Pharmacology.
Clavulanic acid has weak antibacterial activity but is a potent inhibitor of plasmid-mediated Beta-lactamases,including those produced by Haemophilus influenzae, Moraxella (Branhamella) catarrhalis, Staphylococcus aureus, Neisseria gonorrhoeae, and Bacteroides fragilis. Thus, when combined with certain other beta-lactam antibiotics, the combination is very active against many bacteria resistant to the beta-lactam alone.
Adult Dosage.
PO One “250” or “500” tablet q 8 hr or 1 “875” tablet q 12 hr.
Pediatric Dosage.
PO 20–40 mg/kg/day (of the amoxicillin component) in 3 divided doses or 45 mg/kg/day in 2 divided doses.
Dosage Forms.
Do not substitute combinations of lower-dose tablets to make a higher dose because diarrhea is markedly increased. Tab (8 hr) 250 mg amoxicillin/125 mg clavulanic acid, 500 mg amoxicillin/125 mg clavulanic acid; (12 hr) 875 mg amoxicillin/125 mg clavulanic acid; Chew Tab (8 hr) 125 mg amoxicillin/31.25 mg clavulanic acid, 250 mg amoxicillin/62.5 mg clavulanic acid; (12 hr) 200 mg amoxicillin/28.5 mg clavulanic acid, 400 mg amoxicillin/57 mg clavulanic acid; Susp (8 hr) 25 mg amoxicillin/6.25 mg clavulanic acid/mL, 50 mg amoxicillin/12.5 mg clavulanic acid/mL; (12 hr) 40 mg amoxicillin/5.7 mg clavulanic acid/mL, 80 mg amoxicillin/11.4 mg clavulanic acid/mL.
Pharmacokinetics.
Peak serum clavulanate concentration is 2.6 mg/L 40–60 min after an oral dose of 250 mg amoxicillin/125 mg clavulanate. Amoxicillin pharmacokinetics are not affected by clavulanic acid. Clavulanic acid half-life is approximately 60 min.
Adverse Reactions.
Adverse effects of this preparation include those of amoxicillin; however, diarrhea is more frequent with the combination and depends on the dosage of clavulanate. The 12-hr formulations reduce the frequency of diarrhea. Nausea and diarrhea is less frequent when this preparation is administered with food.
