Adrenergic Therapy

Adrenergic agonists are sometimes called sympathomimetics, because they work by mimicking the actions of the sympathetic nervous system. They can be classified as either catecholamines or noncatecholamines. Epinephrine is an example of a catecholamine used in emergency situations like anaphylaxis and cardiac arrest, while albuterol is a noncatecholamine used for the treatment and prevention of bronchospasm.

Now, adrenergic agonists mimic the effect of endogenous catecholamines by stimulating adrenergic receptors, activating the sympathetic nervous system, and triggering the fight or flight response.

There are four main adrenergic receptors, including alpha 1 receptors, which are primarily associated with vasoconstriction and increased blood pressure; alpha 2 receptors, which cause vasodilation, beta 1 receptors which cause effects like increased cardiac contractility and increased heart rate; and beta 2 receptors which are primarily associated with bronchodilation.

Epinephrine’s therapeutic effects are due to activation of alpha 1, beta 1, and beta 2 adrenergic receptors, so it has multiple sympathomimetic effects on the heart, blood vessels, and lungs. Albuterol works by selectively activating beta 2 receptors in the lungs, causing bronchodilation.

Okay, so most side effects of adrenergic agonists are the result of their action on the adrenergic receptors throughout the body. So, both albuterol and epinephrine affect the central nervous system, causing restlessness, anxiety, dizziness, and tremors. Cardiac side effects like palpitations, chest pain, and tachycardia can also occur. In addition, gastrointestinal side effects such as nausea, vomiting, and anorexia are also common. Now, for both epinephrine and albuterol, there are specific life-threatening effects to be aware of. Epinephrine can cause pulmonary edema or ventricular fibrillation; and it’s considered a high alert medication, meaning that there’s an increased risk of patient harm if the medication is used in error. Albuterol can cause cardiac arrythmias, and although it is used to treat bronchospasms, it can also cause them.