Tai C L, Wang C, Weckman T J, Popot M A, Woods W E, Yang J M, Blake J, Tai H H, Tobin T
Kentucky Equine Drug Testing and Research Program, Department of Veterinary Science, College of Pharmacy, University of Kentucky, Lexington 40546.
Am J Vet Res. 1988 May;49(5):622-8.
To improve the sensitivity and specificity of screening for etorphine in horses, an 125I-labeled etorphine analog was synthesized and an antibody to etorphine was raised in rabbits. A radioimmunoassay (RIA) for etorphine was developed, using these reagents. Bound and free 125I-labeled etorphine was separated by a double-antibody method that reduced interference from materials associated with equine urine. The 125I-labeled etorphine binding was rarely greater than 250 pg of background etorphine equivalents/ml in raw urine and was 100 pg/ml in hydrolyzed urine. The 125I-RIA was capable of detecting etorphine equivalents in urine above these background values. Etorphine equivalents were detected in equine urine samples for about 7 days after 4 mares were dosed with 0.22 microgram of etorphine/kg of body weight, IV. The stability of etorphine in urine from these mares was evaluated. Urine from these dosed mares was held in constant -20 C storage, and aliquots were repeatedly frozen and thawed. When analyzed for etorphine equivalents using an 125I-RIA, etorphine and its metabolites in urine samples were stable for less than or equal to 38 days if continuously frozen and also were resistant to repeated freezing and thawing.
为提高马体内埃托啡筛选的灵敏度和特异性，合成了一种125I标记的埃托啡类似物，并在兔体内制备了抗埃托啡抗体。利用这些试剂开发了一种埃托啡放射免疫分析法（RIA）。结合态和游离态的125I标记埃托啡通过双抗体法分离，该方法减少了来自马尿相关物质的干扰。在未处理的尿液中，125I标记埃托啡的结合量很少超过250 pg/ml背景埃托啡当量，在水解尿液中为100 pg/ml。125I-RIA能够检测出尿液中高于这些背景值的埃托啡当量。给4匹母马静脉注射0.22微克/千克体重的埃托啡后，在大约7天内马尿样本中检测到了埃托啡当量。评估了这些母马尿液中埃托啡的稳定性。将这些注射过药物的母马的尿液保存在-20℃恒定温度下，等分试样反复冻融。当使用125I-RIA分析埃托啡当量时，如果持续冷冻，尿液样本中的埃托啡及其代谢产物在38天内稳定，并且也能抵抗反复冻融。
