Detectability of testosterone esters and estradiol benzoate in bovine hair and plasma following pour-on treatment |
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| Authors: | A A M Stolker M J Groot J J P Lasaroms A W J M Nijrolder M H Blokland I Riedmaier C Becker H H D Meyer M W F Nielen |
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| Institution: | (1) RIKILT Institute of Food Safety, P.O. Box 230, 6700, AE, Wageningen, The Netherlands;(2) RIVM National Institute for Public Health and Environment, P.O. Box 1, 3720, BA, Bilthoven, The Netherlands;(3) Physiology Weihenstephan, Technische Universitaet Muenchen, Weihenstephaner Berg 3, 85350 Freising, Germany;(4) Laboratory of Organic Chemistry, Wageningen University, Dreijenplein 8, 6703, HB, Wageningen, The Netherlands |
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| Abstract: | The abuse of synthetic esters of natural steroids such as testosterone and estradiol in cattle fattening and sports is hard
to detect via routine urine testing. The esters are rapidly hydrolysed in vivo into substances which are also endogenously
present in urine. An interesting alternative can be provided by the analysis of the administered synthetic steroids themselves,
i.e., the analysis of intact steroid esters in hair by liquid chromatography tandem mass spectrometry (LC/MS/MS). However,
retrospective estimation of the application date following a non-compliant finding is hindered by the complexity of the kinetics
of the incorporation of steroid esters in hair. In this study, the incorporation of intact steroid esters in hair following
pour-on treatment has been studied and critically compared with results from intramuscular treatment. To this end animals
were pour-on treated with a hormone cocktail containing testosterone cypionate, testosterone decanoate and estradiol benzoate
in different carriers. The animals were either treated using injection and pour-on application once or three times having
1 week between treatments using injection and pour-on application. Animals were slaughtered from 10–12 weeks after the last
treatment. Both hair and blood plasma samples were collected and analysed by LC/MS/MS. From the results, it is concluded that
after single treatment the levels of steroid esters in hair drop to CCβ levels (5–20 μg/kg) after 5–7 weeks. When treatment
is repeated two times, the CCβ levels are reached after 9–11 weeks. Furthermore, in plasma, no steroid esters were detected;
not even at the low microgramme per litre level but—in contrast with the pour-on application—after i.m. injection, significant
increase of 17β-testosterone and 17β-estradiol were observed. These observations suggest that transport of steroid esters
after pour-on application is not only performed by blood but also by alternative fluids in the animal so probably the steroid
esters are already hydrolysed and epimerized before entering the blood. |
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