Iodine-123-iodobenzamide binding in parkinsonism: reduction by dopamine agonists but not L-Dopa.

Abstract

UNLABELLED:

The aim of the present study was to investigate the effect of treatment with L-Dopa or a dopamine agonist, or both, on specific striatal 123I-iodobenzamide (IBZM) binding using an intraindividual longitudinal design.

METHOD:

We prospectively studied the effect of dopaminomimetic treatment on specific [123I]IBZM binding measured by SPECT in 29 patients with a clinical diagnosis of Parkinson's disease, none of whom had previously received dopaminomimetic drugs. The patients had been selected on the basis of normal subsequent specific [123I]IBZM binding, semiquantitatively calculated as the basal ganglia/frontal cortex ratio, and a positive response to the dopamine agonist apomorphine before initiation of dopaminomimetic therapy. A second 123I-IBZM SPECT investigation was performed after 3-6 mo of treatment with L-Dopa or a dopamine agonist, or both.

RESULTS:

Specific [123I]IBZM binding was unchanged in 10 patients treated with L-Dopa alone. However, after treatment with a dopamine agonist there was a significant decline in specific [123I]IBZM binding (p < 0.05). After treatment with a combination of L-Dopa and a dopamine agonist, specific [123I]IBZM binding was reduced without reaching a level of significance (p = 0.08).

CONCLUSION:

Short-term treatment with a dopamine agonist but not with L-Dopa reduces specific [123I]IBZM binding. Therefore, before performing an [123I]IBZM SPECT scan in patients previously treated with dopaminomimetic drugs, dopamine agonists should be discontinued.

• Authors: J Schwarz, W H Oertel, K Tatsch
• Journal: Journal of nuclear medicine : official publication, Society of Nuclear Medicine (J Nucl Med) Vol. 37 Issue 7 Pg. 1112-5 (Jul 1996) ISSN: 0161-5505 [Print] United States
• PMID: 8965179 (Publication Type: Comparative Study, Journal Article)

Chemical References

• Antiparkinson Agents
• Benzamides
• Contrast Media
• Dopamine Agonists
• Dopamine Antagonists
• Pyrrolidines
• Levodopa
• 3-iodo-2-hydroxy-6-methoxy-N-((1-ethyl-2-pyrrolidinyl)methyl)benzamide

Topics

• Antiparkinson Agents (therapeutic use)
• Benzamides (pharmacokinetics)
• Brain (diagnostic imaging, metabolism)
• Case-Control Studies
• Contrast Media
• Dopamine Agonists (therapeutic use)
• Dopamine Antagonists (pharmacokinetics)
• Humans
• Levodopa (therapeutic use)
• Middle Aged
• Parkinson Disease (diagnostic imaging, drug therapy)
• Prospective Studies
• Pyrrolidines (pharmacokinetics)
• Time Factors
• Tomography, Emission-Computed, Single-Photon