title: LC-MS/MS method for confirmation of recombinant human erythropoietin and darbepoetin alpha in equine plasma.
abstract: Recombinant human erythropoietin (rhEPO) and darbepoetin alpha (DPO) are protein-based drugs for the treatment of anemia by stimulating red blood cell production. Consequently, they are abused in human and equine sports. To deter their abuse in the horse racing industry, a sensitive and reliable method for confirmation of these agents in equine plasma has been in urgent need. Such a method by LC-MS/MS is described in this paper. The method involved analyte enrichment by immunoaffinity separation using anti-rhEPO antibody linked to magnetic beads, digestion by trypsin, and analysis by LC-MS/MS. Two specific proteotypic peptides, 46VNFYAWK52 and 144VYSNFLR150 from rhEPO and DPO were employed for confirmation of the analytes based on chromatographic retention times and major product ions. The limit of confirmation of this method was 0.2 ng/mL, and the limit of detection was 0.1 ng/mL for rhEPO and DPO in equine plasma. This method was successful in confirming the presence of rhEPO and DPO in plasma samples collected from research horses to which rhEPO or DPO was administered and from racehorses following competition and in noncompetition samples in North America. To our knowledge, this is the first LC-MS method with adequate sensitivity and specificity in providing unequivocal confirmation of rhEPO and DPO in equine plasma samples. This method provides a powerful enforcement tool that was lacking in the fight against the abuse of rhEPO and DPO in the horse racing industry.
authors.affiliation: University of Pennsylvania School of Veterinary Medicine, New Bolton Center Campus, 382 West Street Road, Kennett Square, Pennsylvania 19348, USA.
authors.forename: Fuyu
authors.initials: F
authors.lastname: Guan
authors.forename: Cornelius E
authors.initials: CE
authors.lastname: Uboh
authors.forename: Lawrence R
authors.initials: LR
authors.lastname: Soma
authors.forename: Eric
authors.initials: E
authors.lastname: Birks
authors.forename: Jinwen
authors.initials: J
authors.lastname: Chen
authors.forename: Janis
authors.initials: J
authors.lastname: Mitchell
authors.forename: Youwen
authors.initials: Y
authors.lastname: You
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Rudy
authors.forename: Fran
authors.initials: F
authors.lastname: Xu
authors.forename: Xiaoqing
authors.initials: X
authors.lastname: Li
authors.forename: Gustave
authors.initials: G
authors.lastname: Mbuy
mesh_terms: D000818:Animals; D000906:Antibodies / Q000276:immunology; D002853:Chromatography, Liquid / Q000379:methods; D000068256:Darbepoetin alfa; D004300:Doping in Sports; D004921:Erythropoietin / Q000031:analogs & derivatives* / Q000097:blood*; D006734:Horse Diseases / Q000097:blood*; D006736:Horses; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods; D011994:Recombinant Proteins; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D015813:Substance Abuse Detection / Q000379:methods*
chemical_list: D000906:Antibodies; D011994:Recombinant Proteins; D004921:Erythropoietin; D000068256:Darbepoetin alfa