This will be a randomized, double blind, 5 way crossover research study in healthy male and female subjects, 18 to 35 years of age, to compare 4 known QT prolonging drugs versus placebo to determine their effects on electrophysiological and other clinical parameters. To maintain the study blind, subjects will be blindfolded during study drug administration. The cardiologists at the central ECG laboratory (Spaulding Clinical Research, LLC) will be blinded to treatment, time, and study day/subject identifiers.