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Published:
Journal of Analytical Toxicology,
ISSN 0146-4760,
Volume 24,
Number 4, May/June 2000, pp. 281-288
Development
of Analytical Methods for the Detection of Metaraminol in the Horse* 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.Dennis
W. Hill1, , Walter G. Hyde2, Albert J. Kind1, Dave Greulich2, and Steve Hopkins2
1Pathobiology Department, Microchemistry Lab, University of Connecticut, Storrs,
Connecticut 06269 and 2Racing Laboratory, Iowa State University, Ames, Iowa 50011 Reproduction
of editorial content of this journal is prohibited without publisher’s
permission.
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