McEvoy J D, McVeigh C E, Currie J W, Kennedy D G, McCaughey W J
Residues Department, Department of Agriculture for Northern Ireland, Belfast, UK.
Vet Res Commun. 1998 Nov;22(7):479-91. doi: 10.1023/a:1006179116231.
The synthetic androgen 19-nortestosterone (beta-NT) has been used illegally as a growth promoter in cattle production in the European Union. Elimination of beta-NT and its metabolites in plasma, urine and bile was studied in three cattle with cannulated gallbladders following intramuscular 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 +/- 0.15 microgram/L (mean +/- SEM). Concentrations of free beta-NT in plasma were consistently greater than the assay limit of quantification (0.12 microgram/L) for 32.7 +/- 13.42 days. Mean residence time for the beta-NT in plasma was 68.5 +/- 20.75 days. Following sample preparation by immunoaffinity chromatography, high-resolution GC-MS was used to quantify beta-NT and alpha-NT in urine and bile. beta-NT was detected irregularly in urine from two of the three animals post injection. The principal metabolite present in the urine, alpha-NT, was detected for 160.3 +/- 22.67 days post injection. Cmax for alpha-NT in urine was 13.7 +/- 5.14 micrograms/L. Mean urinary AUC0-183 days for alpha-NT was 845.7 +/- 400.90 (microgram h)/L. In bile, alpha-NT was the only metabolite detected for 174.3 +/- 8.67 days post treatment. Cmax for alpha-NT in bile was 40.8 +/- 12.70 micrograms/L and mean biliary AUC0-183 days for alpha-NT was 1982.6 +/- 373.81 (microgram h)/L. Concentrations of alpha-NT in bile 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 +/- 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.
合成雄激素19-去甲睾酮（β-NT）在欧盟曾被非法用作养牛业的生长促进剂。对三头安装有胆囊插管的牛单次肌肉注射含300.5mgβ-NT的月桂酸酯（NTL）500mg后，研究了血浆、尿液和胆汁中β-NT及其代谢物的消除情况。采用酶免疫测定法定量，游离β-NT的血浆Cmax为0.5±0.15μg/L（平均值±标准误）。血浆中游离β-NT的浓度在32.7±13.42天内一直高于测定定量限（0.12μg/L）。β-NT在血浆中的平均驻留时间为68.5±20.75天。通过免疫亲和色谱法进行样品制备后，采用高分辨率气相色谱-质谱法对尿液和胆汁中的β-NT和α-NT进行定量。注射后，在三头动物中的两头动物的尿液中不定期检测到β-NT。尿液中存在的主要代谢物α-NT在注射后160.3±22.67天内被检测到。尿液中α-NT的Cmax为13.7±5.14μg/L。α-NT的尿液平均AUC0-183天为845.7±400.90（μg·h）/L。在胆汁中，治疗后174.3±8.67天内仅检测到α-NT这一代谢物。胆汁中α-NT的Cmax为40.8±12.70μg/L，α-NT的胆汁平均AUC0-183天为1982.6±373.81（μg·h）/L。胆汁样品中α-NT的浓度高于同时采集的尿液样品中的浓度。胆汁与尿液的AUC0-183天平均比值为3.0±0.72。得出的结论是，由于注射NTL后残留可被检测到的时间更长，胆汁是检测α-NT的更佳液体。
