Correlation of clinical response in apomorphine test with D2-receptor status as demonstrated by 123I IBZM-SPECT

Mov Disord. 1993 Oct;8(4):453-8. doi: 10.1002/mds.870080406.


The knowledge of functional capacities of postsynaptic dopaminergic receptors in parkinsonian syndromes is important for differential diagnosis and for planning therapeutic approaches. Subcutaneous apomorphine challenges serve as a pharmacological tool in testing dopaminergic responsiveness, but discrepancies between results of the apomorphine test and long-term levodopa treatment remain. 123I IBZM (I-123 labeled iodobenzamide) as a dopaminergic receptor ligand allows depiction of D2-receptors by means of SPECT methods. The correlation between dopaminergic responsiveness and D2-receptor status as demonstrated by 123I IBZM-SPECT imaging was assessed by applying an apomorphine test to 41 patients with parkinsonian syndromes. All subsequently underwent an 123I IBZM-SPECT. Apomorphine responders showed a significantly higher binding of 123I IBZM than nonresponders, and patients with idiopathic Parkinson's disease (IPD) had higher D2-receptor density as visualized by SPECT than patients with other parkinsonian syndromes. The marked overlap between the groups allowed a reliable prediction only in patients with an abnormally low basal ganglia/frontal cortex ratio of 123I IBZM binding.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Apomorphine* / metabolism
  • Basal Ganglia / metabolism
  • Basal Ganglia / physiopathology*
  • Benzamides* / metabolism
  • Binding Sites / physiology
  • Brain / diagnostic imaging
  • Brain / physiopathology
  • Corpus Striatum / metabolism
  • Female
  • Humans
  • Male
  • Middle Aged
  • Parkinson Disease / diagnostic imaging*
  • Parkinson Disease / metabolism
  • Parkinson Disease / physiopathology
  • Pyrrolidines* / metabolism
  • Receptors, Dopamine D2 / metabolism
  • Receptors, Dopamine D2 / physiology*
  • Tomography, Emission-Computed, Single-Photon / methods*


  • Benzamides
  • Pyrrolidines
  • Receptors, Dopamine D2
  • 3-iodo-2-hydroxy-6-methoxy-N-((1-ethyl-2-pyrrolidinyl)methyl)benzamide
  • Apomorphine