Inodilator / Acute Heart Failure Pregnancy: Little or no experience in pregnant women; animal studies have not indicated direct or indirect reproductive toxicity. As a precautionary measure, use during pregnancy should be avoided. It is unknown whether milrinone is excreted in breast milk — decide whether to discontinue breastfeeding or milrinone therapy.

Milrinone

Brand names: Primacor

Milrinone is an intravenous phosphodiesterase-3 inhibitor with positive inotropic and vasodilator (inodilator) properties, used for the short-term treatment of acute, severe heart failure, usually in a critical-care setting.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: Initial (loading) dose 50 micrograms/kg (0.05 mg/kg) administered slowly over 10 minutes, usually followed by a continuous maintenance infusion of 0.5 micrograms/kg/minute (range 0.375 to 0.75 micrograms/kg/minute).

Route: Slow intravenous injection (loading dose) followed by continuous intravenous infusion

Frequency: Loading dose over 10 minutes, then continuous infusion; treatment duration should not exceed 48 hours

Max: The daily dose should not exceed 1.13 mg milrinone/kg (equivalent to a maintenance infusion of 0.75 micrograms/kg/minute plus the 0.05 mg/kg initial dose over 24 hours)

Source: Milrinone 1 mg/ml Solution for Injection and Infusion SPC §4.2. Level of maintenance dose should be selected on the basis of haemodynamic effect and clinical efficacy — minimum 0.375 micrograms/kg/min (0.59 mg/kg/day), standard 0.50 micrograms/kg/min (0.77 mg/kg/day), maximum 0.75 micrograms/kg/min (1.13 mg/kg/day). For the maintenance infusion prepare a solution containing 200 micrograms milrinone/ml (add 40 ml carrier solution to 10 ml undiluted milrinone injection); carriers are 0.9% Sodium Chloride Infusion or 5% Glucose Infusion. At 200 micrograms/ml the corresponding infusion rates are 0.11 ml/kg/hour for 0.375 micrograms/kg/min, 0.15 ml/kg/hour for 0.5 micrograms/kg/min and 0.22 ml/kg/hour for 0.75 micrograms/kg/min. Do not mix with other carrier solutions; use the largest possible vein and avoid extravasation; discard diluted solution after 24 hours. Treatment of heart failure with milrinone has so far only been studied with concomitant administration of a diuretic. Elderly: no special dosage recommendations expected where renal function is normal. PAEDIATRIC (SPC §4.2 — from published studies, not a licensed regimen; verify against a children's formulary and local specialist protocol): intravenous initial dose 50 to 75 micrograms/kg over 30 to 60 minutes, then continuous intravenous infusion 0.25 to 0.75 micrograms/kg/min for up to 35 hours, with due consideration of haemodynamic response and possible side effects. In clinical studies in infants and children under 6 years with low-cardiac-output syndrome after surgical correction of congenital heart disease, an initial dose of 75 micrograms/kg over 60 minutes followed by 0.75 micrograms/kg/min for 35 hours reduced the risk of low-cardiac-output syndrome. Use in children with impaired renal function is not recommended (no data). In preterm infants/neonates with patent ductus arteriosus the therapeutic benefit must be weighed against the potential risks. Risk of thrombocytopenia in infants and children increases significantly with duration of infusion and is more common in children than adults.

Dose adjustments

Renal

Excretion is limited in renal impairment, so the maintenance dose must be reduced (initial dose unchanged). SPC §4.2 table by creatinine clearance (ml/min/1.73 m2): 5 → 0.20 micrograms/kg/min; 10 → 0.23; 20 → 0.28; 30 → 0.33; 40 → 0.38; 50 → 0.43 micrograms/kg/min.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Hypersensitivity to milrinone or any of the excipients
Severe obstructive aortic or pulmonary valve disease
Hypertrophic obstructive cardiomyopathy
Ventricular aneurysm
Severe, previously untreated hypovolaemia
Acute myocardial infarction
Cardiac failure due to hyperthyroidism, acute myocarditis or amyloid cardiomyopathy (insufficient therapy experience)

Side effects

Ventricular ectopia, sustained and non-sustained ventricular tachycardia, supraventricular arrhythmia
Hypotension
Mild to moderately severe headache
Hypokalaemia
Thrombocytopenia (risk higher in infants and children, increasing with infusion duration)

Clinical monograph

How it works

By inhibiting phosphodiesterase-3 it raises intracellular cyclic AMP in cardiac and vascular smooth muscle, increasing myocardial contractility and causing peripheral and pulmonary vasodilatation, thereby augmenting cardiac output while reducing filling pressures.

Prescribing in practice

It can cause ventricular and supraventricular arrhythmias and hypotension, so it must be given with continuous cardiac and blood-pressure monitoring in a monitored environment.
It is renally cleared, so the infusion rate must be reduced in renal impairment to avoid accumulation and toxicity.
As a vasodilator it should be used cautiously in hypovolaemia or severe outflow obstruction, where it can precipitate marked hypotension.

Monitoring

Use continuous ECG, blood pressure and fluid-balance monitoring, with attention to renal function and electrolytes during the infusion.

Counselling the patient

This is a drip given and closely monitored by the critical-care or cardiology team.
The team will watch your heart rhythm and blood pressure continuously while it is running.
Tell the team if you feel palpitations, lightheaded or unwell during the infusion.

Evidence & guidelines

Milrinone is an established short-term inotrope for acute decompensated heart failure; intravenous inotropes are reserved for low-output states and have not been shown to improve long-term survival.

Reference: OPTIME-CHF Trial (Cuffe et al. JAMA 2002); ESC Acute HF Guidelines 2021; SPC Primacor; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

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