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Volume 7 Supplement 2

13th Scientific Symposium of the Austrian Pharmacological Society (APHAR). Joint Meeting with the Austrian Society of Toxicology (ASTOX) and the Hungarian Society for Experimental and Clinical Pharmacology (MFT)

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Metabolism of (R)-[11C]verapamil in epilepsy patients

BMC Pharmacology volume 7, Article number: A23 (2007) Cite this article

Introduction

(R)-[11C]Verapamil (VPM) is a new positron emission tomography (PET) tracer to measure P-glycoprotein (P-gp)-mediated transport at the blood-brain barrier (BBB). Owing to the lack of a suitable reference region in brain that is devoid of P-gp, a metabolite-corrected arterial input function is required for quantitative analysis of VPM PET data [1]. The aim of this study was to compare metabolism of VPM in epilepsy patients and healthy volunteers.

Methods

Selected arterial blood samples from 9 patients, who underwent VPM PET, were analyzed for radiolabeled metabolites by a previously described combined solid-phase extraction/HPLC assay [2].

Results

VPM metabolism was significantly faster in patients as compared to healthy volunteers [1] (unchanged VPM at 60 min after injection: 26.1 ± 6.4 vs. 49.0 ± 13.4%, p < 0.05, t-test).

Conclusion

Faster metabolism of VPM in epilepsy patients may be caused by CyP450 enzyme induction by antiepileptic drugs. Based on these data caution is warranted when using an averaged arterial input function derived from healthy volunteers for the analysis of patient data. As radiolabeled metabolites of VPM are known to cross the BBB [1], different kinetic modeling parameters obtained in patients and healthy volunteers might be at least partly attributed to different rates of tracer metabolism rather than to differences in cerebral P-gp activity.

References

  1. Lubberink M, Luurtsema G, van Berckel BN, Boellaard R, Toornvliet R, Windhorst AD, Franssen EJ, Lammertsma AA: Evaluation of tracer kinetic models for quantification of P-glycoprotein function using (R)-[11C]verapamil and PET. J Cereb Blood Flow Metab. 2007, 27: 424-433. 10.1038/sj.jcbfm.9600349.

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  2. Luurtsema G, Molthoff CF, Schuit RC, Windhorst AD, Lammertsma AA, Franssen EJ: Evaluation of (R)-[11C]verapamil as PET tracer of P-glycoprotein function in the blood-brain barrier: kinetics and metabolism in the rat. Nucl Med Biol. 2005, 32: 87-93. 10.1016/j.nucmedbio.2004.06.007.

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Author information

Authors and Affiliations

  1. Department of Clinical Pharmacology, Medical University of Vienna, Austria

    Aiman Abrahim, Martin Bauer, Markus Müller & Oliver Langer

  2. Department of Medical Computer Sciences, Medical University of Vienna, Austria

    Rudolf Karch

  3. Department of Neurology, Medical University of Vienna, Austria

    Christoph Baumgartner

  4. Department of Nuclear Medicine, Medical University of Vienna, Austria

    Kurt Kletter

  5. Department of Radiopharmaceuticals, ARC GmbH, Seibersdorf, Austria

    Aiman Abrahim & Oliver Langer

  6. Department of Nuclear Medicine and PET Research, VU University Medical Center, Amsterdam, Netherlandss

    Gert Luurtsema

Authors
  1. Aiman Abrahim
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  2. Gert Luurtsema
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  3. Martin Bauer
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  4. Rudolf Karch
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  5. Christoph Baumgartner
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  6. Kurt Kletter
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  7. Markus Müller
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  8. Oliver Langer
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Corresponding author

Correspondence to Oliver Langer.

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Open Access This article is published under license to BioMed Central Ltd. This is an Open Access article is distributed under the terms of the Creative Commons Attribution License ( https://creativecommons.org/licenses/by/2.0 ), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Abrahim, A., Luurtsema, G., Bauer, M. et al. Metabolism of (R)-[11C]verapamil in epilepsy patients. BMC Pharmacol 7 (Suppl 2), A23 (2007). https://doi.org/10.1186/1471-2210-7-S2-A23

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  • DOI: https://doi.org/10.1186/1471-2210-7-S2-A23

Keywords

BMC Pharmacology

ISSN: 1471-2210

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