New anabolic steroid illegally used in cattle—structure elucidation of 19-norchlorotestosterone acetate metabolites in bovine urine

4-Chloro-estr-4-en-17-ol-3-one, trivially named 19-norclostebol acetate or 4-chloro-19-nortestosterone acetate (NClTA), has been identified on the European black market in the late 1990s for possible use in breeding animals. After oral and subcutaneous administration of NClTA to bovine, urine samples were collected over a period of three weeks, and chemical structure of main excreted urinary metabolites was determined. After oral administration, the most abundant metabolites were mainly reduced as 4-chloro-19-norandrostan-3ξ-ol-17-one and 4-chloro-19-norandrostan-3ξ,17ξ-diol. They were identified until 1 week after administration. Following subcutaneous injection, 4-chloro-19-norandrostan-3ξ-ol-17-one was again of major abundance, but so were 4-chloro-19-norandrost-4-ene-3ξ,17ξ-diol and 4-chloro-19-norandrost-4-en-3ξ-ol-17-one. They were detected at least 3 weeks after administration. Whatever the route of administration, metabolites were found mainly glucurono-conjugated; the only exception was metabolite 4-chloro-19-norandrostan-3ξ-ol-17-one which was identified both in the sulpho- and glucurono-fractions.