What are the medications that can cause QT interval prolongation?

Medications That Cause QT Interval Prolongation

The most common medications that cause QT interval prolongation include Class IA and III antiarrhythmics, certain antibiotics, antipsychotics, antidepressants, antiemetics, and antimalarials, which should be avoided in patients at risk for torsades de pointes. 1

High-Risk QT-Prolonging Medications (Frequent QT Prolongation)

Antiarrhythmics

• Class IA: Disopyramide, Procainamide, Quinidine
• Class III: Dofetilide, Ibutilide, Sotalol, Amiodarone (less frequent)
• Other: Ajmaline

Antibiotics

• Macrolides: Azithromycin, Clarithromycin, Erythromycin
• Fluoroquinolones: Ciprofloxacin, Levofloxacin, Moxifloxacin, Sparfloxacin
• Other: Pentamidine

Antipsychotics

• Typical: Chlorpromazine, Haloperidol, Thioridazine, Pimozide
• Atypical: Iloperidone, Ziprasidone

Antiemetics

• Domperidone, Droperidol, Ondansetron

Moderate-Risk QT-Prolonging Medications

Antidepressants

• Tricyclic: Amitriptyline, Desipramine, Nortriptyline
• Other: Citalopram, Escitalopram

Antimalarials

• Chloroquine, Halofantrine, Hydroxychloroquine 2

Antifungals

• Ketoconazole, Voriconazole, Fluconazole

Miscellaneous

• Methadone
• Cisapride (withdrawn from market) 1
• Bepridil

Pediatric QT-Prolonging Medications 1

Antiemetics

• Ondansetron, Dolasetron

Cardiac Medications

• Adenosine, Dopamine, Epinephrine, Dobutamine

Respiratory Medications

• Albuterol, Terbutaline, Phenylephrine

Antihistamines

• Diphenhydramine, Hydroxyzine, Loratadine

Risk Factors for QT Prolongation and Torsades de Pointes 1

• Female gender
• Hypokalemia, hypomagnesemia
• Bradycardia
• Recent conversion from atrial fibrillation
• Congestive heart failure
• Baseline QT prolongation
• Left ventricular hypertrophy
• Congenital long QT syndrome
• Certain DNA polymorphisms
• Severe hypomagnesemia
• Concomitant use of 2+ QT-prolonging drugs
• Use of QT-prolonging drug with its metabolic inhibitor

Management Considerations

1. Avoid combinations of QT-prolonging medications whenever possible 3
2. Monitor ECG at baseline and after starting QT-prolonging medications, particularly in high-risk patients
3. Maintain electrolytes in normal range (potassium >4 mM/L, magnesium >1.8 mg/dL) 1, 3
4. Consider alternatives in patients with congenital long QT syndrome or QTc >500 ms
5. Be vigilant with patients on multiple QT-prolonging medications or those with other risk factors

Special Considerations

• Second-generation antipsychotics (olanzapine, quetiapine, risperidone) generally have lower risk of QT prolongation than first-generation agents 4
• Aripiprazole and lurasidone appear to have minimal risk for QT prolongation 5
• Hydroxychloroquine prolongs QT interval and should not be used with other arrhythmogenic drugs 2
• Azithromycin can prolong QT interval, especially in patients with known QT prolongation, history of torsades de pointes, or uncompensated heart failure 6

Remember that QT prolongation risk is dose-dependent for many medications and is significantly increased when multiple risk factors are present. Always check for drug interactions and consider ECG monitoring when starting high-risk medications in vulnerable patients.