Drug Analysis Department, Laboratory of Racing Chemistry, Utsunomiya, Japan.
Department of Pharmaceutical Sciences, Tohoku University Hospital, Sendai, Japan.
Rapid Commun Mass Spectrom. 2024 Mar 15;38(5):e9695. doi: 10.1002/rcm.9695.
Osilodrostat is an inhibitor of 11-beta-hydroxylase (CYP11B) and is used for the treatment of Cushing's disease but also categorized as an anabolic agent. The use of osilodrostat is prohibited in horseracing and equestrian sports. To the best of our knowledge, this is the first metabolic study of osilodrostat in equine plasma.
Potential metabolites of osilodrostat were identified by differential analysis using data acquired from pre- and post-administration plasma samples after protein precipitation with liquid chromatography electrospray ionization high-resolution mass spectrometry (LC/ESI-HRMS). [Correction added on 27 January 2023, after first online publication: In the preceding sentence, "C-HRMS" was changed to "LC/ESI-HRMS" in this version.] For quantification of osilodrostat, a strong cation exchange solid-phase extraction was employed, and the extracts were analyzed using LC/ESI-triple quadrupole tandem mass spectrometry (LC/ESI-QqQ-MS/MS) to establish its elimination profile. Such extracts were further analyzed using LC/ESI-HRMS to investigate the detectability of osilodrostat and its identified mono-hydroxylated metabolite over a 2-week sampling period.
Mono-hydroxylated osilodrostat was identified based on the differential analysis and mass spectrometric interpretations, and it was found to be the most abundant metabolite in plasma. Elimination profile of osilodrostat in plasma was successfully established over the 24-h post-administration period. Both osilodrostat and its mono-hydroxylated metabolite were detected up to the last sampling point at 2 weeks using HRMS, and osilodrostat could be confirmed up to 8-day post-administration with its reference material using HRMS as well.
For doping control, screening of both the parent drug osilodrostat and its mono-hydroxylated metabolite in equine plasma would be recommended due to their extended detection windows of up to 2 weeks. Given the availability of reference material for potential confirmation in forensic samples, osilodrostat is considered the most appropriate monitoring target.
奥昔司他特是 11-β-羟化酶（CYP11B）抑制剂，用于治疗库欣病，但也被归类为合成代谢剂。奥昔司他特在赛马和马术运动中被禁止使用。据我们所知，这是奥昔司他特在马血浆中的首次代谢研究。
通过使用液相色谱电喷雾电离高分辨质谱（LC/ESI-HRMS）获取给药前后经蛋白沉淀处理的血浆样品获得的数据进行差异分析，鉴定奥昔司他特的潜在代谢物。为了定量分析奥昔司他特，采用强阳离子交换固相萃取法，并用 LC/ESI-三重四极杆串联质谱（LC/ESI-QqQ-MS/MS）分析提取物，以建立其消除曲线。对这些提取物进行进一步分析，使用 LC/ESI-HRMS 调查在 2 周采样期间奥昔司他特及其鉴定的单羟基化代谢物的可检测性。
基于差异分析和质谱解释，鉴定出单羟基化奥昔司他特，发现其是血浆中最丰富的代谢物。在给药后 24 小时内成功建立了奥昔司他特在血浆中的消除曲线。使用 HRMS 可在 2 周的最后采样点检测到奥昔司他特及其单羟基化代谢物，使用 HRMS 也可以在给药后 8 天确认奥昔司他特及其参考物质。
出于兴奋剂控制的目的，建议对马血浆中的母体药物奥昔司他特及其单羟基化代谢物进行筛选，因为它们的检测窗口可延长至 2 周。鉴于在法医样本中确认的潜在确证物质的可用性，奥昔司他特被认为是最合适的监测目标。
