title: Study of dexamethasone urinary excretion profile in cattle by LC-MS/MS: comparison between therapeutic and growth-promoting administration.
abstract: Dexamethasone is a potent synthetic corticosteroid widely employed as a therapeutic agent in cattle. Besides this legal use, corticosteroids are also administered at low dosages as growth-promoters either alone or in combination with other steroids or with beta-agonists. For this reason, appropriate control plans are established to survey corticosteroid misuse, using liver or urine as biological matrices. Since few data are available about the kinetics of dexamethasone excretion in meat cattle, an experimental study was designed to assess the drug residue levels in urines following either a therapeutic (60 microg of dexamethasone sodium phosphate/kg b.w., for three consecutive days) or a growth-promoting schedule (0.7 or 1.4 mg of dexamethasone sodium phosphate per capita/day for 60 days). The urinary elimination of dexamethasone, which was predominantly excreted in the unmodified form, was determined by high-performance liquid chromatography/tandem mass spectrometry at different time intervals, i.e. during the treatments and after appropriate withdrawal times. Our findings confirm the high and rapid rate of dexamethasone urinary excretion irrespective of the nature of the treatment, and provide useful reference values that can be conveniently employed for forensic purposes.
authors.affiliation: Department of Animal Pathology, Division of Pharmacology and Toxicology, University of Turin, Via Leonardo da Vinci 44, 10095 Grugliasco, Torino, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Vincenti
authors.forename: Flavia
authors.initials: F
authors.lastname: Girolami
authors.forename: Pierluigi
authors.initials: P
authors.lastname: Capra
authors.forename: Marco
authors.initials: M
authors.lastname: Pazzi
authors.forename: Monica
authors.initials: M
authors.lastname: Carletti
authors.forename: Giulia
authors.initials: G
authors.lastname: Gardini
authors.forename: Carlo
authors.initials: C
authors.lastname: Nebbia
mesh_terms: D000818:Animals; D002417:Cattle / Q000652:urine*; D002851:Chromatography, High Pressure Liquid; D003907:Dexamethasone / Q000008:administration & dosage* / Q000493:pharmacokinetics / Q000652:urine*; D005938:Glucocorticoids / Q000652:urine*; D006133:Growth Substances; D007700:Kinetics; D007880:Legislation, Drug; D008297:Male; D012016:Reference Values; D012680:Sensitivity and Specificity; D053719:Tandem Mass Spectrometry; D019155:Veterinary Drugs / Q000008:administration & dosage*
chemical_list: D005938:Glucocorticoids; D006133:Growth Substances; D019155:Veterinary Drugs; D003907:Dexamethasone