Chapter 38: Respiratory Drugs – Asthma & COPD Therapy

Chapter 38 details the anatomy and physiology of the respiratory system, emphasizing the distinction between the upper respiratory tract (outside the chest cavity) and the lower respiratory tract (inside the chest, containing the bronchial tree and alveoli), which facilitates vital gas exchange, speech, and pH regulation. The discussion centers on major lower respiratory diseases, primarily Asthma (a chronic inflammatory condition causing variable airflow limitation and hyper-responsiveness) and Chronic Obstructive Pulmonary Disease (COPD) (characterized by persistent, progressive airflow obstruction). Pharmacological management of these conditions targets both bronchoconstriction and the underlying inflammation. Key drug classes include Bronchodilators, which relax smooth muscle to improve airflow: Beta-adrenergic Agonists (like salbutamol) quickly stimulate beta₂ receptors to increase intracellular cAMP, causing rapid dilation; Anticholinergics (like ipratropium) block acetylcholine receptors, preventing constriction, and are used primarily for COPD prevention; and Xanthine Derivatives (like theophylline) increase cAMP by inhibiting phosphodiesterase, offering bronchodilation and CNS/cardiac stimulation, but requiring careful therapeutic level monitoring due to a narrow margin of safety. Nonbronchodilating drugs focus on inflammatory control: Corticosteroids (like fluticasone) are critical maintenance drugs for persistent asthma, reducing inflammation by stabilizing inflammatory cell membranes, and require oral rinsing after inhalation to prevent fungal overgrowth; Leukotriene Receptor Antagonists (LTRAs) (like montelukast) block inflammatory leukotrienes and are used for prophylaxis, not acute attacks. The chapter concludes by outlining comprehensive nursing interventions, including meticulous patient assessment for symptoms and triggers, education on correct inhaler technique (such as using spacers and waiting between doses), adherence to prescribed schedules, and monitoring for adverse effects like tachycardia and adrenal suppression.