Recommended Dosage of Intravenous Diltiazem for Atrial Fibrillation
For atrial fibrillation with rapid ventricular response, the recommended diltiazem infusion dosing is an initial bolus of 0.25 mg/kg (approximately 15-20 mg) administered over 2 minutes, followed by a continuous infusion starting at 5-15 mg/hour, titrated to heart rate response. 1, 2
Initial Bolus Dosing
- Initial bolus dose: 0.25 mg/kg actual body weight administered over 2 minutes (approximately 15-20 mg for average adult) 1, 2
- If response is inadequate after 15 minutes, a second bolus of 0.35 mg/kg (approximately 20-25 mg) may be administered over 2 minutes 1
- Some patients may respond to a lower initial dose of 0.15 mg/kg, though duration of action may be shorter 1
- Low-dose diltiazem (≤0.2 mg/kg) has shown similar efficacy with lower rates of hypotension compared to standard dosing 3
Continuous Infusion
- Begin continuous infusion immediately following bolus administration 1
- Recommended initial infusion rate: 10 mg/hour 1, 2
- Some patients may maintain response at 5 mg/hour 1
- Infusion rate may be increased in 5 mg/hour increments up to 15 mg/hour as needed 1, 2
- Maintenance infusion range: 5-15 mg/hour, titrated to heart rate response 2, 1
- Maximum recommended infusion duration: 24 hours 1
Dilution Guidelines
- Diltiazem should be diluted in either Normal Saline, D5W, or D5W/0.45% NaCl 1
- Diluted solution should be refrigerated until use and used within 24 hours 1
- Common dilution: 125 mg in 100 mL (1 mg/mL) or 250 mg in 250 mL (0.83 mg/mL) 1
Monitoring and Precautions
- Monitor heart rate and blood pressure continuously during administration 2
- Target heart rate is generally considered controlled when between 60-80 bpm at rest 2
- Avoid in patients with heart failure with reduced ejection fraction (LVEF ≤40%) due to negative inotropic effects 2
- Use with caution in combination with beta-blockers 2
- Reduce dose in patients with hepatic impairment 2
- Start with smaller dose in patients with renal impairment 2
Transition to Oral Therapy
- For continued rate control, transition to oral diltiazem can be initiated while IV infusion continues 4
- Oral dosing: 60 mg three times daily up to 360 mg total daily dose, or 120-360 mg once daily with modified-release formulation 2
- Continue IV infusion for approximately 4 hours after first oral dose to ensure adequate transition 4
- Success rate of maintaining heart rate control during transition from IV to oral therapy is approximately 77% 4
Alternative Rate Control Agents
- Beta-blockers (metoprolol, esmolol) are also first-line agents for rate control in AF 2
- Digoxin may be used in patients with heart failure with reduced ejection fraction 2
- In patients with severely impaired LV function, consider amiodarone for rate control 2
Remember that diltiazem should only be used in patients with preserved left ventricular function (LVEF >40%), as it can worsen heart failure in patients with reduced ejection fraction 2.