A Gas Chromatographic Screening Procedure for the detection of Non‐steroidal Anti‐inflammatory Drugs in horse urine

Abstract

SUMMARY A gas chromatographic screening procedure for the non‐steroidal anti‐inflammatory group of drugs is described. The method involves on‐column methylation of the carboxylic acid group using trimethylanilinium hydroxide as the methylating reagent. Fifteen such drugs were studied. Eight of these were detected in urine collected from horses that had received these compounds orally and for these drugs, rates of urinary excretion are recorded. Seven other members of this group of drugs were shown to be detectable by this procedure but in these cases the drug was added to urine and not administered to the horse. RÉSUMÉ Un procédé chromatographique au gaz est décrit. On utilise la méthylation en colonne de la fonction carboxilique acide à l'aide de l'hydroxyde de triméthylalinine. 15 produits différents ont étéétudiés. 8 d'entre eux ont été décélés dans l'urine de chevaux qui avaient reĉus ces produits par voie orale. Et pour ces produits, une appréciation du taux d'élimination urinaire a pu ětre faite. 7 autres produits ont été décelés dans l'urine par la měme méthode, mais après y avoir été simplement ajoutés. ZUSAMMENFASSUNG Es wird eine gaschromatographische Screening‐Methode zum Nachweis nicht‐steroider Entzündungshemmer beschrieben. Die Methode besteht in der Methylierung der Karboxylsäuregruppe in der Säule, wobei als methylierendes Reagens Trimethylanilin=hydroxid verwendet wird. Fünfzehn nicht‐steroide Entzündungs=hemmer wurden untersucht. Acht davon wurden in Urin von Pferden nachgewiesen, die die Medikamente oral erhalten hatten, und für diese Medikamente konnten die im Harn ausgeschiedenen Mengen festgestellt werden. Sieben andere Entzündungshemmer wurden ebenfalls mit dieser Methode nachgeweisen, aber diese Substanzen wurden dem Harn beigefügt und nicht den Pferden verabreicht.

Clinical pharmacology and therapeutic uses of non‐steroidal anti‐inflammatory drugs in the horse

“…Single doses ranging from 3 to 9 mg/kg bwt given orally, produced dullness, disorientation, paresis, neutropenia and occult blood in the faeces. Other equine studies, in which doses of approximately 2.5 mg/kg bwt indomethacin were administered daily, did not cause clinical signs of toxicity (Hunt, Haywood and Moss 1979;Phillips, Salyer and Ray 1980). The significance of Roberts' findings is therefore uncertain, particularly because his doses may have exceeded those required for therapeutic effectiveness.…”

Adverse effects of indomethacin in the horse

“…phenylbutazone, and the recognition of undesirable complications such as severe gastrointestinal haemorrhages in dogs (Ewing, 1972). There is n o record of the clinical use of indomethacin in horses, although this agent has been investigated by equine drug testing laboratories in relation to the presence and persistence of the parent compound and its metabolites in urine (Hunt, Haywood & Moss, 1979).…”

Concentrations of indomethacin and its metabolite desmethylindomethacin in plasma and urine after repeated indomethacin topical application to Thoroughbreds

“…Reports on pharmacokinetic (PK) studies of IND following its systemic administration in horses can be found ; however, information on its topical application is lacking.…”