Due to the widespread use of dexamethasone in racing horses, mostly in low doses by intra-articular administration for the treatment of inflammatory processes, a method is developed to detect this drug in horse urine samples using liquid-liquid extraction followed by immunoaffinity chromatography. Liquid chromatography with diode-array detection is used for the identification of the drug. The use of immunoaffinity columns enhances the selectivity of the analysis, and the results show that dexamethasone can be detected up to 28 h after intra-articular administration. PMID: 9358628 [PubMed - indexed for MEDLINE]