US EPA

7565593 

Journal Article 

Iodine-123 labeled derivatives of methylphenidate: Potential SPECT radiopharmaceuticals for brain dopamine transporters 

Pan, D; Gatley, SJ; Chen, R; Ding, YS 

1996 

Yes 

Journal of Labelled Compounds and Radiopharmaceuticals
ISSN: 0362-4803
EISSN: 1099-1344 

38 

6 

523-532 

10.1002/(sici)1099-1344(199606)38:6<523::Aid-jlcr863>3.3.Co;2-r 

WOS:A1996UQ63200002 

http://://WOS:A1996UQ63200002
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Since dl-threo-[C-11]methylphenidate (Ritalin) and especially the more active enantiomer, d-threo-[C-11]methylphenidate, have favorable properties for PET studies, we prepared two radioiodinated analogs of methylphenidate, p-[I-123]iodomethylphenidate and m-[I-123]iodo-p-hydroxymethylphenidate with a view to evaluating them as potential SPECT tracers. To prepare p-[I-123]iodomethylphenidate, the p-tributyltin derivative was prepared from the previously reported p-bromomethylphenidate and reacted under acidic conditions with I-123 iodide plus chloramine-T at room temperature for 90 seconds. The predominant radioactive product was obtained in 85% radiochemical yield and >10 Ci/mu mol specific radioactivity after HPLC purification. It had the same HPLC retention time as a spectroscopically characterized non-radioactive p-iodomethylphenidate standard prepared via nitration of methylphenidate and diazotizadon, after protection of the secondary amino group by benzoylation. A second radioiodinated methylphenidate derivative, m-[I-123]iodo-p-hydroxymethylphenidate was prepared in 80% radiochemical yield by direct iodination of the known p-hydroxymethylphenidate. In this case the non-radioactive standard was prepared by iodination of p-hydroxyritalinic acid using I-2 and iodic acid, followed by esterification.