8.9 Beta-2 Adrenergic Agonists V2

Andrea Sullivan Degenhardt

8.9 Beta-2 Adrenergic Agonists V2

Bronchodilators are widely used for symptomatic relief of bronchospasm related to asthma or chronic obstructive respiratory disease (COPD). Beta-2 adrenergic agonists are the most commonly used bronchodilator for both quick acting relief and long-term management. Other bronchodilators are anticholinergics, methylxanthines as well as combination inhalers. These will be reviewed in the upcoming units.

Before you begin this unit and the subsequent units, take time to review asthma and COPD in unit 8.1, in particular the management of both diseases. A brief overview is provided below. This unit does not address the many non-pharmacological interventions that are necessary.

Asthma medication management

Following a diagnosis, the treatment of asthma has two goals: terminate bronchospasm during an acute attack and to reduce or prevent risk (preventing reoccurrence, preventing further airway damage). This is accomplished by using a combination of medications.

Beta adrenergic agonists and anticholinergics: bronchodilators
Inhaled corticosteroids: suppress inflammation

COPD medication management

COPD is a chronic, progressive disease. According to the Canadian Thoracic Society, the treatment goals are to reduce dyspnea, improve health status, prevent acute exacerbations and reduce mortality (Bourbeau et al, 2023). Treatment depends on the severity (mild, moderate, severe). This is accomplished by using a combination of medications:

Beta adrenergic agonists and anticholinergics: bronchodilators, short and long acting
Inhaled corticosteroids: suppress inflammation
Phosphodiesterase type 4 inhibitors

In this unit, we will review beta adrenergic agonists: Salbutamol (short acting) and salmeterol (long acting).

See the “Autonomic Nervous System: Beta-2 Agonists” chapter for more information regarding Beta-2 agonists.

Beta Adrenergic Receptor Agonists: salbutamol and salmeterol

Salbutamol is the most widely used bronchodilator for effective relief of acute bronchospasm. It is considered a ‘rescue’ or ‘reliever’ inhaler that reverses airway narrowing. Note that in the U.S, it is called albuterol.

Salmeterol is the long-acting bronchodilator and as the name suggests, it has a long duration of action.

Figure 8.9b A vial of salbutamol for inhalation

Mechanism of Action

Salbutamol and salmeterol stimulate Beta 2-adrenergic receptors in the smooth muscle of bronchi and bronchioles producing bronchodilation. The lungs have a large number of beta-2 receptors. The binding increases the formation of intracellular cAMP by stimulation of adenylyl cyclase which results in relaxing airway smooth muscle, inhibits the release of histamine from mast cells, inhibits macrovascular leakage and to a small degree it increases mucociliary transport (Daily Med, 2025; Vallerand & Sanoski, 2024)

Indications for Use

Short-acting beta agonists (SABA) is used to prevent an acute attack with onset of action almost immediately. They treat bronchospasms to prevent wheezing, chest tightness and difficulty breathing due to respiratory diseases such as asthma and COPD.

Long-acting beta agonists (LABA), salmeterol, is used to prevent bronchospasm. LABA are both inhaled and oral formulas. Terbutaline is an example of an oral LABA taken up to four times a day. It is also available in an inhaled form.

Salbutamol can also be used for hyperkalemia. It causes hypokalemia as a result of an influx of potassium into skeletal muscle cells.

Nursing Considerations

Administration: Inhaled for SABA salbutamol. Inhaled or oral for LABA. Salmeterol inhaled formula.

Short Acting Beta Agonist (SABA):

Onset 5-15 minutes, with a duration 3-6 hours. 1-2 puffs q 20min x 3 doses for acute exacerbation.
MDI, DPI or nebulizer
Hydrophilic, so not stored in tissues

Long-Acting Beta Agonist (LABA):

Fixed schedule dosing i.e. BID
It is lipophilic so longer duration of action.
Onset 10-15 minutes with duration up to 12 hours

Safety Alert

Do not confuse the two beta-2 adrenergic inhalers. Salbutamol is short-acting and used for acute bronchospasm or anticipated exercise-induced bronchoconstriction. It is considered a rescue medication.

Salmeterol is long-acting and used for maintenance therapy for clients with asthma or COPD.

Monitoring:

Assess lung sounds and respiratory rate before therapy. Assess for wheezes and stridor.
Assess pulse and BP
Assess sputum for colour and consistency

Prior to dosing: prime inhaler first by releasing four test sprays into the air.

Pediatric dosing: deliver by metered dose inhaler with a spacer device.

Pregnancy: avoid with pregnancy unless benefits outweigh risks. Do not use during labour due to interfering with uterine contractions.

(Vallerand & Sanoski, 2024)

Adverse/Side Effects

Side effects are related to sympathomimetic action. Anxiety, insomnia, tachycardia and tremor. Usually transient and mild.

Long term over use can lead to hypokalemia and hyperglycemia (stimulates hepatic glucose production).

Beta-2 agonists can cause muscle tremor, excessive cardiac stimulation, and CNS stimulation (Frandsen & Pennington, 2018).

Inhalation administration

The inhalation route has many advantages over other routes. It delivers the drug directly to the lungs or site of action, systemic effects are minimized, the relief of attacks is rapid. There are four types of inhalation devices: metered dose (pressurized device that delivers a measured dose), Respimat (fine mist), dry powder inhaler (dry micronized powder) and nebulizer (converts drug solution into a mist). The most common type is the metered dose (MDI). For any of these devices, correct use is important so the medication reaches the lungs. For example, a spacer is usually recommended for a MDI inhaler so the med does not end up in the mouth instead of the lungs. For more information: Delivery Devices – Asthma Canada (Asthma.ca, 2026).

Client Teaching

Instruct clients to take medications as directed and report to their healthcare provider any sustained or worsening symptoms.
When first using an inhaler, clients should be instructed to prime the inhaler unit prior to administering their medication.
Use of medications like salbutamol can cause an unusual taste in the mouth, and rinsing the mouth with water after use is permitted.
Clients should have an understanding of medication onset and use short-acting and long-acting inhalers appropriately.
Notify the prescriber if pregnant or planning on becoming pregnant.

Salbutamol and Salmeterol Medication Card

Now let’s take a closer look at the medication card for salbutamol and salmeterol (Adams et al, 2020; Frandsen & Pennington, 2018; Vallerand & Sanoski, 2024).

Downloadable file (.docx): Salbutamol and Salmeterol Medication Card

The following Chapter 8 Comparing Respiratory Medications med cards is also an option to support your learning. Download and edit as needed. DC: Should this be pointing to something else? It is linking to this chapter.

Critical Thinking and Decision-Making Questions

Complete the following questions to test your understanding. Go to the chapter 8.9 answer key

A 30-year-old client presents to the ED with acute SOB and bronchospasm. She informs the nurse she has asthma and ran out of her inhaler, Salbutamol.
1. The nurse quickly does a respiratory assessment. Besides SOB, what might be other cues of bronchospasm?
2. The nurse prepares to give salbutamol. What is important to do prior to giving the med?
3. The client’s condition has improved. She tells the nurse she sometimes takes her salbutamol 2 puffs at a time, up to 4 times in a day. What is the concern with this administration?
Which statements are correct about beta 2 adrenergic agonist inhalers? Select all that apply
1. Short acting beta 2 adrenergic agonist inhalers are used for acute bronchospasm.
2. If a beta 2 adrenergic agonist inhaler is used prior to exercise, take the inhaler one hour prior to exercise.
3. These meds may cause temporary tachycardia and tremor which can be severe and lead to long term effects. If this occurs, report to the prescriber.
4. It is safe to use salbutamol if a client is pregnant.
True or False: Salmeterol is used for acute bronchospasm.