Pharmacokinetics of intravenous amoxycillin and potassium clavulanate in seriously ill children.

The pharmacokinetics of amoxycillin and potassium clavulanate were studied in 15 sick children after a 30 min iv infusion of 50 mg/kg amoxycillin and 5 mg/kg clavulanic acid as the potassium salt. Levels of both compounds in plasma were assayed microbiologically. Mean peak concentrations at the end of the infusion were 121.0 mg/l of amoxycillin and 12.0 mg/l of clavulanate, falling to a mean of 15.8 and 1.92 mg/l respectively after 2 h. Mean beta phase T 1/2 was 0.88 h for amoxycillin and 0.79 h for clavulanate. The elimination half-life of clavulanate in some individuals was much shorter because of higher plasma clearance. The data suggest that the treatment of some infections due to beta-lactamase producing organisms in such severely ill children may require more frequent iv administration of amoxycillin and potassium clavulanate, than in less severely affected children.