Pharmacokinetics of cefaronide, ceftriaxone and cefoperazone in sheep

The pharmacokinetics of cefaronide (16 gm/kg dose), ceftriaxone and cefoperazone (47 gm/kg dose), after intravenous (i.v.) administration were determined in six Merino ewes. The mean values for terminal half life, steady state volume of distribution Vd(ss), renal clearance (ClR) and total body clearance (ClB) for cefaronide were 1.5 h, 0.39 l/kg, 0.06 l/h/kg and 0.16 l/h/kg, for ceftriaxone; 1.7 h, 0.30 l/kg, 0.08 l/h/kg, and 0.22 l/h/kg, and 0.7 h, 0.16 l/kg, 0.02 l/h/kg and 0.16 l/h/kg for cefoperazone, respectively. After 5.5 h, approximately 42% cefaronide, and after 8 h, approximately 37% ceftriaxone and 13% cefoperazone, was excreted in urine. The non-renal elimination of ceftriaxone and cefoperazone appeared to be more rapid in sheep than is reported in man. Cefaronide was excreted largely unchanged in the urine of sheep. Therefore, the elimination of cefaronide in sheep was similar to that found in man. Cefaronide was well distributed in sheep, whereas ceftriaxone and cefoperazone appeared to be distributed to a lesser degree. These findings underline the different disposition of drugs in different species.