Determination of Salmeterol in Equine Urine and Serum

Salmeterol is a β₂-adrenergic agonist and an Association of Racing Commissioners International (ARCI) class 3 drug. Trade names of its xinafoate salt are Arial (Dompé), Salmetedur (Menarini), and Serevent (Glaxo). Salmeterol is routinely used to increase ease of breathing in race horses during their training. Due to its bronchodilating and central nervous system stimulant properties, its administration to a horse just prior to race time has the potential to affect the horse’s performance, therefore a reliable method of analysis for this compound is necessary. This paper describes a method for the identification and quantitation of salmeterol in equine urine using liquid-liquid extraction followed by liquid chromatography and tandem mass spectrometry (LC-MS-MS). Urine salmeterol concentrations peaked at about 2 h post-dose following administration of 500 ug both intravenously and intratracheally at concentrations of 14 ng mL^?1 and 4 ng mL^?1, respectively. Serum concentrations at 30 min were below the minimum level of quantitation.