💊Pharmacology for Nurses Unit 25 – Lower Respiratory Disorder Drugs

Key Concepts

• Lower respiratory disorders affect the airways and lungs, causing breathing difficulties and reduced oxygen exchange
• Common disorders include asthma, chronic obstructive pulmonary disease (COPD), bronchitis, and pneumonia
• Pharmacological management aims to relieve symptoms, improve lung function, and prevent exacerbations
• Major drug classes target inflammation, bronchodilation, and mucus production
• Nurses play a crucial role in administering medications, monitoring patient response, and providing education

Types of Lower Respiratory Disorders

• Asthma is a chronic inflammatory disorder characterized by airway hyperresponsiveness and reversible airflow obstruction
  • Triggers include allergens, irritants, exercise, and respiratory infections
• COPD is a progressive disease that encompasses chronic bronchitis and emphysema, leading to irreversible airflow limitation
  • Risk factors include smoking, air pollution, and occupational exposures
• Bronchitis involves inflammation and mucus production in the bronchial tubes, causing cough and sputum production
  • Can be acute (short-term) or chronic (long-term)
• Pneumonia is an infection of the lung parenchyma, causing inflammation, fluid accumulation, and impaired gas exchange
  • Caused by bacteria, viruses, or fungi

Pharmacological Targets

• Inflammation is a key target in managing lower respiratory disorders, particularly in asthma and COPD
  • Corticosteroids are used to reduce airway inflammation and prevent exacerbations
• Bronchodilation is essential for relieving airflow obstruction and improving breathing
  • Beta-2 agonists and anticholinergics relax smooth muscles in the airways
• Mucus production can be targeted to facilitate airway clearance and reduce sputum accumulation
  • Mucolytics and expectorants help thin and expel mucus
• Infection control is crucial in managing pneumonia and preventing complications
  • Antibiotics are used to treat bacterial infections

Major Drug Classes

• Corticosteroids (inhaled and oral) are potent anti-inflammatory agents used in asthma and COPD management
  • Examples include fluticasone, budesonide, and prednisone
• Beta-2 agonists (short-acting and long-acting) stimulate beta-2 receptors to relax airway smooth muscles and promote bronchodilation
  • Examples include albuterol, salmeterol, and formoterol
• Anticholinergics block acetylcholine receptors to reduce bronchoconstriction and mucus secretion
  • Examples include ipratropium and tiotropium
• Leukotriene modifiers inhibit the action of leukotrienes, inflammatory mediators involved in asthma pathogenesis
  • Examples include montelukast and zafirlukast
• Methylxanthines (theophylline) have bronchodilatory and anti-inflammatory effects, but are less commonly used due to narrow therapeutic index

Mechanism of Action

• Corticosteroids bind to glucocorticoid receptors, modulating gene transcription to reduce inflammation and immune response
  • Inhibit the synthesis of pro-inflammatory cytokines and chemokines
• Beta-2 agonists activate beta-2 receptors on airway smooth muscles, increasing cyclic AMP and causing relaxation
  • Also inhibit mast cell degranulation and reduce vascular permeability
• Anticholinergics compete with acetylcholine for muscarinic receptors, preventing bronchoconstriction and mucus secretion
  • Particularly effective in COPD management
• Leukotriene modifiers block the synthesis or action of leukotrienes, reducing inflammation and bronchoconstriction
  • Montelukast is a leukotriene receptor antagonist, while zileuton inhibits 5-lipoxygenase

Common Medications

• Albuterol (ProAir, Ventolin) is a short-acting beta-2 agonist used for quick relief of asthma symptoms
• Fluticasone (Flovent) is an inhaled corticosteroid used for long-term asthma control
• Salmeterol (Serevent) is a long-acting beta-2 agonist used in combination with inhaled corticosteroids for asthma and COPD
• Ipratropium (Atrovent) is a short-acting anticholinergic used for COPD and acute asthma exacerbations
• Tiotropium (Spiriva) is a long-acting anticholinergic used for maintenance treatment of COPD
• Montelukast (Singulair) is a leukotriene receptor antagonist used for asthma and allergic rhinitis

Side Effects and Adverse Reactions

• Inhaled corticosteroids can cause local side effects like oral candidiasis, hoarseness, and throat irritation
  • Systemic side effects are rare with proper use, but may include adrenal suppression and growth retardation in children
• Beta-2 agonists can cause tremor, tachycardia, palpitations, and hypokalemia
  • Overuse of short-acting beta-2 agonists may worsen asthma control
• Anticholinergics can cause dry mouth, constipation, and urinary retention
  • Caution is needed in patients with narrow-angle glaucoma and benign prostatic hyperplasia
• Leukotriene modifiers may cause headache, gastrointestinal disturbances, and elevated liver enzymes
  • Rare cases of Churg-Strauss syndrome have been reported with montelukast

Nursing Considerations

• Assess patient's respiratory status, including vital signs, oxygen saturation, and lung sounds
• Administer medications as prescribed, ensuring proper technique and adherence
• Monitor for side effects and adverse reactions, reporting any concerns to the healthcare provider
• Evaluate patient's response to therapy, including symptom control and peak expiratory flow rates
• Provide patient education on medication use, inhaler technique, and self-management strategies
• Encourage smoking cessation and avoidance of triggers in patients with asthma and COPD

Patient Education

• Teach patients about their specific respiratory disorder, its triggers, and the importance of medication adherence
• Demonstrate proper inhaler technique, using spacers or valved holding chambers when appropriate
• Educate patients on the difference between quick-relief and long-term control medications
• Encourage patients to maintain a symptom diary and action plan for managing exacerbations
• Emphasize the importance of regular follow-up with healthcare providers and pulmonary function testing
• Provide resources for smoking cessation and support groups for patients with chronic respiratory disorders

Drug Interactions

• Corticosteroids may interact with CYP3A4 inhibitors (ketoconazole, ritonavir), increasing the risk of systemic side effects
• Beta-2 agonists can potentiate the hypokalemic effects of diuretics and the cardiovascular effects of monoamine oxidase inhibitors (MAOIs)
• Anticholinergics may enhance the anticholinergic effects of other drugs, such as tricyclic antidepressants and antihistamines
• Theophylline has numerous drug interactions, including with antibiotics, seizure medications, and calcium channel blockers
  • Careful monitoring of serum levels is required when initiating or discontinuing interacting medications

Special Populations

• Pregnancy: Inhaled corticosteroids and short-acting beta-2 agonists are generally considered safe, but the risks and benefits should be discussed
  • Oral corticosteroids may increase the risk of cleft lip/palate and low birth weight
• Pediatrics: Dosing and delivery devices should be adjusted based on age and ability
  • Growth monitoring is essential with long-term corticosteroid use
• Geriatrics: Anticholinergics should be used with caution due to increased risk of cognitive impairment and urinary retention
  • Theophylline clearance may be reduced, requiring dose adjustments
• Comorbidities: Cardiovascular disease, diabetes, and osteoporosis may influence the choice and monitoring of medications
  • Inhaled corticosteroids may increase the risk of pneumonia in patients with COPD

Emerging Therapies

• Biologics targeting specific inflammatory pathways (IL-5, IL-4, IL-13) are being used for severe eosinophilic asthma
  • Examples include mepolizumab, reslizumab, benralizumab, and dupilumab
• Long-acting muscarinic antagonists (LAMAs) and long-acting beta-2 agonists (LABAs) are being combined for COPD management
  • Examples include glycopyrronium/indacaterol and umeclidinium/vilanterol
• Triple therapy with inhaled corticosteroids, LABAs, and LAMAs is being investigated for severe COPD
  • Combinations such as fluticasone/umeclidinium/vilanterol are available
• Targeted lung denervation is a bronchoscopic procedure being studied for the treatment of severe COPD
  • Aims to reduce airway hyperresponsiveness and mucus hypersecretion