Amoxicillin
Amoxicillin. β-lactam — inhibits transpeptidase (PBP) crosslinking peptidoglycan in bacterial cell wall. Broader gram-negative coverage than… Oral half-life 1.7 h.
β-lactam — inhibits transpeptidase (PBP) crosslinking peptidoglycan in bacterial cell wall. Broader gram-negative coverage than penicillin. Renally cleared; no CYP. Allergy cross-reactivity with cephalosporins.
PK: the old citation was an ORAL-ONLY bioequivalence study, so the intravenous row had no arm behind it, and its stored ka of 1.5 was the record own half-life numeral reused as a rate. Re-sourced to Arancibia 1980 (PMID:7387142), healthy fasted subjects dosed both ways: verbatim "The volume of distribution was 20.2 liters (0.30 liter/kg)", "recovery from the urine was 43.4% after the oral dose and 57.4% after the intravenous dose, indicating 76.5% bioavailability", and — rare in this audit — a genuine published absorption rate, "The absorption rate constant, kappa a, in the oral study, calculated by the Loo-Riegelman method, was 1.02 h-1, and the absorption half-life was 0.72 h", the two being internally consistent. Half-life 1.7 h from a true intravenous study (PMID:3986077). BOTH F AND ka ARE DOSE-SPECIFIC: absorption is carrier-mediated and saturable, so the 500 mg figures must not be carried to 875 or 1000 mg.
Pharmacokinetics
- Oral — t½ 1.7 h · F 77% · ka 1.02 h⁻¹ · Vd 20.2 L
- IV — t½ 1.7 h · F 100% · Vd 20.2 L
Sources: PMID:7387142, PMID:3986077