Plasma, urinary and biliary residues in cattle following intramuscular injection of nortestosterone laurate.

摘要

Elimination of 19-nortestosterone (nandrolone; beta-NT) and its metabolites in plasma, urine and bile was studied in 3 cattle with cannulated gall bladders following i.m. injection at a single site of 500 mg of the laurate ester (NTL) containing 300.5 mg beta-NT. Using enzyme immunoassay quantification, plasma Cmax of free beta-NT was 0.5?.15 鎔/litre (mean馭EM). Concentrations of free beta-NT in plasma were consistently greater than the assay limit of quantification (0.12 鎔/litre) for 32.7?3.42days. Mean residence time for free beta-NT in plasma was 68.5?0.75 days. Following sample preparation by immunoaffinity chromatography, high-resolution GC-MS was used to measure beta-NT and alpha-NT in urine and bile. beta-NT was detected irregularly in urine from 2 of the 3 animals after injection. The principal metabolite urine, alpha-NT, was detected for 160.3?2.67 days after injection. Cmax for alpha-NT in urine was 13.7?.14 鎔/litre. Mean urinary AUC0-183 days for alpha-NT was 845.7?00.90 (鎔h)/litre. In bile, alpha-NT was the only metabolite detected for 174.3?.67 days after treatment. Cmax for alpha-NT in bile was 40.8?2.70 鎔/litre and mean biliary AUC0-183 days for alpha-NT was 1982.6?73.81 (鎔 h)/litre. Concentrations of alpha-NT inbile samples were greater than those in urine samples taken at the same time. The mean ratio of biliary:urinary AUC0-183 days was 3.0?.72. It is concluded that bile is a superior fluid for detection of alpha-NT following injection of NTL, owing to the longer period during which residues may be detected after administration.