chapter 36 antihistamines, decongestants, antitussives, and expectorants copyright © 2014 by mosby,...

Chapter 36

Antihistamines, Decongestants, Antitussives, and Expectorants

Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

Most caused by viral infection (rhinovirus or influenza virus)

Virus invades tissues (mucosa) of upper respiratory tract, causing upper respiratory infection (URI)

Understanding the Common Cold

Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 2

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

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

Understanding the Common Cold (cont’d)


Involves combined use of antihistamines, nasal decongestants, antitussives, and expectorants

Treatment is symptomatic only, not curative Symptomatic treatment does not eliminate the

causative pathogen

Treatment of the Common Cold


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

Treatment of the Common Cold (cont’d)


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.


Drugs that directly compete with histamine for specific receptor sites

Two histamine receptors H1 (histamine1)

H2 (histamine2)

Antihistamines


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

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)

Antihistamines (cont’d)


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

Antihistamines: Mechanism of Action


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

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

Antihistamines: Mechanism of Action (cont’d)


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

Histamine vs. Antihistamine Effects


Smooth muscle (on exocrine glands)Histamine effects

Stimulate salivary, gastric, lacrimal, and bronchial secretions

Antihistamine effects Reduce salivary, gastric, lacrimal, and

bronchial secretions

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

Histamine vs. Antihistamine Effects (cont’d)


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

Antihistamines: Other Effects


Management of: Nasal allergies Seasonal or perennial allergic rhinitis

(hay fever) Allergic reactions Motion sickness Parkinson’s disease Sleep disorders

Antihistamines: Indications


Also used to relieve symptoms associated with the common cold Sneezing, runny nose Palliative treatment, not curative

Antihistamines: Indications (cont’d)


Anticholinergic (drying) effects, most common Dry mouth Difficulty urinating Constipation Changes in vision

Drowsiness Mild drowsiness to deep sleep

Antihistamines: Adverse Effects



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


Traditional Nonsedating

Antihistamines: Two Types


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)

Nonsedating/Peripherally Acting 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

Traditional Antihistamines


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

Antihistamines:Nursing Implications


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

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

Antihistamines:Nursing Implications (cont’d)


Excessive nasal secretions Inflamed and swollen nasal mucosa Primary causes

Allergies Upper respiratory infections (common cold)

Nasal Congestion


Three main types are used Adrenergics

• Largest group

• Sympathomimetics

Anticholinergics• Less commonly used

• Parasympatholytics

Corticosteroids• Topical, intranasal steroids

Decongestants: Types


Two dosage forms Oral Inhaled/topically applied to the nasal membranes

Decongestants: Types (cont’d)


Prolonged decongestant effects, but delayed onset

Effect less potent than topical No rebound congestion Exclusively adrenergics Example: pseudoephedrine (Sudafed)

Oral Decongestants


Topical adrenergics Prompt onset Potent Sustained use over several days causes rebound

congestion, making the condition worse

Topical Nasal Decongestants


Adrenergics phenylephrine (Neo-Synephrine)

Intranasal steroids beclomethasone dipropionate (Beconase),

budesonide (Rhinocort), flunisolide (Nasalide), fluticasone (Flonase), triamcinolone (Nasacort), ciclesonide (Omnaris)

Intranasal anticholinergic ipratropium (Atrovent)

Topical Nasal Decongestants (cont’d)


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

Nasal Decongestants:Mechanism of Action


Nasal steroids Antiinflammatory effect Work to turn off the immune system cells involved in

the inflammatory response Decreased inflammation results in decreased

congestion

Nasal Decongestants:Mechanism of Action (cont’d)


Shrink engorged nasal mucous membranes Relieve nasal stuffiness

Nasal Decongestants: Drug Effects


Relief of nasal congestion associated with Acute or chronic rhinitis Common cold Sinusitis Hay fever Other allergies

Nasal Decongestants: Indications


May also be used to reduce swelling of the nasal passage and facilitate visualization of the nasal/pharyngeal membranes before surgery or diagnostic procedures

Nasal Decongestants: Indications (cont’d)


Adrenergics Steroids

Nervousness Local mucosal dryness

Insomnia and irritation

Palpitations

Tremors(Systemic effects caused by adrenergic stimulation

of the heart, blood vessels, and CNS)

Nasal Decongestants: Adverse Effects


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

Nasal Decongestants:Nursing Implications


Patients should avoid caffeine and caffeine-containing products

Report a fever, cough, or other symptoms lasting longer than a week


Nasal Decongestants:Nursing Implications (cont’d)


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

Cough Physiology


Productive cough Congested, removes excessive secretions

Nonproductive cough Dry cough

Two Basic Types of Cough


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

Coughing


Drugs used to stop or reduce coughing Opioid and nonopioid Used only for nonproductive coughs! May be used in cases where coughing is harmful

Antitussives


OpioidsSuppress the cough reflex by direct action on the cough center in the medullaExamples:

codeine (Robitussin A-C, Dimetane-DC) hydrocodone

Antitussives: Mechanism of Action


NonopioidsSuppress the cough reflex by numbing the stretch receptors in the respiratory tract and preventing the cough reflex from being stimulatedExamples:

benzonatate (Tessalon Perles) dextromethorphan (Vicks Formula 44, Robitussin-DM)

Antitussives: Mechanism of Action (cont’d)


Used to stop the cough reflex when the cough is nonproductive and/or harmful

Antitussives: Indications


benzonatate Dizziness, headache, sedation, nausea, and others

dextromethorphan Dizziness, drowsiness, nausea

Opioids Sedation, nausea, vomiting, lightheadedness,

constipation

Antitussives: Adverse Effects


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

Antitussives:Nursing Implications


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

Antitussives:Nursing Implications (cont’d)



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)


Drugs that aid in the expectoration (removal) of mucus

Reduce the viscosity of secretions Disintegrate and thin secretions

Example: guaifenesin (Mucinex)

Expectorants


Reflex stimulation Direct stimulation Final result: thinner mucus that is easier to

remove

Expectorants: Mechanisms of Action


Reflex stimulation Drug causes irritation of the GI tract Loosening and thinning of respiratory tract secretions

occur in response to this irritation

Expectorants: Mechanism of Action (cont’d)


Direct stimulation The secretory glands are stimulated directly to

increase their production of respiratory tract fluids

Expectorants: Mechanism of Action (cont’d)


By loosening and thinning sputum and bronchial secretions, the tendency to cough is indirectly diminished

Expectorants: Drug Effects


Used for the relief of productive coughs associated with: Common cold Bronchitis Laryngitis Pharyngitis Coughs caused by chronic paranasal sinusitis Pertussis Influenza Measles

Expectorants: Indications


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


Expectorants:Nursing Implications


Reduces symptoms of the common cold and recovery time

Adverse effects Dermatitis GI disturbance Dizziness Headache

Herbal Products: Echinacea



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)


chapter 36 antihistamines, decongestants, antitussives, and expectorants copyright © 2014 by mosby,...

Documents

imprint of elsevier

common cold copyright

common cold contd copyright

expectorants copyright

histamine receptors

cold symptoms

antihistamines examples

mechanism of action