Br. vet..]. (1996). 152, 551 PHARMACOKINETICS OF AMOXICIIJJN/CLAVULANIC ACID COMBINATION AND OF BOTH DRUGS ALONE AFI'ER INTRAVENOUS ADMINISTRATION TO GOATS E. ESCUDERO*, C. M. CARCELES and S. VICENTE Depm¢ment of Pharmacology and Therapeutics, Faculty of Veterinary Medicine, University of Murcia, Campus de Espinardo, 30.071-Murcia, Spain SUMMARY The pharmacokinetic behaviour of an amoxicillin/clavulanic acid combi- nation (25 mg kg-'), and both drugs alone (amoxicillin 20 mg kg-~), clavu- lanic acid 5 mg kg-~), was studied after intravenous (i.v.) administration of single doses to 10 goats. The objective was to determine whether there were differences in the plasma kinetics of these drugs when administered in combination or alone. The plasma concentration-time data were ana- lysed by compartmental pharmacokinetics and non-compartmental methods. The disposition curves for both drugs alone and in combination were best described by a biexponential equation (two-compartment open model). The elimination half-lives of amoxicillin were 1.05+0.09 h alone and 1.13+0.19 h in combination, and those of clavulanic acid were 0.87_+ 0.07 h and 0.85_+0.09 h, respectively. The apparent volumes of distribution of amoxicillin and clavulanic acid were similar in the two treatments. Body clearances of amoxicillin were 0.12_+0.01 l h q . kg alone and 0.11+ 0.01 l h -~. kg in combination, and of clavulanic acid were 0.12_+ 0.02 1 h -~ • kg alone and 0.12_+0.01 1 h -~ • kg in combination with amoxicil- lin. The half-lives and body clearances of amoxicillin and clavulanic acid did not differ significantly when administered alone and in combination. It was concluded that the i.v. administration of amoxicillin and ciavulanic acid as a combination product did not alter the disposition kinetics of either drug. I~"a'ORDS: Pharmacokinetics; amoxicillin; clavulanate; goats; intravenous. INTRODUCTION Amoxicillin is a broad spectrum antibiotic of the penam penicillin group, useful for treating urinary tract, respiratory and skin bacterial infections in animals. In *To whom correspondence should be addressed. 0007-1935/96/050551-09/$12.00/0 © 1996 Bailli6re Tindall