From the Guidelines
Taking amlodipine and diltiazem together is not recommended due to the potential for increased risk of significant bradyarrhythmias and heart failure, as cautioned in the 2015 American Heart Association guidelines 1. When considering the management of hypertension, especially in patients with coronary artery disease, the guidelines suggest that if beta-blockers are contraindicated or produce intolerable side effects, a nondihydropyridine calcium channel blocker (CCB) like diltiazem or verapamil may be substituted, but with caution and not in cases of left ventricular dysfunction 1. However, the combination of a beta-blocker and either of the nondihydropyridine CCBs (diltiazem or verapamil) should be used with caution in patients with symptomatic CAD and hypertension because of the increased risk of significant bradyarrhythmias and heart failure (Class IIa; Level of Evidence B) 1. Key points to consider include:
- The potential for excessive blood pressure lowering and increased heart rate problems when using both medications together.
- The risk of worsening side effects like dizziness, headaches, swelling in the legs, and constipation.
- The importance of consulting a healthcare provider before taking both medications, as they may need to adjust the medication regimen.
- Never stopping either medication suddenly without medical guidance to avoid rebound high blood pressure. Given the potential risks and the guidelines' caution against certain combinations of medications, it's crucial to prioritize the patient's safety and adjust the treatment plan accordingly, possibly choosing just one calcium channel blocker or an alternative medication from a different class, under the guidance of a healthcare provider 1.
From the FDA Drug Label
Co-administration of a 180 mg daily dose of diltiazem with 5 mg amlodipine in elderly hypertensive patients resulted in a 60% increase in amlodipine systemic exposure. CYP3A inhibitors: Co-administration of a 180 mg daily dose of diltiazem with 5 mg amlodipine in elderly hypertensive patients resulted in a 60% increase in amlodipine systemic exposure. Diltiazem is both a substrate and an inhibitor of the cytochrome P450 3A4 enzyme system It is not recommended to take amlodipine and diltiazem together, as diltiazem can increase the systemic exposure of amlodipine by 60% 2. This can lead to increased risk of adverse effects.
- Key considerations:
- Diltiazem is a CYP3A4 inhibitor, which can increase the levels of amlodipine in the body 2.
- The combination of amlodipine and diltiazem may increase the risk of adverse effects, such as hypotension and edema 2.
- Patients taking both medications should be closely monitored for signs of adverse effects and dosage adjustments may be necessary 2.
From the Research
Efficacy and Safety of Amlodipine and Diltiazem
- The efficacy and safety of amlodipine and diltiazem have been compared in several studies 3, 4, 5, 6.
- A study published in the Journal of Cardiovascular Pharmacology found that amlodipine was effective and well tolerated in the treatment of patients with symptomatic myocardial ischemia, and was comparable with diltiazem three times daily 3.
- Another study published in Blood Pressure found that both amlodipine and diltiazem once-daily were effective in reducing blood pressure, but amlodipine was more potent than diltiazem in reducing systolic blood pressure 4.
- A comparative study published in Cardiovascular Drugs and Therapy found that both amlodipine and diltiazem controlled release (CR) had a comparable therapeutic effect in patients with stable angina pectoris, but amlodipine was better tolerated and had the advantage of once-daily dosing 5.
- A study published in the American Journal of Hypertension found that amlodipine was more effective than long-acting diltiazem in reducing systolic and diastolic blood pressures in patients with mild or moderate hypertension 6.
Combination Therapy
- There is no direct evidence from the provided studies on the safety and efficacy of taking amlodipine and diltiazem together.
- However, a study published in Cardiovascular Drugs and Therapy discussed the combination of beta-blockers and ACE inhibitors in the treatment of cardiovascular diseases, but did not mention the combination of amlodipine and diltiazem 7.
Key Findings
- Amlodipine and diltiazem have been shown to be effective and well tolerated in the treatment of various cardiovascular conditions, including hypertension and angina pectoris 3, 4, 5, 6.
- Amlodipine may be more potent than diltiazem in reducing systolic blood pressure, but both drugs have a comparable therapeutic effect in patients with stable angina pectoris 4, 5.
- The safety and efficacy of taking amlodipine and diltiazem together are not well established and require further study.