Biodistribution and radiation dosimetry of radioiodinated-SCH 23982, a potential dopamine D-1 receptor imaging agent
Radioiodinated-SCH 23982 is a potential agent for the imaging of dopamine D-1 receptors in the human brain. In vivo binding of (125I)SCH 23982 to D-1 receptors in rat brain was determined over 4 hr. The ratio of activity in striatum and frontal cortex to that in cerebellum increased over the first 2 hr to maximum values of 4.4:1 and 2.1:1, respectively. The percent injected dose in whole brain at 0.5 and 2 hr were 0.62 and 0.15, respectively. Administration of the antagonists propranolol (beta-1), prazosin (alpha-1), haloperidol (D-2) and ketanserin (5HT-2) did not significantly alter the striatum/cerebellum ratio; however, SCH 23390, a D-1 antagonist, totally blocked ligand uptake by striatum and frontal cortex. Biologic distribution data in the rat were determined after injection of 3 microCi of (125I)SCH 23982. 76% of the injected dose was excreted in 48 hr via the liver and kidneys. Internal radiation absorbed dose estimates to nine source organs, total body, the GI tract, gonads and red bone marrow were calculated for humans using the physical decay data for 123I. The critical organ was found to be the lower large intestine which received 1.1 rad/mCi of the administered dose. The total-body dose was 63 mrad/mCi. The data indicate that (123I)SCH 23982 should be a suitable agent for imaging the D-1 dopamine receptor in the human brain by single photon emission computed tomography.
- Research Organization:
- Veterans Administration Medical Center, Gainesville, FL (USA)
- OSTI ID:
- 6558172
- Journal Information:
- J. Nucl. Med.; (United States), Journal Name: J. Nucl. Med.; (United States) Vol. 29:10; ISSN JNMEA
- Country of Publication:
- United States
- Language:
- English
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62 RADIOLOGY AND NUCLEAR MEDICINE
AMINES
ANIMALS
AROMATICS
AUTONOMIC NERVOUS SYSTEM AGENTS
BETA DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
BODY
BRAIN
CARDIOTONICS
CARDIOVASCULAR AGENTS
CENTRAL NERVOUS SYSTEM
DAYS LIVING RADIOISOTOPES
DISTRIBUTION
DOPAMINE
DOSES
DRUGS
ELECTRON CAPTURE RADIOISOTOPES
HOURS LIVING RADIOISOTOPES
HYDROXY COMPOUNDS
INTERMEDIATE MASS NUCLEI
IODINE 123
IODINE 125
IODINE ISOTOPES
ISOTOPES
KINETICS
LABELLED COMPOUNDS
MAMMALS
MEMBRANE PROTEINS
NERVOUS SYSTEM
NEUROREGULATORS
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANS
PHENOLS
POLYPHENOLS
PROTEINS
RADIATION DOSES
RADIOISOTOPES
RADIOPHARMACEUTICALS
RATS
REACTION KINETICS
RECEPTORS
RODENTS
SYMPATHOMIMETICS
TISSUE DISTRIBUTION
VERTEBRATES