Trial Information

Ondansetron and the QT Interval In Adult Emergency Department Patients

Intravenous ondansetron is routinely used in adult emergency department patients
experiencing nausea or vomiting. The FDA has changed the drug label to warn of prolongation
of the QT interval and required the manufacturer to perform additional studies. There are
rare case reports of cardiac electrical toxicity to include QT prolongation, atrial
fibrillation, severe bradycardia, ventricular tachycardia, supraventricular tachycardia, and
the potential for Torsades de Pointes. All of the reported literature on ondansetron comes
from post-operative patients, patients receiving chemotherapy, and healthy volunteers, but
has never been assessed in the emergency department population. Adult emergency department
patients that do not meet the exclusion criteria will be enrolled prior to receiving
intravenous ondansetron. Administration of ondansetron will be at the discretion of the
attending physician. A twelve-lead electrocardiogram (EKG) or 12-lead rhythm strip will be
generated prior to drug administration, and every 2 minutes following drug administration
for 20 minutes after administration. During the entire 20 minutes the patient will be on a
cardiac monitor and if any of the defined adverse cardiac electrical events occur (non-sinus
rhythm, severe bradycardia, sudden cardiac death) the patient will be treated using standard
Advanced Cardiac Life Support methods and admitted for continued monitoring. The mean
maximal QTc prolongation (as measured by the Bazett formula), as well as the rate of adverse
cardiac events with 95% confidence intervals will be reported.

The global objective of this study is to determine if routine use of intravenous ondansetron
in the emergency department is associated with cardiac risks. The primary objective is to
determine the mean maximal prolongation in QTc interval from baseline as measured by the
Bazett formula. The secondary objective is to determine the number of severe adverse cardiac
electrical events (non-sinus rhythm, severe bradycardia, sudden cardiac death) associated
with routine use of intravenous ondansetron in the adult emergency department patient.