DESCRIPTION

Epinephrine is an adrenergic agonist used to treat bronchospasm, anaphylactic reactions, bradycardia, cardiac arrest, and hypotension.

FORMS AND USES

• Epinephrine for inhalation. Adrenalin, AsthmaHaler Mist, AsthmaNefrin, Bronitin Mist, Bronkaid Mist, Medihaler-Epi, Primatene Mist, MicroNefrin, Nephron, Racepinephrine, and Vaponephrin.
• Epinephrine for injection. Adrenalin, Epi-Pen, Epi-Pen Jr., and Sus-Phrine.

TOXIC DOSE

• Pharmacologically active doses are not reached with ingested dosages.
• Injection of any amount above the recommended dosage may produce toxicity.

PATHOPHYSIOLOGY

• Epinephrine stimulates alpha-adrenergic and beta-₁- and beta-₂-adrenergic receptors.
• There is only slight absorption via the inhaled route, and effects are generally localized to the respiratory tract.

EPIDEMIOLOGY

Poisoning is uncommon.

CAUSES

• Toxicity is usually caused by iatrogenic error or marked misuse of inhaler by patient.
• Child neglect should be considered if the patient is under 1 year of age; suicide attempt if the patient is over 6 years of age.

PREGNANCY AND LACTATION

US FDA Pregnancy Category C. The drug exerts animal teratogenic or embryocidal effects, but there are no controlled studies in women, or no studies are available in animals or women.

Section Outline:

• DESCRIPTION
• FORMS AND USES
• TOXIC DOSE
• PATHOPHYSIOLOGY
• EPIDEMIOLOGY
• CAUSES
• PREGNANCY AND LACTATION

DIFFERENTIAL DIAGNOSIS

Toxic causes of agitation and dysrhythmias are numerous, including stimulants, inhaled beta- receptor agonists, and many others.

SIGNS AND SYMPTOMS

• Rapid onset of agitation, hypertension, tachycardia, and dysrhythmias are typical.

Vital Signs

Overdosage can result in tachycardia hypertension, extreme pallor and coldness of skin.

Pulmonary

Dyspnea is common. Pulmonary arterial hypertension may result in potentially fatal pulmonary edema.

Cardiovascular

• Tachycardia may result is myocardial ischemia.
• Ventricular dysrhythmia is common after overdose.

Gastrointestinal

Vomiting is common after overdose.

Fluid and Electrolytes

Hyperglycemia is common with overdose.

Acid-Base

Lactic acidosis and reduced renal and hepatic blood flow occur due to tissue ischemia.

Neurologic

• Severe hypertension may cause intracranial bleeding.
• Agitation and tremulousness are common.

PROCEDURES AND LABORATORY TESTS

Essential tests

No tests may be needed for minimally symptomatic patients.

Recommended Tests

Tests should be ordered according to the manifestations that develop (e.g., ischemia, hemorrhage).

Section Outline:

• DIFFERENTIAL DIAGNOSIS
• SIGNS AND SYMPTOMS
  • Vital Signs
  • Pulmonary
  • Cardiovascular
  • Gastrointestinal
  • Fluid and Electrolytes
  • Acid-Base
  • Neurologic
• PROCEDURES AND LABORATORY TESTS
  • Essential tests
  • Recommended Tests

DIRECTING PATIENT COURSE

Treatment should focus on hypertension and dysrhythmias.

The health-care professional should call the poison control center when:

• Severe or persistent effects develop.
• Coingestant, drug interaction, or underlying disease presents an unusual problem.

The patient should be referred to a health-care facility when:

• Suicide or homicide attempt is possible.
• Toxic effects develop.
• Coingestant, drug interaction, or underlying disease presents an unusual problem.

Admission Considerations

Admission is recommended for patients who develop cardiac manifestations.

DECONTAMINATION

It is not recommended because toxicity is usually caused by repeated misuse or injection of excessive dose.

ANTIDOTES

There is no specific antidote recommended for epinephrine.

ADJUNCTIVE TREATMENT

• Agitation is treated with benzodiazepines titrated to response.
• Hypertension. If end organ injury develops (aortic dissection, CNS effects, myocardial ischemia), consider administration of a short-acting agent such as nitroprusside.
• Ventricular dysrhythmia. Standard advanced cardiac life support algorithms are appropriate.
• Local tissue ischemia caused by injection of epinephrine can be treated with local infiltration of phentolamine (0.5 mg/ml concentration) around the injection site.

Section Outline:

• DIRECTING PATIENT COURSE
  • Admission Considerations
• DECONTAMINATION
• ANTIDOTES
• ADJUNCTIVE TREATMENT

PATIENT MONITORING

In cases with systemic effects, the heart rate, blood pressure, ECG, blood glucose, serum electrolytes, arterial blood gases, and serum creatinine should be monitored.

EXPECTED COURSE AND PROGNOSIS

Recovery is expected within 24 hours with supportive treatment unless sequelae of hypertension or CNS bleed intercede.

DISCHARGE CRITERIA AND INSTRUCTIONS

Patients may be discharged from the emergency room or hospital if they do not develop hypertension, tachycardia, or dysrhythmias within 6 hours of observation.

Section Outline:

• PATIENT MONITORING
• EXPECTED COURSE AND PROGNOSIS
• DISCHARGE CRITERIA AND INSTRUCTIONS

Altered mental status should prompt investigation for CNS bleed.

TREATMENT

Use of beta-receptor blocking drugs alone is not recommended as it may theoretically lead to unopposed alpha stimulation.

Poisoning by drugs primarily affecting the autonomic nervous system: Sympathomimetics (adrenergics).

See Also: SECTION II, Ventricular Dysrhythmia chapter; and SECTION III, Nitroprusside chapter.

RECOMMENDED READING

Kurachek SC, Rockoff MA. Inadvertent intravenous administration of racemic epinephrine. JAMA 1985;253:1441-1442.

Authors: Kevin M. Lier

Reviewer: Richard C. Dart