title: Application of DBS for quantitative assessment of the peptide Exendin-4; comparison of plasma and DBS method by UHPLC-MS/MS.
abstract: BACKGROUND
  An investigation was performed in order to establish if dried blood spots (DBS) could be applied to the quantitation of biopharmaceuticals in biological matrices and perform equivalently in terms of accuracy, precision and stability to traditional plasma methods.
  
  
  RESULTS
  A method was successfully validated for the peptide Exendin-4 (39 amino acids in length) utilizing DBS technology. The validated DBS method resulted in a more sensitive and simplistic method than an existing monkey plasma method and required tenfold less sample volume. The final DBS method resulted in a 10-2000-ng/ml linear calibration range using approximately 5 µl of dried blood, compared with the plasma method in which 150 µl of plasma coupled with SPE sample preparation resulted in a 20-2000-ng/ml linear calibration range. Although not needed for DBS, SPE was required for the plasma method to reduce endogenous matrix interferences and achieve desired LLOQ. Matrix stability was also enhanced by the implementation of the DBS platform when compared with either plasma or whole blood.
  
  
  CONCLUSIONS
  DBS technology can be utilized for the quantitation of biopharmaceuticals and offer advantages over traditional plasma-based methods.
authors.affiliation: Platform Technology and Science, Drug Metabolism and Pharmacokinetics, GlaxoSmithKline Pharmaceuticals, 709 Swedeland Road, King of Prussia, PA 19406, USA. jonathan.r.kehler@gsk.com
authors.forename: Jonathan R
authors.initials: JR
authors.lastname: Kehler
authors.forename: Chester L
authors.initials: CL
authors.lastname: Bowen
authors.forename: Sharon L
authors.initials: SL
authors.lastname: Boram
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Evans
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001774:Blood Chemical Analysis / Q000379:methods*; D001800:Blood Specimen Collection / Q000379:methods*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D003890:Desiccation; D000077270:Exenatide; D000882:Haplorhini; D008969:Molecular Sequence Data; D010455:Peptides / Q000097:blood* / Q000737:chemistry; D010949:Plasma / Q000737:chemistry*; D053719:Tandem Mass Spectrometry / Q000379:methods*; D013997:Time Factors; D014688:Venoms / Q000097:blood* / Q000737:chemistry
chemical_list: D010455:Peptides; D014688:Venoms; D000077270:Exenatide