From the Guidelines
No, patients should not take nifedipine and diltiazem together as this combination is generally contraindicated. Both medications are calcium channel blockers that work by relaxing blood vessels and slowing heart rate, and using them simultaneously can lead to dangerous additive effects. The combination can cause excessive lowering of blood pressure (hypotension), severe bradycardia (slow heart rate), heart block, or heart failure. These medications work through similar mechanisms - they block calcium channels in heart and blood vessel cells, reducing the workload on the heart and decreasing blood pressure.
According to the 2012 ACCF/AHA focused update incorporated into the ACCF/AHA 2007 guidelines for the management of patients with unstable angina/non-st-elevation myocardial infarction 1, calcium channel blockers may be used to control ongoing or recurring ischemia-related symptoms in patients who already are receiving adequate doses of nitrates and beta blockers. However, rapid-release, short-acting dihydropyridines (eg, nifedipine) must be avoided in the absence of concomitant beta blockade because of increased adverse potential.
The treatment of hypertension in patients with coronary artery disease: a scientific statement from the American Heart Association, American College of Cardiology, and American Society of Hypertension 1 also suggests that if β-blockers are contraindicated or produce intolerable side effects, a nondihydropyridine CCB (such as diltiazem or verapamil) may be substituted, but not if there is LV dysfunction. However, the combination of a β-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 HF.
In general, the use of multiple calcium channel blockers, including nifedipine and diltiazem, should be avoided due to the increased risk of adverse effects. If a patient is currently taking one of these medications and their doctor suggests changing to the other, there should typically be a washout period between stopping one medication and starting the other. Patients who have been accidentally taking both medications should contact their healthcare provider immediately for guidance, but should not abruptly stop either medication without medical advice as sudden discontinuation can cause rebound effects.
Some key points to consider when using calcium channel blockers include:
- Nifedipine and amlodipine have the most peripheral arterial dilatory effects but few or no AV or sinus node effects, whereas verapamil and diltiazem have prominent AV and sinus node effects and some peripheral arterial dilatory effects as well 1.
- The combination of a β-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 HF 1.
- Rapid-release, short-acting dihydropyridines (eg, nifedipine) must be avoided in the absence of concomitant beta blockade because of increased adverse potential 1.
From the FDA Drug Label
Diltiazem: Pre-treatment of healthy volunteers with 30 mg or 90 mg t. i.d. diltiazem p.o. increased the AUC of nifedipine after a single dose of 20 mg nifedipine by factors of 2.2 and 3.1, respectively. The corresponding Cmax values of nifedipine increased by factors of 2.0 and 1. 7, respectively. Caution should be exercised when co-administering diltiazem and nifedipine and a reduction of the dose of nifedipine should be considered.
Key Points:
- Co-administration of diltiazem and nifedipine increases the exposure to nifedipine.
- Caution should be exercised when co-administering these two drugs.
- A reduction of the dose of nifedipine should be considered when co-administered with diltiazem.
The patient can take nifedipine and diltiazem together, but with caution and careful monitoring, as the combination may increase the exposure to nifedipine, and a dose reduction of nifedipine may be necessary 2.
From the Research
Combination Therapy with Nifedipine and Diltiazem
- The combination of nifedipine and diltiazem has been studied in various clinical trials to evaluate its efficacy and safety in patients with hypertension, angina pectoris, and other cardiovascular conditions 3, 4, 5, 6.
- Studies have shown that the combination of nifedipine and diltiazem can be effective in reducing angina frequency, improving exercise tolerance, and lowering blood pressure in patients with stable angina pectoris and hypertension 4, 5, 6.
- The combination therapy has also been shown to increase the plasma concentration of nifedipine, which may contribute to its enhanced efficacy 4, 5.
- However, the combination of nifedipine and diltiazem may also increase the risk of side effects, such as hypotension, edema, and headache 5.
Pharmacological Properties
- Nifedipine is a potent vasodilator that has been shown to be effective in relieving anginal symptoms caused by coronary vasospasm 7.
- Diltiazem is a calcium channel blocker that has been shown to be effective in treating angiospastic angina and reducing the frequency of angina attacks 7, 6.
- The combination of nifedipine and diltiazem may have synergistic effects on receptor binding and drug levels, which may contribute to its enhanced efficacy 3.
Clinical Implications
- The combination of nifedipine and diltiazem may be a useful therapeutic option for patients with severe hypertension or angina pectoris who do not respond to monotherapy with either drug 3, 4, 5.
- However, the combination therapy should be used with caution and under close medical supervision due to the potential risk of side effects and interactions 5.