Recommended Diltiazem Dosing for Atrial Fibrillation
For atrial fibrillation, the recommended diltiazem dosing is 0.25 mg/kg IV bolus over 2 minutes initially, with potential repeat at 0.35 mg/kg if needed, followed by 5-15 mg/hour continuous infusion for acute management, and 120-360 mg daily of extended-release formulation for oral maintenance therapy. 1, 2
Intravenous Diltiazem Administration
Initial Dosing
- Administer 0.25 mg/kg (actual body weight) IV bolus over 2 minutes 1, 2
- If inadequate response after initial dose, may repeat with 0.35 mg/kg IV over 2 minutes 1, 2
- Follow with continuous infusion at 5-15 mg/hour for ongoing rate control 1, 2
Monitoring During IV Administration
- Monitor heart rate response continuously during administration 1
- Assess blood pressure frequently to detect hypotension 3
- Lower doses (≤0.2 mg/kg) may provide similar efficacy with reduced risk of hypotension compared to standard dosing 3
Oral Diltiazem Therapy
Maintenance Dosing
- Oral maintenance dose: 120-360 mg daily of extended-release (ER) formulation 1, 2
- Immediate-release formulation has a half-life of 3-4.5 hours 1
- Extended-release formulation has a half-life of 4-9.5 hours 1
Transitioning from IV to Oral Therapy
- Begin oral diltiazem therapy while IV infusion is still running 4
- Continue IV infusion for approximately 4 hours after first oral dose 4
- Median oral dose of 300 mg/day has shown 77% effectiveness in maintaining rate control after transition from IV therapy 4
Important Considerations and Precautions
Contraindications and Cautions
- Avoid diltiazem in patients with heart failure with reduced ejection fraction (HFrEF) 1
- Do not use in patients with decompensated heart failure 1
- Use caution in patients with renal or hepatic impairment 2
Efficacy Measures
- Target heart rate is generally considered controlled when between 60-80 bpm at rest and 90-115 bpm during moderate exercise 1
- A lenient rate control strategy (resting heart rate <110 bpm) may be reasonable for asymptomatic patients with preserved left ventricular function 1
- Higher doses (≥0.13 mg/kg) achieve heart rate control more quickly than lower doses 5
Alternative Rate Control Options
- Beta blockers (metoprolol, atenolol, esmolol) are alternative first-line agents 1, 2
- Verapamil can be used at 5-10 mg IV over ≥2 minutes, with oral maintenance of 180-480 mg daily (ER) 1
- Digoxin may be considered in patients with heart failure 1
- Combination therapy with digoxin and diltiazem has shown enhanced rate control compared to either agent alone 6
Combination Therapy Considerations
- Medium-dose diltiazem (240 mg/day) combined with digoxin provides effective rate control both at rest and during exercise 6
- High-dose diltiazem (360 mg/day) with digoxin provides slightly better rate control but with increased side effects 6
- Combination therapy may be particularly useful for patients who don't achieve adequate rate control with a single agent 6