Diltiazem Dosing for Rate Control in Atrial Fibrillation
For acute rate control in atrial fibrillation, administer diltiazem 0.25 mg/kg IV (based on actual body weight) over 2 minutes, followed by a second bolus of 0.35 mg/kg if needed 15 minutes later, then maintain with a continuous infusion of 5-15 mg/hour titrated to heart rate. 1, 2
Acute/IV Dosing
Initial Bolus
- First dose: 0.25 mg/kg IV (typically 15-20 mg for average adult) administered over 2 minutes 1, 2
- Second dose (if needed): 0.35 mg/kg IV (typically 20-25 mg) given 15 minutes after the first bolus if heart rate remains uncontrolled 1
- Onset of action occurs within 2-7 minutes 1
Continuous Infusion
- Start at 5-15 mg/hour immediately after bolus dosing 1, 2
- Titrate in 5 mg/hour increments to achieve target heart rate 2
- Target heart rate: 60-100 beats per minute at rest 2
- Maximum infusion rate: 15 mg/hour 1
Evidence-Based Dosing Considerations
Recent research demonstrates that weight-based dosing ≥0.13 mg/kg achieves heart rate control significantly faster (169 minutes) compared to lower doses (318 minutes), without increased hypotension risk 3. However, one study suggests that lower doses (≤0.2 mg/kg) may reduce hypotension risk while maintaining similar efficacy to standard dosing 4.
Oral Maintenance Dosing
Transition from IV to Oral
- Administer first oral dose while IV infusion is running 5
- Discontinue IV infusion 4 hours after first oral dose 5
- 77% of patients maintain rate control during this transition 5
Oral Dosing Regimens
- Immediate-release: 120-360 mg daily in divided doses 1
- Extended-release: 180-360 mg once daily 1, 5
- Most common effective dose: 300-360 mg daily 6, 5
- Onset: 2-4 hours for immediate release 1
Comparative Efficacy
Diltiazem 360 mg daily provides superior heart rate reduction compared to verapamil 240 mg, metoprolol 100 mg, or carvedilol 25 mg in permanent atrial fibrillation, achieving a mean 24-hour heart rate of 75 bpm versus 81-84 bpm with other agents 6.
Critical Contraindications and Precautions
Absolute Contraindications
- Heart failure with reduced ejection fraction (LVEF ≤40%) 1, 2
- Pre-excited atrial fibrillation (accessory pathway conduction) 1
- Severe hypotension 1
- Second or third-degree AV block without pacemaker 1
Monitoring Requirements
- Continuous cardiac monitoring during IV administration 2
- Blood pressure monitoring every 5-15 minutes during bolus and infusion initiation 2
- ECG monitoring for heart block or bradycardia 1
Common Adverse Effects
Clinical Pearls
Diltiazem carries a Class I recommendation with Level of Evidence B for acute rate control in atrial fibrillation 1, making it one of the most strongly supported agents for this indication.
The half-life of IV diltiazem is 3-5 hours, while oral formulations range from 3-4.5 hours (immediate-release) to 4-9.5 hours (extended-release) 1. Plasma concentrations of 79-172 ng/mL typically produce 20-30% heart rate reduction 7.
Avoid combining diltiazem with beta-blockers due to additive negative inotropic and chronotropic effects, particularly in patients with any degree of ventricular dysfunction 2.
In patients with heart failure, digoxin or amiodarone should be used instead of diltiazem for rate control 1.