Maximum Number of Diltiazem Boluses
According to FDA labeling and ACC/AHA/HRS guidelines, a maximum of 2 boluses of diltiazem can be administered: an initial dose of 0.25 mg/kg followed by a second dose of 0.35 mg/kg if needed after 15 minutes. 1, 2
Initial Bolus Dosing
- First bolus: Administer 0.25 mg/kg (approximately 20 mg for average adult) IV over 2 minutes 1, 2
- Assess response at 15 minutes after the first dose 1
Second Bolus (If Inadequate Response)
- Second bolus: If the initial response is inadequate, administer 0.35 mg/kg (approximately 25 mg for average adult) IV over 2 minutes, given 15 minutes after the first dose 1, 2
- This is the maximum number of boluses recommended - no third bolus is indicated in guidelines or FDA labeling 1
Transition to Continuous Infusion
- After bolus administration achieves heart rate control, transition to continuous IV infusion rather than additional boluses 1, 2
- Start infusion at 10 mg/hour (some patients may respond to 5 mg/hour) 1, 2
- Titrate in 5 mg/hour increments up to maximum of 15 mg/hour as needed 1, 2
- Infusion can be maintained for up to 24 hours 1, 3
Important Clinical Considerations
Contraindications to avoid before any bolus:
- AV block greater than first degree without pacemaker 2
- Decompensated systolic heart failure or LV dysfunction 2
- Hypotension 2
- Pre-excited atrial fibrillation/flutter (WPW syndrome) 2
- Cardiogenic shock 2
Common pitfall: Some clinicians use lower doses (≤0.2 mg/kg) to reduce hypotension risk, which may be equally effective with lower complication rates 4, 5, but this deviates from FDA-approved dosing 1
Key safety point: Have resuscitation equipment available during administration, with atropine or temporary pacing capability for severe bradycardia 6, 7