Consenting healthy male volunteers were randomized using a double-blind, double-dummy (ie, masking the difference in shape, appearance, and dosing schedule of the active and placebo preparations), placebo-controlled, dose-ranging, crossover study design approved by the institutional review board at Midwestern University, Downers Grove, Illinois. Active capsules contained the contents of one-half of a pulverized Enzyte immediate-release tablet. Lactose-containing placebo capsules were prepared in the pharmaceutics laboratory at Midwestern University. Because interlot variability has been reported with preparations of various dietary supplements and could impact results, we limited the study of Enzyte to tablets purchased from a single lot. Exclusion criteria included the following: risk factors for torsades de pointes,3 concurrent use of potentially interacting drugs (anticoagulants, monoamine oxidase inhibitors, over-the-counter medications containing pseudoephedrine, or any dietary supplements), female sex, or unwillingness to sign informed consent.