ABSTRACT
BACKGROUND: Domain antibodies (dAbs; â¼10-15 kDa) are made up of the variable heavy chain or the variable light chain of the antibody structure, and retain binding capability. dAbs have proved difficult to detect in plasma using immunoassay without specific antibodies raised against the dAb. RESULTS: A sensitive and selective UPLC-MS/MS method for the absolute quantification of a dAb in monkey plasma was developed (range: 1 to 500 ng/ml) without the need for a specific capture antibody. This method was used to analyze pharmacokinetic studies early on in drug development. Furthermore, an immunoassay was developed and the pharmacokinetic samples were reanalyzed. CONCLUSION: The two assays show good correlation (r(2) = 0.92), giving confidence in using either method for quantification of the dAb.
Subject(s)
Blood Chemical Analysis/methods , Chromatography, High Pressure Liquid/methods , Immunoassay/methods , Immunoglobulin Fragments/blood , Tandem Mass Spectrometry/methods , Administration, Inhalation , Animals , Immunoglobulin Fragments/administration & dosage , Immunoglobulin Fragments/metabolism , Immunoglobulin Fragments/therapeutic use , Immunoglobulin G/chemistry , Immunoglobulin G/immunology , Injections, Intravenous , Macaca fascicularis , Trypsin/metabolismABSTRACT
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. CONCLUSION: DBS technology can be utilized for the quantitation of biopharmaceuticals and offer advantages over traditional plasma-based methods.
