An improved method for the preparation of [11C]verapamil

This paper describes an improved preparation of [C-11]verapamil by reaction of [C-11]methyl triflate with desmethylverapamil. The optimal reaction temperature, amount of precursor and reaction time were assessed. With this method [C-11]verapamil can be prepared with a reproducible radiochemical yield of 66+/-4% (EOB, based on [C-11]methyltriflate). Total synthesis time was 60 min. Radiochemical purity was >99% and specific activities varied between 5 and 30TBq/mmol. (C) 2002 Elsevier Science Ltd. All rights reserved.