EPIPEN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for EPIPEN (EPIPEN).
Nonselective alpha-1, alpha-2, beta-1, beta-2, beta-3 adrenergic receptor agonist; causes vasoconstriction (alpha-1), bronchodilation (beta-2), and increased cardiac contractility and heart rate (beta-1).
| Metabolism | Metabolized by monoamine oxidase (MAO) and catechol-O-methyltransferase (COMT); primarily in the liver and other tissues. |
| Excretion | Renal (90% as metabolites, 10% unchanged); biliary/fecal (<5%) |
| Half-life | 2-3 minutes (IV); clinical context: ultra-short half-life necessitates repeated doses or continuous infusion for sustained effect |
| Protein binding | 15-20% (bound to albumin and alpha-1-acid glycoprotein) |
| Volume of Distribution | 0.2-0.7 L/kg (largely confined to extracellular fluid; high Vd suggests extensive distribution into tissues) |
| Bioavailability | IM: 80-100%; SC: 100% (rapid and complete absorption) |
| Onset of Action | IM: within 5-10 minutes; SC: within 5-15 minutes; IV: immediate |
| Duration of Action | IM/SC: 1-2 hours (pressor effect shorter, bronchodilation persists up to 1 hour); IV: 5-10 minutes (rapidly metabolized) |
0.3 mg intramuscularly (lateral thigh) every 5-15 minutes as needed for anaphylaxis.
| Dosage form | INJECTABLE |
| Renal impairment | No dose adjustment required for renal impairment. |
| Liver impairment | No dose adjustment required for hepatic impairment (Child-Pugh A, B, or C). |
| Pediatric use | Body weight 15-30 kg: 0.15 mg intramuscularly (lateral thigh) every 5-15 minutes as needed. Body weight <15 kg: 0.01 mg/kg intramuscularly (lateral thigh) every 5-15 minutes as needed (use 0.15 mg auto-injector only if weight 15-30 kg; otherwise, draw up from ampule). |
| Geriatric use | Same as adult dosing; use 0.3 mg intramuscularly (lateral thigh) every 5-15 minutes as needed. Caution in patients with cardiovascular disease due to potential for hypertension, tachycardia, and myocardial ischemia. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for EPIPEN (EPIPEN).
| Breastfeeding | Epinephrine is excreted into breast milk in negligible amounts; M/P ratio is unknown. Oral bioavailability is poor due to first-pass metabolism. Use caution in breastfeeding women, as epinephrine may inhibit milk ejection reflex via alpha-adrenergic stimulation. |
| Teratogenic Risk | Epinephrine is not teratogenic in animal studies; there is no evidence of human teratogenicity. However, high doses may cause uterine vasoconstriction and reduced placental perfusion, particularly in the third trimester. Use in pregnancy only if clearly needed. |
■ FDA Black Box Warning
None.
| Serious Effects |
["No absolute contraindications in life-threatening anaphylaxis","Relative: hypersensitivity to epinephrine or any component (sulfites) in some formulations; narrow-angle glaucoma; hemorrhagic or traumatic shock; cardiac arrhythmias (e.g., ventricular fibrillation)"]
| Precautions | ["Do not inject into buttocks, digits, or veins; accidental intravenous injection may cause cerebral hemorrhage","Use caution in patients with cardiovascular disease, hypertension, hyperthyroidism, diabetes, or elderly","May exacerbate coronary insufficiency","Risk of pulmonary edema if administered too rapidly"] |
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| Fetal Monitoring |
| Monitor maternal blood pressure, heart rate, and uterine activity during administration. Fetal heart rate monitoring is recommended, especially in third trimester, due to risk of uterine vasoconstriction and fetal hypoxia. |
| Fertility Effects | No adverse effects on fertility in animal studies. In humans, epinephrine may affect ovulation and implantation via altered uterine blood flow, but clinical significance is unknown. |