EPI E Z PEN JR
Clinical safety rating: caution
Comprehensive clinical and safety monograph for EPI E Z PEN JR (EPI E Z PEN JR).
Epinephrine is a direct-acting sympathomimetic amine that acts on alpha- and beta-adrenergic receptors. Alpha receptor activation increases peripheral vascular resistance and reverses hypotension, while beta receptor activation causes bronchodilation, increased heart rate, and myocardial contractility.
| Metabolism | Metabolized primarily by the liver via catechol-O-methyltransferase (COMT) and monoamine oxidase (MAO). Also metabolized in other tissues including smooth muscle and the kidneys. |
| Excretion | Primarily renal: epinephrine is metabolized in the liver and tissues, with metabolites (metanephrine, vanillylmandelic acid) excreted in urine; <5% excreted unchanged. |
| Half-life | Short terminal half-life of approximately 2-3 minutes; requires continuous infusion for sustained effect due to rapid uptake and metabolism. |
| Protein binding | Approximately 50% bound to plasma proteins, primarily albumin; also binds to alpha- and beta-adrenergic receptors. |
| Volume of Distribution | 0.4-0.6 L/kg, indicating distribution into total body water; high distribution into highly perfused tissues (heart, lungs, liver). |
| Bioavailability | Intramuscular: near 100% for epinephrine auto-injectors; subcutaneous: variable (30-80%) due to vasoconstriction at injection site; oral: negligible due to first-pass metabolism. |
| Onset of Action | Intramuscular injection: within minutes (peak effect 5-10 min); subcutaneous: slower onset (5-15 min); intravenous: immediate. |
| Duration of Action | Intramuscular: 1-2 hours for bronchodilation and pressor effects; clinical effects may be brief due to rapid clearance. |
| Molecular Weight | 183.2 |
Epinephrine 0.3 mg (0.3 mL of 1:1000 solution) intramuscularly into the anterolateral thigh, repeated every 5-15 minutes as necessary for anaphylaxis.
| Dosage form | INJECTABLE |
| Renal impairment | No dose adjustment required for renal impairment; epinephrine is metabolized rapidly and renally excreted only minimally. |
| Liver impairment | No dose adjustment required for hepatic impairment; epinephrine metabolism is not significantly affected by liver dysfunction. |
| Pediatric use | Weight less than 30 kg: Epinephrine 0.15 mg (0.15 mL of 1:1000 solution) intramuscularly into the anterolateral thigh, repeated every 5-15 minutes as necessary. |
| Geriatric use | Use with caution due to increased sensitivity and higher risk of adverse effects (e.g., myocardial ischemia, hypertension); consider lower initial dose (0.15-0.3 mg) and monitor closely. |
| 1st trimester | Epinephrine use in first trimester is generally avoided unless necessary for severe allergic reactions; risk of potential teratogenicity is low but not zero. |
| 2nd trimester | Use in second trimester may be considered for anaphylaxis; associated with reduced uterine blood flow; benefits may outweigh risks in emergencies. |
| 3rd trimester | Third trimester use may cause uterine contractions and reduced placental perfusion; use only for life-threatening anaphylaxis. |
Clinical note
Comprehensive clinical and safety monograph for EPI E Z PEN JR (EPI E Z PEN JR).
| Placental transfer | Epinephrine crosses the placenta rapidly via passive diffusion; may cause fetal tachycardia and constriction of uterine vasculature. |
| Breastfeeding | Epinephrine is excreted into breast milk in negligible amounts; short half-life and poor oral bioavailability minimize infant exposure. No adverse effects reported in nursing infants. Compatible with breastfeeding during emergency use. |
■ FDA Black Box Warning
Epinephrine injection should not be used in patients with known hypersensitivity to epinephrine or any component of the product. There is no black box warning specifically for Epi E Z Pen Jr.
| Serious Effects |
Hypersensitivity to epinephrine or any components of the auto-injectorNarrow-angle glaucoma (relative)Cardiac arrhythmias with hypertensionCoronary insufficiency (relative)
| Precautions | May cause serious adverse reactions including cardiac arrhythmias, hypertension, myocardial ischemia, and pulmonary edema. Use with caution in patients with cardiovascular disease, diabetes, hyperthyroidism, and elderly. Do not inject into hands, feet, or buttocks due to risk of tissue necrosis. |
| Food/Dietary | No specific dietary restrictions. However, patients should avoid known allergens and maintain a balanced diet. Epinephrine's effects can be potentiated by caffeine or other stimulants; patients should limit excessive caffeine intake. |
Loading safety data…
| Lactation Rating | L1 (Safe) |
| Teratogenic Risk | Epinephrine is a sympathomimetic amine. Animal studies have shown teratogenic effects at high doses, but human data are limited. During first trimester, there is a potential risk of congenital anomalies (e.g., inguinal hernia, clubfoot) based on some epidemiological studies, though other studies show no increased risk. Second and third trimester exposure may cause fetal tachycardia, hypertension, and reduced uteroplacental blood flow, potentially leading to fetal hypoxia. Use only if clearly needed; avoid in cases where maternal benefit does not outweigh fetal risk. |
| Fetal Monitoring | Monitor maternal blood pressure, heart rate, and cardiac rhythm during administration. Fetal heart rate should be monitored for tachycardia or distress. Assess for signs of uterine hypertonus or reduced uterine blood flow. Continuous fetal monitoring recommended if used near term. |
| Fertility Effects | Limited data. High-dose epinephrine may cause reproductive dysfunction in animal models (e.g., altered estrous cycles, reduced fertility). In humans, no well-documented adverse effects on fertility at therapeutic doses. Caution in assisted reproduction due to potential vasoconstrictive effects on ovarian blood flow. |
| Clinical Pearls | EPI E Z PEN JR is a formulation of epinephrine for pediatric patients weighing 15–30 kg. Administer intramuscularly into the anterolateral thigh; never into the gluteal muscle or vein. Use an auto-injector that delivers 0.15 mg. If symptoms are not relieved, repeat injection at 5- to 15-minute intervals. Monitor for paradoxical bronchospasm, cardiac arrhythmias, and hypertension. Store at room temperature, protect from light, and do not refrigerate. |
| Patient Advice | Use exactly as prescribed; inject into the outer thigh, not in the buttock or other body part. · Hold the auto-injector in place for 3 seconds after activation. · Seek emergency medical help immediately after use. · Do not use if the solution is discolored or contains particles. · Carry two auto-injectors at all times and check expiration dates regularly. · Train family members and caregivers on proper administration. · Avoid overuse; overuse can lead to serious side effects like irregular heartbeat or dangerously high blood pressure. |