From the Guidelines
Medications that can cause prolonged QT intervals include antiarrhythmics, antibiotics, antipsychotics, antidepressants, antiemetics, and antimalarials, among others, with the risk increasing with higher doses and combination of multiple QT-prolonging drugs 1.
Medications Causing Prolonged QT Intervals
The list of medications that can cause prolonged QT intervals is extensive and includes:
- Antiarrhythmics: amiodarone, sotalol, procainamide, quinidine 1
- Antibiotics: macrolides like azithromycin, erythromycin; fluoroquinolones like ciprofloxacin, levofloxacin 1
- Antipsychotics: haloperidol, quetiapine, risperidone 1
- Antidepressants: citalopram, escitalopram, tricyclic antidepressants 1
- Antiemetics: ondansetron, domperidone 1
- Antimalarials: chloroquine, hydroxychloroquine 1
- Other medications: methadone, certain antihistamines (diphenhydramine at high doses), and some antifungals (fluconazole) 1
Risk Factors for Prolonged QT Intervals
Patients with pre-existing heart conditions, electrolyte abnormalities (especially low potassium or magnesium), advanced age, female gender, or genetic predisposition are at higher risk for complications 1.
Management and Prevention
Regular ECG monitoring is recommended when starting these medications, particularly in high-risk patients 1. Removal of the offending agent, correction of electrolyte abnormalities, and prevention of bradycardia and long pauses with temporary pacing if necessary can help prevent torsades de pointes 1. Intravenous magnesium can suppress episodes of torsades de pointes without necessarily shortening QT, even when serum magnesium is normal 1.
From the FDA Drug Label
5.12 QT Prolongation In clinical trials, quetiapine was not associated with a persistent increase in QT intervals. However, the QT effect was not systematically evaluated in a thorough QT study. In post marketing experience, there were cases reported of QT prolongation in patients who overdosed on quetiapine [see OVERDOSAGE (10. 1)] , in patients with concomitant illness, and in patients taking medicines known to cause electrolyte imbalance or increase QT interval [see DRUG INTERACTIONS (7.1)] . 5.2 QT Prolongation Clarithromycin has been associated with prolongation of the QT interval and infrequent cases of arrhythmia. Cases of torsades de pointeshave been spontaneously reported during postmarketing surveillance in patients receiving clarithromycin.
The medications that can cause prolonged QT intervals are:
- Clarithromycin 2
- Quetiapine in certain circumstances, such as overdose, concomitant illness, or taking medicines known to cause electrolyte imbalance or increase QT interval 3 Other medications that may prolong the QT interval include:
- Class 1A antiarrhythmics (e.g., quinidine, procainamide)
- Class III antiarrhythmics (e.g., amiodarone, sotalol)
- Antipsychotic medications (e.g., ziprasidone, chlorpromazine, thioridazine)
- Antibiotics (e.g., gatifloxacin, moxifloxacin)
- Pentamidine, levomethadyl acetate, methadone
From the Research
Medications that Cause Prolonged QT Intervals
Medications that can cause prolonged QT intervals include:
- Antibiotics such as macrolide antibiotics (except azithromycin) and fluoroquinolone antibiotics 4, 5
- Antidepressants such as bupropion, duloxetine, fluoxetine, paroxetine, and tricyclic antidepressants 4, 6, 7
- Antipsychotics such as thioridazine, pimozide, intravenous haloperidol, and ziprasidone 6, 5, 8, 7
- Antiarrhythmic drugs such as amiodarone, sotalol, quinidine, procainamide, verapamil, and diltiazem 5
- Antifungal agents 4
- Drugs to treat human immunodeficiency virus 4
- Ondansetron 5
Risk Factors for Prolonged QT Intervals
Risk factors for prolonged QT intervals include:
- Advanced age 4
- Female sex 4, 8, 7
- Acute myocardial infarction 4
- Heart failure with reduced ejection fraction 4
- Hypokalemia 4, 8
- Hypomagnesemia 4, 8
- Hypocalcemia 4
- Bradycardia 4, 8
- Treatment with diuretics 4
- Elevated plasma concentrations of QTc interval-prolonging drugs due to drug interactions 4
- Inadequate dose adjustment of renally eliminated drugs in patients with kidney disease 4
- Rapid intravenous administration 4
Prevention and Management
Prevention and management of prolonged QT intervals include:
- Discontinuation of the offending drug(s) 4
- Correction of electrolyte abnormalities 4
- Administration of intravenous magnesium sulfate 1 to 2 g 4
- Close monitoring of patients, especially those in the intensive care unit 5
- Electrocardiogram recording of the QT interval at baseline, after introduction of a new drug, and after occurrence of any factor that might influence the QT interval 8