Inodilator — Phosphodiesterase III Inhibitor Pregnancy: Little or no experience with use in pregnant women; as a precautionary measure use during pregnancy should be avoided. Animal studies showed no reproductive toxicity. Excretion in breast milk unknown - weigh benefit of breastfeeding against benefit of therapy.

Milrinone

Brand names: Primacor

Milrinone is a phosphodiesterase-3 inhibitor used as an inotrope and vasodilator (inodilator) in acute decompensated heart failure and in low cardiac output states, including after cardiac surgery.

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: Loading dose 50 micrograms/kg (0.05 mg/kg) by slow IV injection over 10 minutes, followed by a continuous IV maintenance infusion of 0.5 micrograms/kg/minute (range 0.375-0.75 micrograms/kg/minute)

Route: Intravenous (slow IV injection for the loading dose, then continuous IV infusion)

Frequency: Loading dose over 10 minutes, then continuous infusion titrated to haemodynamic and clinical response

Max: Daily (24-hour) dose should not exceed 1.13 mg/kg

Maintenance level is selected on haemodynamic effect and clinical efficacy (0.375 microgram/kg/min = approx 0.59 mg/kg/day; 0.50 = approx 0.77 mg/kg/day; 0.75 = approx 1.13 mg/kg/day, each including the 0.05 mg/kg initial dose). Prepare the maintenance infusion at 200 micrograms/ml (add 40 ml of carrier solution to 10 ml undiluted milrinone) using 0.9% sodium chloride or 5% glucose. Duration of treatment should not exceed 48 hours. Usually given with concomitant diuretic therapy. Infants and children (from published studies): IV initial dose 50-75 microgram/kg over 30-60 minutes, then continuous infusion 0.25-0.75 microgram/kg/min for up to 35 hours; not recommended in children with renal impairment - verify paediatric dosing against a children's formulary.

Dose adjustments

Renal

Initial (loading) dose is unchanged; reduce the maintenance infusion rate in renal impairment according to creatinine clearance - CrCl 5 -> 0.20, 10 -> 0.23, 20 -> 0.28, 30 -> 0.33, 40 -> 0.38, 50 -> 0.43 micrograms/kg/minute. Not recommended in children with renal impairment.

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 excipient
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

Side effects

Ventricular ectopy, non-sustained and sustained ventricular tachycardia
Supraventricular arrhythmia
Hypotension
Mild to moderate headache
Thrombocytopenia (especially with longer infusion in children); torsades de pointes and ventricular fibrillation reported (rare)

Clinical monograph

How it works

By inhibiting phosphodiesterase-3 it raises intracellular cyclic AMP, increasing myocardial contractility while relaxing vascular smooth muscle to reduce both systemic and pulmonary vascular resistance.

Prescribing in practice

Its vasodilator action can cause significant hypotension and it may provoke ventricular and supraventricular arrhythmias, so it should be used with continuous monitoring in a critical care setting.
It is renally cleared, so accumulation and prolonged effect occur in renal impairment and dose adjustment is required.
Because its effect is independent of beta-receptors, it may retain efficacy in patients receiving beta-blockers.

Monitoring

Monitor continuous ECG, blood pressure, fluid balance, renal function, and electrolytes during the infusion.

Counselling the patient

This medicine is given as a continuous infusion and monitored closely in critical care.
Report palpitations, light-headedness, or chest discomfort to the team.

Evidence & guidelines

Use is supported by critical care and heart failure practice; consult current prescribing references and the SPC.

Reference: OPTIME-CHF Trial (JAMA 2002); ESC Acute Heart Failure Guidelines 2021; 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

Pathways