Quantitation of Formoterol, Salbutamol, and Salbutamol-4′-O-Sulfate in Human Urine and Serum via UHPLC-MS/MS

The adrenergic beta-2 agonists formoterol and salbutamol are used for the treatment of asthma COPD but also misused in sports competitions. Therefore, they included WADA regulations. Both drugs mainly excreted urine after administration via inhalation. A four-armed, double-blind cross-over clinical trial was conducted involving endurance-trained participants (12 females 12 males). Inhalation dosages 36 μg formoterol, 1200 salbutamol, a combination both, or placebo were administered before exercise. Serum collected exercise 3 24 h administration. Here, we show successful quantitation its phase II metabolite salbutamol-4′-O-sulfate all serum samples using ultra-high performance liquid chromatography–tandem mass spectrometry. In analysis, results up to 14.2 pg/mL 10.0 ng/mL 21.4 (calculated as equivalent) found. urine, maximum concentrations (after deglucuronidation) 17.2 948.5 2738.5 salbutamol-4′-O-sulfate. Sex-specific differences well urinary excretion observed. pronounce importance implementation elucidation metabolites methods antidoping.