Can Norvasc (Amlodipine) cause bradycardia?

Norvasc (Amlodipine) and Bradycardia

Norvasc (amlodipine) does not typically cause bradycardia and is generally considered safe from a cardiac conduction perspective compared to other calcium channel blockers.

Pharmacological Properties of Amlodipine

Amlodipine is a dihydropyridine calcium channel blocker that has distinct electrophysiological properties compared to non-dihydropyridine calcium channel blockers (like verapamil and diltiazem):

• According to the FDA label, "Amlodipine does not change sinoatrial nodal function or atrioventricular conduction in intact animals or man" 1
• Clinical studies show that "chronic oral administration of amlodipine in clinical trials did not lead to clinically significant changes in heart rate" 1
• In patients with chronic stable angina, even intravenous administration of 10 mg amlodipine did not significantly alter cardiac conduction parameters 1

Dihydropyridine vs. Non-dihydropyridine CCBs

It's important to distinguish between different types of calcium channel blockers:

• Dihydropyridines (like amlodipine/Norvasc):

  • Act primarily on vascular smooth muscle
  • Have minimal effects on cardiac conduction
  • Do not typically cause bradycardia

• Non-dihydropyridines (verapamil, diltiazem):

  • Have pronounced effects on cardiac conduction
  • Can cause significant bradycardia
  • Guidelines note that "unlike beta-blockers, drug interactions must be considered when using verapamil or diltiazem, due to their inhibitory effect on drug transport" 2

Clinical Evidence

The evidence consistently shows that amlodipine has minimal effects on heart rate:

• Hemodynamic studies demonstrate that "amlodipine has not been associated with a negative inotropic effect when administered in the therapeutic dose range to intact animals and man" 1
• When amlodipine is combined with beta-blockers, "no adverse effects on electrocardiographic parameters were observed" 1
• In normotensive subjects, amlodipine "experienced no clinically significant change in blood pressures" and did not affect heart rate 1

Special Considerations

While amlodipine alone rarely causes bradycardia, there are important clinical scenarios to be aware of:

1. Drug combinations: Caution is needed when combining amlodipine with other medications that slow heart rate:

   • When combined with beta-blockers, there is a theoretical risk of additive effects, though clinical studies show this is uncommon at therapeutic doses 2
   • Case reports exist of severe bradycardia with combination products, particularly in overdose situations 3

2. Overdose situations: In cases of significant overdose, amlodipine can contribute to cardiovascular depression, especially when combined with beta-blockers 3

Conclusion

Based on the available evidence, particularly the FDA drug label and clinical guidelines, Norvasc (amlodipine) does not typically cause bradycardia at therapeutic doses. Its electrophysiologic profile shows minimal effects on cardiac conduction and heart rate. This distinguishes it from non-dihydropyridine calcium channel blockers like verapamil and diltiazem, which have more pronounced effects on cardiac conduction and can cause bradycardia.