Can you take Cardizem (Diltiazem) and Amiodarone together?

Concurrent Use of Cardizem (Diltiazem) and Amiodarone

The concurrent use of diltiazem (Cardizem) and amiodarone should be approached with caution due to potential additive effects on cardiac conduction, but may be considered in specific clinical scenarios with appropriate monitoring.

Mechanism of Interaction

The interaction between diltiazem and amiodarone primarily involves:

• Both medications can cause bradycardia and AV conduction disturbances
• Both have negative inotropic effects
• Pharmacokinetic interaction: Diltiazem inhibits CYP3A4, which may affect amiodarone metabolism

Clinical Considerations

Potential Risks

• Bradycardia: Both medications slow heart rate and can have additive effects
• AV block: Increased risk of conduction disturbances
• Hypotension: Combined negative inotropic effects may reduce blood pressure
• Heart failure exacerbation: Particularly in patients with pre-existing left ventricular dysfunction

Situations Where Combination May Be Considered

According to the European Society of Cardiology guidelines, this combination may be considered:

• In patients with atrial fibrillation who don't respond adequately to monotherapy with either agent 1
• As an alternative to amiodarone monotherapy to avoid amiodarone's toxic side effects 1
• When heart rate control is inadequate with single-agent therapy (particularly when heart rate is 110-120 bpm or higher) 1

Monitoring Recommendations

When using this combination:

1. Baseline assessment:

   • ECG to evaluate for pre-existing conduction abnormalities
   • Blood pressure measurement
   • Assessment of heart failure symptoms

2. Ongoing monitoring:

   • Regular ECG monitoring for AV conduction abnormalities
   • Heart rate and blood pressure checks
   • Signs of heart failure exacerbation

3. Target heart rate: <100 bpm, ideally <84 bpm 1, 2

Dosing Considerations

• Start with lower doses of both medications
• Consider spacing administration times (FDA labeling for amiodarone notes that hemodynamic and electrophysiologic interactions have been observed with concomitant administration with diltiazem) 3
• Adjust doses based on clinical response and adverse effects

Special Populations and Contraindications

Avoid or use extreme caution in patients with:

• Pre-existing AV conduction disorders
• Sick sinus syndrome
• Heart failure with reduced ejection fraction (HFrEF)
• Severe bradycardia
• Hypotension

Alternative Approaches

In situations where the combination of diltiazem and amiodarone carries excessive risk:

• Consider alternative rate control agents (beta-blockers alone)
• Consider rhythm control strategy with catheter ablation
• If rate control is inadequate with a single agent, consider referral to an electrophysiologist

Conclusion

While the combination of diltiazem and amiodarone requires caution due to potential additive effects on cardiac conduction, it can be used in selected patients who don't respond adequately to monotherapy. Close monitoring of heart rate, blood pressure, and cardiac conduction is essential when using this combination.