Drugs Acting on the Respiratory SystemSubtitleThe respiratory tract is divided into two major partsThe Upper Respiratory Tract

NaresNasal CavityPharynxLarynx

The Lower Respiratory Tract

TracheaBronchiBronchiolesAlveoliAlveolar-capillary membraneAntihistamines

Histamine is an organic compound that is largely concentrated in the Lungs, Skin, and GIT. 6HistamineInvolved in the local immune response to pathogensBinds to Histamine Receptors which causes these ff. responses:VasodilationHeadacheBronchoconstrictionHistamines are Involved in the local immune response to pathogens. Histamine, acting on H1-receptors, producesvasodilation that would intern result to hypotension,flushing,headache,tachycardia,bronchoconstriction (Bronchoconstrictionis the constriction of the airways in the lungs due to the tightening of surrounding smooth muscle, with consequent coughing, wheezing, and shortness of breath.)

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When you have an allergic response to the external stimuli on your skin Histamine binds to the receptors of that site and causes a build up of white blood cells leading to inflammation in that area.

Histamines also binds with the H1 receptors on your nose which causes and stimulates and causes a person to have an inflammed nose and increases mucus production. This is a common allergic reaction called Hay fever. 8Antihistamines: DefinitionAre also called H1 blockers or H1 antagonists

Primarily act to block histamine effects that occur in an immediate (type I) hypersensitivity reaction, commonly called an allergic reaction.

Antihistamines, H1 blockers or H1 antagonists are drugs that directly compete with histamine for the H1 receptor. 9- BLOCK action of histamine at receptor sites

- Compete with histamine for binding at unoccupied receptors.

- CANNOT push histamine off the receptor if already bound

- Decrease nasopharyngeal secretions by blocking the H1 receptor.

Antihistamines: Mechanism of Action10How does Histamine and Anti-Histamine work?

This is an illustrated example of how Anti-histamines work so that it could help you better understand the actions of antihistamine11Used in the management of:

- Nasal Allergies- Seasonal or perennial allergic rhinitis (hay fever)- Allergic reactions- Motion sickness- Sleep disorders

Antihistamines: Therapeutic Uses12Also used to relieve symptoms associated with the common cold:

Sneezing, runny nosePalliative treatment, not curative

Antihistamines: Two Types

Antihistamines: Two Types

First Generation Antihistamines (Traditional)Second-Generation Antihistamines (Nonsedating/Peripherally Acting)

First Generation Antihistamines (Traditional)

Effects: Dry mouthDrowsinessDizzinessFatigueDisturbed CoordinationNausea and other anticholinergic symptoms.

16Examples: Diphenhydramine (Benadryl) Chlorpheniramine (Chlor-Trimeton)

Second Generation Antihistamines (Nonsedating/Peripherally Acting)

Effects: Longer duration of action (increases compliance)Developed to eliminate unwanted side effectsMainly sedationWork peripherally to block the actions of histamine; thus fewer CNS side effects

Examples:Cetirizine (Zyrtec)Fexofenadine (Allegra)Ioratadine (Claritin)Azelastine (Astelin, Optivar)

19BronchodilatorsBronchodilators: Definition

Also known as antiasthmaticsSimplify respiration by expanding the airwaysRelief of bronchial asthma and spasmAdministered orally and with nebulizerBronchodilators are also referred to antiasthmatic medications. They are called bronchodilators because they opened and relax the bronchial tubes of the lungs allowing more air to flow through them. The now relaxed bronchial tubes usually allow for the breathing to return to normal. They are often used to give relief to patients with bronchial asthma and bronchospasm associated with COPD. 21Bronchodilators: Therapeutic Uses

Used in the management of:Asthma (Acute or Chronic)COPDChronic BronchitisBronchiectasisEmphysemaBronchial AsthmaChronic Bronchitis is a progressive lung disease caused by smoking or chronic lung infections.

Bronchiectasis is an abnormal dilation of the bronchi and bronchioles

Emphysema is a progressive lung disease caused by cigarette smoking, atmospheric contaminants, or lack of alpha1- antitrypsin protein that inhibits proteolytic enzymes that destroy alveoli (air sacs)22Two Types of BronchodilatorsBronchodilators: Two TypesBeta-agonistsXanthine DerivativesBeta-agonistsBronchodilators: Beta-AgonistsLarge group, sympathomimeticsUsed during acute phase of asthmatic attacksQuickly reduce airway constriction and restore normal airflowStimulate beta2 adrenergic receptors throughout the lungsBronchodilators: Beta-Agonists Mechanism of ActionBegins at the specific receptor stimulatedEnds with the dilation of the airways

Activation of beta2 receptors activate cAMP, which relaxes smooth muscles of the airway and results in bronchial dilation and increased airflow.27Bronchodilators: Beta-Agonists Therapeutic UsesRelief of bronchospasm, bronchial asthma, bronchitis, and other pulmonary disease.Useful in treatment of acute attacks as well as prevention.Bronchodilators: Beta-Agonists Three typesNonselective adrenergicsExample: epinephrine

Stimulate alpha1, beta1 (cardiac), and beta2 (respiratory) receptors.Given SC to promote bronchodilation and elevated blood pressureIs administered in emergency situations to restore circulation and increase airway patency29Bronchodilators: Beta-Agonists Three typesNonselective beta-adrenergicsExample: isoproterenol (Isuprel)Stimulate both beta1 and beta2 receptors:

Because the beta1 receptors are stimulated, the heart rate increases, and tachycardia may result

Beta2 however simulates and promotes bronchodilation 30Bronchodilators: Beta-Agonists Three typesSelective beta2 drugsExample: Albuterol- Stimulate only beta2 receptors.

- Beta2 simulates and promotes bronchodilation

31Bronchodilators: Beta-Agonists Side EffectsAlpha-Beta Beta1 and Beta2Beta2(epinephrine)(isoproterenol)(albuterol)

insomniacardiac stimulationhypotensionrestlessnesstremorvascularheadacheanorexiaanginal paintremorcardiac stimulationvascular headachetremorvascular headacheXanthine DerivativesBronchodilators: Xanthine Derivatives Mechanism of ActionResult: decreased cAMP levels, smooth muscle relaxation, bronchodilation, and increased airflow*cAMP = cyclic adenosine monophosphate34Bronchodilators: Xanthine Derivatives Drug EffectsCause bronchodilation by relaxing smooth muscles of the airways.Result: relief of bronchospasm and greater airflow into and out of the lungs.Also causes CNS stimulation.Also causes cardiovascular stimulation: increased force of contraction and increased HR, resulting in increased cardiac output and increased blood flow to the kidneys (diuretic effect).Bronchodilators: Xanthine Derivatives Therapeutic UsesDilation of airways in asthmas, chronic bronchitis, and emphysemaMild to moderate cases of asthmaAdjunct agent in the management of COPDBronchodilators: Xanthine Derivatives Side EffectsNausea, vomiting, anorexiaGastroesophageal reflux during sleepSinus tachycardia, extrasystole, palpitations, ventricular dysrhythmiasTransient increased urinationAntitussives

38Types of coughsProductiveA productive cough brings up sputum from the respiratory tract; this process helps speed recovery from inflammation of the airways and lungs

Nonproductive- A nonproductive cough is dry and scratchy, raises no sputum, and is typically a response to allergies or medication. Coughing is an important reflex that keeps lungs and airways free of secretions or foreign objects that might interfere with breathing. Coughing can be a response to an irritation or obstruction in the throat, larynx, bronchial tubes, or lungs, but in most cases a cough doesn't require medical attention

39AntitussivesDrugs used to stop or reduce coughingOpioid and nonopioid (narcotic and non-narcotic)Used only for NONPRODUCTIVE coughs.Antitussives: Mechanism of ActionOpioid (Narcotic)Suppress the cough reflex by direct action on the cough center in the medulla.Examples:codeine (Robitussin A-C, Dimetane-DC) hydrocodoneAntitussives: Mechanism of ActionNonopioid (Non-narcotic)Suppress the cough reflex by numbing the stretch receptors in the respiratory tract and preventing the cough reflex from being stimulated.Examples:benzonatate (Tessalon)dextromethorphan (Vicks Formula 44, Robitussin-DM)42Antitussives: Side EffectsBenzonatate (nonnarcotic)Dizziness, headache, sedationDextromethorphan (nonnarcotic)Dizziness, drowsiness, nauseaOpioidsSedation, nausea, vomiting, lightheadedness, constipationNursing Implications: Antitussive AgentsPerform respiratory and cough assessment, and assess for allergies.Instruct patients to avoid driving or operating heavy equipment due to possible sedation, drowsiness, or dizziness.If taking chewable tablets or lozenges, do not drink liquids for 30 to 35 minutes afterward.Nursing Implications: Antitussive AgentsReport any of the following symptoms:Cough that lasts more than a weekA persistent headacheFever RashAntitussive agents are for NONPRODUCTIVE coughs.Monitor for intended therapeutic effects.45ExpectorantsExpectorantsDrugs that aid in the expectoration (removal) of mucusReduce the viscosity of secretionsDisintegrate and thin secretionsExpectorants: Mechanisms of ActionDirect stimulation orReflex stimulation

Final result: thinner mucus that is easier to removeExpectorants: Mechanism of ActionDirect stimulation:The secretory glands are stimulated directly to increase their production of respiratory tract fluids.Examples: terpin hydrate, iodine-containing products such as iodinated glycerol and potassium iodide (direct and indirect stimulation)Expectorants: Mechanism of ActionReflex stimulation:Agent causes irritation of the GI tract.Loosening and thinning of respiratory tract secretions occur in response to this irritation.Examples: guaifenesin, syrup of ipecacExpectorants: Drug EffectsBy loosening and thinning sputum and bronchial secretions, the tendency to cough is indirectly diminished.Expectorants: Therapeutic UsesUsed for the relief of nonproductive coughs associated with:Common coldPertussisBronchitisInfluenzaLaryngitisMeaslesPharyngitisCoughs caused by chronic paranasal sinusitis52Expectorants: Common Side Effectsguaifenesinterpin hydrateNausea, vomitingGastric upsetGastric irritation(Elixir has high alcohol content)Nursing Implications: ExpectorantsExpectorants 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.

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