17 alpha-ethyl-5 beta-estrane-3 alpha, 17 beta-diol, a biological marker for the abuse of norethandrolone and ethylestrenol in slaughter cattle

The metabolism of the illegal growth promoter ethylestrenol (EES) was evalu ated in bovine liver cells and subcellular fractions of bovine liver prepar ations. Incubations with bovine microsomal preparations revealed that EES i s extensively biotransformed into norethandrolone (NE), another illegal gro wth promoter. Furthermore, incubations of monolayer cultures of hepatocytes with NE indicated that NE itself is rapidly reduced to 17 alpha-ethyl-5 be ta-estrane-3 alpha,17 beta-diol (EED). In vivo tests confirmed that, after administration of either EES or NE, EED is excreted as a major metabolite. Therefore, it was concluded that, both in urine and faeces samples, EED can be used as a biological marker for the illegal use of EES and/or NE. Moreo ver, by monitoring EED in urine or faeces samples, the detection period aft er NE administration is significantly prolonged. These findings were furthe r confirmed by three cases of norethandrolone abuse in a routine screening program for forbidden growth promoters. (C) 1999 Elsevier Science B.V. All rights reserved.