1. Antihistamines, Decongestants, Antitussives, and Expectorants
Chapter 36
Antihistamines, Decongestants, Antitussives, and Expectorants
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2. Understanding the Common Cold
Most caused by viral infection (rhinovirus or influenza virus)
Virus invades tissues (mucosa) of upper respiratory tract, causing upper respiratory infection (URI)
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3. Understanding the Common Cold (cont’d)
Excessive mucus production results from the inflammatory response to this invasion
Fluid drips down the pharynx into the esophagus and lower respiratory tract, causing cold symptoms: sore throat, coughing, upset stomach
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4. Understanding the Common Cold (cont’d)
Irritation of nasal mucosa often triggers the sneeze reflex
Mucosal irritation also causes release of several inflammatory and vasoactive substances, dilating small blood vessels in the nasal sinuses and causing nasal congestion
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5. Treatment of the Common Cold
Involves combined use of antihistamines, nasal decongestants, antitussives, and expectorants
Treatment is symptomatic only, not curative
Symptomatic treatment does not eliminate the causative pathogen
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6. Treatment of the Common Cold (cont’d)
Difficult to identify whether cause is viral or bacterial
Treatment is “empiric therapy,” treating the most likely cause
Antivirals and antibiotics may be used, but a definite viral or bacterial cause may not be easily identified
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7. Classroom Response Question
The common cold is treated with empiric therapy, which means:
the medications cure the cold.
the medications only treat the symptoms.
herbal medications are useful to eliminate symptoms.
it is prevented with careful use of medications.
Correct answer: B
Rationale: There is no cure for the common cold, and the efficacy of herbal products is not proven. Treatment rendered can only treat the presenting clinical symptoms.
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8. Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Antihistamines
Drugs that directly compete with histamine for specific receptor sites
Two histamine receptors
H1 (histamine1)
H2 (histamine2)
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9. Antihistamines (cont’d)
H1 antagonists are commonly referred to as antihistamines
Examples: chlorpheniramine, fexofenadine (Allegra), loratadine (Claritin), cetirizine (Zyrtec),diphenhydramine (Benadryl)
Antihistamines have several properties
Antihistaminic
Anticholinergic
Sedative
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10. Antihistamines (cont’d)
H2 blockers or H2 antagonists
Used to reduce gastric acid in peptic ulcer disease
Examples: cimetidine (Tagamet), ranitidine (Zantac), famotidine (Pepcid), nizatidine (Axid)
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11. Antihistamines: Mechanism of Action
Block action of histamine at H1 receptor sites
Compete with histamine for binding at unoccupied receptors
Cannot push histamine off the receptor if already bound
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12. Antihistamines: Mechanism of Action (cont’d)
The binding of H1 blockers to the histamine receptors prevents the adverse consequences of histamine stimulation
Vasodilation
Increased GI and respiratory secretions
Increased capillary permeability
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13. Antihistamines: Mechanism of Action (cont’d)
More effective in preventing the actions of histamine rather than reversing them
Should be given early in treatment, before all the histamine binds to the receptors
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14. Histamine vs. Antihistamine Effects
Cardiovascular (small blood vessels)
Histamine effects
Dilation and increased permeability (allowing substances to leak into tissues)
Antihistamine effects
Reduce dilation of blood vessels
Reduce increased permeability of blood vessels
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15. Histamine vs. Antihistamine Effects (cont’d)
Smooth muscle (on exocrine glands)
Histamine effects
Stimulate salivary, gastric, lacrimal, and bronchial secretions
Antihistamine effects
Reduce salivary, gastric, lacrimal, and bronchial secretions
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16. Histamine vs. Antihistamine Effects (cont’d)
Immune system (release of substances commonly associated with allergic reactions)
Histamine effects
Mast cells release histamine and other substances, resulting in allergic reactions
Antihistamine effects
Binds to histamine receptors, thus preventing histamine from causing a response
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17. Antihistamines: Other Effects
Skin
Reduce capillary permeability, wheal-and-flare formation, itching
Anticholinergic
Drying effect that reduces nasal, salivary, and lacrimal gland secretions (runny nose, tearing, and itching eyes)
Sedative
Some antihistamines cause drowsiness
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18. Antihistamines: Indications
Management of:
Nasal allergies
Seasonal or perennial allergic rhinitis (hay fever)
Allergic reactions
Motion sickness
Parkinson’s disease
Sleep disorders
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19. Antihistamines: Indications (cont’d)
Also used to relieve symptoms associated with the common cold
Sneezing, runny nose
Palliative treatment, not curative
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20. Antihistamines: Adverse Effects
Anticholinergic (drying) effects, most common
Dry mouth
Difficulty urinating
Constipation
Changes in vision
Drowsiness
Mild drowsiness to deep sleep
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21. Classroom Response Question
Prior to administering an antihistamine to a patient, it is most important for the nurse to assess the patient for a history of which condition?
Chronic urticaria
Motion sickness
Urinary retention
Insomnia
Correct answer: C
Rationale: The anticholinergic effects of antihistamines may cause difficulty urinating. The other answers are potential indications for an antihistamine.
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22. Antihistamines: Two Types
Traditional
Nonsedating
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23. Nonsedating/Peripherally Acting Antihistamines
Developed to eliminate unwanted adverse effects, mainly sedation
Work peripherally to block the actions of histamine; thus, fewer CNS adverse effects
Longer duration of action (increases compliance)
Examples: fexofenadine (Allegra), loratadine (Claritin), cetirizine (Zyrtec)
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24. Traditional Antihistamines
Older
Work both peripherally and centrally
Have anticholinergic effects, making them more effective than nonsedating drugs in some cases
Examples: diphenhydramine, brompheniramine, chlorpheniramine, dimenhydrinate, meclizine, promethazine
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25. Antihistamines: Nursing Implications
Gather data about the condition or allergic reaction that required treatment; also assess for drug allergies
Contraindicated in the presence of acute asthma attacks and lower respiratory diseases, such as pneumonia
Use with caution in increased intraocular pressure, cardiac or renal disease, hypertension, asthma, COPD, peptic ulcer disease, BPH, or pregnancy
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26. Antihistamines: Nursing Implications (cont’d)
Instruct patients to report excessive sedation, confusion, or hypotension
Instruct patients to avoid driving or operating heavy machinery; advise against consuming alcohol or other CNS depressants
Instruct patients not to take these medications with other prescribed or over-the-counter medications without checking with prescriber
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27. Antihistamines: Nursing Implications (cont’d)
Best tolerated when taken with meals—reduces GI upset
If dry mouth occurs, teach patient to perform frequent mouth care, chew gum, or suck on hard candy (preferably sugarless) to ease discomfort
Monitor for intended therapeutic effects
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28. Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Nasal Congestion
Excessive nasal secretions
Inflamed and swollen nasal mucosa
Primary causes
Allergies
Upper respiratory infections (common cold)
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29. Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Decongestants: Types
Three main types are used
Adrenergics
Largest group
Sympathomimetics
Anticholinergics
Less commonly used
Parasympatholytics
Corticosteroids
Topical, intranasal steroids
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30. Decongestants: Types (cont’d)
Two dosage forms
Oral
Inhaled/topically applied to the nasal membranes
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31. Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Oral Decongestants
Prolonged decongestant effects, but delayed onset
Effect less potent than topical
No rebound congestion
Exclusively adrenergics
Example: pseudoephedrine (Sudafed)
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32. Topical Nasal Decongestants
Topical adrenergics
Prompt onset
Potent
Sustained use over several days causes rebound congestion, making the condition worse
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33. Topical Nasal Decongestants (cont’d)
Adrenergics
phenylephrine (Neo-Synephrine)
Intranasal steroids
beclomethasone dipropionate (Beconase), budesonide (Rhinocort), flunisolide (Nasalide), fluticasone (Flonase), triamcinolone (Nasacort), ciclesonide (Omnaris)
Intranasal anticholinergic
ipratropium (Atrovent)
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34. Nasal Decongestants: Mechanism of Action
Site of action: blood vessels surrounding nasal sinuses
Adrenergics
Constrict small blood vessels that supply upper respiratory tract structures
As a result these tissues shrink, and nasal secretions in the swollen mucous membranes are better able to drain
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35. Nasal Decongestants: Mechanism of Action (cont’d)
Nasal steroids
Antiinflammatory effect
Work to turn off the immune system cells involved in the inflammatory response
Decreased inflammation results in decreased congestion
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36. Nasal Decongestants: Drug Effects
Shrink engorged nasal mucous membranes
Relieve nasal stuffiness
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37. Nasal Decongestants: Indications
Relief of nasal congestion associated with
Acute or chronic rhinitis
Common cold
Sinusitis
Hay fever
Other allergies
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38. Nasal Decongestants: Indications (cont’d)
May also be used to reduce swelling of the nasal passage and facilitate visualization of the nasal/pharyngeal membranes before surgery or diagnostic procedures
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39. Nasal Decongestants: Adverse Effects
Adrenergics Steroids
Nervousness Local mucosal dryness
Insomnia and irritation
Palpitations
Tremors
(Systemic effects caused by adrenergic stimulation
of the heart, blood vessels, and CNS)
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40. Nasal Decongestants: Nursing Implications
Decongestants may cause hypertension, palpitations, and CNS stimulation—avoid in patients with these conditions
Patients on medication therapy for hypertension should check with their prescriber before taking over-the-counter decongestants
Assess for drug allergies
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41. Nasal Decongestants: Nursing Implications (cont’d)
Patients should avoid caffeine and caffeine-containing products
Report a fever, cough, or other symptoms lasting longer than a week
Monitor for intended therapeutic effects
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42. Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Cough Physiology
Respiratory secretions and foreign objects are naturally removed by the:
Cough reflex
Induces coughing and expectoration
Initiated by irritation of sensory receptors in the respiratory tract
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43. Two Basic Types of Cough
Productive cough
Congested, removes excessive secretions
Nonproductive cough
Dry cough
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44. Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Coughing
Most of the time, coughing is beneficial
Removes excessive secretions
Removes potentially harmful foreign substances
In some situations, coughing can be harmful, such as after hernia repair surgery
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45. Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Antitussives
Drugs used to stop or reduce coughing
Opioid and nonopioid
Used only for nonproductive coughs!
May be used in cases where coughing is harmful
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46. Antitussives: Mechanism of Action
Opioids
Suppress the cough reflex by direct action on the cough center in the medulla
Examples:
codeine (Robitussin A-C, Dimetane-DC)
hydrocodone
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47. Antitussives: Mechanism of Action (cont’d)
Nonopioids
Suppress the cough reflex by numbing the stretch receptors in the respiratory tract and preventing the cough reflex from being stimulated
Examples:
benzonatate (Tessalon Perles)
dextromethorphan (Vicks Formula 44, Robitussin-DM)
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48. Antitussives: Indications
Used to stop the cough reflex when the cough is nonproductive and/or harmful
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49. Antitussives: Adverse Effects
benzonatate
Dizziness, headache, sedation, nausea, and others
dextromethorphan
Dizziness, drowsiness, nausea
Opioids
Sedation, nausea, vomiting, lightheadedness, constipation
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50. Antitussives: Nursing Implications
Perform respiratory and cough assessment, and assess for allergies
Instruct patients to avoid driving or operating heavy equipment because of possible sedation, drowsiness, or dizziness
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51. Antitussives: Nursing Implications (cont’d)
Report any of the following symptoms to the caregiver:
Cough that lasts more than a week
A persistent headache
Fever
Rash
Antitussive drugs are for nonproductive coughs
Monitor for intended therapeutic effects
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52. Classroom Response Question
A 94-year-old patient has a severe dry cough. He has coughed so hard that the muscles in his chest are hurting. He is unsteady on his feet and slightly confused. Which drug would be the best choice for this patient’s cough?
benzonatate (Tessalon Perles) capsules
dextromethorphan (Robitussin-DM) oral solution
codeine cough syrup
guaifenesin (Mucinex)
Correct answer: B
Rationale: Dextromethorphan does not cause respiratory or central nervous system depression, and it is not an opioid. Guaifenesin is an expectorant that is used to thin excessive mucus, which this patient does not have.
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53. Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Expectorants
Drugs that aid in the expectoration (removal) of mucus
Reduce the viscosity of secretions
Disintegrate and thin secretions
Example: guaifenesin (Mucinex)
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54. Expectorants: Mechanisms of Action
Reflex stimulation
Direct stimulation
Final result: thinner mucus that is easier to remove
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55. Expectorants: Mechanism of Action (cont’d)
Reflex stimulation
Drug causes irritation of the GI tract
Loosening and thinning of respiratory tract secretions occur in response to this irritation
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56. Expectorants: Mechanism of Action (cont’d)
Direct stimulation
The secretory glands are stimulated directly to increase their production of respiratory tract fluids
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57. Expectorants: Drug Effects
By loosening and thinning sputum and bronchial secretions, the tendency to cough is indirectly diminished
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58. Expectorants: Indications
Used for the relief of productive coughs associated with:
Common cold
Bronchitis
Laryngitis
Pharyngitis
Coughs caused by chronic paranasal sinusitis
Pertussis
Influenza
Measles
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59. Expectorants: Nursing Implications
Expectorants should be used with caution in the elderly or those with asthma or respiratory insufficiency
Patients taking expectorants should receive more fluids, if permitted, to help loosen and liquefy secretions
Report a fever, cough, or other symptoms lasting longer than a week
Monitor for intended therapeutic effects
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60. Herbal Products: Echinacea
Reduces symptoms of the common cold and recovery time
Adverse effects
Dermatitis
GI disturbance
Dizziness
Headache
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61. Classroom Response Question
A patient with a tracheostomy developed pneumonia. It is very difficult for the patient to cough up the thick, dry secretions he has developed. The nurse identifies which drug as being most effective in helping this patient?
benzonatate (Tessalon Perles) capsules
dextromethorphan (Robitussin-DM) oral solution
codeine cough syrup
guaifenesin (Mucinex)
Correct answer: D
Rationale: Expectorants such as guaifenesin aid in the expectoration (i.e., coughing up and spitting out) of excessive mucus that has accumulated in the respiratory tract by breaking down and thinning out the secretions.
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Elsevier items and derived items © 2009, 2005, 2001 by Saunders, an imprint of Elsevier Inc.