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Analysis of erlotinib and its metabolites in rat tissue sections by MALDI quadrupole time-of-flight mass spectrometry

Authors

  • Luca Signor,

    1. University of Geneva, University of Lausanne, School of Pharmaceutical Sciences, Life Sciences Mass Spectrometry, 20, Bd d'Yvoy, CH—1211 Geneva 4, Switzerland
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  • Emmanuel Varesio,

    1. University of Geneva, University of Lausanne, School of Pharmaceutical Sciences, Life Sciences Mass Spectrometry, 20, Bd d'Yvoy, CH—1211 Geneva 4, Switzerland
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  • Roland F. Staack,

    1. University of Geneva, University of Lausanne, School of Pharmaceutical Sciences, Life Sciences Mass Spectrometry, 20, Bd d'Yvoy, CH—1211 Geneva 4, Switzerland
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  • Volkmar Starke,

    1. F.Hoffmann-La Roche Ltd., Pharmaceuticals Division, Pharma Research—Safety and Technical Sciences, Basel, Switzerland
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  • Wolfgang F. Richter,

    1. F.Hoffmann-La Roche Ltd., Pharmaceuticals Division, Pharma Research—Safety and Technical Sciences, Basel, Switzerland
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  • Gérard Hopfgartner

    Corresponding author
    1. University of Geneva, University of Lausanne, School of Pharmaceutical Sciences, Life Sciences Mass Spectrometry, 20, Bd d'Yvoy, CH—1211 Geneva 4, Switzerland
    • Life Sciences Mass Spectrometry, School of Pharmaceutical Sciences, University of Lausanne, University of Geneva, 20 Bd d'Yvoy, CH-1211 Geneva 4, Switzerland.
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Abstract

A qualitative and quantitative analysis of erlotinib (RO0508231) and its metabolites was carried out on rat tissue sections from liver, spleen and muscle. Following oral administration at a dose of 5 mg/kg, samples were analyzed by matrix-assisted laser desorption ionization (MALDI) with mass spectrometry (MS) using an orthogonal quadrupole time-of-flight instrument. The parent compound was detected in all tissues analyzed. The metabolites following drug O-dealkylation could also be detected in liver sections. Sinapinic acid (SA) matrix combined with the dried-droplet method resulted in better conditions for our analysis on tissues. Drug quantitation was investigated by the standard addition method and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis on the tissue extracts. The presence of the parent compound and of its O-demethylated metabolites was confirmed in all tissue types and their absolute amounts calculated. In liver the intact drug was found to be 3.76 ng/mg tissue, while in spleen and muscle 6- and 30-fold lower values, respectively, were estimated. These results were compared with drug quantitation obtained by whole-body autoradiography, which was found to be similar. The potential for direct quantitation on tissue sections in the presence of an internal standard was also investigated using MALDI-MS. The use of α-cyano-4-hydroxycinnamic acid (CHCA) as the matrix resulted in better linearity for the calibration curves obtained with reference solutions of the drug when compared to SA, but on tissue samples no reliable quantitative analysis was possible owing to the large variability in the signal response. MS imaging experiments using MALDI in MS/MS mode allowed visualizing the distribution of the parent compound in liver and spleen tissues. By calculating the ratio between the total ion intensities of MS images for liver and spleen sections, a value of 6 : 1 was found, which is in good agreement with the quantitative data obtained by LC-MS/MS analysis. Copyright © 2007 John Wiley & Sons, Ltd.

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