Characterisation of flucloxacillin and 5-hydroxymethyl flucloxacillin haptenated HSA in vitro and in vivo

Authors

  • Rosalind E. Jenkins,

    Corresponding author
    1. MRC Centre for Drug Safety Science, Department of Pharmacology and Therapeutics, University of Liverpool, UK
    • MRC Centre for Drug Safety Science, Department of Pharmacology and Therapeutics, School of Biomedical Sciences, The Sherrington Building, Ashton Street, Liverpool L69 3GE, UK Fax: +44-151-794-8368
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    • These authors contributed equally to this study.

  • Xiaoli Meng,

    1. MRC Centre for Drug Safety Science, Department of Pharmacology and Therapeutics, University of Liverpool, UK
    2. NIHR Biomedical Research Centre, Royal Liverpool and Broadgreen University Hospital Trust, Liverpool, UK
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    • These authors contributed equally to this study.

  • Victoria L. Elliott,

    1. MRC Centre for Drug Safety Science, Department of Pharmacology and Therapeutics, University of Liverpool, UK
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  • Neil R. Kitteringham,

    1. MRC Centre for Drug Safety Science, Department of Pharmacology and Therapeutics, University of Liverpool, UK
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  • Munir Pirmohamed,

    1. MRC Centre for Drug Safety Science, Department of Pharmacology and Therapeutics, University of Liverpool, UK
    2. NIHR Biomedical Research Centre, Royal Liverpool and Broadgreen University Hospital Trust, Liverpool, UK
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  • B. Kevin Park

    1. MRC Centre for Drug Safety Science, Department of Pharmacology and Therapeutics, University of Liverpool, UK
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Abstract

Flucloxacillin is a synthetic penicillin used in the treatment of Staphylococcal infections. Adverse reactions to the drug are believed to arise through covalent modification of proteins, with tissue damage occurring secondary to an immune reaction. Serum proteins have been shown by adduct-specific antibodies to be modified by flucloxacillin, but the nature and sites of modification have not been characterised. Here, in vitro studies on HSA have shown by MS that the modification of protein lysine residues occurs in a dose-, time- and site-dependent manner. Affinity, cation exchange and reversed phase chromatography prior to MS revealed in vivo modification of HSA with flucloxacillin in tolerant patients, with up to nine modified lysine residues being detected in each patient, and with modification of Lys190 and Lys212 being detected in 8/8 patients. It was also revealed for the first time that plasma proteins could be modified with the 5-hydroxymethyl metabolite of flucloxacillin, and that essentially the same Lys residues were targeted by both the parent drug and its metabolite. This study provides a detailed characterisation of sites of chemical modification of an endogenous target and reveals candidate peptides for T-cell and antibody assays of flucloxacillin hypersensitivity.

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