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Open Access

P-Glycoprotein inhibition at the blood-brain barrier visualized with (R)-[11C]verapamil μPET

  • Claudia Kuntner1,
  • Jens Bankstahl5,
  • Aiman Abrahim1, 2,
  • Rudolf Karch3,
  • Johann Stanek1,
  • Thomas Wanek1,
  • Maria Zsebedics1,
  • Kurt Kletter4,
  • Wolfgang Löscher5,
  • Herbert Kvaternik1,
  • Markus Müller2 and
  • Oliver Langer1, 2Email author
BMC Pharmacology20077(Suppl 2):A24

Published: 14 November 2007


Inhibition of the multidrug efflux transporter P-glycoprotein (P-gp) at the blood-brain barrier (BBB) is considered a promising strategy in order to increase intracerebral penetration of therapeutics, such as antiepileptic and anticancer drugs. The aim of this study was to evaluate the usefulness of (R)-[11C]verapamil (VPM) and small-animal positron emission tomography (μPET) to measure P-gp inhibition at the BBB following administration of the third-generation P-gp inhibitor tariquidar (TQD, Xenova, UK).


Five Wistar Unilever rats underwent paired VPM μPET scans, one baseline scan followed by i.v. administration of TQD (15 mg/kg) and a second PET scan at 2 hour after TQD administration. Arterial blood sampling was performed along with analysis of metabolism and plasma protein binding of VPM.


Following TQD administration, the brain-to-plasma ratio of radioactivity was increased by a factor of 11–16 as compared to baseline scans, whereas VPM metabolism and plasma protein binding were left unaffected.


Our pilot data suggest that VPM PET is a sensitive tool to quantitatively visualize P-gp inhibition at the animal and human BBB.

Authors’ Affiliations

Department of Radiopharmaceuticals, ARC GmbH
Department of Clinical Pharmacology, Medical University of Vienna
Department of Medical Computer Sciences, Medical University of Vienna
Department of Nuclear Medicine, Medical University of Vienna
Department of Pharmacology, Toxicology and Pharmacy, School of Veterinary Medicine Hannover


© Kuntner et al; licensee BioMed Central Ltd. 2007

This article is published under license to BioMed Central Ltd.