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CHAPTER 32

CHAPTER 32. Bronchodilator Drugs and the Treatment of Asthma. Common Diseases Affecting the Respiratory Tract. Chronic bronchitis – condition caused by chronic respiratory irritation, inflammation, and characterized by increased secretions and infection (COPD) smoking

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CHAPTER 32

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  1. CHAPTER 32 Bronchodilator Drugs and the Treatment of Asthma

  2. Common Diseases Affecting the Respiratory Tract • Chronic bronchitis – condition caused by chronic respiratory irritation, inflammation, and characterized by increased secretions and infection (COPD) smoking • Emphysema – disease characterized by destruction of alveoli, labored respiratory gas exchange, and shortness of breath (↓exhale) • Asthma – inflammatory disease of the respiratory passageways characterized by bronchoconstriction and shortness of breath

  3. Emphysema • Destruction of alveolar walls – dose dependently related to smoking • Limits exercise tolerance – requires supplemental O2

  4. Asthma • 5% of US population – 5000 deaths / y • Bronchoconstriction – reversible smooth muscle contraction – controlled by • Contraction - parasympathetic – AC • Dilation – sym – β2 adrenergic receptor • Inflammation of bronchiolar mucosa • Shortness of breath, cough, wheezing, smothering feeling,  mucous secretion

  5. COPD • Affects 20% of Us pop. • Secondary to smoking “mucous escalator” • Combination of chronic bronchitis and emphysema irreversible, progressive does respond to treatment

  6. Inflammatory Mediators of the Respiratory Tract • Histamine • Eosinophilic chemotactic factor of anaphylaxis (ECF-A) • Prostaglandins and leukotrienes • Slow-reacting substance of anaphylaxis (SRS-A)

  7. Autonomic Control of the Respiratory Tract • Bronchiolar smooth muscle is relaxed by beta-2 adrenergic receptor stimulation • Bronchiolar smooth muscle is contracted by cholinergic receptor stimulation • Respiratory secretions are increased by cholinergic stimulation • Drugs that increase intracellular levels of cyclic AMP produce bronchodilation

  8. Bronchodilator Drugs • Sympathomimetics – drugs that stimulate beta-2 adrenergic receptors • Xanthine derivatives – theophylline • Parasympatholytics – drugs that block cholinergic receptors (anticholinergic drugs)

  9. Bronchodilators • Short acting – “rescue inhalers” 4-6 hr • Terbutaline (Brethine) • Albuterol (Proventil) • Long acting – 12 hr • Salmeterol (Severent) • Drugs of choice for mild asthma

  10. Beta Adrenergic Drugs • Epinephrine and isoproterenol are nonselective beta-1 and beta-2 agonists • Albuterol, terbutaline, and salmeterol are selective beta-2 agonists that do not cause excessive cardiac stimulation • Selective beta-2 drugs are preferred for the control of asthma • Epinephrine SC is the drug of choice to treat an acute attack of asthma

  11. Theophylline • Increases cyclic AMP levels to cause bronchodilation and inhibition of chemical mediator release from mast cells • Theophylline is usually administered orally • In COPD theophylline decreases secretions and stimulates respiration • Overdosage produces cardiac and CNS stimulation, and may cause seizures

  12. Corticosteroids • Drugs of choice for moderate – severe asthma • Anti-inflammatory – decrease airway lymphocytes & eosinophills - no effect on muscle spasm • Mucosal edema • Leukotriene secretion • Mucous secretion

  13. Corticosteroids • Given by aerosol BID-QID • Must use a “spacer” – prevents thrush • Beclomethasone (Vanceril) • Budesonide (Pulmocourt)

  14. Corticosteroids • Adrenal gland hormone derivatives used in inflammatory and allergic conditions • Administered orally or parenterally in acute asthmatic and inflammatory diseases • Administered by oral inhalation for the chronic control of asthma and related inflammatory conditions • Inhalation limits systemic toxicity

  15. Anticholinergic Drugs • Ipratropium bromide (Atrovent) is the only drug currently available • By blocking cholinergic receptors ipratropium produces bronchodilation and decreased respiratory secretions • The drug is administered by oral inhalation

  16. Leukotrienes Inhibitors • Anti-inflammatory drugs that interfere with the inflammatory actions of the leukotrienes • Zafirlukast (Accolate) and montelukast (Singulair) block leukotriene receptors • Zileuton (Zyflo) blocks the enzyme required for the formation of leukotrienes • Drugs are indicated for the chronic treatment and control of asthma

  17. Ant allergic Drugs • Cromolyn and nedocromil (Tilade) inhibit the antigen-antibody reaction on mast cells that triggers allergic reactions • Administration is by oral inhalation • Drugs are used on a daily basis and are intended to prevent or decrease allergic reactions • Several weeks are usually required for the full therapeutic effect

  18. Mucolytics • Mucolytics are intended to break apart and liquefy thick respiratory secretions to facilitate easier removal • Acetylcysteine (Mucomist) is the most widely used mucolytic and is inhaled by nebulization • Administration is usually followed by postural drainage and tracheal suction

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