drugs affecting the respiratory system. antihistamines,decongestants,antitussives,andexpectorants
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Antihistamines,Antihistamines,
Decongestants,Decongestants,
Antitussives,Antitussives,
andand
ExpectorantsExpectorants
Drugs Affecting theDrugs Affecting theRespiratory Respiratory
SystemSystem
Understanding the Understanding the Common ColdCommon Cold Most caused by viral infection Most caused by viral infection
(rhinovirus or influenza virus—the (rhinovirus or influenza virus—the “flu”)“flu”)
Understanding the Understanding the ColdCold Virus invades tissues (mucosa) of Virus invades tissues (mucosa) of
upper respiratory tract, causing upper upper respiratory tract, causing upper respiratory infection (URI).respiratory infection (URI).
Excessive mucus production results Excessive mucus production results from the inflammatory response to from the inflammatory response to this invasion.this invasion.
Fluid drips down the pharynx into the Fluid drips down the pharynx into the esophagus and lower respiratory esophagus and lower respiratory tract, causing cold symptoms: sore tract, causing cold symptoms: sore throat, coughing, upset stomach.throat, coughing, upset stomach.
Irritation of nasal mucosa often Irritation of nasal mucosa often triggers the sneeze reflex.triggers the sneeze reflex.
Mucosal irritation also causes Mucosal irritation also causes release of several inflammatory release of several inflammatory and vasoactive substances, and vasoactive substances, dilating small blood vessels in the dilating small blood vessels in the nasal sinuses and causing nasal nasal sinuses and causing nasal congestion.congestion.
Involves combined use of Involves combined use of antihistamines, nasal antihistamines, nasal decongestants, antitussives, and decongestants, antitussives, and expectorants.expectorants.
Treatment is SYMPTOMATIC only, Treatment is SYMPTOMATIC only, not curative.not curative.
Symptomatic treatment does not Symptomatic treatment does not eliminate the causative pathogen.eliminate the causative pathogen.
Treatment of the Treatment of the Common ColdCommon Cold Difficult to identify whether cause Difficult to identify whether cause
is viral or bacterial.is viral or bacterial. Treatment is “empiric therapy,” Treatment is “empiric therapy,”
treating the most likely cause.treating the most likely cause. Antivirals and antibiotics may be Antivirals and antibiotics may be
used, but viral or bacterial cause used, but viral or bacterial cause may not be easily identified.may not be easily identified.
AntihistaminesAntihistamines
Drugs that directly compete with Drugs that directly compete with histamine histamine for specific receptor for specific receptor sites.sites.
Two histamine receptors:Two histamine receptors:– HH11 histamine histamine
– HH22 histamine histamine
Antihistamines: Antihistamines: Mechanism of ActionMechanism of Action
The binding of HThe binding of H11 blockers to the blockers to the histamine receptors prevents the histamine receptors prevents the adverse consequences of adverse consequences of histamine stimulation:histamine stimulation:– VasodilationVasodilation– Increased gastrointestinal and Increased gastrointestinal and
respiratory secretionsrespiratory secretions– Increased capillary permeabilityIncreased capillary permeability
Histamine vs. Histamine vs. Antihistamine EffectsAntihistamine Effects
Smooth Muscle (on exocrine glands)Smooth Muscle (on exocrine glands) Histamine effects:Histamine effects:
– Stimulate salivary, gastric, lacrimal, Stimulate salivary, gastric, lacrimal, and and bronchial secretionsbronchial secretions
Antihistamine effects:Antihistamine effects:– Prevent salivary, gastric, lacrimal, Prevent salivary, gastric, lacrimal,
and and bronchial secretionsbronchial secretions
Histamine vs. Histamine vs. Antihistamine EffectsAntihistamine Effects
Immune System Immune System
(Release of substances commonly (Release of substances commonly associated with allergic reactions)associated with allergic reactions)
Histamine effects:Histamine effects:– Mast cells release histamine and other Mast cells release histamine and other
substances, resulting in allergic reactions.substances, resulting in allergic reactions. Antihistamine effect:Antihistamine effect:
– Binds to histamine receptors, thus Binds to histamine receptors, thus preventing histamine from causing a preventing histamine from causing a response.response.
Antihistamines: Other Antihistamines: Other EffectsEffects
Skin:Skin: Block capillary permeability, wheal-Block capillary permeability, wheal-
and-flare formation, itchingand-flare formation, itching
Anticholinergic:Anticholinergic: Drying effect that reduces nasal, Drying effect that reduces nasal,
salivary, and lacrimal gland secretions salivary, and lacrimal gland secretions (runny nose, tearing, and itching eyes)(runny nose, tearing, and itching eyes)
Sedative:Sedative: Some antihistamines cause drowsinessSome antihistamines cause drowsiness
Antihistamines: Antihistamines: Therapeutic UsesTherapeutic Uses
Management of:Management of:
Nasal allergiesNasal allergies
Seasonal or perennial allergic rhinitis Seasonal or perennial allergic rhinitis (hay fever)(hay fever)
Allergic reactionsAllergic reactions
Motion sicknessMotion sickness
Sleep disordersSleep disorders
Antihistamines: Side Antihistamines: Side effectseffects
Anticholinergic (drying) effects, Anticholinergic (drying) effects, most common:most common:– Dry mouthDry mouth– Difficulty urinatingDifficulty urinating– ConstipationConstipation– Changes in visionChanges in vision
DrowsinessDrowsiness– (Mild drowsiness to deep sleep)(Mild drowsiness to deep sleep)
Nasal CongestionNasal Congestion
Excessive nasal secretionsExcessive nasal secretions Inflamed and swollen nasal Inflamed and swollen nasal
mucosamucosa
Primary causes:Primary causes:– AllergiesAllergies– Upper respiratory infections Upper respiratory infections
(common cold)(common cold)
DecongestantsDecongestants
Two main types are used:Two main types are used: Adrenergics (largest group)Adrenergics (largest group) CorticosteroidsCorticosteroids
DecongestantsDecongestants
Two dosage forms:Two dosage forms: OralOral Inhaled/topically applied to the nasal Inhaled/topically applied to the nasal
membranesmembranes
Topical Nasal Topical Nasal DecongestantsDecongestants
Adrenergics:Adrenergics:ephedrine (Vicks)ephedrine (Vicks) naphazoline naphazoline (Privine)(Privine)
oxymetazoline (Afrin)oxymetazoline (Afrin) phenylephrine phenylephrine (Neo (Neo
Synephrine)Synephrine) Intranasal Steroids:Intranasal Steroids:
beclomethasone dipropionate beclomethasone dipropionate (Beconase)(Beconase)
Nasal Decongestants: Nasal Decongestants: Therapeutic UsesTherapeutic Uses
Relief of nasal congestion Relief of nasal congestion associated with:associated with:
Acute or chronic rhinitisAcute or chronic rhinitis Common coldCommon cold SinusitisSinusitis Hay feverHay fever Other allergiesOther allergies
Cough PhysiologyCough Physiology
Respiratory secretions and foreign Respiratory secretions and foreign objects are naturally removed by objects are naturally removed by the the
cough reflexcough reflex– Induces coughing and expectorationInduces coughing and expectoration– Initiated by irritation of sensory Initiated by irritation of sensory
receptors in the respiratory tractreceptors in the respiratory tract
Two Basic Types of Two Basic Types of Cough Cough
Productive CoughProductive Cough– Congested, removes excessive Congested, removes excessive
secretionssecretions Nonproductive CoughNonproductive Cough
– Dry coughDry cough
CoughingCoughing
Most of the time, coughing is Most of the time, coughing is beneficialbeneficial
Removes excessive secretionsRemoves excessive secretions Removes potentially harmful foreign Removes potentially harmful foreign
substancessubstances
In some situations, coughing can be In some situations, coughing can be harmful, such as after hernia harmful, such as after hernia repair surgeryrepair surgery
AntitussivesAntitussives
Drugs used to stop or reduce Drugs used to stop or reduce coughingcoughing
Opioid and nonopioid Opioid and nonopioid (narcotic and non-narcotic)(narcotic and non-narcotic)
Used only for NONPRODUCTIVE Used only for NONPRODUCTIVE coughs!coughs!
Antitussives: Antitussives: Mechanism of ActionMechanism of Action
OpioidOpioid Suppress the cough reflex by direct Suppress the cough reflex by direct
action on the cough center in the action on the cough center in the medulla.medulla.
Examples:Examples: codeine ,,,hydrocodonecodeine ,,,hydrocodone
Antitussives: Antitussives: Mechanism of ActionMechanism of Action
NonopioidNonopioid Suppress the cough reflex by numbing Suppress the cough reflex by numbing
the stretch receptors in the respiratory the stretch receptors in the respiratory tract and preventing the cough reflex tract and preventing the cough reflex from being stimulated.from being stimulated.
Examples:Examples: benzonatate (Tessalon)benzonatate (Tessalon)dextromethorphan (Vicks dextromethorphan (Vicks
Formula)Formula)
Antitussives: Antitussives: Therapeutic UsesTherapeutic Uses
Used to stop the cough reflex Used to stop the cough reflex when the cough is nonproductive when the cough is nonproductive and/or harmfuland/or harmful
Antitussives: Side Antitussives: Side EffectsEffects
DextromethorphanDextromethorphan Dizziness, drowsiness, nauseaDizziness, drowsiness, nausea
OpioidsOpioids Sedation, nausea, vomiting, Sedation, nausea, vomiting,
lightheadedness, constipationlightheadedness, constipation
ExpectorantsExpectorants
Drugs that aid in the Drugs that aid in the expectoration expectoration (removal) of mucus(removal) of mucus
Reduce the viscosity of secretionsReduce the viscosity of secretions Disintegrate and thin secretionsDisintegrate and thin secretions
Expectorants: Expectorants: Mechanisms of ActionMechanisms of Action
Direct stimulation Direct stimulation
oror Reflex stimulationReflex stimulation
Final result: thinner mucus that is easier Final result: thinner mucus that is easier to removeto remove
Expectorants: Expectorants: Mechanism of ActionMechanism of Action
Direct stimulation:Direct stimulation: The secretory glands are stimulated The secretory glands are stimulated
directly to increase their production of directly to increase their production of respiratory tract fluids.respiratory tract fluids.
Examples: iodine-containing Examples: iodine-containing products such as iodinated products such as iodinated
glycerol and glycerol and potassium iodide (direct potassium iodide (direct and indirect and indirect stimulation)stimulation)
Expectorants: Expectorants: Mechanism of ActionMechanism of Action
Reflex stimulation:Reflex stimulation: Agent causes irritation of the GI tract.Agent causes irritation of the GI tract. Loosening and thinning of respiratory Loosening and thinning of respiratory
tract secretions occur in response to tract secretions occur in response to this irritation.this irritation.
Examples: guaifenesin, syrup of ipecacExamples: guaifenesin, syrup of ipecac
Expectorants: Common Expectorants: Common Side EffectsSide Effects
guaifenesinguaifenesinNausea, vomitingNausea, vomiting
Gastric irritationGastric irritation
Nursing Implications: Nursing Implications: ExpectorantsExpectorants
Expectorants should be used with Expectorants should be used with caution in the elderly, or those with caution in the elderly, or those with asthma or respiratory insufficiency.asthma or respiratory insufficiency.
Patients taking expectorants should Patients taking expectorants should receive more fluids, if permitted, to receive more fluids, if permitted, to help loosen and liquefy secretions.help loosen and liquefy secretions.
Report a fever, cough, or other Report a fever, cough, or other symptoms lasting longer than a symptoms lasting longer than a week.week.
Bronchodilators: Bronchodilators: Xanthine DerivativesXanthine Derivatives Plant alkaloids: caffeine, Plant alkaloids: caffeine,
theobromine, and theophyllinetheobromine, and theophylline Only theophylline is used as a Only theophylline is used as a
bronchodilatorbronchodilator
Bronchodilators: Bronchodilators: Xanthine Derivatives Xanthine Derivatives Side EffectsSide Effects
Nausea, vomiting, anorexiaNausea, vomiting, anorexia Gastroesophageal reflux during Gastroesophageal reflux during
sleepsleep Sinus tachycardia, palpitations, Sinus tachycardia, palpitations,
ventricular dysrhythmiasventricular dysrhythmias Transient increased urinationTransient increased urination