From the Guidelines
Administering metoprolol while a patient is on a diltiazem drip is not recommended due to the risk of additive effects on heart rate and blood pressure, as stated in the 2015 ACC/AHA/HRS guideline for the management of adult patients with supraventricular tachycardia 1.
Key Considerations
- Both metoprolol and diltiazem can slow heart rate and reduce blood pressure, increasing the risk of profound bradycardia, hypotension, or heart block when used together.
- The 2015 ACC/AHA/HRS guideline warns against using beta blockers, such as metoprolol, in patients with AV block greater than first degree or SA node dysfunction (in absence of pacemaker), decompensated systolic HF, hypotension, reactive airway disease, or severe renal dysfunction, all of which could be exacerbated by concurrent use of diltiazem 1.
- Diltiazem, a nondihydropyridine calcium channel antagonist, has potential adverse effects including hypotension, worsening HF in patients with pre-existing ventricular dysfunction, bradycardia, and abnormal liver function studies, which could be worsened by the addition of metoprolol 1.
Clinical Implications
- In emergency situations where both medications might be considered, careful cardiac monitoring is essential, including continuous ECG, frequent blood pressure checks, and close observation for signs of hemodynamic compromise.
- If treatment with both agents is deemed necessary by the physician, reduced dosing of one or both medications should be considered, with the diltiazem drip potentially being discontinued before initiating metoprolol, as guided by the patient's specific cardiac condition, hemodynamic stability, and overall clinical picture 1.
From the FDA Drug Label
Intravenous diltiazem and intravenous beta-blockers should not be administered together or in close proximity (within a few hours). If intravenous diltiazem is administered to patients receiving chronic oral beta-blocker therapy, the possibility for bradycardia, AV block, and/or depression of contractility should be considered
The administration of metoprolol, a beta-blocker, while a patient is on a diltiazem drip is not recommended due to the risk of bradycardia, AV block, and/or depression of contractility. This combination should be avoided, if possible, or used with extreme caution and close monitoring. 2
From the Research
Administration of Metoprolol with Diltiazem Drip
- The administration of metoprolol while a patient is on a diltiazem drip can be considered based on the patient's specific condition and medical history 3, 4, 5, 6, 7.
- Studies have shown that the combined administration of metoprolol and diltiazem can lead to adverse effects, such as amplification of negative inotropic and chronotropic properties 3.
- However, other studies have found that metoprolol and diltiazem can be used together safely and effectively for rate control in patients with atrial fibrillation 4, 6, 7.
Safety and Efficacy
- A study published in 1992 found that high-dose intravenous diltiazem can be safely administered to patients receiving long-term metoprolol treatment, but it can cause significant reductions in systemic vascular resistance, left ventricular systolic and mean aortic pressures, and cardiac output 3.
- Another study published in 2021 found that metoprolol and diltiazem have similar effectiveness for rate control in patients with supraventricular tachycardia, but diltiazem is associated with a higher risk of hypotension 4.
- A systematic review and meta-analysis published in 2024 found that metoprolol is associated with a lower risk of adverse events compared to diltiazem for rate control in patients with atrial fibrillation 5.
Patient-Specific Factors
- Patient-specific factors, such as a history of atrial fibrillation, diabetes mellitus, and prior medication use, can influence the choice of metoprolol versus diltiazem for rate control 7.
- A study published in 2019 found that metoprolol and diltiazem have similar effectiveness and safety profiles for rate control in patients with heart failure with reduced ejection fraction 6.