title: Long-term monitoring of opioid, sedative and anti-inflammatory drugs in horse hair using a selective and sensitive LC-MS/MS procedure.
abstract: BACKGROUND
  Compared to blood or urine, drugs can be detected for much longer periods in the long hair of horses. The aim of this study was to establish and validate a highly sensitive liquid chromatography tandem mass spectrometry (LC-MS/MS) method for the detection and quantification of frequently prescribed opioids, sedatives and non-steroidal anti-inflammatory agents in the mane and tail hair of horses. Based on an average growth rate of about 2 cm per month, times of administration reported by horse owners or veterinary physicians were related to drug localizations in hair. Hair samples were collected from ten horses that received drug treatments and analyzed in segments of 2, 4 or 6 cm in length. Hair segments were decontaminated, cut into fragments and methanol-extracted under sonication. The extracts were analyzed by LC-MS/MS for 13 commonly used drugs using the validated procedure. Deuterated analogs were included as internal standards.
  
  
  RESULTS
  Analytes were detected in hair samples with a length of up to 70 cm. Fourteen out of 16 hair samples were positive for at least one of the tested drugs. Segmentation allowed for time-resolved monitoring of periods of 1 to 3 months of drug administration. Concentrations in dark hair reached a maximum of 4.0 pg/mg for butorphanol, 6.0 pg/mg for tramadol, 1.4 pg/mg for morphine, 1.8 pg/mg for detomidine, 1.2 pg/mg for acepromazine, 39 pg/mg for flunixin, 5.0 pg/mg for firocoxib, and 3'600 pg/mg for phenylbutazone. Only trace amounts of meloxicam were detected. Drug detection correlated well with the reported period of medical treatment. No analytes were detected in the light-colored mane and tail hair samples from one horse despite preceding administrations of acepromazine and phenylbutazone.
  
  
  CONCLUSIONS
  This study describes a sensitive and selective technique suitable for the validated detection and quantification of frequently prescribed veterinary drugs in horse hair. The segmental method can be applied for time-resolved long-term retrospective drug monitoring, for example in prepurchase examinations of horses as drug detection in hair can prove preceding medical treatments.
authors.affiliation: Zurich Institute of Forensic Medicine, Center for Forensic Hair Analytics, University of Zurich, Zurich, Switzerland. milena.madry@irm.uzh.ch.
authors.forename: Milena M
authors.initials: MM
authors.lastname: Madry
authors.affiliation: Zurich Institute of Forensic Medicine, Center for Forensic Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland.
authors.forename: Barbara S
authors.initials: BS
authors.lastname: Spycher
authors.affiliation: Institute of Veterinary Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland.
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Kupper
authors.affiliation: Clinic of Veterinary Surgery, Department of Large Animal Surgery, University of Zurich, Zurich, Switzerland.
authors.forename: Anton
authors.initials: A
authors.lastname: Fuerst
authors.affiliation: Zurich Institute of Forensic Medicine, Center for Forensic Hair Analytics, University of Zurich, Zurich, Switzerland.
authors.forename: Markus R
authors.initials: MR
authors.lastname: Baumgartner
authors.affiliation: Zurich Institute of Forensic Medicine, Center for Forensic Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland.
authors.forename: Thomas
authors.initials: T
authors.lastname: Kraemer
authors.affiliation: Institute of Veterinary Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland. hanspeter.naegeli@vetpharm.uzh.ch.
authors.forename: Hanspeter
authors.initials: H
authors.lastname: Naegeli
mesh_terms: D000701:Analgesics, Opioid / Q000032:analysis* / Q000493:pharmacokinetics; D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000032:analysis* / Q000493:pharmacokinetics; D002853:Chromatography, Liquid / Q000662:veterinary*; D006197:Hair / Q000737:chemistry*; D006736:Horses; D006993:Hypnotics and Sedatives / Q000032:analysis* / Q000493:pharmacokinetics; D012680:Sensitivity and Specificity; D053719:Tandem Mass Spectrometry / Q000662:veterinary*
chemical_list: D000701:Analgesics, Opioid; D000894:Anti-Inflammatory Agents, Non-Steroidal; D006993:Hypnotics and Sedatives
keywords: Doping; Horse hair; LC-MS/MS; Pre-purchase examination