COMPARATIVE PHARMACOKINETICS OF AMPICILLIN-SULBACTAM COMBINATION IN CALVES AND SHEEP

The pharmacokinetics of ampicillin and sulbactam administered in combi nation were studied in calves and sheep. The animals were administered an aqueous solution of ampicillin/sulbactam (2:1, w/w) intravenously and intramuscularly at doses of 13.2 and 6.6 mg.kg-1, respectively. A microbiological method was used to detect ampicillin, and HPLC was use d to detect sulbactam in serum. Following intravenous (i.v.) administr ation, the distribution phases were rapid and similar (about 15 min) f or both drugs in both species, whereas sulbactam in calves and ampicil lin in sheep showed a faster elimination rate. After intramuscular (i. m.) administration both drugs showed peak concentrations higher in cal ves than in sheep; the peak time of sulbactam was shorter in calves th an in sheep. No other significant differences in the pharmacokinetics of the combination were observed between the species after i.m. inject ion. The mean residence and absorption times, calculated by non-compar tmental analysis, for both calves and sheep suggested that the differe nces in ampicillin and sulbactam pharmacokinetics could be attributabl e to the different molecular structures.