Drug interactions between Anzemet and Pamelor

MONITOR CLOSELY: Dolasetron can cause dose-related prolongation of the QT interval via its pharmacologically active metabolite, hydrodolasetron. Theoretically, coadministration with other agents that can prolong the QT interval may result in elevated risk of ventricular arrhythmias, including ventricular tachycardia and torsade de pointes, because of additive arrhythmogenic potential related to their effects on cardiac conduction. In clinical trials, ECG interval prolongations usually returned to baseline within 6 to 8 hours after administration but lasted more than 24 hours in some patients. In general, the risk of an individual agent or a combination of agents causing ventricular arrhythmia in association with QT prolongation is largely unpredictable but may be increased by certain underlying risk factors such as congenital long QT syndrome, cardiac disease, and electrolyte disturbances (e.g., hypokalemia, hypomagnesemia). In addition, the extent of drug-induced QT prolongation is dependent on the particular drug(s) involved and dosage(s) of the drug(s).

MANAGEMENT: Caution is recommended when dolasetron is administered concomitantly with drugs that prolong the QT interval (including cumulative high-dose anthracycline therapy), especially to patients with underlying risk factors. ECG monitoring may be appropriate in high-risk patients. Patients should be advised to seek medical attention if they experience symptoms that could indicate the occurrence of torsade de pointes such as dizziness, palpitations, or syncope.