New positron emission tomography tracer [(11)C]carvedilol reveals P-glycoprotein modulation kinetics.

Imaging of P-glycoprotein (P-gp) function in the blood-brain barrier (BBB) may support development of strategies, which will improve drug delivery to the brain. [(11)C]verapamil has been developed as a positron emission tomography (PET) tracer, to image P-gp function in vivo. Ideally, for the purpose of brain imaging, tracers should have a log P between 0.

Quantitative assessment of P-glycoprotein function in the rat blood-brain barrier by distribution volume of [11C]verapamil measured with PET.

The blood-brain barrier (BBB) is a functional barrier that hampers the delivery of various drugs to the brain by its physicoanatomical properties and by the presence of ATP-driven drug efflux pumps, such as P-glycoprotein (P-gp). The aims of this study were (1) to study whether the distribution volume (DV) is useful for quantification of (labeled) P-gp substrate kinetics over the BBB and (2) to study how brain DV is affected by P-gp modulation. We measured the kinetics of the P-gp substrate [11C]verapamil (0.