Does diazepam (Diazepam) prolong the QTc (corrected QT) interval?

Diazepam Does Not Prolong QTc Interval

Benzodiazepines, including diazepam, do not cause QT interval prolongation in clinical use and are considered safe from a cardiac arrhythmia perspective. 1, 2

Evidence on Diazepam and QTc Interval

• Benzodiazepines, which include diazepam, are classified as "Class A" drugs, considered to be without any risk of QT prolongation or Torsades de Pointes according to European Heart Journal guidelines 1, 2
• In vitro studies have shown both inhibition and activation of potassium currents during exposure to benzodiazepines, but no changes in QT duration have been reported in clinical use 1
• Unlike many psychotropic medications that carry arrhythmia risks, benzodiazepines are consistently absent from comprehensive lists of QT-prolonging medications in major cardiology guidelines 2
• A 2010 study examining QTc prolongation in 1017 patients with schizophrenia confirmed that benzodiazepines did not prolong the QTc interval 3

Comparison with Other Psychotropic Medications

• Antipsychotics frequently cause QT prolongation with varying degrees of risk:
  • High risk: Thioridazine (25-30ms prolongation) 1
  • Moderate risk: Haloperidol (7ms prolongation), Quetiapine (6ms) 1
  • Low risk: Aripiprazole (0ms prolongation), Olanzapine (2ms) 1
• Antidepressants can also affect cardiac conduction:
  • Tricyclic antidepressants increase risk of cardiac arrest (OR=1.69) 1
  • SSRIs like citalopram have prompted FDA warnings about QT prolongation 1
• Methadone causes pronounced QT-prolongation with several reported cases of Torsades de Pointes 1

Clinical Implications for Practice

• When a medication with minimal cardiac risk is needed, diazepam can be safely used in patients at risk for QTc prolongation 2
• No specific ECG monitoring is required when administering diazepam alone, unlike medications known to prolong QT interval 2
• In a 2016 multicenter study examining drugs associated with QTc prolongation in everyday practice, diazepam was initially identified in univariate analysis but did not remain significantly associated with QT prolongation after multivariate analysis 4

Risk Factors for QTc Prolongation to Consider

When prescribing any medication, be aware of these risk factors for QTc prolongation:

• Female gender 2
• Electrolyte abnormalities, especially hypokalemia and hypomagnesemia 2
• Bradycardia or recent conversion from atrial fibrillation 2
• Heart failure or structural heart disease 2
• Concomitant use of QT-prolonging medications 2

Clinical Decision Making

• When treating patients requiring anxiolytic therapy who have risk factors for QTc prolongation, benzodiazepines like diazepam represent a safer choice compared to other psychotropic medications 2
• For patients requiring multiple psychotropic medications, diazepam can be safely combined with other medications without adding to QTc prolongation risk 3, 4
• In intensive care settings where QTc monitoring is routine, diazepam does not require the same level of electrocardiographic monitoring as other psychotropic medications 5, 6