Beschreibung:
<jats:p> As P-glycoprotein (Pgp) inhibition at the blood–brain barrier (BBB) after administration of a single dose of tariquidar is transient, we performed positron emission tomography (PET) scans with the Pgp substrate ( R)-[<jats:sup>11</jats:sup>C]verapamil in five healthy volunteers during continuous intravenous tariquidar infusion. Total distribution volume ( V<jats:sub>T</jats:sub>) of ( R)-[<jats:sup>11</jats:sup>C]verapamil in whole-brain gray matter increased by 273 ± 78% relative to baseline scans without tariquidar, which was higher than previously reported V<jats:sub>T</jats:sub> increases. During tariquidar infusion whole-brain V<jats:sub>T</jats:sub> was comparable to V<jats:sub>T</jats:sub> in the pituitary gland, a region not protected by the BBB, which suggested that we were approaching complete Pgp inhibition at the human BBB. </jats:p>