Precautions for Using Zyprexa (Olanzapine) in Patients with Prolonged QTc Interval

Risk Assessment and Monitoring

ECG monitoring should be performed before initiating treatment and periodically during treatment in patients with known QTc prolongation, as QTc interval >500 ms is associated with increased risk of adverse cardiac events 1

Avoid concurrent use of olanzapine with other QT-prolonging medications, such as Class III antiarrhythmics (amiodarone, sotalol, dofetilide) 1, 2
Common medications to avoid in combination with olanzapine in patients with QTc prolongation include certain antiemetics (domperidone, metoclopramide, 5HT3 antagonists) 3
Other antipsychotics, particularly thioridazine, haloperidol, chlorpromazine, should be avoided in combination with olanzapine 2, 3
Certain antibiotics (macrolides, fluoroquinolones) should also be avoided in combination with olanzapine 1, 3

Monitor and correct electrolyte abnormalities (particularly potassium and magnesium) before and during olanzapine treatment 1
Be especially cautious in patients with additional risk factors for torsades de pointes, including female gender 2, hypokalemia 2, bradycardia 2, congestive heart failure 2, and baseline QT prolongation 1