title: Dopamine D2-receptor density in humans as assessed with SPET and the new high-affinity ligand 123I-NCQ298: a pilot study.
abstract: Astra (S)-3-[123I]iodo-5,6-dimethoxyl-N-[(1-ethyl-2-pyrrolidinyl)methyl] -salicylamide (123I-NCQ298) is a new high-affinity D2-receptor ligand for use in single photon emission tomography (SPET) studies. We have studied the biodistribution and absorbed radiation dose of 123I-NCQ298 in humans. The mean effective dose for adults was 0.055 mSv MBq(-1). Brain uptake and clearance was measured with a head dedicated SPET camera. 123I-NCQ298 showed specific uptake in the basal ganglia with a low clearance rate (time constant of 9-34 h). The extrastriatal binding was variable (average 30%, maximum 60% of that in the basal ganglia at 1 h), but with a clearance rate twice that of the basal ganglia. The fairly high level of extrastriatal binding precluded the use of a quotient between the basal ganglia and cerebellum-to-frontal cortex 123I-NCQ298 concentration as a measure for basal ganglia D2-receptor density. Chronic schizophrenic patients treated with conventional neuroleptics had a decreased affinity for 123I-NCQ298 in the basal ganglia in the range 10-60% of the median value for the control, untreated subjects.
authors.affiliation: Department of Clinical Neurophysiology, University Hospital, Lund, Sweden.
authors.forename: E
authors.initials: E
authors.lastname: Ryding
authors.forename: E
authors.initials: E
authors.lastname: Tuninger
authors.forename: T
authors.initials: T
authors.lastname: Ohlsson
authors.forename: H
authors.initials: H
authors.lastname: Sjöholm
authors.forename: K
authors.initials: K
authors.lastname: Freccero-Rosman
authors.forename: S
authors.initials: S
authors.lastname: Levander
authors.forename: I
authors.initials: I
authors.lastname: Rosén
mesh_terms: D000328:Adult; D000368:Aged; D014150:Antipsychotic Agents / Q000627:therapeutic use; D001921:Brain / Q000098:blood supply / Q000000981:diagnostic imaging* / Q000378:metabolism; D002560:Cerebrovascular Circulation; D018491:Dopamine Agonists / Q000493:pharmacokinetics; D005260:Female; D006220:Haloperidol / Q000031:analogs & derivatives / Q000627:therapeutic use; D006801:Humans; D007457:Iodine Radioisotopes; D008297:Male; D008875:Middle Aged; D010546:Perphenazine / Q000031:analogs & derivatives / Q000627:therapeutic use; D010865:Pilot Projects; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D017448:Receptors, Dopamine D2 / Q000032:analysis*; D012039:Regional Blood Flow; D012457:Salicylamides / Q000493:pharmacokinetics; D012559:Schizophrenia / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000378:metabolism*; D014018:Tissue Distribution; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*
chemical_list: D014150:Antipsychotic Agents; D018491:Dopamine Agonists; D007457:Iodine Radioisotopes; D019275:Radiopharmaceuticals; D017448:Receptors, Dopamine D2; D012457:Salicylamides; C033563:haloperidol decanoate; D010546:Perphenazine; D006220:Haloperidol; C047342:perphenazine decanoate; C064246:NCQ 298