SESSION E. FOOD SAFETY AND RESIDUES

Boldenone (1,4-androstadiene-3–one, 17-ol) (BOL) and boldione(1, 4-androstadiene-3,17-dione) (ADD) are chemical derivativesof testosterone, known as strong anabolics and low to moderateandrogenic agents. ADD, the dione form of BOL, is a directprecursor of that anabolic steroid, and it is activated by the samewidely distributed 17beta-hydroxysteroid dehydrogenaseenzyme that converts androstenedione to testosterone . ADDis one of the most orally active pro-hormones, and displays alevel of oral bioavailability far superior to any other compound. To optimize anabolicsurveillance strategies, ADD and BOL were administered to vealcalves, at a similar dosage and the same ratio present in ‘ready touse’ cocktails; their disposition in plasma and their eliminationrate in urine were followed for 24 h.Analysis Urinary concentrations of b-BOL, a-BOL and ADD were determined(before and after deconjugation with Helix pomatia extracts)using a validated liquid chromatography-tandem mass spectrometry(LC-MS-MS) method. To measure plasma concentrations,the same method with slight modifications was adopted.ADD was not detectable in any of the urine or plasma samples atany time.For both 17 a- and 17b-BOL the highest concentrations were detected in the firstplasma samples (15 min after administration), their concentrationsthen decreased at similar rates and both were undetectablewithin 4 h after administration. In urine samples collectedwithin 4 h after administration, concentrations of a-BOL wereconsiderably higher than those of b-BOL, and 36 h afteradministration a-BOL was the only detectable metabolite.b-BOL was detectable over a period of 24 h only.The absence of ADD confirmed its double identity, i.e. not only asa metabolite but also a precursor of b-BOL, as already shown invitro after incubation of ADD or b-BOL with calf liver microsomes. The in vivo results confirm that both ADD and b-BOL werepromptly absorbed when administered to veal calves beforefeeding, and that their disappearance from plasma was evenmore rapid. About 3 h after administration a significant quantityof a-BOL was recovered in urine, while b-BOL attainedconcentrations only slightly higher than the EU action limit.Surprisingly, after 9 h a-BOL concentrations were already lessthan 2% of those detected at the previous sampling time andb-BOL concentrations were closed to the limit of quantitation.One day after treatment only a-BOL gave a feeble indication ofthe ‘illegal’ treatment. These findings indicate that sampling timeis crucial when urine samples are collected from farmed calvesfor surveillance purposes