Can bupropion cause atrioventricular (AV) block?

Bupropion and Atrioventricular Block

Bupropion can cause atrioventricular (AV) block, particularly in overdose situations or in patients with pre-existing cardiac conduction abnormalities, but it is rare at therapeutic doses.

Cardiac Effects of Bupropion

Bupropion has several potential cardiac effects that should be considered:

• At therapeutic doses: Bupropion generally has a favorable cardiovascular profile compared to tricyclic antidepressants, with minimal effects on cardiac conduction at standard therapeutic doses 1.

• In overdose: Bupropion overdose can cause significant cardiac conduction disturbances, including:

  • ECG changes and conduction disturbances 2
  • Intraventricular conduction delays 3
  • Sinus tachycardia 2
  • Potential for QRS widening and QTc prolongation 4

Risk Factors for Bupropion-Associated AV Block

Several factors increase the risk of cardiac conduction abnormalities with bupropion:

• Pre-existing cardiac conduction disease: Patients with pre-existing conduction abnormalities may be at higher risk 1
• Overdose: Seizures occur in approximately one-third of overdose cases, and ECG changes are common in significant overdoses 2
• Age: Increasing age is independently associated with adverse cardiovascular events in bupropion exposures 4
• QRS widening and QTc prolongation: Both are associated with increased risk of adverse cardiovascular events 4

Clinical Considerations

When prescribing bupropion, consider the following:

1. Screening: Assess for pre-existing cardiac conduction abnormalities, especially in older patients or those with cardiac disease.

2. Monitoring: Consider ECG monitoring in patients with:

   • Known cardiac disease
   • History of conduction abnormalities
   • Symptoms suggesting arrhythmias

3. Dose considerations:

   • Standard therapeutic doses (up to 450 mg/day) generally have minimal cardiac effects in patients without cardiac disease
   • Higher doses may increase risk of cardiac effects

4. Drug interactions: Be cautious with concomitant medications that can affect cardiac conduction, particularly other drugs with SA and/or AV nodal-blocking properties 5.

Management of Suspected AV Block

If AV block is suspected:

1. Immediate discontinuation: Stop bupropion immediately if significant conduction abnormalities develop.

2. Supportive care: Provide close medical supervision and monitoring 2.

3. Consult cardiology: For management of AV block and consideration of temporary or permanent pacing if needed.

4. Consider alternative antidepressants: Switch to medications with lower risk of cardiac conduction effects.

Important Caveats

• The risk of clinically significant AV block with bupropion at therapeutic doses is low in patients without pre-existing cardiac disease.

• Most serious cardiac conduction abnormalities occur in the context of overdose rather than therapeutic use.

• Bupropion may cause a rise in supine blood pressure but generally does not cause significant conduction complications at therapeutic doses in most patients 1.

• Patients with pre-existing cardiac disease should be monitored more closely, as exacerbation of baseline hypertension has been reported in some cases 1.

By understanding these risks and implementing appropriate monitoring, clinicians can safely prescribe bupropion while minimizing the risk of AV block and other cardiac conduction abnormalities.