Can you take 2 calcium channel blockers (CCBs) at the same time?

Combining Calcium Channel Blockers: Safety and Efficacy

Taking two calcium channel blockers (CCBs) simultaneously is generally not recommended due to the increased risk of additive side effects, particularly hypotension, without proportional therapeutic benefit.

Types of Calcium Channel Blockers and Their Effects

• CCBs reduce cell transmembrane inward calcium flux, inhibiting both myocardial and vascular smooth muscle contraction; some also affect AV conduction and sinus node function 1
• CCBs can be divided into two main classes with different properties:
  • Dihydropyridines (e.g., nifedipine, amlodipine, felodipine): Primarily cause peripheral arterial dilation with minimal effects on AV node and sinus node 1
  • Non-dihydropyridines (e.g., verapamil, diltiazem): Have prominent effects on AV and sinus nodes with moderate peripheral arterial dilation 1

Risks of Combining Calcium Channel Blockers

• Combining two CCBs can lead to additive or synergistic adverse effects 2, 3:

  • Severe hypotension (particularly problematic with two dihydropyridines)
  • Enhanced negative inotropic effects (especially with verapamil or diltiazem)
  • Excessive bradycardia and conduction disturbances (particularly with two non-dihydropyridines)
  • Increased risk of heart failure exacerbation 1

• The European Society of Cardiology specifically highlights that while various antihypertensive combinations are effective, certain combinations should be avoided or used with caution 1

Limited Evidence for Dual CCB Therapy

• While a meta-analysis of small studies suggested dual CCB therapy (combining a dihydropyridine with a non-dihydropyridine) produced greater blood pressure reduction than monotherapy, the authors concluded that "given the lack of long-term outcome data on efficacy and safety, dual CCB therapy should be used with restraint, if at all" 4

• The potential for serious additive deleterious hemodynamic or electrophysiologic reactions makes this combination controversial 5

Preferred Alternative Combinations

• Instead of combining two CCBs, guidelines recommend combining a CCB with a different class of antihypertensive medication 1, 6:
  • CCB + ACE inhibitor is a preferred combination with complementary mechanisms and proven cardiovascular benefits 6
  • CCB + ARB is another effective combination 1
  • For patients with specific indications, CCB + beta-blocker may be appropriate (particularly dihydropyridine CCBs with beta-blockers) 1, 5

Special Considerations

• If a patient is not responding adequately to a single CCB, the recommended approach is to:

  • Optimize the dose of the current CCB before adding another agent 1
  • Add a medication from a different class rather than a second CCB 1, 6
  • Consider fixed-dose combinations to improve adherence 1

• Patients with certain conditions require extra caution with any CCB therapy:

  • Heart failure: Verapamil and diltiazem should be avoided in patients with pulmonary edema or severe LV dysfunction 1
  • Conduction disorders: Non-dihydropyridine CCBs are contraindicated in patients with second or third-degree heart block or sick sinus syndrome 2

Conclusion

While combining a dihydropyridine and non-dihydropyridine CCB might theoretically provide complementary effects, the increased risk of adverse events and lack of long-term safety data make this approach inadvisable for routine clinical practice. Alternative combinations with medications from different antihypertensive classes are better supported by evidence and guidelines.