Identification of hypoxene metabolites in urine samples using gas chromatography–tandem mass spectrometry for anti-doping control

Objectives . Hypoxen is a drug which possesses antioxidant and antihypoxic effects. It achieves this by increasing the utilization of oxygen by mitochondria, intensifying oxidative phosphorylation, and as a result, improving tissue respiration. Athletes take it during prolonged exercise, in order to increase efficiency and reduce physical overwork. Since 2023, the World Anti-Doping Agency has included the drug in the monitoring program, in the belief that it can be used to gain a competitive advantage. It is thus a candidate for inclusion in the Prohibited List as a potential regulator of the human metabolism. Currently, there are no studies or scientific publications focusing on the identification of hypoxene in biofluids for the purpose of anti-doping control. The aim of this study is to determine the possible metabolites of the drug and their chromato-mass spectrometric characteristics in urine samples using gas chromatography–tandem mass spectrometry (GC–MS/MS) for doping control screening purposes. Methods . Sample preparation of urine samples was carried out using enzymatic hydrolysis, liquid–liquid extraction and derivatization. The GC–MS/MS method was used for analysis. Screening of hypoxene metabolites was carried out in the mode of total ion current after fragmentation of selected parent ions. Results . Three specific metabolites of hypoxene (m/z 342, 300, and 346, including trimethylsilyl derivatives) were identified in urine samples of volunteers (n = 3). They can act as markers for taking the target antihypoxant, and their possible structural formulas are given. The excretion curves of two metabolites with an m/z of 300 and 346 respectively in urine were studied. The maximum concentration is reached after 8–14 and 1.5–6 h, respectively. It was established, that these metabolites are reliably identified in urine 90 h or more after a single dose of the drug. Conclusions . Possible structures of hypoxene metabolites in urine samples from volunteers were determined for the first time and their chromato-mass spectrometric characteristics were established. The approach developed in this study can be used for screening analysis of hypoxene for the purpose of anti-doping control.