Cefaclor is a second generation β-lactam cephalosporin antibiotic. Cefaclor exhibits antibacterial efficacy against gram positive and gram negative bacteria, inhibiting penicillin binding proteins to prevent peptidoglycan synthesis and bacterial cell wall formation. Cefaclor also displays immunomodulatory and gastrointestinal motility modulating activities. Cefaclor enhances phagocytosis and bactericidal activity of granulocytes and macrophages and increases T lymphocyte activity. Additionally, this compound slows gastric emptying and intestinal transit by stimulating release of cholestocystokinin (CCK).