Chapter 36
Antihistamines, Decongestants,
Antitussives, and Expectorants
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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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2
Understanding the
Common Cold (Cont.)


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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3
Understanding the
Common Cold (Cont.)


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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4
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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5
Treatment of the
Common Cold (Cont.)



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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6
Pediatric Concerns



In 2008, the U.S. Food and Drug Administration
(FDA) issued recommendations that over-thecounter (OTC) cough and cold products not be
given to children younger than 2 years of age.
Oversedation, seizures, tachycardia, and even
death in toddlers
Evidence that such medications are simply not
effective in small children
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7
Pediatric Concerns (Cont.)


Parents are advised to consult their children’s
pediatricians on the best ways to manage these
illnesses.
A 2010 study showed a dramatic decrease in
young children’s emergency department visits
since the 2008 FDA recommendation.
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8
Audience Response System
Question #1
The common cold is treated with empiric therapy.
How can the nurse interpret this meaning?
A. Medications cure the cold.
B. Medications only treat the symptoms.
C. Herbal medications are useful to eliminate
symptoms.
D. Prevention with careful use of medications
NOTE: No input is required to proceed.
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9
Answer to System Question #1
ANS: B
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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10
Supplements and Herbal Products



Vitamin C
Echinacea
Goldenseal
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11
Antihistamines


Drugs that directly compete with histamine for
specific receptor sites
Two histamine receptors


H1 (histamine 1)
H2 (histamine 2)
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12
Anaphylaxis: Severe Allergic Reactions

Release of excessive amounts of histamine can
lead to:



Constriction of smooth muscle, especially in the
stomach and lungs
Increase in body secretions
Vasodilatation and increased capillary permeability,
movement of fluid out of the blood vessels and into
the tissues, and drop in blood pressure and edema
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13
Histamine

Major inflammatory mediator in many allergic
disorders

Allergic rhinitis (e.g., hay fever and mold, dust
allergies)
 Anaphylaxis
 Angioedema
 Drug fevers
 Insect bite reactions
 Urticaria (itching)
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14
Antihistamines and Histamine
Antagonists

H1 antagonists (also called H1 blockers)


Examples: chlorpheniramine, fexofenadine (Allegra),
loratadine (Claritin), cetirizine (Zyrtec),
diphenhydramine (Benadryl)
Antihistamines have several properties

Antihistaminic
 Anticholinergic
 Sedative
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15
Antihistamines

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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16
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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17
Antihistamines:
Mechanism of Action (Cont.)

The binding of H1 blockers to the histamine
receptors prevents the adverse consequences of
histamine stimulation.

Vasodilation
 Increased gastrointestinal (GI) and respiratory secretions
 Increased capillary permeability


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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18
Histamine Versus
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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19
Histamine Versus
Antihistamine Effects (Cont.)

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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20
Histamine Versus
Antihistamine Effects (Cont.)

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: bind to histamine receptors,
thus preventing histamine from causing a response
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21
Antihistamines: Other Effects



Skin: reduce capillary permeability, wheal-andflare 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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22
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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23
Antihistamines: Indications (Cont.)

Also used to relieve symptoms associated with
the common cold

Sneezing, runny nose
 Palliative treatment; not curative
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24
Antihistamines: Contraindications






Known drug allergy
Narrow-angle glaucoma
Cardiac disease, hypertension
Kidney disease
Bronchial asthma, chronic obstructive pulmonary
disease (COPD)
Sole drug therapy during acute asthmatic
attacks

Albuterol or epinephrine
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25
Antihistamines: Contraindications (Cont.)




Peptic ulcer disease
Seizure disorders
Benign prostatic hyperplasia (BPH)
Pregnancy
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26
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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27
Audience Response System
Question #2
Before administering an antihistamine to a patient,
it is most important for the nurse to assess the
patient for a history of which condition?
A.
B.
C.
D.
Chronic urticaria
Motion sickness
Urinary retention
Insomnia
NOTE: No input is required to proceed.
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28
Answer to System Question #2
ANS: C
The anticholinergic effects of antihistamines may
cause difficulty urinating. The other answers are
potential indications for an antihistamine.
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29
Antihistamines: Two Types


Traditional: brompheniramine, chlorpheniramine,
dimenhydrinate, diphenhydramine, meclizine,
and promethazine
Nonsedating: loratadine, cetirizine, and
fexofenadine
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30
Nonsedating/Peripherally Acting
Antihistamines



Developed to eliminate unwanted adverse
effects, mainly sedation
Work peripherally to block the actions of
histamine; thus, fewer central nervous system
(CNS) adverse effects
Longer duration of action (increases
compliance)

Examples: fexofenadine (Allegra),
loratadine (Claritin), cetirizine (Zyrtec)
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31
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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32
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 patients with increased
intraocular pressure, cardiac or renal disease,
hypertension, asthma, COPD, peptic ulcer
disease, BPH, or pregnancy.
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33
Antihistamines:
Nursing Implications (Cont.)



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 OTC medications
without checking with their prescribers.
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34
Antihistamines:
Nursing Implications (Cont.)



Best tolerated when taken with meals; reduces
GI upset
If dry mouth occurs, teach patients 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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35
Nasal Congestion



Excessive nasal secretions
Inflamed and swollen nasal mucosa
Primary causes


Allergies
URIs (common cold)
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36
Decongestants: Types

Three main types are used:



Adrenergics
• Largest group
• Sympathomimetics
Anticholinergics
• Less commonly used
• Parasympatholytics
Corticosteroids
• Topical, intranasal steroids
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37
Decongestants: Types (Cont.)

Two dosage forms


Oral
Inhaled or topically applied to the nasal membranes
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38
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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39
Topical Nasal Decongestants

Topical adrenergics




Prompt onset
Potent
Sustained use over several days causes rebound
congestion, making the condition worse.
Ephedrine, oxymetazoline, phenylephrine, and
tetrahydrozoline
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40
Inhaled Intranasal Steroids and
Anticholinergic Drugs


Not associated with rebound congestion
Often used prophylactically to prevent nasal
congestion in patients with chronic upper
respiratory tract symptoms
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41
Topical Nasal Decongestants

Adrenergics


Intranasal steroids


Ephedrine, oxymetazoline
Beclomethasone dipropionate (Beconase),
budesonide (Rhinocort), flunisolide (Nasalide),
fluticasone (Flonase), triamcinolone (Nasacort),
ciclesonide (Omnaris)
Intranasal anticholinergic

Ipratropium (Atrovent)
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42
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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43
Nasal Decongestants:
Mechanism of Action (Cont.)

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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44
Nasal Decongestants:
Drug Effects


Shrink engorged nasal mucous membranes
Relieve nasal stuffiness
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45
Nasal Decongestants:
Indications

Relief of nasal congestion associated with:






Acute or chronic rhinitis
Common cold
Sinusitis
Hay fever
Other allergies
May also be used to reduce swelling of the nasal
passage and facilitate visualization of the nasal
or pharyngeal membranes before surgery or
diagnostic procedures
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46
Nasal Decongestants:
Contraindications








Drug allergy
Narrow-angle glaucoma
Uncontrolled cardiovascular disease, hypertension
Diabetes and hyperthyroidism
History of cerebrovascular accident or transient
ischemic attacks
Long-standing asthma
BPH
Diabetes
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47
Nasal Decongestants:
Adverse Effects
Adrenergics
Nervousness
Insomnia
Palpitations
Tremors
Steroids
Local mucosal dryness
and irritation
(Systemic effects caused by adrenergic stimulation of the
heart, blood vessels, and CNS)
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48
Nasal Decongestants:
Interactions




Systemic sympathomimetic drugs and
sympathomimetic nasal decongestants are likely
to cause drug toxicity when given together.
Monoamine oxidase inhibitors and
sympathomimetic nasal decongestants raise
blood pressure.
Methyldopa
Urinary acidifiers and alkalinizers
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49
Nasal Decongestants:
Nursing Implications



Patients should avoid caffeine and caffeinecontaining products.
Patients should report a fever, cough, or other
symptoms lasting longer than 1 week.
Monitor for intended therapeutic effects.
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50
Audience Response System
Question #3
Before administering an adrenergic decongestant,
it is most important for the nurse to assess the
patient for a history of which condition?
A.
B.
C.
D.
Cataracts
Gastric ulcer
Diabetes mellitus
Hypothyroidism
NOTE: No input is required to proceed.
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51
Answer to System Question #3
ANS: C
Adrenergic drugs are contraindicated in patients with
narrow-angle glaucoma, uncontrolled cardiovascular
disease, hypertension, diabetes, and hyperthyroidism.
They are also contraindicated when the patient is
unable to close his or her eyes (e.g., after a
cerebrovascular accident), as well as in patients with a
history of cerebrovascular accident or transient
ischemic attacks, long-standing asthma, BPH, or
diabetes.
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52
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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53
Two Basic Types of Cough


Productive cough: congested; removes
excessive secretions
Nonproductive cough: dry cough
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54
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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55
Antitussives




Drugs used to stop or reduce coughing
Opioid and nonopioid
Used only for nonproductive coughs!
May be used in cases when coughing is harmful
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56
Antitussives:
Mechanism of Action

Opioids

Suppress the cough reflex by direct action on the
cough center in the medulla
 Analgesia, drying effect on the mucosa of the
respiratory tract, increased viscosity of respiratory
secretions, reduction of runny nose and postnasal
drip
 Examples
• Codeine
• Hydrocodone
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57
Antitussives:
Mechanism of Action (Cont.)

Nonopioids

Dextromethorphan: works in the same way
 Not an opioid
 No analgesic properties
 No CNS depression
 Benzonatate
 Suppress the cough reflex by numbing the stretch
receptors in the respiratory tract and prevent reflex
stimulation of the medullary cough center
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58
Antitussives: Indications

Used to stop the cough reflex when the cough is
nonproductive or harmful
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59
Antitussives: Contraindications




Drug allergy
Opioid dependency
Respiratory depression
Others
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60
Antitussives: Adverse Effects

Benzonatate


Dextromethorphan


Dizziness, headache, sedation, nausea, and others
Dizziness, drowsiness, nausea
Opioids

Sedation, nausea, vomiting, lightheadedness,
constipation
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61
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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62
Antitussives:
Nursing Implications (Cont.)

Report any of the following symptoms to the
caregiver:

Cough that lasts more than 1 week
 Persistent headache
 Fever
 Rash


Antitussive drugs are for nonproductive coughs.
Monitor for intended therapeutic effects.
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63
Audience Response System
Question #4
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?
A.
B.
C.
D.
Benzonatate (Tessalon Perles) capsules
Dextromethorphan (Robitussin-DM) oral solution
Codeine cough syrup
Guaifenesin (Mucinex)
NOTE: No input is required to proceed.
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64
Answer to System Question #4
ANS: B
Dextromethorphan does not cause respiratory or
CNS 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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65
Expectorants



Drugs that aid in the expectoration (removal) of
mucus
Reduce the viscosity of secretions
Disintegrate and thin secretions

Example: guaifenesin
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66
Expectorants:
Mechanisms of Action

Reflex stimulation



Direct stimulation


Drug causes irritation of the GI tract.
Loosening and thinning of respiratory tract secretions
occur in response to this irritation.
The secretory glands are stimulated directly to
increase their production of respiratory tract fluids.
Final result: thinner mucus that is easier to
remove
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67
Expectorants: Drug Effects

By loosening and thinning sputum and bronchial
secretions, the tendency to cough is indirectly
diminished.
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68
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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69
Expectorants:
Nursing Implications




Expectorants should be used with caution in
older adults and patients 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 1 week.
Monitor for intended therapeutic effects.
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70
Herbal Products: Echinacea


Reduces symptoms of the common cold and
recovery time
Adverse effects




Dermatitis
GI disturbance
Dizziness
Headache
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71
Audience Response System
Question #5
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?
A.
B.
C.
D.
Benzonatate (Tessalon Perles) capsules
Dextromethorphan (Robitussin-DM) oral solution
Codeine cough syrup
Guaifenesin (Mucinex)
NOTE: No input is required to proceed.
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72
Answer to System Question #5
ANS: D
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.
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73