Detection and characterization of a new metabolite of 17alpha-methyltestosterone.

The misuse of the anabolic steroid methyltestosterone is currently routinely monitored in doping control laboratories by gas chromatography-mass spectrometry (GC-MS) of two of its metabolites: 17alpha-methyl-5beta-androstane-3alpha,17beta-diol and 17alpha-methyl-5alpha-androstane-3alpha,17beta-diol. Because of the absence of any easy ionizable moiety, these metabolites are poorly detectable using liquid chromatography-tandem mass spectrometry (LC-MS/MS) with electrospray ionization (ESI). In this study, the metabolism of methyltestosterone has been reinvestigated by the use of a precursor ion scan method in LC-ESI-MS/MS. Two metabolites have been detected using this method. Both compounds have been confirmed in postadministration urine samples of an urokinase plasminogen activator-severe combined immunodeficiency (uPA-SCID) mouse with humanized liver and were characterized by LC-MS/MS and GC-MS using both quadrupole and time of flight analyzers. From the detailed study of the fragmentation, these metabolites were proposed to be epimethyltestosterone and a dehydrogenated compound. Epimethyltestosterone has previously been described as a minor metabolite, whereas the occurrence of the oxidized metabolite has not been reported. Comparison with the synthesized reference revealed that the structure of the dehydrogenated metabolite is 6-ene-epimethyltestosterone. A selected reaction monitoring method including three transitions for each metabolite has been developed and applied to samples from an excretion study and to samples declared positive after GC-MS analysis. 6-Ene-epimethyltestosterone was found in all samples, showing its applicability in the detection of methyltestosterone misuse.

Direct quantification of steroid glucuronides in human urine by liquid chromatography-electrospray tandem mass spectrometry.

A method based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the direct quantification of glucuronides of testosterone (TG), epitestosterone (EPG), androsterone (AG) and etiocholanolone (ETG) has been developed. The method allowed for the direct determination of these analytes avoiding hydrolysis and derivatization, which are usual steps in commonly used methods based on gas chromatography-mass spectrometry (GC-MS). The electrospray ionization and the product ion spectra of the glucuronides have been studied in order to obtain the most specific transitions. The use of the selected transitions is necessary for the determination of the analytes at low ng/ml concentration levels. Two different approaches have been tested for sample preparation: direct injection after filtration and acidic liquid-liquid extraction (LLE) with ethyl acetate. Both approaches have been validated obtaining satisfactory values for accuracy and precision with limits of detection lower than 1 ng/ml for TG and EPG. Ion suppression was more pronounced after LLE probably due to the concentration of interferences from acidic urine. The applicability of the method has been checked by the analysis of 40 urine samples. The results were compared with those obtained with the common GC-MS method. Results have shown a good correlation between both methods with correlation coefficients higher than 0.97. A slope close to 1 was obtained for all analytes except for AG possibly due to losses during the extraction process prior to GC-MS.

Elucidation of urinary metabolites of fluoxymesterone by liquid chromatography-tandem mass spectrometry and gas chromatography-mass spectrometry.

The suitability of liquid chromatography tandem mass spectrometry (LC-MS/MS) and gas chromatography mass spectrometry (GC-MS) for the elucidation of fluoxymesterone metabolism has been evaluated. Electrospray ionization (ESI) and collision induced dissociation (CID) fragmentation in LC-MS/MS and electron impact spectra (EI) in GC-MS have been studied for fluoxymesterone and two commercially available metabolites. MS(n) experiments and accurate mass measurements performed by an ion-trap analyser and a QTOF instrument respectively have been used for the elucidation of the fragmentation pathway. The neutral loss scan of 20 Da (loss of HF) in LC-MS/MS has been applied for the selective detection of fluoxymesterone metabolites. In a positive fluoxymesterone doping control sample, 9 different analytes have been detected including the parent compound. Seven of these metabolites were also confirmed by GC-MS including 5 previously unreported metabolites. On the basis of the ionization, the CID fragmentation, the accurate mass of the product ions and the EI spectra of these analytes, a tentative elucidation as well as a proposal for the metabolic pathway of fluoxymesterone has been suggested. The presence of these compounds has also been confirmed by the analysis of five other positive fluoxymesterone urine samples.

Prohormones and sport.

Several precursors of testosterone and nandrolone introduced on the nutritional supplement market as performance enhancing drugs are banned in sports. Until now they are legally sold without a prescription in the US. Results of excretion studies with related compounds including 7-keto-DHEA and 1-androstenediol are presented. The main metabolites of 7-keto-DHEA are 7-hydroxylated compounds. The commercial 1-androstenediol preparation was contaminated with several other anabolic steroids. Oxidation of 1-androstenediol to 1-androstenedione seems to be the major renal metabolic pathway. Additionally contaminated nutritional supplements containing banned substances not indicated on the label were administered. The results of the excretion studies indicate that after the intake of amounts substantially lower than the recommended dose athletes can fail a doping test for periods up to 120 h.