What are the uses and effects of adrenergic agonist pharmaceuticals?

From the Guidelines

Adrenergic agonist pharmaceuticals are a class of medications that stimulate adrenergic receptors in the body, used to treat various conditions including asthma, COPD, hypotension, cardiac arrest, anaphylaxis, and nasal congestion, with common examples being epinephrine, albuterol, and phenylephrine. These medications work by binding to adrenergic receptors, which activates intracellular signaling pathways that ultimately produce the desired physiological response, such as bronchodilation or increased cardiac output 1. The effects of these medications depend on which adrenergic receptors they target:

• alpha-1 agonists cause vasoconstriction and increased blood pressure
• beta-1 agonists increase heart rate and contractility
• beta-2 agonists relax bronchial smooth muscle and dilate airways. Some common adrenergic agonists and their uses include:
• Epinephrine (Adrenalin), used at 0.1–0.5 mcg/kg/min for symptomatic bradycardia, severe hypotension, and anaphylaxis associated with hemodynamic instability or respiratory distress 1
• Albuterol (Ventolin, ProAir), typically administered as 2 puffs (90mcg/puff) every 4-6 hours for asthma
• Phenylephrine, used as nasal drops (0.25-1%) for congestion, and at 0.5–2.0 mcg/kg/min to treat severe hypotension and low total peripheral resistance 1
• Dobutamine, used at 5–10 mcg/kg/min to treat low cardiac output, with its (+) isomer being a potent beta-adrenergic agonist and its (–) isomer being a potent alpha-1-agonist 1. Side effects can include tremors, anxiety, increased heart rate, palpitations, and elevated blood pressure, and patients should be aware that overuse of certain adrenergic agonists can lead to tolerance and potentially worsen the underlying condition 1. It is essential to monitor patients closely during the administration of these medications, especially when using them for stress testing, as complications such as nausea, headache, tremor, anxiety, angina, and arrhythmias can occur 1. The most critical consideration in using adrenergic agonist pharmaceuticals is to carefully select the appropriate medication and dosage based on the patient's specific condition and response, while minimizing the risk of adverse effects and optimizing the therapeutic outcome.

From the FDA Drug Label

Salmeterol is a selective LABA. In vitro studies show salmeterol to be at least 50 times more selective for beta2-adrenoceptors than albuterol Although beta2-adrenoceptors are the predominant adrenergic receptors in bronchial smooth muscle and beta1-adrenoceptors are the predominant receptors in the heart, there are also beta2-adrenoceptors in the human heart comprising 10% to 50% of the total beta-adrenoceptors The pharmacologic effects of beta2-adrenoceptor agonist drugs, including salmeterol, are at least in part attributable to stimulation of intracellular adenyl cyclase, the enzyme that catalyzes the conversion of adenosine triphosphate (ATP) to cyclic-3′,5′-adenosine monophosphate (cyclic AMP) Increased cyclic AMP levels cause relaxation of bronchial smooth muscle and inhibition of release of mediators of immediate hypersensitivity from cells, especially from mast cells.

The uses of adrenergic agonist pharmaceuticals, such as salmeterol, include:

• Relaxation of bronchial smooth muscle
• Inhibition of release of mediators of immediate hypersensitivity from cells The effects of adrenergic agonist pharmaceuticals include:
• Increased cyclic AMP levels
• Relaxation of bronchial smooth muscle
• Inhibition of release of mediators of immediate hypersensitivity from cells Note: The information provided is based on the drug label for salmeterol, a specific adrenergic agonist pharmaceutical 2, 2, 2.

From the Research

Uses of Adrenergic Agonist Pharmaceuticals

• Adrenergic agonist pharmaceuticals, such as long-acting beta-adrenergic agonists (LABAs), are used in combination with inhaled corticosteroids (ICS) to treat chronic airways diseases like asthma and chronic obstructive pulmonary disease (COPD) 3.
• LABAs, like salmeterol, are used to improve lung function, reduce symptoms, and increase health-related quality of life in patients with COPD 4.
• Adrenergic agonists are also used as bronchodilators to treat patients with COPD, and they may have additional effects such as inhibiting airway smooth-muscle cell proliferation and inflammatory mediator release 5.

Effects of Adrenergic Agonist Pharmaceuticals

• The use of LABAs in combination with ICS has been shown to increase the efficacy of ICS effects in moderate-to-severe asthma, reducing severe exacerbation rates and improving lung function 3.
• Adrenergic agonists can increase heart rate and reduce potassium concentrations, which may precipitate ischemia, congestive heart failure, arrhythmias, and sudden death in patients with obstructive airway disease 6.
• LABAs may have adverse effects on asthma control due to their pharmacological properties, and their use has been associated with an increased risk of asthma exacerbations and associated deaths 7.
• The combination of LABAs and ICS may reduce the risk of asthma-related events, including deaths, compared to the use of LABAs alone 3.

Benefits and Risks

• The benefits of adrenergic agonist pharmaceuticals include improved lung function, reduced symptoms, and increased health-related quality of life in patients with COPD and asthma 3, 4.
• The risks of adrenergic agonist pharmaceuticals include increased heart rate, reduced potassium concentrations, and adverse cardiovascular events, such as myocardial infarction, congestive heart failure, and cardiac arrest 6.
• The use of LABAs in certain situations may have adverse effects on asthma control, and their use should be carefully considered and monitored 7.