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  • Multiple dosing of ephedra-free dietary supplements: hemodynamic, electrocardiographic, and bacterial contamination effects.

Multiple dosing of ephedra-free dietary supplements: hemodynamic, electrocardiographic, and bacterial contamination effects.

Clinical pharmacology and therapeutics (2013-01-31)
L Foster, M C Allan, A Khan, P Moore, D K Williams, M Hubbard, L Dixon, B J Gurley
ABSTRACT

Four popular ephedra-free dietary supplements were evaluated for their effects on heart rate (HR), blood pressure (BP), and electrocardiographic (ECG) parameters. Twelve healthy men participated in a study randomized for product sequence, with a 21-day washout period between supplement-administration phases. Throughout the study, Holter monitors were used to assess ECG and HR activity. BP was assessed automatically on multiple occasions. The supplements were ingested three times daily for 3 days. Caffeine content, microbial load, and serum caffeine concentrations were determined. Mean systolic (SBP) and diastolic BP (DBP) readings showed significant increases relative to baseline (10.8 ± 2.5 and 5.3 ± 3.1 mm Hg, respectively; P < 0.05). All supplements significantly increased HR and decreased bradycardia runs; abnormal atrial/ventricular events were frequently noted. Gastrointestinal and sympathomimetic symptoms were also common. Two supplements were heavily contaminated with Bacillus species. In light of these findings, the use of ephedra-free dietary supplements should be discouraged in individuals with hypertension, diabetes, or other cardiovascular diseases.

MATERIALS
Product Number
Brand
Product Description

Supelco
Theophylline, Pharmaceutical Secondary Standard; Certified Reference Material
Theophylline, European Pharmacopoeia (EP) Reference Standard
Sigma-Aldrich
Theophylline, anhydrous, ≥99%, powder
Supelco
Paraxanthine solution, 1.0 mg/mL in methanol, ampule of 1 mL, certified reference material, Cerilliant®
Sigma-Aldrich
1,7-Dimethylxanthine, ~98%, solid