PHARMACOKINETICS OF ADITOPRIM IN TURKEYS AFTER INTRAVENOUS AND ORAL-ADMINISTRATION

The pharmacokinetics of aditoprim, a not yet commercialized selective reversible inhibitor of dihydrofolate reductase, were determined in turkeys after intravenous (5 mg/kg BW) and oral (5.46 +/- .44 mg/kg BW) administration. The mean (+/- SD) total body clearance of 26.9 +/- 2.3 mL/min per kg BW was high when compared with that determined for other species, presumably a consequence of the higher metabolic rate of birds. Consequently, mean aditoprim elimination half-life was relatively short (3.3 +/- .2 h). As determined in mammalian species, the apparent volume of distribution at steady state was large. Aditoprim in drinking water (100 and 300 mg/L water) provided plasma concentrations between .08 and .19 mug/mL. Circadian rhythms with highest concentrations in the late afternoon and lowest concentrations in the morning were observed. Despite its short elimination half-life, aditoprim may still be a valuable antimicrobial for use in avian medicine pending safety, efficacy, and residue depletion studies.