Ondansetron, also known as Zofran, is a marketed compound used for the prevention of nausea
and vomiting. This study, called a thorough QT study, will characterize the effects of a
single intravenous (IV) dose of ondansetron on cardiac repolarization as compared to placebo.
Moxifloxacin, a commercially available antibiotic known to cause a mild QT prolongation, will
be used as a positive control and will be given orally. The cardiac repolarization will be
measured by taking consecutive ECGs on a recording device known as a Holter monitor and
measuring the QT interval at specified times. In addition, blood samples will also be taken
at specified times and will be used to measure the amount of study medication in the body.