Abstract |
DAR-0100A, the active enantiomer of dihydrexidine, is a potent dopamine D1 agonist under investigation for treatment of cognitive impairment and negative symptoms of schizophrenia. We measured the dose-occupancy relationship for DAR-0100A at D1 receptors using positron emission tomography (PET) imaging in baboons with [(11)C] NNC112 and its binding to D2 with [(11)C] raclopride. Two baboons were scanned with [(11)C] NNC112 at baseline and after three different doses of DAR-0100A. Two baboons were scanned with [(11)C] raclopride at baseline and after one dose of DAR-0100A. Occupancy (ΔBP(ND)) was computed in the striatum and cortex. A clear relationship was observed between plasma concentration of DAR-0100A and ΔBP(ND). ΔBP(ND) was larger in the striatum than in the cortex, consistent with reports showing that 25% of [(11)C] NNC112 BP(ND) in the cortex is attributed to 5-HT(2A). Plasma EC(50) estimates ranged from 150 to 550 ng/mL according to the constraints on the model. There was no detectable effect of DAR-0100A on [(11)C] raclopride BP(ND). These data suggest that at doses likely to be administered to patients, occupancy will not be detectable with [(11)C] NNC112 PET and binding of DAR-0100A to D2 will be negligible. This is the first demonstration with PET of a significant occupancy by a full D1 agonist in vivo.
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Authors | Mark Slifstein, Raymond F Suckow, Jonathan A Javitch, Thomas Cooper, Jeffrey Lieberman, Anissa Abi-Dargham |
Journal | Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism
(J Cereb Blood Flow Metab)
Vol. 31
Issue 1
Pg. 293-304
(Jan 2011)
ISSN: 1559-7016 [Electronic] United States |
PMID | 20571519
(Publication Type: Journal Article, Research Support, N.I.H., Extramural)
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Chemical References |
- Benzazepines
- Dopamine Agonists
- Dopamine Antagonists
- NNC 01-0012
- Phenanthridines
- Radiopharmaceuticals
- Receptors, Dopamine D1
- Receptors, Dopamine D2
- dihydrexidine
- Raclopride
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Topics |
- Animals
- Benzazepines
- Blood Pressure
(drug effects)
- Cerebral Cortex
(diagnostic imaging, metabolism)
- Dopamine Agonists
(blood, pharmacokinetics)
- Dopamine Antagonists
- Image Processing, Computer-Assisted
- Male
- Papio anubis
- Phenanthridines
(pharmacokinetics)
- Positron-Emission Tomography
- Raclopride
- Radiopharmaceuticals
- Receptors, Dopamine D1
(agonists)
- Receptors, Dopamine D2
(metabolism)
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