EMERPHED
Clinical safety rating: caution
Comprehensive clinical and safety monograph for EMERPHED (EMERPHED).
EMERPHED is a combination of ephedrine and phenylephrine. Ephedrine is a sympathomimetic amine that acts directly on alpha and beta adrenergic receptors and indirectly by releasing norepinephrine from nerve endings, causing vasoconstriction, bronchodilation, and increased heart rate and blood pressure. Phenylephrine is a selective alpha-1 adrenergic receptor agonist causing vasoconstriction and increased blood pressure.
| Metabolism | Ephedrine is partially metabolized by hepatic enzymes including CYP2D6 and monoamine oxidase (MAO). Phenylephrine undergoes first-pass metabolism in the gut wall and liver via sulfation and oxidation, predominantly by MAO and to a lesser extent by CYP2D6. |
| Excretion | Renal excretion of unchanged drug (~30-50%) and metabolites; minor biliary/fecal elimination (<10%). |
| Half-life | Terminal elimination half-life: 3-6 hours (prolonged in renal impairment: up to 15 hours). |
| Protein binding | ~50% bound primarily to albumin and alpha-1-acid glycoprotein. |
| Volume of Distribution | 2.5-4.0 L/kg, indicating extensive tissue distribution. |
| Bioavailability | Oral: ~40% due to first-pass metabolism; IM: 70-90%; IV: 100%. |
| Onset of Action | Oral: 15-30 minutes. Intramuscular: 5-10 minutes. Intravenous: Immediate (<1 minute). |
| Duration of Action | Oral: 3-6 hours. IV: 1-3 hours (duration dose-dependent due to tachyphylaxis). |
Adults: 1-2 capsules (25-50 mg ephedrine sulfate) orally every 3-4 hours as needed, not to exceed 150 mg in 24 hours.
| Dosage form | SOLUTION |
| Renal impairment | GFR 30-60 mL/min: Reduce dose by 50%; GFR <30 mL/min: Avoid use or extend interval to every 8-12 hours. |
| Liver impairment | Child-Pugh A: No adjustment; Child-Pugh B: Reduce dose by 50%; Child-Pugh C: Avoid use. |
| Pediatric use | Children 2-12 years: 0.5-1 mg/kg/dose orally every 4-6 hours, maximum 5 mg/kg/day or 150 mg/day. |
| Geriatric use | Elderly: Start at lowest effective dose (12.5-25 mg) every 6 hours due to increased sensitivity and risk of CNS stimulation, hypertension, and urinary retention. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for EMERPHED (EMERPHED).
| Breastfeeding | Ephedrine is excreted into breast milk (M/P ratio ~2.4). Avoid use due to possible infant irritability, sleep disturbances, and cardiovascular effects. Limited data; consider risk vs. benefit. |
| Teratogenic Risk | First trimester: Avoid due to potential for ephedrine-induced vasoconstriction reducing uteroplacental blood flow and possible neural tube defects (limited data). Second and third trimesters: Ephedrine may cause fetal tachycardia, increased risk of intraventricular hemorrhage if used near delivery. Risk of preterm labor with prolonged use. Overall, FDA Category C. |
■ FDA Black Box Warning
No FDA black box warnings.
| Serious Effects |
["Hypersensitivity to ephedrine or phenylephrine","Concurrent use of monoamine oxidase inhibitors (MAOIs) or within 14 days of discontinuation","Severe hypertension or tachyarrhythmias","Narrow-angle glaucoma","Myocardial ischemia","Pheochromocytoma"]
| Precautions | ["Cardiovascular effects: May cause hypertension, tachycardia, arrhythmias","Increased heart rate and contractility in patients with coronary artery disease","Potential for hypertensive crisis with MAO inhibitors","Pheochromocytoma: may precipitate hypertensive crisis","Hyperthyroidism: may exacerbate symptoms","Diabetes mellitus: may increase blood glucose","Prostatic hypertrophy: may cause urinary retention"] |
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| Fetal Monitoring |
| Monitor maternal blood pressure, heart rate, and signs of uterine hyperstimulation. Fetal: Heart rate monitoring (tachycardia may occur). Assess for signs of fetal distress or preterm labor. |
| Fertility Effects | No documented adverse effects on fertility in humans. Animal studies show no significant reproductive impairment. |