Chapter 26
Respiratory System Drugs and
Antihistamines
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Introduction
• Respiratory diseases and disorders
– According to the American Lung Association,
lung disease is the third leading cause of
death in the U.S.
– Respiratory diseases range from mild and
self-limiting such as the common cold, to lifethreatening such as bacterial pneumonia,
pulmonary embolism, and lung cancer
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Introduction (cont’d.)
• Therapeutic measures for respiratory
distress
– Oxygen therapy
– Respiratory stimulants
– Bronchodilators
– Corticosteroids
– Mucolytics and expectorants
– Antitussives
– Smoking cessation
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Introduction (cont’d.)
• The following slides discuss various
respiratory system drugs and
antihistamines
– Refer to the chapter for specific side effects,
contraindications, and interactions
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Oxygen
• Oxygen treatment
– Used therapeutically for hypoxia (insufficient
oxygen supply to the tissues)
– Decreases the workload of the heart and
respiratory system (especially during distress)
– Treats heart and lung diseases and some
central nervous system (CNS) conditions with
respiratory difficulty or failure
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Respiratory Stimulants
• Caffeine citrate
– Treats neonatal apnea of prematurity
• Theophylline
– Administered IV and orally to stimulate
respiration in infants (as an alternative to
caffeine)
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Bronchodilators
• Act by relaxing smooth muscles of the
bronchial tree, relieving bronchospasm
and decreasing the work of breathing
– For symptomatic treatment of acute
respiratory conditions such as asthma and
some forms of COPD
– Can be given orally, parenterally, and by
inhalation
• Metered dose inhalers (MDIs), dry-powder inhalers
(DPIs), and small volume nebulizers (SVNs)
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Bronchodilators (cont’d.)
• Sympathomimetics (adrenergics)
– Potent bronchodilators that increase vital
capacity and decrease airway resistance
– Examples: albuterol, epinephrine, salmeterol,
and others
• Anticholinergics (parasympatholytics)
– Decrease the chemical that promotes
bronchospasm
– Example: Atrovent
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Bronchodilators (cont’d.)
• Xanthines
– Relaxes the smooth muscle of the bronchial
airways and pulmonary blood vessels
– May possess anti-inflammatory actions
– No longer a first-line treatment
• Modest clinical effectiveness
• Need for serum monitoring
• Many adverse effects and drug interactions
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Corticosteroids
• Synthetic corticosteroids
– Relieve inflammation, reduce swelling,
decrease bronchial hyper-responsiveness to
triggers, and suppress symptoms in acute and
chronic reactive airway disease
– Administered systemically for short-term
“bursts” during exacerbations, and
occasionally at the beginning of treatment
until symptoms are controlled
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Corticosteroids (cont’d.)
• Inhaled corticosteroids (SVN aerosol, DPI,
MDI)
– Preferred drug therapy in long-term
prophylactic management of persistent
asthma of various severities
• Intranasal corticosteroids
– Increasingly considered first-line therapy for
most noninfectious types of rhinitis
– Reduce congestion, edema, and inflammation
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Asthma Prophylaxis
• Leukotriene inhibitors
– Zafirlukast (Accolate) and montelukast
(Singulair)
• Oral leukotriene receptor antagonists for asthma
prophylaxis, prevention of exercise-induced
bronchoconstriction, and treatment of chronic
asthma
• Help control inflammatory process of asthma
caused by leukotriene production, thus helping to
prevent asthma symptoms and acute attacks
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Asthma Prophylaxis (cont’d.)
• Mast cell stabilizers
– Rupture or degranulation of mast cells and
subsequent spilling of their chemical mediator
contents cause an inflammatory response that
can lead to asthma
– Stabilizing the mast cell membrane has antiinflammatory actions that modify the release
of mediators from mast cells and eosinophils
– Example: cromolyn
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Mucolytics and Expectorants
• Mucolytics
– Decrease hypersecretion and increase
thinning of pulmonary secretions
– Example: acetylcysteine
• Expectorants
– Increase secretions, reduce viscosity, and
help to expel sputum
– Example: guaifenesin
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Antitussives
• Prevent coughing in patients not requiring
a productive cough
– Most produce cough suppression by acting
centrally on the cough center located in the
brainstem
– Narcotic antitussive example: codeine
– Nonnarcotic antitussive example:
dextromethorphan
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Antihistamines
• Competitively antagonize the histamine1
receptor sites
– Combat the increased capillary permeability
and edema, inflammation, and itch caused by
sudden histamine release
• To treat allergy symptoms
– First generation: diphenhydramine (Benadryl)
– Second-generation: fexofenadine (Allegra)
and loratadine (Claritin)
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Decongestants
• Constrict blood vessels in the respiratory
tract
– Results in shrinkage of swollen mucous
membranes and helps to open nasal airway
passages
– Frequently combined with antihistamines,
analgesics, caffeine, and/or antitussives
– Examples: phenylephrine (Neo-Synephrine)
or pseudoephedrine (Sudafed)
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Safety of Cough/Cold/Allergy
Products
• Many cough and cold formulations
combine several drugs
– Use only if the corresponding symptom is
present and each individual component is
available in the proper strength and dosing
interval a patient may need
– Caution patients to seek advice from a
healthcare professional familiar with each
ingredient
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Smoking Cessation Aids
• Nicotine replacement therapy
– Help lessen withdrawal symptoms by slowly
lowering the level of nicotine in the body
– Examples: Nicorette gum, Commit lozenges,
Nicoderm CQ patch, and Nicotrol inhaler and
nasal spray
• Buproprion
– Oral antidepressant drug (Wellbutrin)
– Associated with decreases in cravings and
lessening of nicotine withdrawal
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Smoking Cessation Aids (cont’d.)
• Varenicline (Chantix)
– Partial nicotine receptor agonist-antagonist
– Alleviates symptoms of nicotine craving and
withdrawal through agonist activity while
inhibiting the effects of repeated nicotine
exposure by its antagonist activity
– Eliminates the pleasurable feelings
associated with smoking
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