If penicillins are the friendly old neighbors of the antibiotic world, cephalosporins are their well-dressed cousins: broad coverage, versatile, and ready to step in when things get serious. * Class: β-lactam antibiotics (same core structure as penicillins; inhibit bacterial cell wall synthesis by binding PBPs). * Mechanism: Bactericidal, time-dependent killing. * General Trends

* Definition: Chronic inflammatory disorder of the airways with reversible airflow obstruction and bronchial hyperresponsiveness. * Typical presentation: Episodic wheeze, cough, dyspnea, chest tightness, often worse at night or early morning. * Common triggers: Allergens, viral URIs, exercise, cold air, smoke, occupational exposures. Pathophysiology * Inflammation: Th2-mediated → ↑ IL-4 (IgE), IL-5 (eosinophils), IL-13 (mucus). * Bronchospasm:

COPD is an obstructive persistent, progressive airflow limitation that is not fully reversible, usually caused by chronic exposure to noxious particles (most often cigarette smoke). * Main Phenotypes: * Chronic bronchitis: Productive cough ≥ 3 months/year for ≥ 2 consecutive years. * Emphysema: Destruction of alveolar walls → loss of elastic recoil → hyperinflation. Pathophysiology * Chronic