Milrinone

# milrinone ## Overview - **Classification**: Phosphodiesterase-3 (PDE-3) inhibitor, Inodilator - **Mechanism**: Increases intracellular cAMP by inhibiting PDE-3, leading to positive inotropy (increased contractility) and vasodilation (reduced preload/afterload). ## Primary Indications 1. **Acute Decompensated Heart Failure (ADHF)** - Short-term IV therapy for severe, acute decompensated heart failure. 2. **Cardiogenic Shock** - To improve cardiac output and reduce systemic vascular resistance. ## Adult Dosing ### Standard Dosing **Acute Decompensated Heart Failure** - **Loading Dose**: **50 mcg/kg** - **Frequency**: Administer over **10 minutes** - **Maintenance Infusion**: **0.375-0.75 mcg/kg/min** - **Route**: Intravenous (IV) infusion - **Duration**: Typically **48-72 hours**, or as clinically indicated - **Maximum Infusion**: **1.13 mg/kg/day** (from 0.75 mcg/kg/min) ### Dose Adjustments - **Renal Impairment**: - CrCl **>50 mL/min**: No adjustment needed. - CrCl **20-50 mL/min**: **0.25 mcg/kg/min** - CrCl **5-19 mL/min**: **0.2 mcg/kg/min** - **Hepatic Impairment**: No specific adjustments provided; use with caution. - **Elderly Patients**: No specific dose adjustments based solely on age, but consider age-related renal decline. Start at lower end of dosing range. ## Pediatric Dosing ### Neonates (0-28 days) - **Loading Dose**: **50-75 mcg/kg** - **Frequency**: Administer over **30-60 minutes** - **Maintenance Infusion**: **0.25-0.75 mcg/kg/min** - **Maximum**: Individualize based on response; generally **0.75 mcg/kg/min**. - **Special Notes**: Monitor closely for hypotension and arrhythmias. Slower titration may be preferred. ### Infants (1-12 months) - **Loading Dose**: **50-75 mcg/kg** - **Frequency**: Administer over **10-60 minutes** - **Maintenance Infusion**: **0.25-0.75 mcg/kg/min** - **Maximum**: **0.75 mcg/kg/min** (infusion rate). ### Children (1-12 years) - **Loading Dose**: **50-75 mcg/kg** - **Frequency**: Administer over **10-60 minutes** - **Maintenance Infusion**: **0.25-0.75 mcg/kg/min** - **Maximum**: **0.75 mcg/kg/min** (infusion rate). ### Adolescents (13-18 years) - **Dose**: Typically follows **adult dosing guidelines** based on weight. - **Loading Dose**: **50 mcg/kg** over 10 min. - **Maintenance Infusion**: **0.375-0.75 mcg/kg/min**. - **Maximum**: **0.75 mcg/kg/min** (infusion rate). ## Safety Information ### Contraindications - **Absolute**: Severe obstructive aortic or pulmonary valvular disease. - **Absolute**: Hypersensitivity to milrinone or components. ### Common Adverse Effects - **Very Common (>10%)**: Ventricular arrhythmias (PVCs, VT, VF), Hypotension, Headache. - **Common (1-10%)**: Atrial arrhythmias, Angina/chest pain, Hypokalemia, Tremor. - **Serious but Rare**: Torsades de Pointes, Thrombocytopenia (rare, dose-related), Bronchospasm. ### Key Drug Interactions - **Diuretics (especially Furosemide)**: Potential for additive hypokalemia. Monitor potassium. - **Antiarrhythmics**: Increased risk of arrhythmias, especially if hypokalemia occurs. - **Other Vasodilators/Hypotensive Agents**: Potentiation of hypotension. Monitor BP closely. ## Monitoring & Follow-up - **Before Treatment**: Baseline ECG, blood pressure (BP), heart rate (HR), renal function (Cr, BUN), electrolytes (K+, Mg++), platelet count. - **During Treatment**: - Continuous ECG monitoring for arrhythmias. - Continuous BP and HR monitoring (e.g., arterial line). - Daily fluid balance, weight. - Daily electrolytes (K+, Mg++). - Daily renal function (Cr, BUN). - Platelet count (periodically, especially with prolonged use). - **Clinical Signs**: Watch for signs of hypotension (dizziness, decreased mentation), new onset arrhythmias (palpitations, irregular pulse), or worsening renal function. ## Clinical Pearls - 💡 **Titration**: Always titrate infusion to desired hemodynamic response and patient tolerance (e.g., BP, cardiac output, urine output). - 💡 **Preparation**: Milrinone should not be diluted with sodium bicarbonate injection. Stable in D5W, NS, LR. - 💡 **Fluid Status**: Optimize fluid status and correct hypokalemia/hypomagnesemia *before* starting milrinone to reduce arrhythmia risk. - 💡 **Extravasation**: Infuse via central line if possible. If peripheral, monitor site for extravasation (though rare). - 💡 **Off-label use**: Sometimes used off-label for pulmonary hypertension, but requires careful consideration and specific expertise. > **⚠️ Important**: This information is for educational purposes only. Always consult current prescribing information, local guidelines, and clinical judgment before prescribing.