Are Seroquel (quetiapine) and Depakote (valproate) considered QT-prolonging medications?

QT Prolongation Risk with Seroquel and Depakote

Quetiapine (Seroquel) has a moderate risk of QT prolongation, while valproate (Depakote) is not considered a QT-prolonging medication.

Quetiapine (Seroquel) and QT Prolongation

• According to the FDA drug label, quetiapine can cause QT prolongation, though it was not associated with persistent QT interval increases in clinical trials 1
• Post-marketing reports have documented cases of QT prolongation, particularly in overdose situations or in patients with concomitant illnesses or taking other QT-prolonging medications 1
• Quetiapine is considered to have a moderate QT-prolonging effect, with studies showing it causes approximately 6 ms of QT prolongation on average 2
• The European Heart Journal guidelines classify antipsychotics like quetiapine as having QT-prolonging potential, though less than some other antipsychotics like thioridazine 2

Valproate (Depakote) and QT Prolongation

• Valproate (Depakote) is not listed among medications known to cause QT prolongation in major guidelines 2
• Unlike antipsychotics and certain antidepressants, valproate is not classified as a QT-prolonging agent in the European Heart Journal guidelines 2
• Studies on antiepileptic drugs and QT prolongation do not identify valproate as a significant risk factor for QT prolongation or torsades de pointes 3

Risk Stratification for QT Prolongation with Quetiapine

• The risk of QT prolongation with quetiapine increases in certain conditions:
  • Concomitant use of other QT-prolonging medications 1
  • Electrolyte abnormalities, particularly hypokalemia and hypomagnesemia 1
  • Pre-existing cardiac conditions, especially congenital long QT syndrome 1
  • Advanced age and female gender 4
  • Overdose situations 1

Clinical Implications and Monitoring

• The FDA recommends avoiding quetiapine in combination with other drugs known to prolong QT interval, including Class IA and III antiarrhythmics 1
• ECG monitoring is not mandatory for all patients on quetiapine but should be considered for those with:
  • Pre-existing cardiovascular disease 1, 5
  • Family history of QT prolongation 1
  • Concomitant use of other QT-prolonging medications 1, 5
  • Electrolyte disturbances 1, 5

Management Recommendations

• For patients requiring quetiapine who have risk factors for QT prolongation:
  • Obtain baseline ECG before starting treatment 5
  • Monitor and correct electrolyte abnormalities 1
  • Consider periodic ECG monitoring during treatment 5
  • Use the lowest effective dose 4
• Valproate (Depakote) can be considered a safer alternative from a cardiac perspective when a mood stabilizer is needed in patients at high risk for QT prolongation 3

Common Pitfalls to Avoid

• Failing to recognize that multiple QT-prolonging medications can have additive effects 2
• Overlooking the importance of electrolyte monitoring, particularly potassium and magnesium levels, in patients taking quetiapine 1
• Not considering alternative medications for patients with multiple risk factors for QT prolongation 4
• Assuming all psychiatric medications carry the same risk of QT prolongation 2