PRIMACOR IN DEXTROSE 5% IN PLASTIC CONTAINER
Clinical safety rating: caution
Comprehensive clinical and safety monograph for PRIMACOR IN DEXTROSE 5% IN PLASTIC CONTAINER (PRIMACOR IN DEXTROSE 5% IN PLASTIC CONTAINER).
Milrinone is a selective phosphodiesterase III (PDE3) inhibitor that increases intracellular cyclic adenosine monophosphate (cAMP) in cardiac and vascular smooth muscle, leading to positive inotropy and vasodilation.
| Metabolism | Primarily hepatic metabolism via glucuronidation; only about 15% is excreted unchanged in urine. |
| Excretion | Renal: 50-70% unchanged; biliary/fecal: minimal |
| Half-life | Terminal elimination half-life: 2.5-3.5 hours; prolonged in heart failure (up to 4.5-5 hours) and renal impairment |
| Protein binding | 70-80% bound to albumin |
| Volume of Distribution | Vd: 0.3-0.6 L/kg; increased in heart failure (up to 0.8 L/kg) indicating extensive tissue distribution |
| Bioavailability | Oral: 70-85% (not used clinically due to gastrointestinal side effects); IV: 100% |
| Onset of Action | IV: 2-5 minutes; oral: not clinically relevant |
| Duration of Action | IV: 0.5-2 hours; effects on hemodynamics persist for 30-60 minutes after infusion; positive inotropic effect may last longer |
IV loading dose of 50 mcg/kg over 10 minutes, followed by continuous IV infusion of 0.375-0.75 mcg/kg/min; adjust based on hemodynamic response; maximum infusion rate 1.13 mg/kg/day.
| Dosage form | INJECTABLE |
| Renal impairment | In patients with GFR <30 mL/min, reduce infusion rate by 50% and monitor closely; no specific guidelines for mild-moderate renal impairment. |
| Liver impairment | No specific Child-Pugh based adjustments; use with caution in severe hepatic impairment due to reduced clearance. |
| Pediatric use | Safety and efficacy not established in pediatric patients; limited data suggest infusion starting at 0.5 mcg/kg/min with titration, but use is not recommended. |
| Geriatric use | Elderly patients may have reduced clearance; start at lower end of dosing range and titrate slowly; monitor renal function and hemodynamic response. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for PRIMACOR IN DEXTROSE 5% IN PLASTIC CONTAINER (PRIMACOR IN DEXTROSE 5% IN PLASTIC CONTAINER).
| Breastfeeding | Not recommended during breastfeeding. Milrinone is excreted in human milk; M/P ratio not established. Potential for adverse effects in nursing infant (e.g., tachycardia, hypotension). Consider alternative therapy. |
| Teratogenic Risk | FDA Pregnancy Category C. In first trimester, insufficient human data; animal studies show fetal toxicity at high doses. Second/third trimesters: risk of preterm labor, fetal tachycardia, and maternal hypotension; no evidence of teratogenicity in humans. Use only if benefit outweighs risk. |
■ FDA Black Box Warning
May increase mortality in patients with severe heart failure (NYHA Class IV) when used for long-term therapy; not recommended for long-term use.
| Serious Effects |
["Hypersensitivity to milrinone or any component","Severe aortic or pulmonary valvular disease (e.g., aortic stenosis)","Acute myocardial infarction","Obstructive hypertrophic cardiomyopathy","Severe hypotension"]
| Precautions | ["Hypotension due to vasodilation","Tachyarrhythmias including ventricular arrhythmias","Thrombocytopenia","Renal impairment requiring dose adjustment","Electrolyte disturbances (hypokalemia, hypomagnesemia) may increase arrhythmia risk"] |
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| Fetal Monitoring | Continuous ECG monitoring for maternal arrhythmias; blood pressure monitoring for hypotension; fetal heart rate monitoring during labor for signs of distress; monitor maternal fluid status and electrolytes due to risk of hypokalemia and thrombocytopenia. |
| Fertility Effects | No specific studies on human fertility. Animal studies: no impairment of fertility at therapeutic doses. Theoretical risk from hemodynamic changes during use. |