4.15 Alpha- and Beta-Receptor Agonists (Catecholamines)
4.15 Alpha- and Beta-Receptor Agonists (Catecholamines)
Epinephrine and Norepinephrine
Epinephrine and norepinephrine (NE) are adrenergics (also referred to as catecholamines) that stimulate the beta- and alpha-receptors on the target cell.
Mechanism of Action: Epinephrine acts on both alpha- and beta-adrenergic receptors and is used in several routes, including intravenously (IV), subcutaneously, intramuscularly, and inhalation. Epinephrine decreases vasodilation and increases vascular permeability through its alpha-adrenergic receptor action, which can lead to loss of intravascular fluid volume and hypotension. Through its action on beta-adrenergic receptors, epinephrine causes bronchial smooth muscle relaxation and helps alleviate bronchospasm, wheezing, and dyspnea that may occur during anaphylaxis.
Indications: Epinephrine is used for severe allergic reactions, acute bronchospasm during asthma attacks, cardiac resuscitation, hypotension in severe shock, or for local injection to control superficial bleeding.
Norepinephrine is used as a peripheral vasoconstrictor (due to alpha-adrenergic action) and as an inotropic stimulator of the heart and dilator of coronary arteries (due to beta-adrenergic action) in clients with critically low blood pressure.
Nursing Considerations: Epinephrine is contraindicated for use in fingers, toes, ears, nose, or genitalia when used with local anesthetic due to the vasoconstrictive action. It is also contraindicated in clients with narrow angle glaucoma. Administer with caution to the elderly and those with preexisting cardiovascular disease. Discard IV solution if discolored. When administering IV, monitor vitals (blood pressure, heart rate, and respiratory rate) and cardiovascular and respiratory systems closely; if blood pressure increases sharply, give rapid-acting vasodilators. Monitor IV site for extravasation. If extravasation occurs, immediately stop IV administration and follow agency policy. Phentolamine, an alpha-adrenergic antagonist, is the reversal agent used to reverse local vasoconstrictive effects if digital ischemia occurs.
Side Effects/Adverse Effects: Common side effects include hypertension and tachycardia.
Health Teaching & Health Promotion: Epinephrine formulated in a pen for injection is known as an EpiPen. An EpiPen is used for severe allergic reactions after exposure to an allergen such as a bee sting. Check expiration date, store at room temperature, and protect from light. Effects fade after 15-20 minutes, so seek medical care immediately.[1]
Now let’s take a closer look at the medication grid on epinephrine and norepinephrine in Table 4.15a.[2]
Table 4.15a Epinephrine and Norepinephrine Medication Grid
Class/Subclass |
Prototype/Generic |
Nursing Considerations |
Therapeutic Effects |
Side/Adverse Effects |
|---|---|---|---|---|
| Catecholamine | epinephrine | Contraindicated for use in fingers, toes, ears, nose, or genitalia when used with local anesthetic
Monitor vitals (blood press