title: Development of analytical methods for the detection of metaraminol in the horse.
abstract: Aramine (metaraminol bitartrate) has been found in the possession of horse trainers and veterinarians who have been investigated for possible inappropriate drug administration to racing horses. Metaraminol (3-hydroxyphenylisopropanolamine) is a sympathomimetic amine that directly and indirectly affects adrenergic receptors, with alpha effects being predominant. Because it has the potential to affect the performance of a racing horse, its use is prohibited. In the present study, methods for the detection of metaraminol were developed. Metaraminol was found to be extracted with poor recovery (< 50%) from aqueous solutions by routine basic extraction or cation exchange/reversed-phase solid-phase extraction techniques. However, an extractive acetylation method gave good (> 90%) recovery of metaraminol from aqueous samples. Sequential urine samples collected from horses administered metaraminol intramuscularly at 0.02, 0.10, and 0.23 mg/kg were extracted by the developed extractive acetylation procedure and analyzed by gas chromatography-mass spectrometry (GC-MS) in full-scan and selected ion monitoring modes. Norphenylephrine was used as an internal standard for quantitative analysis. The maximum concentration of metaraminol occurred between 1 and 2 h postadministration. Metaraminol was detected in the 0.23 mg/kg administration urine for 24 h postadministration. Metaraminol was detected for the 0.10 and 0.02 mg/kg doses for approximately 8 h postadministration. No apparent biotransformation products were observed in a reaction mixture of metaraminol and horse liver microsomal reaction mixture. Comparison of gas chromatograms of the extracts of the postadministration urine samples with those of the pre-administration samples failed to reveal any exogenous compound other than metaraminol.
authors.affiliation: Pathobiology Department, University of Connecticut, Storrs 06269, USA.
authors.forename: D W
authors.initials: DW
authors.lastname: Hill
authors.forename: W G
authors.initials: WG
authors.lastname: Hyde
authors.forename: A J
authors.initials: AJ
authors.lastname: Kind
authors.forename: D
authors.initials: D
authors.lastname: Greulich
authors.forename: S
authors.initials: S
authors.lastname: Hopkins
mesh_terms: D018663:Adrenergic Agents / Q000008:administration & dosage / Q000032:analysis*; D000818:Animals; D001711:Biotransformation; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods / Q000662:veterinary*; D006736:Horses; D007273:Injections, Intramuscular; D008680:Metaraminol / Q000008:administration & dosage / Q000032:analysis*; D011786:Quality Control; D012680:Sensitivity and Specificity
chemical_list: D018663:Adrenergic Agents; D008680:Metaraminol