Farmacocinetica e determinação de residuos de enrofloxacina e seu metabolito em tecidos de frangos

AUTOR(ES)
DATA DE PUBLICAÇÃO

2004

RESUMO

Enrofloxacin (EFX) is a synthetic fluoroquinolone antimicrobial agent widely employed in veterinary medicine, particularly in poultry. Its major metabolite is ciprofloxacin (CFX). The HPLC analyses were carried out using a cationic-octadecil mixed column and a 0.05 mol L (pH 2.5) phosphate buffer/ACN as mobile phase, with a linear elution gradient and a flow rate of 1 mL min. The quantification was carried out employing ofloxacin (OFX) as internal standard and detection of EFX and CFX at 278 nm and OFX at 294 nm. The sample preparation of plasma and chicken tissues consisted of the precipitation of proteins with 10 % tricloroacetic acid /ACN (80/20 v/v) followed by solid phase extraction on cationic-octadecil mixed cartridges. The method was validated using the following parameters: linear range, linearity, selectivity, sensitivity, detection and quantification limits, intra- and inter-day precisions, accuracy and robustness. The limits of quantification, for both fluoroquinolonas, were 200 ng mL for plasma, 200 mg kg for liver and 100 mg kg for muscle and kidney tissues. The validated method was adequate for the determination of EFX and CFX in pharmaceutical formulations, as well as for the quantification of these substances in plasma and chicken tissues. The pharmacokinetic parameters of EFX were evaluated in broiler chickens (Cobb) after a single oral administration of 10 mg of EFX/kg body weight. The resulting plasma concentration versus time graph was characteristic of a two-compartment open model, with a maximum plasma concentration and time to reach this concentration of 1.5 ± 0.2 mg mL and 9 ± 2 h, respectively. The half-life and the mean residence time of EFX were 1.5 ± 0.2 h and 15.64 h, respectively. The area under the curve (AUC) was calculated as 35 ± 4 mg h mL. The average residence time was 15.64 h. Residue levels of EFX and CFX were determined in muscle, liver and kidney tissues of broiler chickens after oral administration of 10 mg of EFX/kg of body weight once daily for 3 sucessive days, with a preslaughter time of 3, 5 and 7 days. It was verified that a preslaughter withdrawal time of 7 days is appropriate for this animal destined for human consumption.

ASSUNTO(S)

farmacocinetica frangos

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