What is the dose of Cardizem (Diltiazem) for atrial fibrillation (AFib) with rapid ventricular response (RVR)?

From the Guidelines

For atrial fibrillation with rapid ventricular response (AFib with RVR), Cardizem (diltiazem) is typically administered as an initial IV bolus of 15-20 mg over 2 minutes, with a possible second bolus of 20-25 mg after 15 minutes if needed, followed by a continuous IV infusion of 5-15 mg/hour, titrated to heart rate, as recommended by the most recent guidelines 1.

The dosing of Cardizem for AFib with RVR is based on the drug's ability to block calcium channels in the heart, which slows conduction through the AV node, thereby reducing ventricular rate in AFib. The initial IV bolus dose is usually 0.25 mg/kg, which translates to 15-20 mg for most adults. If the response is inadequate after 15 minutes, a second bolus of 0.35 mg/kg (usually 20-25 mg) can be given. Once rate control is achieved, continuous IV infusion is started at 5-15 mg/hour, titrated to heart rate.

It's essential to monitor blood pressure during administration as hypotension is a common side effect of Cardizem. The drug should be used cautiously in patients with heart failure, hypotension, or those on beta-blockers due to potential additive effects. Alternative rate control agents include beta-blockers (like metoprolol) or amiodarone if Cardizem is contraindicated or ineffective.

Some key points to consider when using Cardizem for AFib with RVR include:

• Monitoring blood pressure and heart rate closely during administration
• Adjusting the dose based on the patient's response and tolerance
• Being cautious when using Cardizem in patients with heart failure or those on beta-blockers
• Considering alternative rate control agents if Cardizem is not effective or is contraindicated

Overall, the use of Cardizem for AFib with RVR is supported by the most recent guidelines and should be tailored to the individual patient's needs and response to treatment, as recommended by the 2024 ESC guidelines for the management of atrial fibrillation 1.

From the FDA Drug Label

DOSAGE AND ADMINISTRATION Direct Intravenous Single Injections (Bolus) 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). If response is inadequate, a second dose may be administered after 15 minutes. The second bolus dose of diltiazem hydrochloride injection should be 0. 35 mg/kg actual body weight administered over 2 minutes (25 mg is a reasonable dose for the average patient). Continuous Intravenous Infusion For continued reduction of the heart rate (up to 24 hours) in patients with atrial fibrillation or atrial flutter, an intravenous infusion of diltiazem hydrochloride injection or diltiazem hydrochloride for injection may be administered... The recommended initial infusion rate of diltiazem hydrochloride injection or diltiazem hydrochloride for injection is 10 mg/h.

The dose of Cardizem (Diltiazem) for atrial fibrillation (AFib) with rapid ventricular response (RVR) is:

• Initial bolus dose: 0.25 mg/kg actual body weight (or 20 mg for the average patient) administered over 2 minutes
• Second bolus dose (if needed): 0.35 mg/kg actual body weight (or 25 mg for the average patient) administered over 2 minutes
• Continuous infusion: initial rate of 10 mg/h, which may be increased in 5 mg/h increments up to 15 mg/h as needed 2

From the Research

Dose of Cardizem (Diltiazem) for Atrial Fibrillation (AFib) with Rapid Ventricular Response (RVR)

The dose of Cardizem (Diltiazem) for atrial fibrillation (AFib) with rapid ventricular response (RVR) can vary depending on the specific clinical scenario and patient population.

• The recommended starting dose is an intravenous bolus of 0.25 mg/kg over 2 minutes 3.
• However, a lower dose of diltiazem (≤ 0.2 mg/kg) may be as effective as the standard dose in controlling rapid AF and reduce the risk of hypotension 3.
• For oral administration, the median dose of long-acting diltiazem (diltiazem CD) was 300 mg/day 4.
• In another study, the median dose of oral immediate-release diltiazem was 30 mg, and the median dose of IV continuous infusion diltiazem was 10 mg/hour 5.

Comparison of Different Doses and Administration Routes

• A study compared the efficacy and safety of different doses of diltiazem in rapid AF and found no significant differences in the rates of therapeutic response for the low-, standard-, and high-dose groups 3.
• Another study found that oral immediate-release diltiazem was associated with a lower rate of treatment failure at four hours than IV continuous infusion in patients with AF with RVR 5.
• A study also compared the IV combination of diltiazem and digoxin vs. IV diltiazem alone for acute ventricular rate control in patients with atrial fibrillation and found that the combination arm had a shorter time to achieve successful rate control and fewer episodes of loss of rate control 6.

Special Considerations

• In patients with heart failure with reduced ejection fraction (HFrEF), the use of IV diltiazem may be associated with a higher incidence of worsening heart failure symptoms compared to metoprolol 7.
• However, the overall adverse effects of IV diltiazem and metoprolol were similar in this patient population 7.