IV Diltiazem Dosing for Heart Rate Control
For heart rate control, IV diltiazem should be administered at an initial bolus dose of 0.25 mg/kg (approximately 15-20 mg for an average adult) over 2 minutes, followed by a second dose of 0.35 mg/kg (approximately 20-25 mg) after 15 minutes if needed, and then a maintenance infusion of 5-15 mg/hour titrated to heart rate response. 1
Initial Bolus Dosing
- Initial bolus: 0.25 mg/kg IV over 2 minutes (typically 15-20 mg for an average adult) 2, 1
- If inadequate response after 15 minutes: Second bolus of 0.35 mg/kg IV over 2 minutes (typically 20-25 mg) 1
- For patients at higher risk of hypotension, consider a lower initial dose of 0.15-0.2 mg/kg 1, 3
Maintenance Infusion
- Start infusion immediately following bolus administration at 10 mg/hour (range 5-15 mg/hour) 2, 1
- Some patients may respond to a lower initial rate of 5 mg/hour 1, 4
- Titrate in 5 mg/hour increments up to 15 mg/hour as needed for heart rate control 1
- Continue infusion for up to 24 hours as needed 1
Efficacy and Response Rates
Research shows that IV diltiazem effectively controls heart rate in:
- 94% of patients respond to the initial bolus dose 5
- 76% maintain response with appropriate titration during continuous infusion 5
- Target heart rate is typically <100 beats/min or a ≥20% reduction from baseline 4, 5
Monitoring and Precautions
- Monitor heart rate, blood pressure, and ECG continuously during administration 2
- Diltiazem shows dose-dependent, non-linear pharmacokinetics 1, 6
- Risk of hypotension increases with higher doses (18% with low dose vs 35-42% with standard/high doses) 3
Contraindications
Do not use IV diltiazem in patients with:
- AV block greater than first degree (without pacemaker) 2
- Sinus node dysfunction (without pacemaker) 2
- Hypotension 2
- Decompensated heart failure/LV dysfunction 2
- Cardiogenic shock 2
- Wolff-Parkinson-White (WPW) syndrome with atrial fibrillation/flutter 2
- Severe hepatic or renal dysfunction 2
Preparation for Continuous Infusion
For continuous infusion, dilute appropriately:
- 125 mg (25 mL) in 100 mL diluent = 1 mg/mL concentration
- 250 mg (50 mL) in 250 mL diluent = 0.83 mg/mL concentration
- 250 mg (50 mL) in 500 mL diluent = 0.45 mg/mL concentration 1
Transition to Oral Therapy
If long-term rate control is needed, transition to oral diltiazem can be achieved:
- Administer oral long-acting diltiazem (typically 180-360 mg/day)
- Continue IV infusion for 4 hours after first oral dose
- 77% of patients maintain heart rate control during transition to oral therapy 7