Pharmacokinetics and urinary excretion of clavulanic acid after oral administration of amoxicillin and potassium clavulanate.

Clavulanic acid is a beta-lactamase inhibitor which prevents microbial lactamase inactivation of beta-lactam antibiotics. The pharmacokinetics and urinary excretion of clavulanic acid were studied in eight healthy adult volunteers after oral administration of 500 mg amoxicillin and 125 mg potassium clavulanate. Serum and urine clavulanic acid concentrations were assayed using high-performance liquid chromatography. Pharmacokinetic parameters were: t 1/2 beta = 1.019 +/- 0.090 hour, t 1/2 alpha = 0.276 +/- 0.031 hour, lag time = 0.321 +/- 0.018 hour, tmax = 1.042 +/- 0.80 hour, Cmax = 2.098 +/- 0.441 micrograms/ml, and AUC = 4.897 +/- 0.979 micrograms X hr/ml. Cumulative urinary excretion of clavulanic acid (as percentage of dose administered) was: 14.05 +/- 2.87 within 2 hours, 25.77 +/- 3.98 within 4 hours, and 27.85 +/- 4.27 within 6 hours after administration.