epinephrin

Action

Stimulates alpha- and beta-adrenergic receptors, causing relaxation of cardiac and bronchial smooth muscle and dilation of skeletal muscles. Also decreases aqueous humor production, increases aqueous outflow, and dilates pupils by contracting dilator muscle.

Availability

Auto-injector for I.M. injection: 1:2,000 (0.5 mg/ml)

Injection: 0.1 mg/ml, 0.5 mg/ml, 1 mg/ml

Ophthalmic drops: 0.5%, 1%, 2% Solution for inhalation (as racepinephrine): 2.5% (equivalent to 1% epinephrine)

Indications and dosages

➣ Bronchodilation; anaphylaxis; hypersensitivity reaction

Adults: 0.1 to 0.5 ml of 1:1,000 solution subcutaneously or I.M., repeated q 10 to 15 minutes p.r.n. Or 0.1 to 0.25 ml of 1:10,000 solution I.V. slowly over 5 to 10 minutes; may repeat q 5 to 15 minutes p.r.n. or follow with a continuous infusion of 1 mcg/minute, increased to 4 mcg/minute p.r.n. For emergency treatment, EpiPen delivers 0.3 mg I.M. of 1:1,000 epinephrine.

Children: For emergency treatment, EpiPen Jr. delivers 0.15 mg I.M. of 1:2,000 epinephrine.

➣ Acute asthma attack

Adults and children ages 4 and older: One to three deep inhalations of inhalation solution with hand-held nebulizer, repeated q 3 hours p.r.n.

➣ To restore cardiac rhythm in cardiac arrest

Adults: 0.5 to 1 mg I.V., repeated q 3 to 5 minutes, if needed. If no response, may give 3 to 5 mg I.V. q 3 to 5 minutes.

➣ Chronic simple glaucoma

Adults: One drop in affected eye once or twice daily. Adjust dosage to meet patient's needs.

➣ To prolong local anesthetic effects

Adults and children: 1:200,000 concentration with local anesthetic

Contraindications

• Hypersensitivity to drug, its components, or sulfites

• Angle-closure glaucoma

• Cardiac dilatation, cardiac insufficiency

• Cerebral arteriosclerosis, organic brain syndrome

• Shock with use of general anesthetics and halogenated hydrocarbons or cyclosporine

• MAO inhibitor use within past 14 days

• Labor

• Breastfeeding

Precautions

Use cautiously in:

• hypertension, hyperthyroidism, diabetes, prostatic hypertrophy

• elderly patients

• pregnant patients

• children.

Administration

• In anaphylaxis, use I.M. route, not subcutaneous route, if possible.

☞ Inject EpiPen and EpiPen Jr. only into anterolateral aspect of thigh. Don't inject into buttocks or give I.V.

☞ Be aware that not all epinephrine solutions can be given I.V. Check manufacturer's label.

• For I.V. injection, give each 1-mg dose over at least 1 minute. For continuous infusion, use rate of 1 to 10 mcg/minute, adjusting to desired response.

• Use Epi-Pen Jr. for patients weighing less than 30 kg (66 lb).

☞ Don't give within 14 days of MAO inhibitors.

Adverse reactions

CNS: nervousness, anxiety, tremor, vertigo, headache, disorientation, agitation, drowsiness, fear, dizziness, asthenia,cerebral hemorrhage, cerebrovascular accident (CVA)

CV: palpitations, widened pulse pressure, hypertension, tachycardia, angina, ECG changes,ventricular fibrillation, shock

GI: nausea, vomiting

GU: decreased urinary output, urinary retention, dysuria

Respiratory: dyspnea, pulmonary edema

Skin: urticaria, pallor, diaphoresis, necrosis

Other: hemorrhage at injection site

Interactions

Drug-drug. Alpha-adrenergic blockers: hypotension from unopposed beta-adrenergic effects

Antihistamines, thyroid hormone, tricyclic antidepressants: severe sympathomimetic effects

Beta-adrenergic blockers (such as propranolol): vasodilation and reflex tachycardia

Cardiac glycosides, general anesthetics: increased risk of ventricular arrhythmias

Diuretics: decreased vascular response Doxapram, mazindol, methylphenidate: enhanced CNS stimulation or pressor effects

Ergot alkaloids: decreased vasoconstriction

Guanadrel, guanethidine: enhanced pressor effects of epinephrine

Levodopa: increased risk of arrhythmias

Levothyroxine: potentiation of epinephrine effects

MAO inhibitors: increased risk of hypertensive crisis

Drug-diagnostic tests. Glucose: transient elevation

Lactic acid: elevated level (with prolonged use)

Patient monitoring

☞ Monitor vital signs, ECG, and cardiovascular and respiratory status. Watch for ventricular fibrillation, tachycardia, arrhythmias, and signs and symptoms of shock. Ask patient about anginal pain.

• Assess drug's effect on underlying problem (such as anaphylaxis or asthma attack), and repeat dose as needed.

☞ Monitor neurologic status, particularly for decreased level of consciousness and other signs and symptoms of cerebral hemorrhage or CVA.

• Monitor fluid intake and output, watching for urinary retention or decreased urinary output.

• Inspect injection site for hemorrhage or skin necrosis.

Patient teaching

• Teach patient who uses auto-injector how to use syringe correctly, when to inject drug, and when to repeat doses.

• Teach patient who uses hand-held nebulizer correct use of equipment and drug. Explain indications for both initial dose and repeat doses.

☞ Inform patient that drug may cause serious adverse effects. Tell him which symptoms to report.

• If patient will self-administer drug outside of health care setting, explain need for prompt evaluation by a health care provider to ensure that underlying disorder has been corrected.

• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs and tests mentioned above.