Chapter 76
Drugs for Asthma
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
Asthma
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Chronic inflammatory disorder of the airway
Characteristic signs and symptoms
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Sense of breathlessness
Tightening of the chest
Wheezing
Dyspnea
Cough
Cause: immune-mediated airway
inflammation
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
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Pathophysiology
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Symptoms of asthma result from a
combination of inflammation and
bronchoconstriction, so treatment must
address both components
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Overview of Drugs for Asthma
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Two main pharmacologic classes
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Anti-inflammatory agents
• Glucocorticoids (prednisone)
Bronchodilators
• Beta2 agonists (albuterol)
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Inhalation Drug Therapy
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Three obvious advantages
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Therapeutic effects are enhanced
Systemic effects are minimized
Relief of acute attacks is rapid
Three types
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Metered-dose inhalers (MDIs)
Dry-powder inhalers (DPIs)
Nebulizers
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Anti-Inflammatory Drugs
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Foundation of asthma therapy
Taken daily for long-term control
Principal anti-inflammatory drugs are the
glucocorticoids
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Anti-Inflammatory Drugs:
Glucocorticoids
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Include budesonide and fluticasone
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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
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Anti-Inflammatory Drugs:
Glucocorticoids
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Mechanism of action = Suppress inflammation
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Decreased synthesis and release of inflammatory
mediators
Decreased infiltration and activity of inflammatory
cells
Decreased edema of the airway mucosa
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
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Anti-Inflammatory Drugs:
Glucocorticoids
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Adverse effects
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Minor when taken acutely
Can be severe when used long-term (adrenal
suppression, osteoporosis, hyperglycemia, and
others)
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Anti-Inflammatory Drugs:
Leukotriene Modifiers
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Suppress effects of leukotrienes
Less effective than inhaled glucocorticoids
Available agents
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Zileuton (Zyflo)
Zafirlukast (Accolate)
Montelukast (Singulair)
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Anti-Inflammatory Drugs:
Cromolyn
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Used for prophylaxis, not for quick relief
Suppresses inflammation; not a
bronchodilator
Route—inhalation
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Nebulizer
MDI
Adverse effects
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Safest of all antiasthma medications
 Cough
 Bronchospasm
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Bronchodilators
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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 beta2adrenergic agonists
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Bronchodilators:
Beta2-Adrenergic Agonists
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Include albuterol, salmeterol, terbutaline
Most effective drugs for relief of acute
bronchospasm and prevention of exerciseinduced bronchospasm
Use in asthma: both quick relief and longterm control
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Bronchodilators:
Beta2-Adrenergic Agonists
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Adverse effects
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Inhaled preparations
• Systemic effects: tachycardia, angina, and tremor
Oral preparations
• Excessive dosage: angina pectoris, tachydysrhythmias
• Tremor
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Bronchodilators:
Beta2-Adrenergic Agonists
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Mechanism of action
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Activate beta2 receptors in smooth muscle of lung,
promoting bronchodilation and thereby relieving
bronchospasm
Also suppress histamine release in lung and
increase ciliary motility
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Bronchodilators: Methylxanthines
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Theophylline
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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
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Glucocorticoid/LABA
Combinations
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Available combinations
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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.
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Management of Chronic Asthma
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Tests of lung function
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Forced expiratory volume in 1 second (FEV1)
Forced vital capacity (FVC)
Peak expiratory flow (PEF)
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Management of Chronic Asthma
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Four classes of chronic asthma
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Intermittent
Mild persistent
Moderate persistent
Severe persistent
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Management of Chronic Asthma
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Treatment goals
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Reducing impairment
Reducing risk
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Management of Chronic Asthma
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Long-term drug therapy
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Agents for long-term control (eg, inhaled
glucocorticoids)
Agents for quick relief of ongoing attack (eg,
inhaled SABAs)
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Management of Chronic Asthma
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Stepwise therapy
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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
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Management of Chronic Asthma
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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
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Drugs for Acute Severe
Exacerbations
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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.
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Reducing Exposure to Allergens
and Triggers
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Measures to control or avoid dust mites and
their feces include
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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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