To study the absorption and disposition of clavulanic acid, ten healthy men received one intravenous and one oral dose of 125 mg clavulanic acid in combination with amoxycillin. Serum and urine concentrations were measured with high-performance liquid chromatography. The mean terminal half-lives in serum were 0.97 and 0.94 h, respectively. Total serum clearance was 248 +/- 55 ml/min X 1.73 m2. Renal clearance was 108 +/- 20 and 115 +/- 18 ml/min X 1.73 m2 after intravenous and peroral administration. Urinary recovery over 12 h was 49.4 +/- 8.7% of the intravenous and 35.7 +/- 13.0% of the oral dose. The bioavailability of the oral dose averaged 60.0 +/- 23.1% but varied considerably (range 31.4-98.8%), indicating very variable absorption from the gastrointestinal tract.