Pharmacology Flashcards: Respiratory Drugs, Bronchodilators, Inhalers, Corticosteroids

Short-acting beta-2 agonists, or SABAs, like albuterol are rescue medications that rapidly relax bronchial smooth muscle by stimulating beta-2 adrenergic receptors in the airways. Albuterol begins working within 5 minutes, peaks in 30 to 60 minutes, and lasts 4 to 6 hours. SABAs are used for acute bronchospasm and exercise-induced asthma. They do not treat inflammation. Side effects include tachycardia, tremor, and hypokalemia. Using a rescue inhaler more than twice per week suggests uncontrolled asthma requiring a step-up in controller therapy.

Inhaled corticosteroids, or ICS, like fluticasone, budesonide, and beclomethasone are the most effective long-term controller medications for persistent asthma. They reduce airway inflammation, mucus production, and bronchial hyperresponsiveness. ICS are first-line because they reduce asthma exacerbations, hospitalizations, and deaths more effectively than any other single controller medication. They are taken daily regardless of symptoms. Local side effects include oral thrush from candida overgrowth and dysphonia or hoarseness. Rinsing the mouth after each use prevents thrush.

Long-acting beta-2 agonists, or LABAs, like salmeterol and formoterol provide sustained bronchodilation lasting 12 hours and are used as add-on controller therapy for asthma and chronic obstructive pulmonary disease. LABAs must never be used alone for asthma because an FDA black box warning found increased asthma-related death risk when used without an inhaled corticosteroid. They are always prescribed in combination inhalers with an ICS, such as fluticasone-salmeterol or budesonide-formoterol. LABAs are not rescue medications and should not be used for acute bronchospasm.

Ipratropium is a short-acting anticholinergic bronchodilator that works by blocking muscarinic receptors in airway smooth muscle, reducing bronchoconstriction and mucus secretion. It is slower in onset than albuterol, taking 15 to 30 minutes to work, but lasts longer at 6 to 8 hours. Ipratropium is often combined with albuterol in nebulizer treatments for acute exacerbations of chronic obstructive pulmonary disease and severe asthma attacks because the two drugs work through different mechanisms. Tiotropium is the long-acting version used as a daily maintenance medication for COPD.

Montelukast, brand name Singulair, is a leukotriene receptor antagonist that blocks leukotrienes, inflammatory mediators that cause bronchoconstriction, mucus production, and airway edema. It is used for asthma prevention, exercise-induced bronchoconstriction, and allergic rhinitis. Montelukast is taken once daily and is not a rescue medication. The FDA issued a black box warning in 2020 for neuropsychiatric side effects including agitation, depression, suicidal thinking, and sleep disturbances.

Asthma treatment centers on inhaled corticosteroids as first-line controllers, with step-up therapy adding LABAs, leukotriene modifiers, and biologics. The goal is complete symptom control and normal lung function. COPD treatment starts with bronchodilators, either a long-acting muscarinic antagonist like tiotropium or a LABA, with inhaled corticosteroids added only for patients with frequent exacerbations and elevated eosinophils. COPD therapy aims to reduce symptoms and exacerbation frequency since lung function decline cannot be fully reversed.

Systemic corticosteroids like prednisone, prednisolone, methylprednisolone, and dexamethasone are powerful anti-inflammatory drugs used for acute asthma exacerbations, severe allergic reactions, autoimmune diseases, and organ transplant rejection prevention. Short courses of 5 to 10 days are relatively safe. Long-term use causes serious adverse effects including osteoporosis, adrenal suppression, hyperglycemia, weight gain, cataracts, immunosuppression, mood changes, and Cushing syndrome features. ---