Synthesis of N‐(¹¹C) methyl, N‐(methyl‐1 propyl), (chloro‐2 phenyl)‐1 isoquinoleine carboxamide‐3 (PK 11195): A new ligand for peripheral benzodiazepine receptors

Abstract

Abstract N‐( 11 c) methyl, N‐(methyl‐1 propyl), (chloro‐2 phenyl)‐1 isoquinoleine carboxamide‐3 (PK 11195) or ( 11 C) MPCI was synthetized in a short time (45 min) and high specific activity (769 Ci/mmo 1) for the positron emission tomography of peripheral benzodiazepine receptors in heart, kidney and brain. The precursor used was the N‐desmethyl MPCI (PCI). The radioactive reagent was the ( 11 C) methyl iodide obtained from nuclear reaction 14 N (p, α) 11 C via 11 CO 2 and 11 CH 3 OH. The chemical purity of the end‐product was checked, after HPLC purification, by chemical ionisation mass spectrometry in the parallel synthesis of cold MPCI. The methylation, reversed phase HPLC purification, evaporation times were 10, 6 min respectively so that sterile and isotonic injectable solution of ( 11 C) MPCI ready for use may be obtained, in less than 45 min after the end of nuclear bombardment.