title: Detection, quantification, metabolism, and behavioral effects of selegiline in horses.
abstract: Selegiline ([R]-[-]N,alpha-dimethyl-N-2- propynylphenethylamine or l-deprenyl), an irreversible inhibitor of monoamine oxidase, is a classic antidyskinetic and antiparkinsonian agent widely used in human medicine both as monotherapy and as an adjunct to levodopa therapy. Selegiline is classified by the Association of Racing Commissioners International (ARCI) as a class 2 agent, and is considered to have high abuse potential in racing horses. A highly sensitive LC/MS/MS quantitative analytical method has been developed for selegiline and its potential metabolites amphetamine and methamphetamine using commercially available deuterated analogs of these compounds as internal standards. After administering 40 mg of selegiline orally to two horses, relatively low (<60 ng/ml) concentrations of parent selegiline, amphetamine, and methamphetamine were recovered in urine samples. However, relatively high urinary concentrations of another selegiline metabolite were found, tentatively identified as N- desmethylselegiline. This metabolite was synthesized and found to be indistinguishable from the new metabolite recovered from horse urine, thereby confirming the chemical identity of the equine metabolite. Additionally, analysis of urine samples from four horses dosed with 50 mg of selegiline confirmed that N-desmethylselegiline is the major urinary metabolite of selegiline in horses. In related behavior studies, p.o. and i.v. administration of 30 mg of selegiline produced no significant changes in either locomotor activities or heart rates.
authors.affiliation: Department of Biomedical Sciences, College of Veterinary Medicine, Nursing and Allied Health, Tuskegee University, Tuskegee, AL 36088, USA.
authors.forename: Levent
authors.initials: L
authors.lastname: Dirikolu
authors.forename: Andreas F
authors.initials: AF
authors.lastname: Lehner
authors.forename: Wojciech
authors.initials: W
authors.lastname: Karpiesiuk
authors.forename: Charlie
authors.initials: C
authors.lastname: Hughes
authors.forename: William E
authors.initials: WE
authors.lastname: Woods
authors.forename: Jeff
authors.initials: J
authors.lastname: Boyles
authors.forename: John D
authors.initials: JD
authors.lastname: Harkins
authors.forename: Amy
authors.initials: A
authors.lastname: Troppmann
authors.forename: Thomas
authors.initials: T
authors.lastname: Tobin
mesh_terms: D000284:Administration, Oral; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D005260:Female; D006736:Horses / Q000378:metabolism*; D013058:Mass Spectrometry / Q000662:veterinary; D008996:Monoamine Oxidase Inhibitors / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics* / Q000494:pharmacology / Q000652:urine; D012642:Selegiline / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics* / Q000494:pharmacology / Q000652:urine; D015813:Substance Abuse Detection / Q000662:veterinary
chemical_list: D008996:Monoamine Oxidase Inhibitors; D012642:Selegiline