Abstract of research

PHARMACOKINETICS AND TISSUE RESIDUES OF NORFLOXACIN IN NORMAL AND EXPERIMENTALLY E.COLI INFECTED BROILER CHICKEN.

Mossad, G.A. El-Sayed, Ashraf, A.A. El-Komy, Mohamed, H. Aboubakr and Ahmed, M. Elsaid

Abstract

The pharmacokinetics of norfloxacin was studied following single intravenous, oral administration in normal chicken and repeated oral administrations of norfloxacin in normal and experimentally E.coli infected broiler chicken. The pharmacokinetic parameters following a single intravenous injection of 10 mg/kg b.wt., revealed that norfloxacin obeyed a two compartments open model, distribution halflife (t0.5(α)) was 0.149±0.001 h, volume of distribution (Vdss) was 2223.17±65.62 ml/kg, elimination half-life (t0.5(β)) was 4.71±0.06 h and total body clearance (CLtot) was 1.72±0.02 ml/kg/min. Following oral administration, norfloxacin was rapidly and efficiently absorbed through gastrointestinal tract of chicken as the absorption half-life (t0.5(ab): 0.57±0.01 h). Maximum serum concentration (Cmax) was 3.87±0.04 μg/ml, reached its maximum time (tmax) at about 2.09±0.03 h, elimination half-life (t0.5(el)) was 5.72±0.05 h and total body clearance (CLtot) was 4.02±0.06 ml/kg/min indicating the tendency of chicken to eliminate norfloxacin in slow rate. Oral bioavailability was 66.89±1.95 % indicating moderate absorption of norfloxacin after oral administration from oral site. The in- vitro protein binding was 10.37±0.22 %. Serum concentrations of norfloxacin following repeated oral administration of 10 mg/kg BW once daily for five consecutive days, peaked 2 hours after each oral dose with lower significant values recorded in experimentally infected chicken than in normal ones. Tissues residues of norfloxacin in slaughtered normal and experimentally E.coli infected chicken could not be detected by microbiological assay in all tested tissues except in lung, liver, and kidneys in chicken at 48 hours post last administration, so the chicken must not be slaughtered before 3 days of stopping of drug administration.