The production in high yield of N'-(4-[11C]methyl)-imipramine

A method for the routine production in high yield of N'-(4-[11C]methyl)-imipramine is presented. The label is incorporated by reaction of C-11 methyl iodide (11CH3I) upon desipramine in dimethylsulfoxide. Quaternization of the tertiary amine by 11CH3I is minimized by using an excess of desipramine. The reaction proceeds at room temperature for 10 min and the product is isolated by means of high-performance liquid chromatography (HPLC). The entire production takes only 40 min and results in a radiochemical yield of 60%. About 60 mCi of labeled product are available for medical application; the specific activity, at the time of use, is 50 mCi/mumole. The product was characterized by chromatographic and spectrometric methods.