Effect of treatment with L-dopa/carbidopa or L-selegiline on striatal dopamine transporter SPECT imaging with [123I]beta-CIT

Mov Disord. 1999 May;14(3):436-42. doi: 10.1002/1531-8257(199905)14:3<436::aid-mds1008>3.0.co;2-j.


The effect of subchronic treatment with L-dopa/carbidopa or L-selegiline on striatal dopamine transporters (DAT) was examined in patients with idiopathic Parkinson's disease with SPECT (single photon emission computed tomography) using [123I]beta-CIT (2beta-carbomethoxy-3beta-[4-iodophenyl]tropane) as the radiotracer. Patients who were not currently being treated with these medications were given either 750 mg L-dopa/carbidopa per day (n = 8) or 10 mg L-selegiline per day (n = 8). [123I]beta-CIT imaging was performed three times in each patient: at baseline before treatment, while on medication and after 4-6 weeks of drug treatment, and following withdrawal from medication (approximately 1 week for L-dopa/carbidopa and 9 weeks for L-selegiline). Comparison of scans 2 and 3 provided a measure of drug occupancy of the [123I]beta-CIT binding site; comparison of scans 1 and 2 provided a measure of both up- or downregulation of DAT levels and drug occupancy following subchronic drug treatment. DAT levels were assessed from an image acquired approximately 22 hours after radiotracer injection as a ratio of regional brain activities: (striatum - occipital)/occipital. Striatal DAT levels were not significantly different when any two of the three scans were compared for both drug treatments. These results suggest that typical clinical doses of L-dopa/carbidopa and L-selegiline do not induce significant occupancy of the [123I]beta-CIT binding site and that 4-6 weeks of treatment causes no significant modulation of DAT levels. These results support the validity of measuring DAT levels with [123I]beta-CIT without the need to withdraw patients from medication treatment.

Publication types

  • Clinical Trial
  • Controlled Clinical Trial
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Aged
  • Antiparkinson Agents / therapeutic use*
  • Biological Transport
  • Carbidopa / therapeutic use*
  • Cocaine / analogs & derivatives*
  • Corpus Striatum / diagnostic imaging*
  • Corpus Striatum / metabolism
  • Dopamine / metabolism
  • Drug Therapy, Combination
  • Female
  • Humans
  • Iodine Radioisotopes*
  • Levodopa / therapeutic use*
  • Male
  • Monoamine Oxidase / metabolism
  • Occipital Lobe / metabolism
  • Parkinson Disease / diagnostic imaging*
  • Parkinson Disease / drug therapy*
  • Selegiline / pharmacology
  • Selegiline / therapeutic use*
  • Tomography, Emission-Computed, Single-Photon*
  • Treatment Outcome


  • Antiparkinson Agents
  • Iodine Radioisotopes
  • Selegiline
  • Levodopa
  • 2beta-carbomethoxy-3beta-(4-iodophenyl)tropane
  • Monoamine Oxidase
  • Cocaine
  • Carbidopa
  • Dopamine