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  1. Pharmacology. Epinephrine is an endogenous catecholamine with alpha- and beta-adrenergic agonist properties that is used primarily in emergency situations to treat anaphylaxis or cardiac arrest. Beneficial effects include inhibition of histamine release from mast cells and basophils, bronchodilation, positive inotropic effects, and peripheral vasoconstriction. Epinephrine is not active after oral administration. Subcutaneous injection produces effects within 5–10 minutes, with peak effects at 20 minutes. Intravenous or inhalational administration produces much more rapid onset. Epinephrine is inactivated rapidly in the body, with an elimination half-life of 2 minutes.

  2. Indications

    1. Anaphylaxis and anaphylactoid reactions.

    2. Epinephrine occasionally is used for hypotension resulting from overdose with beta blockers, calcium antagonists, and other cardiac-depressant drugs.

  3. Contraindications

    1. Tachyarrhythmias or ventricular fibrillation and uncorrected hypovolemia.

    2. Epinephrine is relatively contraindicated in patients with organic heart disease, peripheral arterial occlusive vascular disease with thrombosis, or ergot poisoning (See Ergot Derivatives).

    3. Narrow-angle glaucoma.

  4. Adverse effects

    1. Anxiety, restlessness, tremor, and headache.

    2. Severe hypertension, which may result in intracranial hemorrhage, pulmonary edema, or myocardial necrosis or infarction.

    3. Use with caution in patients intoxicated by halogenated or aromatic hydrocarbon solvents and anesthetics because these agents may sensitize the myocardium to the arrhythmogenic effects of epinephrine.

    4. Tissue necrosis after extravasation or intra-arterial injection.

    5. Aggravation of tissue ischemia, resulting in gangrene.

    6. Anaphylactoid reaction, which may occur owing to the bisulfite preservative in patients with sulfite hypersensitivity.

    7. Hypokalemia, hypophosphatemia, hyperglycemia, and leukocytosis may occur owing to the beta-adrenergic effects of epinephrine.

    8. Use in pregnancy. FDA Category C (indeterminate). Epinephrine is teratogenic in animals, crosses the placenta, can cause placental ischemia, and may suppress uterine contractions, but these effects do not preclude its acute, short-term use for a seriously symptomatic patient (See Introduction in Section III).

  5. Drug or laboratory interactions

    1. An enhanced arrhythmogenic effect may occur when epinephrine is given to patients with chloral hydrate overdose or anesthetized with cyclopropane or halogenated general anesthetics.

    2. Use in patients taking propranolol and other nonselective beta blockers may produce severe hypertension owing to blockade of beta2-mediated vasodilation, resulting in unopposed alpha-mediated vasoconstriction.

    3. Cocaine and cyclic antidepressants may enhance stimulant effects owing to inhibition of neuronal epinephrine reuptake.

    4. Monoamine oxidase inhibitors may enhance pressor effects because of decreased neuronal epinephrine metabolism.

    5. Digitalis intoxication may enhance the arrhythmogenicity of epinephrine.

  6. Dosage and method of administration

    1. Caution: Avoid extravasation. The intravenous infusion must be free-flowing, and the infused vein should be observed frequently for signs of subcutaneous infiltration (pallor, coldness, or induration).

      1. If extravasation occurs, immediately infiltrate the affected area with phentolamine (See Phentolamine), 5–10 mg in 10–15 mL of normal saline (children: 0.1–0.2 mg/kg; maximum, 10 mg total) via a fine (25- to 27-gauge) hypodermic needle; improvement is evidenced by hyperemia and return to normal temperature.

      2. Alternatively, topical application of nitroglycerin paste and infiltration of terbutaline have been reported to be successful.

    2. Mild to moderate allergic reaction. Give 0.3–0.5 mg SC or IM (children: 0.01 mg/kg of 1:1000 solution or 1:200 suspension; maximum, 0.5 mg). May be repeated after 10–15 minutes if needed.

    3. Severe anaphylaxis....

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