Pharmacology
Mechanism of Action
Amoxicillin binds to penicillin-binding proteins, thus inhibiting final transpeptidation step of peptidoglycan synthesis in bacterial cell walls; addition of clavulanate inhibits beta-lactamase-producing bacteria, allowing amoxicillin extended spectrum of action
It is a semisynthetic antibiotic with a broad spectrum of bactericidal activity, covering both gram-negative and gram-positive microorganisms
Not effective against Mycoplasma and Legionella spp
Absorption
Peak plasma time: 2 hr (amoxicillin); 1.1 hr (clavulanic acid)
Peak concentration: 8-22 mcg/mL (amoxicillin); 0.8-2.6 mcg/mL (clavulanic acid)
AUC: 40-80 mcg•hr/mL (amoxicillin); 2-6 mcg•hr/mL (clavulanic acid)
Distribution
Protein bound: 18% (amoxicillin); 25% (clavulanic acid)
Widely distributed (except CNS)
Metabolism
Partially metabolized by liver
Elimination
Half-life
- Amoxicillin: 3.7 hr (full-term neonates); 1-2 hr (infants and children); 0.7-1.4 hr (adults)
- Clavulanic acid: 0.8-1.4 hr
Excretion: Urine, unchanged; 50-70% (amoxicillin), 25-40% (clavulanic acid)