milrinone
Brand: Primacor
ISMP High Alert Prototype Drug
Drug Class: inodilator
Drug Family: inotrope
Subclass: phosphodiesterase-3 inhibitor (PDE3-I)
Organ Systems: cardiovascular
Mechanism of Action
Inhibits PDE3 preventing breakdown of cAMP in cardiac and vascular smooth muscle; increased cAMP raises intracellular Ca2+ in myocardium (inotropy) and reduces Ca2+ in vascular smooth muscle (vasodilation); no increase in myocardial oxygen demand per unit of CO increase.
phosphodiesterase-3 (PDE3)
Indications
- acute decompensated heart failure (cardiogenic shock, severe ADHF)
- weaning from CPB
Contraindications
- severe aortic/pulmonic stenosis
- obstructive cardiomyopathy
- severe hypotension
Adverse Effects
Common
- hypotension
- arrhythmias (both atrial and ventricular)
- headache
Serious
- severe hypotension
- ventricular arrhythmias (OPTIME-CHF)
Pharmacokinetics (ADME)
| Absorption | IV only |
| Distribution | moderate |
| Metabolism | hepatic 10-20% |
| Excretion | renal 85% unchanged |
| Half-life | 2.3-2.5 hours |
| Onset | immediate IV |
| Peak | immediate |
| Duration | variable |
| Protein Binding | 70% |
| Vd | 0.45 L/kg |
Drug Interactions
| Drug / Agent | Mechanism | Severity |
|---|---|---|
| antihypertensives | additive hypotension | moderate |
Nursing Considerations
- OPTIME-CHF: milrinone increased arrhythmias and worsened outcomes in acute HF due to CABG surgery
- Monitor BP continuously — profound hypotension possible
- Volume loading before initiating may reduce hypotension
- Particularly useful when beta-blockade is present (mechanism bypasses beta receptors)
Clinical Pearls
- PDE3 inhibition bypasses beta-receptors — effective even when beta-blocked or at maximum doses of catecholamines
- OPTIME-CHF: increased arrhythmias and hospitalization vs placebo in ADHF — use only when other measures exhausted
Safety Profile
Pregnancy avoid
Lactation avoid
Renal Adjustment Required
Hepatic Adjustment Not required
TDM Not required
Concordance Terms
Cross-referenced clinical concepts — click any term to see all content where it appears.