What is the recommended initial dose of IV Cardizem (diltiazem) for rapid atrial fibrillation?

From the Guidelines

The recommended initial dose of IV Cardizem (diltiazem) for rapid atrial fibrillation is 0.25 mg/kg (typically 15-20 mg for an average adult) administered as a slow intravenous bolus over 2 minutes. This dose is based on the most recent and highest quality study available, which is the 2010 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care 1. After this initial dose, if the heart rate response is inadequate, a second bolus of 0.35 mg/kg (typically 20-25 mg) can be given after 15 minutes. Following the bolus administration, a continuous infusion may be initiated at 5-15 mg/hour, titrated to achieve the desired heart rate control. The maximum recommended dose is typically 15 mg/hour for maintenance therapy.

Key Considerations

• When administering IV diltiazem, continuous cardiac monitoring is essential as the medication can cause hypotension and bradycardia.
• The medication works by blocking calcium channels in cardiac tissue, which slows conduction through the AV node, thereby reducing ventricular response rate in atrial fibrillation.
• Diltiazem should be used cautiously in patients with heart failure, hypotension, or impaired liver or kidney function, and dose adjustments may be necessary in these populations.

Additional Guidance

• Other studies, such as the 2006 ACC/AHA/ESC guidelines for the management of patients with atrial fibrillation 1 and the 2001 ACC/AHA/ESC guidelines for the management of patients with atrial fibrillation 1, also support the use of diltiazem for heart rate control in atrial fibrillation.
• The 2006 ACC/AHA/ESC guidelines for the management of patients with atrial fibrillation 1 provide additional guidance on the use of diltiazem and other medications for heart rate control in atrial fibrillation.

From the FDA Drug Label

The initial dose of diltiazem hydrochloride injection should be 0.25 mg/kg actual body weight as a bolus administered over 2 minutes (20 mg is a reasonable dose for the average patient). The recommended initial dose of IV Cardizem (diltiazem) for rapid atrial fibrillation is 0.25 mg/kg actual body weight, which can be approximated to 20 mg for the average patient, administered over 2 minutes 2.

• The dose may vary based on patient weight, with 0.15 mg/kg being a possible alternative, although experience with this dose is limited.
• A second dose of 0.35 mg/kg (approximately 25 mg for the average patient) may be administered after 15 minutes if the initial response is inadequate.

From the Research

Recommended Initial Dose of IV Cardizem for Rapid A-Fib

The recommended initial dose of IV Cardizem (diltiazem) for rapid atrial fibrillation is:

• 0.25 mg/kg over 2 minutes, as stated in the study 3
• However, other studies suggest that a lower dose of 0.2 mg/kg 4 or 0.13 mg/kg 5 may be effective and reduce the risk of hypotension

Comparison of Dosing Strategies

• A study comparing weight-based dose vs. standard dose diltiazem found that standard dose diltiazem was noninferior to weight-based dosing in the initial treatment of AF with RVR 4
• Another study found that patients treated with ≥ 0.13 mg/kg diltiazem achieved heart rate control faster than those treated with < 0.13 mg/kg 5
• A study examining the efficacy of various doses of intravenous diltiazem found that 94% of patients responded to the bolus dose with a > 20% reduction in heart rate from baseline 6

Key Findings

• The majority of patients with AFIB RVR received a 10 mg non-weight-based diltiazem bolus dose in the ED 5
• Diltiazem bolus dosing ≥ 0.13 mg/kg was associated with significantly improved times to achieve heart rate control compared to < 0.13 mg/kg 5
• Low-dose diltiazem might be as effective as the standard dose in controlling rapid AF and reduce the risk of hypotension 3