Drugs Affecting theDrugs Affecting theRespiratory SystemRespiratory System

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.

Upper Respiratory TractUpper Respiratory Tract

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)

DecongestantsDecongestants

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

AntitussivesAntitussives

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

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.

BronchodilatorsBronchodilators

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