Automated radiosynthesis of [11C]morphine for clinical investigation

To meet a multiple-dose clinical evaluation of the P-gp modulation of [11C]morphine delivery into the human brain, radiosynthesis of [11C]morphine was accomplished on an automated system by N-methylation of normorphine with [11C]CH3I. A methodology employing optimized solid phase extraction of the HPLC eluent was developed. Radiosynthesis took 45 min with a radiochemical yield ranging from 45% to 50% and specific activity ranging from 20 to 26 Ci/μmol (decay corrected to end-of-bombardment); radiochemical and chemical purities were >95% (n=28).