Milrinone Dosing in Cardiomyopathy
For patients with cardiomyopathy, milrinone should be administered with a loading dose of 50 mcg/kg given slowly over 10 minutes, followed by a continuous infusion of 0.375-0.75 mcg/kg/min, with dose adjustments based on renal function. 1, 2
Standard Dosing Protocol
Loading Dose
- 50 mcg/kg administered slowly over 10 minutes 1
- May be given undiluted or diluted to a total volume of 10-20 mL for easier visualization of injection rate 1
Maintenance Infusion
- Minimum: 0.375 mcg/kg/min (0.59 mg/kg/day) 1, 2
- Standard: 0.5 mcg/kg/min (0.77 mg/kg/day) 1, 2
- Maximum: 0.75 mcg/kg/min (1.13 mg/kg/day) 1, 2
Dose Adjustments for Renal Impairment
Renal function significantly affects milrinone elimination. Adjust infusion rates according to creatinine clearance:
| Creatinine Clearance (mL/min/1.73m²) | Recommended Infusion Rate (mcg/kg/min) |
|---|---|
| 5 | 0.2 |
| 10 | 0.23 |
| 20 | 0.28 |
| 30 | 0.33 |
| 40 | 0.38 |
| 50 | 0.43 |
Preparation and Administration
- Dilute milrinone prior to maintenance infusion
- Acceptable diluents: 0.45% Sodium Chloride, 0.9% Sodium Chloride, or 5% Dextrose 1
- Target concentration for infusion: 200 mcg/mL 1
Clinical Considerations
Indications
- Refractory heart failure with reduced ejection fraction 3, 2
- Low cardiac output states with evidence of end-organ hypoperfusion 2
- Patients with systolic blood pressure >90 mmHg 2
Hemodynamic Effects
- Increases cardiac index by 21-31% 4, 5
- Decreases pulmonary capillary wedge pressure by 13-41% 4
- Effects begin within 15 minutes of administration 4
Monitoring Requirements
- Continuous hemodynamic monitoring during infusion 2
- Continuous ECG monitoring due to potential arrhythmogenic effects 2, 6
- Monitor for 1-2 hours after discontinuation 2
Important Precautions
- Titrate dose based on hemodynamic response 1
- Use calibrated electronic infusion devices for administration 1
- Gradually taper when discontinuing to prevent hemodynamic deterioration 2
- Consider alternative to bolus loading dose in hemodynamically unstable patients, as a continuous infusion without bolus may have improved safety profile 7
Potential Adverse Effects
Comparative Considerations
- Milrinone maintains effectiveness during beta-blocker therapy 2
- Causes less tachycardia than dobutamine, making it suitable for patients on beta-blockers 2, 8
- Has both positive inotropic and vasodilatory effects, unlike pure inotropes 5, 8
Remember that milrinone should be used for short-term management of acute decompensated heart failure rather than long-term therapy, as prolonged use may be associated with increased mortality in patients with coronary artery disease 2.