title: Simultaneous analysis of tiaramide metabolites in horse urine and plasma by solid-phase extraction and reversed-phase ion-pair liquid chromatography.
abstract: A simple method for the simultaneous analysis of tiaramide (TRA) metabolites in the horse is described. The sample preparation method using a Bond-Elut PH cartridge and stepwise elution with ice-cold, 30% aqueous methanol followed by additional methanol is effective for recovering the metabolites with different properties. The extraction method gives good recoveries (greater than 80%) and reproducibility. Each metabolite is well separated by high-performance liquid chromatography using an octadecyl-type column of polymer-based packing with a solvent system of 20 mM phosphate buffer (pH 6.5)-acetonitrile-tetrahydrofuran (6:1:0.2) containing a quaternary ammonium salt as an ion-pairing reagent. The detection limit of each metabolite is in the range of 20-80 ng/ml. The major metabolites of TRA in equine urine and plasma are N-acetic acid (TRAA) and N-oxide. The N-oxide of TRAA is detected as a metabolite in the urine. A dealkylation product PER) is detected as a minor metabolite. Unchanged TRA is detected only at low concentrations in the urine. Several minor metabolites of DER or TRAA or both are detected in the urine.
authors.affiliation: Laboratory of Racing Chemistry, Tokyo, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Takeda
authors.forename: T
authors.initials: T
authors.lastname: Shinohara
mesh_terms: D019342:Acetic Acid / Q000378:metabolism; D000097:Acetonitriles / Q000737:chemistry; D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000652:urine*; D052160:Benzothiazoles; D002138:Calibration; D002851:Chromatography, High Pressure Liquid; D005663:Furans / Q000737:chemistry; D006736:Horses; D000432:Methanol / Q000737:chemistry; D010084:Oxidation-Reduction; D010710:Phosphates / Q000737:chemistry; D010879:Piperazines / Q000097:blood / Q000378:metabolism* / Q000652:urine*; D011108:Polymers; D012015:Reference Standards; D015203:Reproducibility of Results
chemical_list: D000097:Acetonitriles; D000894:Anti-Inflammatory Agents, Non-Steroidal; D052160:Benzothiazoles; D005663:Furans; D010710:Phosphates; D010879:Piperazines; D011108:Polymers; C018674:tetrahydrofuran; C003468:tiaramide; D019342:Acetic Acid; D000432:Methanol; C032159:acetonitrile