Airway Pharmacology: Overview and Practice Questions (2025)

Airway pharmacology plays a critical role in the management of respiratory conditions by focusing on medications that target the respiratory tract.

From asthma and chronic obstructive pulmonary disease (COPD) to acute respiratory distress, understanding how various drugs affect the airways is essential for effective treatment. These medications work by relieving airway obstruction, reducing inflammation, and controlling symptoms to improve breathing.

In this article, we’ll explore the key classes of respiratory medications, their mechanisms of action, and their applications in clinical practice.

What is Airway Pharmacology?

Airway pharmacology involves the study of medications used to manage and treat respiratory conditions by targeting the airways. It focuses on drugs that improve breathing by reducing airway inflammation, relaxing airway muscles, or clearing mucus.

Key medication classes include bronchodilators (e.g., beta-agonists like albuterol), corticosteroids (for reducing inflammation), anticholinergics (for long-term bronchodilation), and mucolytics (for thinning mucus).

Airway pharmacology is crucial for conditions like asthma, chronic obstructive pulmonary disease (COPD), and bronchitis. Treatment regimens often combine medications to address multiple aspects of respiratory disease, ensuring better symptom control and improved patient outcomes.

Airway pharmacology is not only important for the treatment of chronic conditions but also has applications in acute settings such as emergency rooms, where immediate intervention is often required for issues like acute asthma attacks or anaphylaxis affecting the airways.

Note: Understanding airway pharmacology is crucial for healthcare professionals, including physicians, respiratory therapists, and pharmacists, to prescribe the most effective treatments, manage drug interactions, and monitor side effects to improve patient outcomes in respiratory health.

Types of Orally Inhaled Aerosol Drugs

Orally inhaled aerosol drugs are commonly used in the management of respiratory diseases and conditions requiring immediate drug delivery to the lungs.

These aerosol medications can come in different forms, such as metered-dose inhalers (MDIs), dry powder inhalers (DPIs), and nebulizers

Here are some examples of the most common types of inhaled aerosol drugs:

• β-agonist bronchodilators
• Anticholinergic (anti-muscarinic) bronchodilators
• Mucolytic agents
• Corticosteroids
• Nonsteroidal anti-asthma drugs
• Anti-infective agents
• Inhaled pulmonary vasodilators

Watch this video and keep reading to learn more about the different types of inhaled medications used in respiratory care.

β-agonist Bronchodilators

β-agonist bronchodilators are a class of drugs that act on the β2-adrenergic receptors in the smooth muscles lining the airways. Activation of these receptors leads to relaxation of the smooth muscles, resulting in bronchodilation—the widening of the airways.

This provides rapid relief from acute symptoms such as wheezing, shortness of breath, and chest tightness commonly associated with asthma and COPD.

Examples include short-acting agents like albuterol and long-acting agents like salmeterol. Despite their efficacy, overuse can lead to tachycardia, tremors, and increased risk of exacerbations.

Anticholinergic Bronchodilators

Anticholinergic bronchodilators work by inhibiting the action of acetylcholine, a neurotransmitter that causes contraction of airway smooth muscles. By blocking the muscarinic receptors in the airways, these drugs effectively reduce bronchoconstriction. They are often used in combination with β-agonists for conditions like COPD. Examples include ipratropium and tiotropium.

Anticholinergic bronchodilators are generally slower to act compared to β-agonists but have a longer duration of action. Side effects may include dry mouth and, in rare cases, urinary retention.

Mucolytic Agents

Mucolytic agents focus on breaking down the structure of mucus in the respiratory tract, making it easier to expel. These are particularly useful for conditions where mucus build-up can exacerbate breathing problems, such as in chronic bronchitis or cystic fibrosis.

Examples include acetylcysteine and dornase alfa. These agents work by breaking disulfide bonds in the mucus, effectively reducing its viscosity.

This helps in improving mucociliary clearance, making it easier for patients to breathe. However, their use may be associated with side effects like bronchospasm or irritation of the airways.

Corticosteroids

Inhaled corticosteroids are anti-inflammatory agents that reduce the swelling and inflammation in the airways. They are commonly used in the long-term management of chronic respiratory diseases like asthma and COPD to maintain airway patency and prevent exacerbations.

Examples include fluticasone, budesonide, and beclomethasone. These drugs act by binding to glucocorticoid receptors, which in turn modulate gene expression to produce anti-inflammatory effects.

Regular use of inhaled corticosteroids can lead to a significant reduction in the frequency and severity of symptoms, although they may also cause side effects such as oral thrush and hoarseness.

Nonsteroidal Anti-Asthma Drugs

Nonsteroidal anti-asthma drugs, also known as leukotriene modifiers, are primarily used for the prevention and chronic treatment of asthma. Unlike corticosteroids, they do not have steroid-related side effects. Examples include montelukast and zafirlukast.

These drugs work by inhibiting the action of leukotrienes, lipid-derived compounds that induce bronchoconstriction and inflammation in the airways. They are generally taken orally and are useful for patients who either cannot tolerate inhaled corticosteroids or require additional control of symptoms.

Possible side effects may include liver dysfunction and neuropsychiatric symptoms such as agitation or depression.

Anti-Infective Agents

Anti-infective agents for inhalation include antibiotics, antifungals, and antivirals that target respiratory infections directly at the site. These are particularly useful for treating localized infections in the lungs without subjecting the whole body to the drug, thereby reducing systemic side effects.

For example, tobramycin and aztreonam are antibiotics used in the management of chronic Pseudomonas aeruginosa infections in cystic fibrosis patients.

Inhaled anti-infective agents are administered via nebulizers or dry powder inhalers, allowing for high concentrations of the drug to reach the infected areas. However, the risk of developing drug-resistant strains exists and must be carefully managed.

Inhaled Pulmonary Vasodilators

Inhaled pulmonary vasodilators, such as nitric oxide or iloprost, act directly on the pulmonary arteries to dilate them, thereby reducing pulmonary vascular resistance. These agents are primarily used in the treatment of pulmonary arterial hypertension (PAH) and acute hypoxemic respiratory failure, including conditions like acute respiratory distress syndrome (ARDS).

Unlike systemic vasodilators, the inhaled form of these drugs targets the lung vasculature specifically, minimizing systemic side effects like hypotension. However, their use can be limited by the need for specialized delivery systems and close monitoring to manage potential complications like rebound pulmonary hypertension upon discontinuation.

Note: Each of these types of orally inhaled aerosol drugs plays a vital role in the management of various respiratory conditions. They operate via different mechanisms, have distinct pharmacokinetic profiles, and come with their own sets of advantages and limitations.

Airway Pharmacology Practice Questions

1. What are the adverse effects of inhaled corticosteroids?
Systemic adverse effects: adrenal Insufficiency, extrapulmonary allergies, acute asthma, HPA suppression, growth retardation, and osteoporosis. Local adverse effects: oropharyngeal fungal infections, dysphonia, cough, and bronchoconstriction.

2. What are the common inhaled corticosteroid brand names?
Azmacort, Flovent, Pulmicort, Advair, and Symbicort

3. What are the side effects of nonsteroidal anti-asthma drugs?
Cromolyn-like: none; Antileukotrienes: headache, dyspepsia, and liver enzyme elevation; Monoclonal Antibodies: injection site reaction and viral infections

4. What are some adverse effects of using adrenergic bronchodilators?
CFC-induced bronchospasm, dizziness, hypokalemia, loss of bronchoprotection, nausea, tachyphylaxis, worsening ventilation/perfusion ratio, and a decrease in PaO2

5. What are some common side effects of using adrenergic bronchodilators?
Tremor, headache, insomnia, and nervousness

6. What are the adverse effects of Spiriva and Atrovent?
Almost none because they are fully ionized

7. What are some examples of inhaled anti-infective agents?
Pentamidine isethionate (Nebupent), ribavirin (Virazole), tobramycin (TOBI), and zanamivir (Relenza)

8. What are the four advantages of using inhaled aerosols?
(1) Aerosol doses are smaller than systemic doses, (2) The onset of drug action is rapid, (3) Delivery is targeted to the organ requiring treatment, and (4) Systemic effects are often fewer and less severe

9. What are the indications for dornase alfa?
It is used to treat patients with cystic fibrosis and aims to reduce the frequency of infections while improving pulmonary function.

10. What are the indications for inhaled corticosteroids?
They are used for the anti-inflammatory maintenance of asthma and COPD.

11. What are the indications for long-acting (maintenance) agents?
They are used for the maintenance and control of bronchospasm and other symptoms of asthma and COPD.

12. What are the indications for nonsteroidal anti-asthma drugs?
They are used to manage mild to severe persistent asthma and as an alternative to steroidal treatments. They do not provide any benefits for acute asthma episodes.

13. What are the indications for racemic epinephrine?
It is recommended for strong α-adrenergic vasoconstriction effects and is used after extubation. It can also be used to treat epiglottitis, croup, or bronchiolitis, and it is administered to help control airway bleeding during an endoscopy.

14. What are the indications for short-acting (rescue) agents?
They are used for immediate relief of acute reversible airflow obstruction caused by asthma or other obstructive airway diseases.

15. What are the indications for using anticholinergic drugs?
They are used for the maintenance of COPD.

16. What are the indications for using combined anticholinergic and β-agonist bronchodilator drugs?
They are used for COPD patients to provide relief for an airflow obstruction. They are also useful in patients with severe asthma who have not responded well to β-agonist drugs.

17. What are the most common devices used to administer respiratory drugs?
MDI (metered-dose inhaler), SVN (small volume nebulizer), and DPI (dry powder inhaler)

18. What are the three phases of drug action?
Drug administration, pharmacokinetic, and pharmacodynamic

19. What are the three types of nonsteroidal anti-asthma drugs?
Cromolyn-like agents (Cromolyn sodium, Nedocromil sodium), antiLeukotrienes (Zarfirlukast, Zileuton), monoclonal antibodies or anti-IgE agents (Omalizumab).

20. What are the two inhaled vasodilators?
(1) Nitric Oxide (INOmax), which is used for the treatment of neonates with hypoxemic respiratory failure, and (2) Iloprost (Ventavis), which is used for the treatment of pulmonary hypertension

21. What does an α-receptor do?
It causes vasoconstriction and has vasopressor effects, such as increased blood pressure.

22. What does a β1-receptor do?
It causes an increased heart rate and myocardial contractility.

23. What does a β2-receptor do?
It relaxes bronchial smooth muscle, stimulates mucociliary activity, and has some inhibitory action on the release of inflammatory mediators.

24. What is a fully ionized drug?
A drug that is not absorbed across a lipid membrane (e.g., Atrovent)

25. What is a muscarinic drug?
A drug that stimulates ACh receptors, specifically at the parasympathetic nerve-ending sites

26. What is the difference between an agonist and an antagonist?
Agonists are the stimulating agents, while antagonists are the blocking agents.

27. What is an isomer?
Isomers are compounds with the same molecular formula but different structural formulas that compare to the structures of albuterol and levalbuterol.

28. What are sympathetic and parasympathetic receptors?
Sympathetic = adrenergic; Parasympathetic = cholinergic

29. What is a prodrug?
A drug that is not active until it is metabolized

30. What is Combivent?
A medication combination of ipratropium bromide and albuterol

31. What is DuoNeb, and what is its proper dose?
Ipratropium Bromide 0.5 mg and Albuterol 2.5 mg, administered with an SVN

32. When should an inhaled corticosteroid be administered during an asthma attack?
This drug class should not be given during an acute asthma attack because it does not provide short-term relief. Inhaled corticosteroids are maintenance medications.

33. What is the brand name for acetylcysteine?
Mucomyst

34. What is the brand name for Dornase Alfa?
Pulmozyme

35. What is the brand name for ipratropium bromide?
Atrovent

36. What is the brand name for tiotropium bromide?
Spiriva

37. What is the drug administration phase?
It describes the method by which a drug dose is made available to the body.

38. What is the mode of action for cromolyn sodium?
It inhibits the degranulation of mast cells, which prevents the release of histamine and other mediators of inflammation.

39. What is the mode of action for inhaled corticosteroids?
They are lipid-soluble drugs that act on intracellular receptors. The full effect takes multiple hours; therefore, they do not provide instant relief.

40. What is the pharmacodynamic phase?
Describes the mechanism by which a drug molecule causes its effects

41. What is the pharmacokinetic phase?
It describes the time, course, and disposition of a drug in the body.

42. What should a patient know about inhaled corticosteroids?
They are not to be used as a rescue drug.

43. Why is it recommended to administer albuterol with Mucomyst?
Mucomyst is known to cause bronchospasm; therefore, a bronchodilator is needed.

44. What is the most common route of drug administration for a pulmonary patient?
Aerosol therapy

45. What are the advantages of inhaled aerosols?
You can use smaller doses compared to the systemic route; the onset of the drug is rapid; the delivery is targeted to the specific organ needing treatment; and there are fewer systemic side effects

46. What are the disadvantages of inhaled aerosols?
There are more variables that can affect the delivered dose, and there is often a lack of knowledge of device performance by the patient and caregiver.

47. Inhaled bronchoactive aerosols are intended for local effects in the airway, but some undesired systemic effects can result from what?
From the absorption and distribution throughout the body

48. What is the difference between a fully ionized aerosol drug and a non-ionized aerosol drug?
A fully ionized drug has little or no systemic side effects (it is not absorbed across lipid membranes). A non-ionized drug does produce systemic side effects (it is lipid-soluble and diffuses across cell membranes into the bloodstream).

49. What is the L/T ratio?
Lung availability/total systemic availability; quantifies the efficiency of an aerosol drug in the lungs

50. Using the L/T ratio, which aerosol delivery method is more efficient?
MDI (46%) works slightly better than DPI (23%)

51. What are drug effects caused by?
The combination of a drug with a matching receptor

52. What is the usual neurotransmitter in the parasympathetic system?
Acetylcholine

53. What do adrenergic drugs help directly dilate?
The bronchial tree

54. Cholinergic causes what?
Bronchoconstriction

55. What are the indications for short-acting adrenergic agents?
They are rescue drugs that are good for approximately four hours and are used to provide relief for an acute airflow obstruction.

56. What are the indications for long-acting adrenergic agents?
They are drugs that will last approximately 12 hours and are used for the maintenance of obstructive lung diseases.

57. What is the most common use of adrenergic bronchodilators?
To improve the airflow in patients with asthma

58. What happens during beta-1-receptor stimulation?
It causes an increase in heart rate and myocardial contractility.

59. What happens during beta-2-receptor stimulation?
It relaxes bronchial smooth muscle tissue, stimulates mucociliary activity, and has some inhibitory action on the release of inflammatory mediators.

60. Why would you choose Xopenex over albuterol?
Xopenex is indicated over albuterol in patients with tachycardia.

61. What is the most common side effect of beta-2 selective agents?
Tremors

62. How can you evaluate a patient’s response to bronchodilator therapy?
By using pre and post-bronchodilator studies; arterial blood gas (ABG) and pulse oximetry; blood glucose and potassium; and blood pressure

63. What are the two inhaled anticholinergic bronchodilators?
Ipratropium and tiotropium

64. What is combined anticholinergic and beta-agonist indicated for?
Ipratropium bromide and albuterol (DuoNeb) are indicated for the treatment of patients with COPD or asthma.

65. What are the side effects of anticholinergic aerosol agents?
Cough and dry mouth

66. What are the two mucus-controlling agents?
N-acetylcysteine (MucoMyst) and dornase alfa

67. How is N-acetylcysteine administered?
Either by nebulization or direct tracheal installation

68. How does N-acetylcysteine work?
It breaks down the disulfide bonds of the mucus so that the patient can cough it up more easily.

69. What can N-acetylcysteine cause?
It can cause bronchospasm, which is why it should never be given without a bronchodilator.

70. What type of patients are treated with dornase alfa?
Cystic fibrosis

71. What is the mode of action of dornase alfa?
It breaks down protein bonds.

72. What is another name for dornase alfa?
Pulmozyme

73. What is the mode of action of inhaled corticosteroids?
They act on intracellular receptors.

74. What are the three types of drugs that prevent asthma from happening?
(1) Cromolyn sodium, (2) Antileukotrienes, and (3) Monoclonal antibodies or anti-IgE agents

75. What are the indications for nonsteroidal anti-asthma drugs?
They are indicated for the prophylactic management of asthma and offer no benefit for treating an acute airway obstruction.

76. What is pentamidine isethionate?
It is used to treat pneumonia caused by pneumocystis jiroveci, which is seen in patients with AIDS.

77. What is ribavirin?
It is a drug used to treat respiratory syncytial virus (RSV) using a SPAG generator.

78. What is inhaled tobramycin?
It is a drug used to fight pseudomonas aeruginosa in patients with cystic fibrosis.

79. What is inhaled zanamivir?
It is a drug that is used to treat influenza.

80. What is nitric oxide used for?
It is used for the treatment of pulmonary hypertension.

81. The acting length of a bronchodilator refers to what?
It refers to how long the drug lasts.

82. What should be performed before and after the administration of a bronchodilator?
You should test the patient with a peak flow meter before and after administering a breathing treatment to check if the drug is effective.

83. What are the three subgroups of adrenergic bronchodilators?
(1) Ultra-short catecholamine agents, (2) Short-acting non-catecholamine agents, and (3) Long-acting adrenergic bronchodilators

84. What is the major risk of administering a bronchodilator?
The major risk is an increased heart rate. If it increases by more than 20 beats/min, you should stop the treatment and notify the physician.

85. What is the speed of onset for inhaled aerosol drugs?
The onset is rapid.

86. What are the two main types of bronchodilators?
Beta-agonists and anticholinergics.

87. How do beta-agonist bronchodilators work?
They stimulate beta-2 receptors, causing relaxation of bronchial smooth muscle and dilation of airways.

88. What is the role of anticholinergic bronchodilators?
They block muscarinic receptors, preventing bronchoconstriction caused by the parasympathetic nervous system.

89. Why is it important to rinse the mouth after using an inhaled corticosteroid?
To prevent oral thrush and reduce the risk of irritation and fungal infections.

90. What is the most common side effect of inhaled beta-agonists?
Tremors, due to beta-2 receptor stimulation in skeletal muscles.

91. Why should a bronchodilator be given before a corticosteroid in combination therapy?
To open the airways, allowing the corticosteroid to reach deeper into the lungs for better anti-inflammatory action.

92. What does “MDI” stand for, and how is it used?
MDI stands for “Metered-Dose Inhaler,” and it delivers a specific amount of medication in aerosol form directly to the lungs.

93. What is the role of leukotriene modifiers in asthma treatment?
They reduce inflammation and prevent bronchoconstriction by blocking leukotrienes, which are involved in the inflammatory response.

94. What are the main indications for long-acting beta-agonists (LABAs)?
They are used for long-term maintenance of asthma and COPD but should not be used as rescue inhalers.

95. What is the mode of action of mast cell stabilizers like cromolyn sodium?
They prevent the release of histamine and other inflammatory mediators from mast cells, reducing asthma symptoms.

96. Why are combination inhalers commonly prescribed for COPD?
They combine a bronchodilator and corticosteroid to provide both airway relaxation and inflammation reduction.

97. How does ipratropium bromide relieve COPD symptoms?
It blocks acetylcholine at muscarinic receptors, reducing bronchoconstriction and easing airflow.

98. What is the clinical use of omalizumab (Xolair)?
It is used to treat moderate to severe allergic asthma by targeting IgE antibodies that trigger allergic responses.

99. What is the recommended treatment for exercise-induced bronchospasm?
Short-acting beta-agonists (SABAs) taken 15-30 minutes before exercise.

100. How do corticosteroids reduce inflammation in the airways?
They suppress inflammatory responses by inhibiting cytokine production and reducing swelling in the bronchial lining.

Final Thoughts

Airway pharmacology forms the foundation of respiratory care by offering targeted treatments for a wide range of pulmonary conditions.

Understanding how different drug classes work enables healthcare providers to create personalized treatment plans that optimize respiratory function and enhance patients’ quality of life.

With continued advancements in respiratory medicine, airway pharmacology remains at the forefront of managing and improving outcomes for individuals with respiratory diseases.