Respiratory Drugs Chapter 37 PDF

Chapter 37 RESPIRATORY DRUGS Main function of the respiratory system Deliver oxygen to and remove carbon dioxide from the cells of the body Upper respiratory tract (URT) Overview Lower respiratory tract (LRT) Alveoli: Point of gas exchange 2 Diseases of the Lower Respiratory Tract Chronic obstructiv...

Chapter 37 RESPIRATORY DRUGS Main function of the respiratory system Deliver oxygen to and remove carbon dioxide from the cells of the body Upper respiratory tract (URT) Overview Lower respiratory tract (LRT) Alveoli: Point of gas exchange 2 Diseases of the Lower Respiratory Tract Chronic obstructive pulmonary disease (COPD) ◦ Asthma (persistent and present most of the time despite treatment) ◦ Emphysema ◦ Chronic bronchitis 3 Bronchial Asthma Recurrent and reversible shortness of breath Occurs when the airways of the lungs become narrow as a result of: Bronchospasms Inflammation of the bronchial mucosa Edema of the bronchial mucosa Production of viscous mucus The alveolar ducts and alveoli remain open, but airflow to them is obstructed. Symptoms Wheezing & Difficulty breathing 4 Asthma Four categories Intrinsic (occurring in patients with no history of allergies) Extrinsic (occurring in patients exposed to a known allergen) Exercise induced Drug induced Status asthmaticus Prolonged asthma attack that does not respond to typical drug therapy May last several minutes to hours Medical emergency 5 Chronic Obstructive Pulmonary Disease (COPD) Chronic obstruction of lung airflow that interferes with normal breathing Not fully reversible Chronic bronchitis & emphysema 6 Chronic Bronchitis Continuous inflammation and lowgrade infection of the bronchi Excessive secretion of mucus and certain pathologic changes in the bronchial structure Often occurs as a result of prolonged exposure to bronchial irritants 7 Emphysema Air spaces enlarge as a result of the destruction of alveolar walls. Caused by the effect of proteolytic enzymes released from leukocytes in response to alveolar inflammation The surface area where gas exchange takes place is reduced. Effective respiration is impaired. 8 Pharmacologic Overview Bronchodilators ◦ These drugs relax bronchial smooth muscle, which causes dilation of the bronchi and bronchioles that are narrowed as a result of the disease process. ◦ Three classes ◦ beta-adrenergic agonists ◦ Anticholinergics ◦ xanthine derivatives 9 Bronchodilators Beta-Adrenergic Agonists SHORT ACTING SABAs are used as rescue inhalers for acute episodes ◦ Albuterol (Ventolin, ProAir) ◦ Levalbuterol (Xopenex) ◦ Terbutaline (Brethine) LONG ACTING beta agonist (LABA) inhalers ◦ *LABAs are never used for acute treatment! ◦ Formoterol (Foradil, Perforomist) ◦ Salmeterol (Serevent) 10 Bronchodilators Beta-Adrenergic Agonists Used during acute phase of asthmatic attacks Quickly reduce airway constriction and restore normal airflow Agonists, or stimulators, of the adrenergic receptors in the sympathetic nervous system Sympathomimetics 11 Bronchodilators Beta-Adrenergic Agonists (Cont.) Three types ◦ Nonselective adrenergics ◦ Stimulate alpha, beta1 (cardiac), and beta2 (respiratory) receptors ◦ Example: epinephrine (EpiPen) ◦ Nonselective betaadrenergics ◦ Stimulate both beta1 and beta2 receptors ◦ Example: metaproterenol ◦ Selective beta2 drugs ◦ Stimulate only beta2 receptors ◦ Example: albuterol 12 Beta-Adrenergic Agonists: Mechanism of Action Begins at the specific receptor stimulated Ends with dilation of the airways Activation of beta2 receptors activates cyclic adenosine monophosphate (cAMP), which relaxes smooth muscle in the airway and results in bronchial dilation and increased airflow. 13 Beta-Adrenergic Agonists Indications Relief of bronchospasm related to asthma, bronchitis, and other pulmonary diseases Used in treatment and prevention of acute attacks Used in hypotension and shock 14 Beta-Adrenergic Agonists Contraindications Known drug allergy Uncontrolled hypertension Cardiac dysrhythmias High risk of stroke (because of the vasoconstrictive drug action) 15 Beta-Adrenergic Agonists: Adverse Effects Alpha and beta (epinephrine) ◦ Insomnia ◦ Restlessness ◦ Anorexia ◦ Vascular headache ◦ Hyperglycemia ◦ Tremor ◦ Cardiac stimulation ◦ Beta1 and beta2 (metaproterenol) Cardiac stimulation ◦ Tremor ◦ Anginal pain ◦ Vascular headache Beta2 (albuterol) ◦ Hypotension or hypertension ◦ Vascular headache ◦ Tremor 16 Monoamine oxidase inhibitors BetaAdrenergic Agonists Sympathomimetics Interactions Monitor patients with diabetes; an increase in blood glucose levels can occur. 17 Beta-Adrenergic Agonists: Albuterol (Proventil) (Most common) Short-acting beta2-specific bronchodilating beta agonist Must not be used too frequently Increased systemic effects Oral and inhalational use Inhalational dosage forms include metered-dose inhalers (MDIs) as well as solutions for inhalation. 18 Beta-Adrenergic Agonists: Salmeterol (Serevent) Long-acting beta2 agonist bronchodilator Never to be used for acute treatment Used for the maintenance treatment of asthma and COPD and is used in conjunction with an inhaled corticosteroid Salmeterol should never be given more than twice daily nor should the maximum daily dose (one puff twice daily) be exceeded. 19 Albuterol, if used too frequently, loses its beta2specific actions at larger doses & causes systemic effects As a result, beta1 receptors are stimulated, causing nausea, increased anxiety, palpitations, tremors, and increased heart rate. Ensure that patients take medications exactly as prescribed Nursing Implications BetaAdrenergic Agonists Inform patients to report insomnia, jitteriness, restlessness, palpitations, chest pain, or any change in symptoms. 20 Anticholinergics Mechanism of Action Acetylcholine (ACh) causes bronchial constriction and narrowing of the airways. Anticholinergics bind to the ACh receptors, preventing ACh from binding. Result bronchoconstriction is prevented, airways dilate 21 Anticholinergics: Mechanism of Action (Cont.) Ipratropium (Atrovent), tiotropium (Spiriva) Indirectly cause airway relaxation and dilation Help reduce secretions in COPD patients Indications: prevention of the bronchospasm associated with chronic bronchitis or emphysema; not for the management of acute symptoms 22 Anticholinergics Adverse Effects Dry mouth or throat Nasal congestion Heart palpitations Gastrointestinal (GI) distress Headache Coughing Anxiety 23 Anticholinergics Ipratropium (Atrovent) Oldest and most commonly used Available both as a liquid aerosol for inhalation and as a multidose inhaler Usually dosed twice daily Others: Tiotropium (Spiriva) Umeclidinium (Incruse Ellipta) 24 Xanthine Derivatives Plant alkaloids: caffeine, theobromine, and theophylline Only theophylline is used as a bronchodilator. 25 Xanthine Derivatives Mechanism of Action Increase levels of energyproducing cAMP This is done by competitively inhibiting phosphodiesterase, the enzyme that breaks down cAMP. Result: smooth muscle relaxation, bronchodilation, and increased airflow 26 Xanthine Derivatives Drug Effects Cause bronchodilation by relaxing smooth muscle in the airways Result relief of bronchospasm and greater airflow into and out of the lungs Cause central nervous system (CNS) stimulation Cause force of contraction and heart rate, resulting in cardiac output and blood flow to the kidneys (diuretic effect) 27 Xanthine Derivatives: Indications Dilation of airways in asthmas, chronic bronchitis, and emphysema Mild to moderate cases of acute asthma Adjunct drug in the management of COPD Not used as frequently because of potential for drug interactions and variables related to drug levels in the blood 28 Xanthine Derivatives: Adverse Effects Nausea, vomiting, anorexia Gastroesophageal reflux during sleep Transient increased urination Sinus tachycardia, extrasystole, palpitations, ventricular dysrhythmias Hyperglycemia 29 Xanthine Derivatives: Caffeine Used without prescription as a CNS stimulant or analeptic to promote alertness (e.g., for long-duration driving or studying) Cardiac stimulant in infants with bradycardia Enhancement of respiratory drive in infants 30 Xanthine Derivatives: Theophylline Most commonly used Oral, rectal, injectable (as aminophylline), and topical dosage forms Aminophylline: intravenous (IV) treatment of patients with status asthmaticus who have not responded to fast-acting beta agonists such as epinephrine Most clinicians now advise levels between 5 and 15 mcg/mL. 31 Nursing Implications: Xanthine Derivatives Contraindications: history of PUD or GI disorders Cautious use: cardiac disease Timed-release preparations should not be crushed or chewed (cause gastric irritation). Report to prescriber: Nausea Vomiting Restlessness Insomnia Irritability Tremors 32 Nursing Implications: Xanthine Derivatives (Cont.) Be aware of drug interactions with cimetidine, oral contraceptives, allopurinol, certain antibiotics, influenza vaccine, and others. Cigarette smoking enhances xanthine metabolism. Interacting foods include charcoal-broiled, highprotein, and lowcarbohydrate foods. These foods may reduce serum levels of xanthines through various metabolic mechanisms. 33 Nonbronchodilating Respiratory Drugs Leukotriene receptor antagonists (montelukast, zafirlukast, and zileuton) Corticosteroids (beclomethasone, budesonide, dexamethasone, flunisolide, fluticasone, and triamcinolone) 34 Leukotriene Receptor Antagonists (LTRAs) Nonbronchodilating Newer class of asthma medications Currently available drugs Montelukast (Singulair) Zafirlukast (Accolate) Zileuton (Zyflo) 35 Leukotriene Receptor Antagonists LTRAs Mechanism of Action Leukotrienes are substances released when a trigger, such as cat hair or dust, starts a series of chemical reactions in the body. Leukotrienes cause inflammation, bronchoconstriction, and mucus production. Result: coughing, wheezing, shortness of breath LTRAs prevent leukotrienes from attaching to receptors on cells in the lungs and in circulation. Inflammation in the lungs is blocked, and asthma symptoms are relieved. 36 Leukotriene Receptor Antagonists LTRAs Drug Effects By blocking leukotrienes: Prevent smooth muscle contraction of the bronchial airways Decrease mucus secretion Prevent vascular permeability Decrease neutrophil and leukocyte infiltration to the lungs, preventing inflammation Black Box warning for montelukast Serious mood related changes and behaviours 37 Leukotriene Receptor Antagonists LTRAs Indications Contraindications Prophylaxis and long-term treatment Known drug allergy and prevention of asthma in adults Previous adverse drug reaction and children 12 years of age and older Not for acute asthmatic attacks Allergic rhinitis Improvement with their use is typically seen in about 1 week. 38 LTRAs: Adverse Effects Montelukast & Zafirlukast Headache, nausea, diarrhea 39 Nursing Implications: LTRAs chronic management of asthma Teach the patient the purpose of the therapy. Improvement should be seen in about 1 week. Check with prescriber before taking OTC or prescribed medications Assess liver function before beginning therapy and throughout. take medications every night on a continuous schedule even if symptoms improve. 40 Corticosteroids (Glucocorticoids) Antiinflammatory properties May be administered IV Used for chronic asthma Oral or inhaled forms Inhaled forms reduce systemic effects. Do not relieve symptoms of acute asthma attacks May take several weeks before full effects are seen 41 Stabilize membranes of cells, leukocytes) that release harmful bronchoconstricting substances Increase responsiveness of bronchial smooth muscle to betaadrenergic stimulation / Dual effect of both reducing inflammation and enhancing the activity of beta agonists Corticosteroids: Mechanism of Action 42 Inhaled Corticosteroids Budesonide (Pulmicort Turbuhaler) Flunisolide (AeroBid) Fluticasone Flovent—inhaler Flonase--intranasal 43 Inhaled Corticosteroids: Indications Primary treatment of bronchospastic disorders to control the inflammatory responses that are believed to be the cause of these disorders Persistent asthma Systemic corticosteroids are generally used only to treat acute exacerbations, or severe asthma. Often used concurrently with the beta-adrenergic agonists IV corticosteroids: acute exacerbation of asthma or other COPD 44 Inhaled Corticosteroids: Contraindications Drug allergy Not intended as sole therapy for acute asthma attacks Hypersensitivity to glucocorticoids Patients whose sputum tests positive for Candida organisms Patients with systemic fungal infection 45 Inhaled Corticosteroids: Adverse Effects Pharyngeal irritation Coughing Dry mouth Oral fungal infections Systemic effects are rare because low doses are used for inhalation therapy. 46 more likely to occur with systemic (versus inhaled) corticosteroids. May increase serum glucose levels, possibly requiring adjustments in dosages of antidiabetic drugs Inhaled Corticosteroids: Drug Interactions Phenytoin, phenobarbital, and rifampin 47 Nursing Implications: Inhaled Corticosteroids Teach Use Teach Encourage Teach oral care; prevent the development of oral fungal infections. beta agonist bronchodilator before corticosteroid inhaler patients to monitor disease with a peak flow meter. use of a spacer device patient how to keep inhalers and nebulizer equipment clean after use. 48 Nursing Implications Encourage patients ◦ Promote Health ◦ Avoid exposure to conditions that precipitate bronchospasm ◦ Adequate fluid intake ◦ Compliance with medical treatment & seek tx if needed ◦ Avoid excessive fatigue, heat, extremes in temperature, and caffeine. Perform a thorough assessment before beginning therapy, including: ◦ Baseline vital signs ◦ Respiratory assessment, including pulse oximetry ◦ Sputum production ◦ Allergies ◦ History of respiratory problems ◦ Smoking history ◦ Monitor for adverse effects. 49 Nursing Implications Monitor for therapeutic effects: ◦ dyspnea, wheezing, restlessness, and anxiety, symptoms and increased ease of breathing respiratory patterns with return to normal rate and quality & activity tolerance 50 Inhalers: Patient Education For any inhaler prescribed, ensure that the patient is able to self-administer the medication. ◦ Provide demonstration and return demonstration. ◦ Ensure that the patient knows the correct time intervals for inhalers. ◦ Provide a spacer if the patient has difficulty coordinating breathing with inhaler activation. ◦ Ensure that the patient knows how to keep track of the number of doses in the inhaler device. 51