Transcript Pharmacology and the Nursing Process, 4th ed. Lilley/Harrington

Chapter 36
Antihistamines, Decongestants,
Antitussives, and Expectorants
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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)
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
2
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
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
3
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
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
5
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
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
6
Classroom Response Question
The common cold is treated with empiric therapy,
which means:
A. the medications cure the cold.
B. the medications only treat the symptoms.
C. herbal medications are useful to eliminate
symptoms.
D. it is prevented with careful use of medications.
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
7
Antihistamines


Drugs that directly compete with histamine for
specific receptor sites
Two histamine receptors

H1 (histamine1)
 H2 (histamine2)
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
8
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
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
9
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)
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
10
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
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
11
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
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
12
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
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
13
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
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
14
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
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
15
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
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
16
Antihistamines: Other Effects

Skin


Anticholinergic


Reduce capillary permeability, wheal-and-flare
formation, itching
Drying effect that reduces nasal, salivary, and lacrimal
gland secretions (runny nose, tearing, and itching
eyes)
Sedative

Some antihistamines cause drowsiness
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
17
Antihistamines: Indications

Management of:

Nasal allergies
 Seasonal or perennial allergic rhinitis
(hay fever)
 Allergic reactions
 Motion sickness
 Parkinson’s disease
 Sleep disorders
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
18
Antihistamines: Indications (cont’d)

Also used to relieve symptoms associated with
the common cold


Sneezing, runny nose
Palliative treatment, not curative
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
19
Antihistamines: Adverse Effects

Anticholinergic (drying) effects, most common

Dry mouth
 Difficulty urinating
 Constipation
 Changes in vision

Drowsiness

Mild drowsiness to deep sleep
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
20
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?
A.
Chronic urticaria
B.
Motion sickness
C.
Urinary retention
D.
Insomnia
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
21
Antihistamines: Two Types


Traditional
Nonsedating
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
22
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)
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
23
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
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
24
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
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
25
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
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
26
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
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
27
Nasal Congestion



Excessive nasal secretions
Inflamed and swollen nasal mucosa
Primary causes


Allergies
Upper respiratory infections (common cold)
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
28
Decongestants: Types

Three main types are used



Adrenergics
• Largest group
• Sympathomimetics
Anticholinergics
• Less commonly used
• Parasympatholytics
Corticosteroids
• Topical, intranasal steroids
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
29
Decongestants: Types (cont’d)

Two dosage forms


Oral
Inhaled/topically applied to the nasal membranes
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
30
Oral Decongestants





Prolonged decongestant effects, but delayed
onset
Effect less potent than topical
No rebound congestion
Exclusively adrenergics
Example: pseudoephedrine (Sudafed)
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
31
Topical Nasal Decongestants

Topical adrenergics



Prompt onset
Potent
Sustained use over several days causes rebound
congestion, making the condition worse
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
32
Topical Nasal
Decongestants (cont’d)

Adrenergics


Intranasal steroids


phenylephrine (Neo-Synephrine)
beclomethasone dipropionate (Beconase),
budesonide (Rhinocort), flunisolide (Nasalide),
fluticasone (Flonase), triamcinolone (Nasacort),
ciclesonide (Omnaris)
Intranasal anticholinergic

ipratropium (Atrovent)
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
33
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
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
34
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
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
35
Nasal Decongestants:
Drug Effects


Shrink engorged nasal mucous membranes
Relieve nasal stuffiness
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
36
Nasal Decongestants:
Indications

Relief of nasal congestion associated with

Acute or chronic rhinitis
 Common cold
 Sinusitis
 Hay fever
 Other allergies
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
37
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
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
38
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)
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
39
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
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
40
Nasal Decongestants:
Nursing Implications (cont’d)



Patients should avoid caffeine and caffeinecontaining products
Report a fever, cough, or other symptoms lasting
longer than a week
Monitor for intended therapeutic effects
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
41
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
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
42
Two Basic Types of Cough

Productive cough


Congested, removes excessive secretions
Nonproductive cough

Dry cough
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
43
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
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
44
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
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
45
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
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
46
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)
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
47
Antitussives: Indications

Used to stop the cough reflex when the cough is
nonproductive and/or harmful
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
48
Antitussives: Adverse Effects

benzonatate


dextromethorphan


Dizziness, headache, sedation, nausea, and others
Dizziness, drowsiness, nausea
Opioids

Sedation, nausea, vomiting, lightheadedness,
constipation
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
49
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
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
50
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
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
51
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?
A. benzonatate (Tessalon Perles) capsules
B. dextromethorphan (Robitussin-DM) oral solution
C. codeine cough syrup
D. guaifenesin (Mucinex)
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
52
Expectorants



Drugs that aid in the expectoration (removal) of
mucus
Reduce the viscosity of secretions
Disintegrate and thin secretions

Example: guaifenesin (Mucinex)
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
53
Expectorants:
Mechanisms of Action



Reflex stimulation
Direct stimulation
Final result: thinner mucus that is easier to
remove
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
54
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
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
55
Expectorants:
Mechanism of Action (cont’d)


Direct stimulation
The secretory glands are stimulated directly to
increase their production of respiratory tract
fluids
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
56
Expectorants: Drug Effects

By loosening and thinning sputum and bronchial
secretions, the tendency to cough is indirectly
diminished
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
57
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
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
58
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
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
59
Herbal Products: Echinacea


Reduces symptoms of the common cold and
recovery time
Adverse effects

Dermatitis
 GI disturbance
 Dizziness
 Headache
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
60
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?
A. benzonatate (Tessalon Perles) capsules
B. dextromethorphan (Robitussin-DM) oral
solution
C. codeine cough syrup
D. guaifenesin (Mucinex)
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
61