Chapter 76

Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.

Chapter 76

Drugs for Asthma

Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc. 2

Asthma Chronic inflammatory disorder of the airway Characteristic signs and symptoms

Sense of breathlessness Tightening of the chest Wheezing Dyspnea Cough

Cause: immune-mediated airway inflammation


Pathophysiology Symptoms of asthma result from a

combination of inflammation and bronchoconstriction, so treatment must address both components


Overview of Drugs for Asthma Two main pharmacologic classes

Anti-inflammatory agents• Glucocorticoids (prednisone)

Bronchodilators• Beta2 agonists (albuterol)


Inhalation Drug Therapy Three obvious advantages

Therapeutic effects are enhanced Systemic effects are minimized Relief of acute attacks is rapid

Three types Metered-dose inhalers (MDIs) Dry-powder inhalers (DPIs) Nebulizers


Anti-Inflammatory Drugs Foundation of asthma therapy Taken daily for long-term control Principal anti-inflammatory drugs are the

glucocorticoids


Anti-Inflammatory Drugs: Glucocorticoids

Include budesonide and fluticasone Considered the most effective anti-asthma drugs

available Reduce bronchial hyperreactivity Also decrease airway mucus production and

increase the number of bronchial beta2 receptors as well as their responsiveness to beta2 agonists.

Usually administered by inhalation, but IV and oral are also options



Mechanism of action = Suppress inflammation Decreased synthesis and release of inflammatory

mediators Decreased infiltration and activity of inflammatory

cells Decreased edema of the airway mucosa



Adverse effects Minor when taken acutely Can be severe when used long-term (adrenal

suppression, osteoporosis, hyperglycemia, and others)


Anti-Inflammatory Drugs: Leukotriene Modifiers

Suppress effects of leukotrienes Less effective than inhaled glucocorticoids Available agents

Zileuton (Zyflo) Zafirlukast (Accolate) Montelukast (Singulair)


Anti-Inflammatory Drugs: Cromolyn

Used for prophylaxis, not for quick relief Suppresses inflammation; not a

bronchodilator Route—inhalation

Nebulizer MDI

Adverse effects Safest of all antiasthma medications Cough Bronchospasm


Bronchodilators Provide symptomatic relief but do not alter

the underlying disease process (inflammation)

In almost all cases, patient taking a bronchodilator should also be taking a glucocorticoid for long-term suppression of inflammation

Principal bronchodilators are the beta2-adrenergic agonists


Bronchodilators: Beta2-Adrenergic Agonists

Include albuterol, salmeterol, terbutaline Most effective drugs for relief of acute

bronchospasm and prevention of exercise-induced bronchospasm

Use in asthma: both quick relief and long-term control



Adverse effects Inhaled preparations

• Systemic effects: tachycardia, angina, and tremor Oral preparations

• Excessive dosage: angina pectoris, tachydysrhythmias• Tremor



Mechanism of action Activate beta2 receptors in smooth muscle of lung,

promoting bronchodilation and thereby relieving bronchospasm

Also suppress histamine release in lung and increase ciliary motility


Bronchodilators: Methylxanthines Theophylline

Benefits derive primarily from bronchodilation Narrow therapeutic index Plasma level 10 to 20 mcg/mL Toxicity is related to theophylline levels

Other methylxanthines include aminophylline and dyphylline


Glucocorticoid/LABA Combinations

Available combinations Fluticasone/salmeterol (Advair) Budesonide/formoterol (Symbicort)

Indicated for long-term maintenance in adults and children

Not recommended for initial therapy

LABA = long-acting beta2 agonist.


Management of Chronic Asthma Tests of lung function

Forced expiratory volume in 1 second (FEV1) Forced vital capacity (FVC) Peak expiratory flow (PEF)


Management of Chronic Asthma Four classes of chronic asthma

Intermittent Mild persistent Moderate persistent Severe persistent


Management of Chronic Asthma Treatment goals

Reducing impairment Reducing risk


Management of Chronic Asthma Long-term drug therapy

Agents for long-term control (eg, inhaled glucocorticoids)

Agents for quick relief of ongoing attack (eg, inhaled SABAs)


Management of Chronic Asthma Stepwise therapy

Step chosen for initial therapy is based on pretreatment classification of asthma severity

Moving up or down a step is based on ongoing assessment of asthma control


Management of Chronic Asthma Important to reduce exposure to allergens

and triggers Sources of allergens: house dust mites, pets,

cockroaches, mold Factors that can exacerbate asthma: tobacco

smoke, wood smoke, household sprays


Drugs for Acute Severe Exacerbations

Requires immediate attention Goal is to relieve airway obstruction and

hypoxemia, and normalize lung function as quickly as possible.

Initial therapy consists of• Giving oxygen to relieve hypoxemia• Giving a systemic glucocorticoid to reduce airway

inflammation• Giving a nebulized high-dose SABA to relieve airflow

obstruction• Giving nebulized ipratropium to further reduce airflow

obstruction.


Reducing Exposure to Allergens and Triggers

Measures to control or avoid dust mites and their feces include Encasing the patient’s pillow, mattress, and box

spring with covers that are impermeable to allergens

Washing all bedding and stuffed animals weekly in a hot-water wash cycle (130 °F)

Removing carpeting or rugs from the bedroom Avoiding sleeping or lying on upholstered furniture Keeping indoor humidity below 50%

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