusionAt half the recommended single dose, Metabolife Ephedra Free does not affect the QTc interval or other ECG variables over 5 hours. Dose-response studies and studies of longer duration should be conducted.

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