[11C]-Flumazenil metabolites: Measurements of unchanged ligand in plasma using thin layer chromatography and rapid liquid chromatography

To study in vivo benzodiazepine (BZ) receptors using PET, Flumazenil, an imidazobenzodiazepine with selective antagonistic actions, has been labeled with 11C on its methyl group. The accurate determination of in vivo binding parameters using biomathematical models requires the knowledge of radioligand metabolism and the measurement of the plasmatic concentration of unchanged radioligand is mandatory. The present report describes and compares rapid and simple analytical procedures to measure unchanged [11C]-Flumazenil in plasma