Beta-2 Adrenergic Agonists are a class of medications that are common in the field of Respiratory Care. They’re used to treat obstructive conditions such as asthma and COPD.

This study guide provides you with an overview of the Beta-2 Adrenergic Bronchodilators to help make the learning process easier. It also has free practice questions for your benefit as well. So if you’re ready, let’s get started.

What is a Beta-2 Adrenergic Agonist?

They are a class of drugs that act on the beta-2 adrenergic receptors. This causes the smooth muscles of the airways to relax, which is why they are effective in treating conditions that cause acute bronchospasm.

Beta-2 Adrenergic Agonists cause smooth muscle relaxation, bronchodilation, vasodilation, and the release of insulin. Many patients with respiratory conditions are treated with both Beta-2 Agonists and Anticholinergic Agents.

Types of Beta-2 Adrenergic Agonists:

There are three primary types of Beta-2 Adrenergic Agonists (Bronchodilators):

  1. Short-Acting Beta-2 Agonists
  2. Long-Acting Beta-2 Agonists
  3. Ultra-Long-Acting Beta-2 Agonists

Short-Acting Beta-2 Agonists are known as the rescue drugs because they are used to treat acute bronchospasm. For example, an acute asthma attack.

Long-Acting Beta-2 Agonists are known as maintenance medications because they are used to control and maintain conditions that cause chronic bronchospasm. For example, patients with asthma and COPD who are not having an acute exacerbation. Ultra-Long-Acting Beta-2 Agonists have a similar mechanism of action.

Types of Beta-2 Adrenergic Agonist Bronchodilators
Here are some examples of each type of Beta-2 Adrenergic Agonists:

Short-Acting Beta-2 Agonists:

  • Albuterol (Ventolin, Proventil)
  • Levalbuterol (Xopenex)
  • Metaproterenol (Alupent)
  • Salbutamol
  • Pirbuterol (Maxair)
  • Isoproterenol (Isuprel)
  • Bitolterol (Tornalate)

Long-Acting Beta-2 Agonists:

  • Arformoterol (Brovana)
  • Salmeterol (Serevent)
  • Formoterol (Foradil, Perforomist)
  • Bambuterol (Bambec)
  • Clenbuterol (Dilaterol)

Ultra-Long-Acting Beta-2 Agonists:

  • Umeclidinium Bromide (Anoro Ellipta)
  • Fluticasone Furoate (Breo Ellipta)
  • Carmoterol
  • Abediterol
  • Indacaterol (Arcapta Neohaler)
  • Olodaterol (Striverdi Respimat)

Side Effects of Beta-2 Adrenergic Agonists:

Here are the most common adverse side effects of Beta-2 Adrenergic Agonists:

  • Tachycardia
  • Shakiness, tremors, and quivering
  • Palpitations
  • Excessive sweating
  • Anxiety
  • Insomnia

The severity of each side effect varies from patient to patient.

What are Adrenergic Bronchodilators?

Adrenergic bronchodilators represent the largest group of drugs among the aerosolized agents used for oral inhalation.

They are generally indicated in the presence of reversible airflow obstruction and are most commonly used to improve flow rates in patients with asthma, bronchitis, emphysema, bronchiectasis, cystic fibrosis, and other obstructive airway diseases.

Now let’s dive a little bit deeper into some terms and practice questions that can really help embed this information into your brain. 

Adrenergic Bronchodilators Practice Questions:

1. What is an adrenergic bronchodilator?
It is an agent that stimulates sympathetic nervous fibers, which allows relaxation of smooth muscle in the airway. It is also known as a sympathomimetic bronchodilator or B2 agonist.

2. What happens during a-receptor stimulation?
It causes vasoconstriction and vasopressor effect; in the upper airway (nasal passages), this can provide decongestion.

3. What is the asthma paradox?
Refers to the increasing incidence of asthma morbidity, and especially asthma mortality, despite advances in the understanding of asthma and availability of improved drugs to treat asthma.

4. What happens during B1-receptor stimulation?
Causes increased myocardial conductivity, heart rate, and contract force.

5. What happens during B2-receptor stimulation?
Causes relaxation of bronchial smooth muscle, with some inhibition of inflammatory mediator release and stimulation of mucociliary clearance.

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6. What is bronchospasm?
Narrowing of the bronchial airways caused by contraction of smooth muscles.

7. What are catecholamines?
Group of similar compounds having sympathomimetic action and they mimic the actions of epinephrine causing increase HR, smooth muscle relaxation of bronchioles and skeletal muscle blood vessels. It is used for tachycardia, elevated BP, smooth muscle relaxation, glycogenolysis, skeletal muscle tremor and CNS stimulation. Duration is 1.5 to 3 hours and inactivated by gut/liver, heat, air and light.

8. What is cyclic adenosine 3′ and 5′-monophosphate cAMP?
Nucleotide produced by B2-receptor stimulation. It affects many cells, but causes relaxation of bronchial smooth muscle.

9. What is a sympathomimetic?
It produces effects similar to those of the sympathetic nervous system.

10. What is a short-acting B2 agonist?
Albuterol, levalbuterol, or metaproterenol are indicated for relief of acute reversible airflow obstruction in asthma or other obstructive airway diseases like COPD.

11. What diseases are treated with long-acting agents such as salmeterol, formoterol, arformoterol, indacaterol, and olodaterol?
The maintenance of bronchodilation and control of bronchospasm and nocturnal symptoms in asthma or other obstructive diseases like COPD.

12. What is racemic epinephrine?
Used as in inhaled aerosol or by direct lung instillation and control airway bleeding during endoscopy to reduce airway swelling. It is used for the strong a-adrenergic vasoconstriction effect and for reducing airway swelling after extubation. It is also done during epiglottitis, croup, or bronchiolitis and to control airway bleeding during endoscopy.

13. What is the duration of racemic epinephrine?
It is an ultra-short acting drug (duration less than 3 hours).

14. What types of drugs are albuterol, levalbuterol, and metaproterenol?
Short-acting (duration 4 to 6 hours).

15. What types of drugs are salmeterol, formoterol, arformoterol, indacatferol, olodaterol?
Long-acting (duration 12 to 24 hours).

16. What should be done by the respiratory therapist before a treatment?
Assess the effectiveness of drug therapy b, monitor flow rates, perform a respiratory assessment, and assess pulse.

17. What should be done by the respiratory therapist during a treatment?
Assess patient subjective reaction, assess arterial blood gases sat, and note the effect of B agonists.

18. What is a benefit of Xopenex?
Does not affect heart rate.

19. What is Brovana?
It is a long-acting inhalation solution given for COPD and has to be refrigerated. Arformoterol (nebulizer solution), duration: up to 12 hours, use: maintenance treatment of COPD and asthma not controlled by corticosteroids.

20. What is the FiO2 of room air?

21. What is Micronefrin?
The brand name of Racemic Epinephrine

22. What is the dose of Racemic Epinephrine?
0.5ml of 2.25%/2.5ml NS.

23. What kind of adrenergic bronchodilator is racemic and epinephrine?
Ultra-short-acting (acute therapy).

24. What are the brand names of albuterol?
Accuneb, Ventolin, Proventil, ProAir, and Vospire.

25. What are the modes of delivery for albuterol?
SVN, MDI, and tablet.

26. What is the dose for SVN albuterol?
0.5ml of 0.5%/2.5ml NS.

27. What is the dose for MDI albuterol?
90 ug/puff.

28. What is the brand name of levalbuterol?

29. What are the modes of delivery for levalbuterol?
SVN and MDI.

30. What is the dose for SVN levalbuterol?
0.63mg/3ml NS and 1.25mg/3ml NS.

31. What is the dose for MDI levalbuterol?

32. What kind of adrenergic bronchodilator are levalbuterol and albuterol?
Short-acting (acute therapy).

33. What is the mode of delivery for arformoterol?

34. What is the SVN dose for arformoterol?
15 ug/2ml NS

35. What are the brand names for formoterol?
Perforomist and foradil.

36. What are the modes of delivery for formoterol?
SVN and DPI.

37. What is the SVN dose for formoterol?
20 ug/2ml NS.

38. What is the DPI dose for formoterol?
12 ug/inhalation.

39. What is the Brand name for salmeterol?

40. What is the mode of delivery for salmeterol?

41. What is the DPI dose of salmeterol?
50 ug/inhalation.

42. What type of adrenergic bronchodilator are arformoterol, formoterol, and salmeterol?
Long-acting (Maintenance Therapy).

43. What are the indications for adrenergic bronchodilators?
Asthma, bronchitis, emphysema, bronchiectasis, and obstructive airway diseases.

44. What are the indications for short-acting agents?
Acute reversible airflow obstruction.

45. What are examples of short-acting agents?
Albuterol, levalbuterol, and metaproterenol.

46. What are the indications for long-acting agents?
Maintenance bronchodilation, control bronchospasm, and control nocturnal symptoms.

47. What are examples of long-acting agents?
Salmeterol, formoterol, arformoterol, indacaterol, and olodaterol.

48. What is used to treat postextubation strider?
Racemic epinephrine.

49. What is used to treat epiglottitis, croup, and bronchiolitis?
Racemic epinephrine.

50. What is an ultra-short acting drug?
Duration <3 hours. Example is racemic epinephrine.

51. What is a short-acting drug?
Duration 4 to 6 hours. Examples are albuterol, levalbuterol, and metaproterenol.

52. What is a long-acting drug?
Duration 12 to 24 hours. Examples are salmeterol, formoterol, arformoterol, indacaterol, and olodarerol.

53. What is epinephrine?
Potent catecholamine bronchodilator and stimulates alpha and beta receptors. It helps in vasoconstriction of peripheral blood vessels.

54. What are the side effects of epinephrine?
Tachycardia, elevated blood pressure, tremor, headaches, and insomnia.

55. What is a characteristic of contact B-adrenergic agents?
They offer less frequent dosing and nocturnal protection.

56. What is performist/foradil?
B2-selective agonist (SVN and DPI), short peak effect 3 minutes, duration of up to 12 hours and used for: asthma, exercise induced bronchospasm (both 5yrs or older), and COPD.

57. What are the safety concerns of long-acting B2 agonists?
Not to be used with a controller medicine, only by patients on low dose or medium dose ICS and should only be used short term and if patients are not controlled by ICS.

58. What does an a-receptor do?
Vasoconstriction effect.

59. What does a B1-receptor do?
Increase HR and contractile force.

60. What does a B2-receptor do?
Relaxation of bronchial smooth muscle.

61. What is the purpose of continuous nebulization of albuterol?
Management of asthma reduces the need for frequent therapist attendance and dose: 10-15 mg/hour.

62. What are the complications of continuous nebulization of albuterol?
Cardiac arrhythmias, hypokalemia, hyperglycemia, and tremor.

63. What is good about oral delivery?
Easy to use/short admin time/reproducibility and controlled dosage. The longer onset of action, systematic side effects, and loss due to the first pass of the liver.

64. What are the side effects of albuterol?
Tremor, cardiac effects, tolerance to bronchodilator effect, loss of Broncho protection, CNS effects, fall in PaO2, metabolic disturbances, propellant toxicity, and sensitivity to additives

65. What are the two types of ultrashort-acting drugs involved with adrenergic bronchodilators?
Epinephrine and racemic epinephrine.

66. What are the trade names for epinephrine?
Primatene mist, adrenalin chloride, asthmahaler and medihaler-epi.

67. What is the onset, peak, and duration of epinephrine?
Onset: 3-5 mins; Peak: 5-20 mins; and, duration: 1-3 hours.

68. What are the trade names of racemic epinephrine?
Micronephrine, nephron and asthmanefrin.

69. What is the onset, peak, and duration of racemic epinephrine?
Onset: 3-5 mins; Peak: 5-20 mins; and, duration: .5-2 hours.

70. What are the dosages needed when prescribing racemic epinephrine (solutions, mL, and mg)?
2.25% solution, .025-0.5 mL and 5.63-11.25 mg, QID.

71. What are the seven short-acting drugs associated with adrenergic bronchodilators?
Albuterol sulfate, pirbuterol, levalbuterol, isoproterenol, terbutaline, isoetharine and bitolterol.

72. What are the two trade names associated with metaproterenol?
Alupent and metraprel.

73. What are the trade names associated with albuterol sulfate?
Ventolin, Ventolin HFA, Proventil HFA, Proventil, volmax, ProAir HFA, Vospire ER, AccuNeb and Airet.

74. What are the dosages needed when distributing albuterol sulfate?
SNV: 0.5% solution; 2.5 mg QID; (10 mg for K+tx) and MDI: 90 micrograms/puff QID.

75. What are the onset, duration, and peak of albuterol sulfate?
Onset: 15 mins; peak: 30-60 mins; and, duration: 5-8 hours.

76. What are the two trade names associated with pirbuterol?
Maxair and maxair autohaler.

77. What are the two trade names associated with levabuterol?
Xopenex HFA and Xopenex.

78. What is the dosage amount of Xopenex HFA?
MDI: 45 micrograms/puffs and TID/QID.

79. What are the onset, peak, and duration of Xopenex HFA?
Onset: 15 minutes; Peak: 30-60 minutes; and, duration: 5-8 hours.

80. What is the dosage amount of Xopenex?
Adult: 1.25 mg; Ped: 0.63 mg; and, TID.

81. What are the three trade names associated with isoproterenol?
Isuprel, isuprel mistometer, and medihaler-iso.

82. What are the two trade names associated with isoetharine?
Bronkometer and bronkosol.

83. What is the trade name associated with bitolterol?

84. What are the three long-acting drugs associated with adrenergic bronchodilators?
Salmeterol, formoterol, and arformoterol.

85. What is the trade name associated with salmeterol?
Serevent diskus.

86. What is the dosage amount of salmeterol?
DPI: 50 micrograms BID.

87. What are the onset, peak, and duration of salmeterol/Serevent Diskus?
Onset: 20 mins; peak: 3-5 hours; and, duration: 12 hours.

88. What are the trade names associated with arformoterol?
Brovana and fortadil certihaler.

89. Where are alpha-adrenergic receptors usually found when they are stimulated by epinephrine or non-epinephrine?
The smooth muscle membranes.

90. Where are beta-adrenergic receptors found?
On cardiac muscles and some smooth muscle.

91. What does Beta 1 – (cardiac muscles) do when stimulated by epinephrine or norepinephrine?
They increase the heart rate and strength of contraction.

92. What causes Beta 2- (smooth muscle in the lungs) when stimulated by epinephrine?
Vasodilatation of certain vessels and bronchodilation of the bronchial smooth muscles.

93. What are the two main types of classifications that affect the sympathetic system?
Sympathomimetic and sympatholytic.

94. What do sympathomimetics do to the body?
Increase BP, increase HR and Broncho dilate.

95. How do drugs, including epinephrine and norepinephrine, produce contractions of the smooth muscle?
They do so by stimulating the alpha receptors.

96. What happens when using drugs containing epinephrine stimulate both the alpha and the beta receptors?
Relaxation of the bronchial smooth muscle Beta 2 along with the alpha stimulation effects and the Beta.

97. What do sympatholytic drugs do?
They block the sympathothetic system, decrease in BP, and decrease in HR. They are used for: hypertension, angina, and certain cardiac arrhythmias.

98. What is the function of alpha receptors?
Generally excite, with the exception of the intestine and CNS receptors, where inhibition or relaxation occur.

99. Where are alpha sympathetic receptors found?
On peripheral blood vessels.

100. What does the stimulation of alpha sympathetic receptors cause?

101. What is the function of beta receptors?
Generally inhibit or relax, with the exception of the heart where stimulation occurs.

102. Where is beta 1 receptors located?
The heart as it increases the rate and contractile force.

103. Where is beta 2 receptors located?
The lungs; bronchial, vascular, and smooth muscle. It relaxes bronchial smooth muscle and vascular beds of skeletal muscle.

104. How does the sympathetic nervous system control bronchial smooth muscle tone?
By circulating epinephrine and norepinephrine.

105. What does epinephrine stimulate?
Alpha and beta receptors.

106. What does norepinephrine stimulate?
Primarily alpha receptors.

107. What do parasympathetic vagal nerves innervate?
The lungs.

108. What do vagus nerves in the lungs release?

109. What are short-acting beta 2 agonists (levalbuterol, albuterol) indicated for?
Relief of acute reversible airflow obstruction, rescue agents or relievers, COPD and asthma.

110. What are indications for long-acting agents (salmeterol)?
Maintenance of bronchodilation, control of bronchospasm, nocturnal symptoms and controllers.

111. When is racemic epinephrine used?
To reduce airway swelling after: extubation, epiglottitis, croup, bronchiolitis, and control airway bleeding during endoscopy.

112. How long do ultrashort-acting bronchodilators last?
Less than 3 hours. These are epinephrine and racemic epinephrine.

113. How long do short-acting bronchodilators last?
4-6 hours. These are albuterol, levalbuterol, metaproterenol, and pirbuterol.

114. How long do long-acting bronchodilators last?
12 hours: Salmeterol.

115. What does epinephrine stimulate?
Alpha and beta receptors.

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116. Where is epinephrine stored?
Adrenal medulla.

117. What is the onset of epinephrine?

118. What is the duration of epinephrine?

119. What is epinephrine typically used for?
Acute asthma, post-extubation, and airway edema.

120. What are examples of catecholamines?
Epinephrine, Isoproterenol, Isoetharine and Bitolterol.

121. What are examples of non-catecholamines?
Metaproterenol, Terbutaline, Albuterol, Pirbuterol and Salmeterol.

122. How will patients sputum appear after using aerosols of catecholamines?

123. What are resorcinol and saligenin?
Increased duration of action (up to 6 hours), may be taken orally and minimal beta 1 side effects.

124. What are the adverse side effects of adrenergic bronchodilators?
Tremor, palpitations, tachycardia, headache, insomnia, increased BP, nervousness, nausea, tolerance, decreased PaO2 as O2 is going to airways that are not open yet, hypokalemia and propellant induced bronchospasm.

125. What are tremors caused by?
They are caused by the stimulation of beta-2 receptors in skeletal muscle.

Final Thoughts

And that wraps up our complete study guide on Beta-2 Adrenergic Agonist Bronchodilators. I truly hope that this information, including the practice questions, was helpful for you.

As I mentioned before, this is definitely a class of medications that each medical professional should be familiar with. This is especially true for Respiratory Therapists. Thank you so much for reading and as always, breathe easy my friend. 

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The following are the sources that were used while doing research for this article:

  • Faarc, Gardenhire Douglas EdD Rrt-Nps. Rau’s Respiratory Care Pharmacology. 10th ed., Mosby, 2019. [Link]
  • Faarc, Kacmarek Robert PhD Rrt, et al. Egan’s Fundamentals of Respiratory Care. 12th ed., Mosby, 2020. [Link]
  • Reed, C. “Adrenergic Bronchodilators: Pharmacology and Toxicology.” PubMed, Aug. 1985,
  • “Beta 2 Agonists – StatPearls – NCBI Bookshelf.” StatPearls,

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