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Ligand metabolites in plasma during PET‐studies with the 11 C‐labelled dopamine antagonists, raclopride, SCH 23390 and N‐methylspiroperidol
Author(s) -
Swahn CarlGunnar,
Farde Lars,
Halldin Christer,
Sedvall Göoran
Publication year - 1992
Publication title -
human psychopharmacology: clinical and experimental
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.461
H-Index - 78
eISSN - 1099-1077
pISSN - 0885-6222
DOI - 10.1002/hup.470070204
Subject(s) - raclopride , sch 23390 , chemistry , ligand (biochemistry) , metabolism , dopamine , metabolite , receptor , dopamine receptor , medicine , pharmacology , endocrinology , biochemistry
The 11 C‐labelled radioligands raclopride, SCH 23390 and N‐methyl‐spiroperidol are well established for examination of central dopamine receptors by positron emission tomography (PET). Thin layer chromatography was used to examine the composition of radioactivity in plasma after intravenous injection of any of these three ligands into human subjects. For all three ligands there was a considerable metabolism during the time of a PET‐experiment but to a different degree. Forty‐two minutes after injection ( 11 C)raclopride was unchanged to 76 per cent, ( 11 C)N‐methylspiroperidol to 57 per cent and ( 11 C) SCH 23390 only to 13 per cent. A time curve for ligand metabolism is necessary for compartmental analysis with an arterial input function. The considerable ligand metabolism demonstrated shortly after i.v. injection motivates further the identification of main metabolites to evaluate if they pass the blood‐brain barrier and bind to the receptors.