COMPARATIVE PHARMACOKINETICS AND BIOAVAILABILITY OF OXOLINIC ACID IN CHANNEL CATFISH (ICTALURUS-PUNCTATUS) AND RAINBOW-TROUT (ONCORHYNCHUS-MYKISS)

The pharmacokinetics, bioavailability, and disposition of oxolinic aci d (OA), a quinolone antibacterial drug, were examined in a warmwater ( channel catfish (Ictalurus punctatus)) and coldwater fish species (rai nbow trout (Oncorhynchus mykiss)). Studies were performed at 24 and 14 -degrees-C for catfish and at 14-degrees-C for trout to compare temper ature- and species-related differences. Analysis of OA pharmacokinetic s when determined by HPLC provided elimination half-life (t1/2beta), v olume of distribution (V(ss)), and clearance (Cl(b)) estimates for 24- degrees-C catfish, 14-degrees-C catfish, and 14-degrees-C trout of 40. 9, 69.3, and 81.3 h, 939, 880, and 1817 mL/kg, and 16.3, 8.9, and 16.9 mL.kg-1.h-1, respectively. Following oral administration, OA plasma c oncentrations peaked between 8 and 24 h for all treatments; however, 1 4-degrees-C trout and 14-degrees-C catfish sustained peak concentratio ns for a longer duration than 24-degrees-C catfish. Oral OA bioavailab ilities were 56.0, 91.8, and 90.7% for 24-degrees-C catfish, 14-degree s-C catfish, and 14-degrees-C trout, respectively. OA distribution dat a for muscle of 14-degrees-C catfish demonstrated an inordinately high peak concentration and delayed time to peak relative to other treatme nts. Elimination half-lives of OA in muscle were 33.1, 54.3, and 141 h for 24-degrees-C catfish, 14-degrees-C catfish, and 14-degrees-C trou t, respectively.