PHARMACOKINETICS OF FLORFENICOL AND ITS METABOLITE, FLORFENICOL|AMINE, IN RED SWAMP CRAYFISH, PROCAMBARUS CLARKII

Pharmacokinetics of florfenicol and its metabolite, florfenicol amine in red swamp crayfish (Procambarusclarkii) were investigated at the water temperature (21±1)℃ after they were given a single oral dose of 50mg/kg bodyweight(b.w.) and intra-sinus administration(i.a) of 20 mg/kg (b.w.) respectively. Four red swamp crayfish per samplingpoint were examined after treatment. Hemolymph were collected and analyzed by reversed-phase high-performanceliquid chromatography (HPLC) method and pharmacokinetic parameters were calculated by non-compartment methodof 3p97 Practical Pharmacokinetic Program software. After i.a florfenicol injection, the elimination half-life (t1/2), thevolume of distribution Vd(ss) and the total body clearance (CL) of florfenicol were 8.26h, 14.43L/kg and 1.21L·kg/hrespectively. The t1/2 and metabolic rate (MR) of florfenicol amine were 20.28h and 9.3%. After oral administration (o.a)of florfenicol, the Cmax, Tmax, t1/2 and bioavailability (F) of florfenicol were 2.49mg/kg, 1.0h, 10.01h, 21.6% respectively.The t1/2 and MR of florfenicol amine were 16.0h, 37.5%. The elimination rate of florfenicol was quicker than that offlorfenicol amine and the distribution of florfenicol was wider in tissues of red swamp crayfish. Florfenicol was absorbedrapidly through the gastrointestinal tract but the bioavailability and metabolite rate were low by oral administration.