What is the recommended dosing of Diltiazem (Calcium Channel Blocker) in milligrams per kilogram for the treatment of atrial fibrillation (Afib)?

From the Guidelines

For atrial fibrillation treatment, diltiazem dosing is not explicitly stated in mg/kg for oral maintenance, but the intravenous administration is not recommended according to the provided evidence, however, the usual oral maintenance dose is 60 mg t.i.d. to 360 mg (ER) o.d. The provided evidence from the European Heart Journal 1 does not specify the intravenous dosing of diltiazem in mg/kg, but it does provide recommendations for long-term rate control using pharmacological agents, including non-dihydropyridine calcium channel antagonists like diltiazem. Some key points to consider when using diltiazem for atrial fibrillation treatment include:

• The choice of medication should be individualized and the dose modulated to avoid bradycardia 1.
• In patients who experience symptoms related to AF during activity, the adequacy of rate control should be assessed during exercise, and therapy should be adjusted to achieve a physiological chronotropic response and to avoid bradycardia 1.
• It is reasonable to initiate treatment with a lenient rate control protocol aimed at a resting heart rate <110 bpm 1.
• Diltiazem works by blocking calcium channels in cardiac tissue, which slows conduction through the AV node, thereby reducing ventricular rate in atrial fibrillation.
• Monitor blood pressure closely during administration as hypotension is a common side effect, especially in volume-depleted patients or those on other antihypertensive medications.
• Reduce dosing in patients with hepatic or renal impairment and use caution in those with heart failure or conduction abnormalities.

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). 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).

The recommended diltiazem dosing for afib treatment is:

• Initial dose: 0.25 mg/kg actual body weight
• Second dose (if needed): 0.35 mg/kg actual body weight 2

From the Research

Diltiazem Dosing in Atrial Fibrillation Treatment

• The recommended starting dose of diltiazem for controlling rapid ventricular response in atrial fibrillation is an intravenous bolus of 0.25 mg/kg over 2 minutes 3.
• A study found that low-dose diltiazem (≤ 0.2 mg/kg) might be as effective as the standard dose in controlling rapid AF and reduce the risk of hypotension 3.
• Another study suggested that diltiazem bolus dosing ≥ 0.13 mg/kg was associated with significantly improved times to achieve heart rate control compared to < 0.13 mg/kg 4.
• The efficacy and safety of intravenous diltiazem for the treatment of atrial fibrillation and atrial flutter was evaluated in a study, which found that 93% of patients responded to diltiazem 5.
• The dose of intravenous diltiazem used in this study was 0.25 mg/kg/2 minutes, followed by 0.35 mg/kg/2 minutes if the first dose was tolerated but ineffective 5.

Comparison of Diltiazem Doses

• A study compared the efficacy and safety of different doses of diltiazem in rapid AF, and found that the rates of therapeutic response were similar for low-, standard-, and high-dose groups 3.
• However, the rates of hypotension were significantly lower in the low-dose group compared to the standard-dose group 3.
• 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 4.

Clinical Guidelines

• The management of atrial fibrillation in the elderly involves immediate direct-current cardioversion in certain situations, and the use of intravenous beta blockers, diltiazem, or verapamil to slow a rapid ventricular rate 6.
• Oral beta blockers, verapamil, or diltiazem may be used to control heart rate in patients with atrial fibrillation, and amiodarone may be used in selected patients with symptomatic life-threatening AF refractory to other drugs 6.
• The treatment of atrial fibrillation should be individualized, taking into account the patient's symptoms, underlying heart disease, and other factors 7.