* The antiemetic ondansetron (Zofran) has undergone a label revision to emphasize the risk of cardiac arrhythmias such as QT-interval prolongation and torsade de pointes.
* Patients with congenital long QT syndrome shouldn't receive ondansetron.
* Cardiac monitoring should be conducted in patients taking ondansetron who have electrolyte imbalances, congestive heart failure, bradyarrythmias, or a history of taking other drugs that prolong the QT interval.
Diane S. Aschenbrenner is the course coordinator for undergraduate pharmacology at Johns Hopkins University School of Nursing in Baltimore, MD. She also coordinates Drug Watch: email@example.com.