Simultaneous detection of different chemical classes of selective androgen receptor modulators in urine by liquid chromatography-mass spectrometry-based techniques.

Analytical procedures to detect the misuse of selective androgen receptor modulators in human urine, targeting either the parent drugs and/or their main metabolites, were developed and validated. In detail, 19 target compounds belonging to 9 different chemical classes were considered: arylpropionamide (i.e., andarine (S4), ostarine (S22), S1, S6, S9 and S23), diarylhydantoin (i.e., GLPG0492), indole (i.e., LY2452473, GSK2881078), isoquinoline-carbonyle (i.e., PF-02620414), phenyl-oxadiazole (i.e., RAD140), pyrrolidinyl-benzonitrile (i.e., LGD4033), quinolinone (i.e., LGD2226, LGD3303), steroidal (i.e., Cl-4AS-1, MK0773 and TFM-4AS-1), and tropanol (i.e., AC-262536 and ACP105) derivatives. The metabolites of the target compounds considered were enzymatically synthesized by using human liver microsomes. Sample pre-treatment included enzymatic hydrolysis followed by liquid-liquid extraction at neutral pH. The instrumental analysis was performed by ultra-high-performance liquid chromatography coupled to either high- or low-resolution mass spectrometry. Validation was performed according to the ISO 17025 and the World Anti-Doping Agency guidelines. The analyses carried out on negative samples confirmed the method's selectivity, not showing any significant interferences at the retention times of the analytes of interest. Detection capability was determined in the range of 0.1-1.0 ng/mL for the screening procedure and 0.2-1.0 ng/mL for the confirmation procedure (except for GLPG0492 and GSK2881078). The recovery was greater than 80 % for all analytes, and the matrix effect was smaller than 35 %. The method also matched the criteria of the World Anti-Doping Agency in terms of repeatability of the relative retention times (CV% < 1.0) and of the relative abundances of the selected ion transitions (performed only in the case of triple quadrupole, CV% < 15), ensuring the correct identification of all the analytes considered. Urine samples containing andarine, ostarine, or LGD4033 were used to confirm the actual applicability of the selected analytical strategies. All target compounds (parent drugs and their main metabolites) were detected and correctly identified.

Absorption, Distribution, Metabolism, and Excretion of the Androgen Receptor Inhibitor Enzalutamide in Rats and Dogs.

BACKGROUND AND OBJECTIVES: Enzalutamide is an androgen receptor inhibitor that has been approved in several countries. Absorption, distribution, metabolism, and excretion (ADME) data in animals would facilitate understanding of the efficacy and safety profiles of enzalutamide, but little information has been reported in public. The purpose of this study was to clarify the missing ADME profile in animals. METHODS: ADME of 14C-enzalutamide after oral administration as Labrasol solution were investigated in non-fasted male Sprague-Dawley rats and beagle dogs. RESULTS: Plasma concentrations of 14C-enzalutamide peaked in rats and dogs at 6-8 h after a single oral administration. In most tissues, radioactivity concentration peaked at 4 h after administration. Excluding the gastrointestinal tract, tissues with the highest concentration of radioactivity were liver, fat, and adrenal glands. The tissue concentrations of radioactivity declined below the limit of quantitation or <0.89 % of maximum concentration by 168 h post-dose. Two known metabolites (M1 and M2) and at least 15 novel possible metabolites were detected in this study. M1 was the most abundant metabolite in both rats and dogs. Unchanged drug was a minor component in excreta. In intact rats, the mean urinary and fecal excretion of radioactivity accounted for 44.20 and 49.80 % of administered radioactivity, respectively. In intact dogs, mean urinary and fecal excretion was 62.00 and 22.30 % of the administered radioactivity, respectively. CONCLUSIONS: Rapid oral absorption was observed in rats and dogs when 14C-enzalutamide was administered as Labrasol solution. Tissue distribution in rats was clarified. The elimination of enzalutamide is mediated primarily by metabolism. Species differences were observed in excretion route.

Selective androgen receptor modulators: in vitro and in vivo metabolism and analysis.

For future targeted screening in National Residue Control Programmes, the metabolism of seven SARMs, from the arylpropionamide and the quinolinone classes, was studied in vitro using S9 bovine liver enzymes. Metabolites were detected and identified with ultra-performance liquid chromatography (UPLC) coupled to time-of-flight mass spectrometry (ToF-MS) and triple quadrupole mass spectrometry (QqQ-MS). Several metabolites were identified and results were compared with literature data on metabolism using a human cell line. Monohydroxylation, nitro-reduction, dephenylation and demethylation were the main S9 in vitro metabolic routes established. Next, an in vivo study was performed by oral administration of the arylpropionamide ostarine to a male calf and urine samples were analysed with UPLC-QToF-MS. Apart from two metabolites resulting from hydroxylation and dephenylation that were also observed in the in vitro study, the bovine in vivo metabolites of ostarine resulted in glucuronidation, sulfation and carboxylation, combined with either a hydroxylation or a dephenylation step. As the intact mother compounds of all SARMs tested are the main compounds present after in vitro incubations, and ostarine is still clearly present in the urine after the in vivo metabolism study in veal calves, the intact mother molecules were selected as the indicator to reveal treatment. The analytical UPLC-QqQ-MS/MS procedure was validated for three commercially available arylpropionamides according to European Union criteria (Commission Decision 2002/657/EC), and resulted in decision limits ranging from 0.025 to 0.05 µg l⁻¹ and a detection capability of 0.025 µg l⁻¹ in all cases. Adequate precision and intra-laboratory reproducibility (relative standard deviation below 20%) were obtained for all SARMs and the linearity was 0.999 for all compounds. This newly developed method is sensitive and robust, and therefore useful for confirmation and quantification of SARMs in bovine urine samples for residue control programmes and research purposes.