Zofran Special Precautions

Hypersensitivity reactions have been reported in patients who have exhibited hypersensitivity to other selective 5HT₃ receptor antagonists.
Ondansetron prolongs the QT interval in a dose-dependent manner (see PHARMACOLOGY under ACTIONS). In addition, post-marketing cases of Torsade de Pointes have been reported in patients using ondansetron. Avoid ondansetron in patients with congenital long QT syndrome. Ondansetron should be administered with caution to patients who have or may develop prolongation of QTc, including patients with electrolyte abnormalities, congestive heart failure, bradyarrhythmias or patients taking other medicinal products that lead to QT prolongation or electrolyte abnormalities.
Myocardial ischemia has been reported in patients treated with ondansetron. In some cases, predominantly during intravenous administration, the symptoms appeared immediately after administration but recovered with prompt treatment. Therefore, caution should be exercised during and after administration of ondansetron.
Hypokalemia and hypomagnesemia should be corrected prior to ondansetron administration.
Serotonin syndrome has been described following the concomitant use of ondansetron (Zofran) and other serotonergic drugs (see Interactions). If concomitant treatment with ondansetron (Zofran) and other serotonergic drugs is clinically warranted, appropriate observation of the patient is advised.
As ondansetron (Zofran) is known to increase large bowel transit time, patients with signs of subacute intestinal obstruction should be monitored following administration.