What medications prolong the QT (quantum time) interval?

From the Guidelines

Medications that prolong the QT interval should be avoided or used with extreme caution, as they can increase the risk of developing torsades de pointes, a potentially fatal arrhythmia, and removal of the offending agent is indicated in patients with drug-induced long QT syndrome 1.

Key Considerations

• The risk of torsades de pointes is higher in patients with certain risk factors, including female gender, hypokalemia, bradycardia, recent conversion from atrial fibrillation, congestive heart failure, digitalis therapy, and high drug concentrations 1.
• Common medications that prolong QT include certain antipsychotics, antidepressants, antibiotics, antiarrhythmics, and antiemetics, and an up-to-date list of these medications can be found at www.torsades.org and www.qtdrugs.org 1.
• When prescribing these medications, it's essential to check baseline ECG, monitor electrolytes, and avoid combinations of QT-prolonging drugs 1.

Management of QT Prolongation

• Intravenous magnesium can suppress episodes of torsades de pointes without necessarily shortening QT, even when serum magnesium is normal 1.
• Temporary pacing is highly effective in managing torsades de pointes that is recurrent after potassium repletion and magnesium supplementation 1.

Recommendations

• In patients with drug-induced LQTS, removal of the offending agent is indicated 1.
• Patients with congenital long QT syndrome, heart failure, bradycardia, or electrolyte abnormalities are at higher risk and should be closely monitored 1.
• If QT prolongation occurs, consider dose reduction or medication discontinuation, especially if the patient develops symptoms like palpitations, dizziness, or syncope 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)] . The use of quetiapine should be avoided in combination with other drugs that are known to prolong QTc including Class 1A antiarrythmics (e.g., quinidine, procainamide) or Class III antiarrythmics (e.g., amiodarone, sotalol), antipsychotic medications (e.g., ziprasidone, chlorpromazine, thioridazine), antibiotics (e.g., gatifloxacin, moxifloxacin), or any other class of medications known to prolong the QTc interval (e.g., pentamidine, levomethadyl acetate, methadone)

Meds with QT interval:

• Quetiapine may prolong the QT interval, particularly when used in combination with other medications that prolong the QT interval or in patients with certain medical conditions.
• QT interval prolongation can increase the risk of Torsade de Pointes and sudden death.
• The use of quetiapine should be avoided in combination with other drugs that are known to prolong QTc, including:
  • 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)
  • Other medications known to prolong the QTc interval (e.g., pentamidine, levomethadyl acetate, methadone) 2
• Amiodarone and sotalol are also known to prolong the QT interval and should be used with caution in patients with a history of QT prolongation or other risk factors for Torsade de Pointes 3 4

From the Research

Medications with QT Interval Prolongation

• Antipsychotic drugs, such as amisulpride, clozapine, flupenthixol, fluphenazine, haloperidol, melperone, olanzapine, perphenazine, pimozide, quetiapine, risperidone, sulpiride, thioridazine, and ziprasidone, can cause QT interval prolongation, with effects ranging from 4 ms for risperidone to 30 ms for thioridazine 5
• Atypical antipsychotic drugs, including aripiprazole, brexpiprazole, olanzapine, quetiapine, risperidone, and ziprasidone, have varying effects on QT interval, with some increasing the risk of QT prolongation and torsades de pointes ventricular tachycardia 6
• Other medications, such as anticancer drugs, antiarrhythmic medications, and certain antibiotics, can also contribute to QT interval prolongation 7

Risk Factors for QT Interval Prolongation

• Polypharmacy, or the use of multiple medications, is a primary contributing factor to QT interval prolongation and complications 7
• Other risk factors include hypokalemia, hypomagnesemia, bradycardia, increased age, female sex, congestive heart failure, and polymorphisms of genes coding ion channels or enzymes involved in drug metabolism 5, 8
• Co-occurring medical, mental health, and/or substance use disorders can increase the risk of QT interval prolongation due to the use of multiple medications 7

Management and Prevention of QT Interval Prolongation

• Clinicians may recommend medications with lower risks of QT interval prolongation, such as aripiprazole, brexpiprazole, or olanzapine, in licensed doses 6
• Regular monitoring of QT interval and electrocardiogram recordings can help identify patients at risk of QT interval prolongation 5, 8
• Decision-making trees grounded in evidence-based research can guide thorough assessment and safe treatment of patients requiring psychotropic medications 7