In vitro and in vivo testing of the dopamine D1 ligand [123I]SCH 23982 with respect to its potential application in SPET investigations.
[123I]SCH 23982, a dopamine D1 ligand, was labelled in a large scale process and then tested in vitro for binding to rat brain sections and membranes. Because of the promising values of KD = 1.5 x 10(-10) M and Bmax = 0.7 x 10(-11) mol/g, in vivo evaluation was performed on rats and normal volunteers to test its possible usefulness for SPET imaging. In competition experiments, a higher binding in the presence of sulpiride was found while ketanserin displaced [123I]SCH 23982 only at a 10,000-fold excess. Differences between rats and men were seen with respect to their metabolism. SPET investigations failed because the washout of [123I]SCH 23982 was too rapid.
Beer
H F
HF
Division of Radiopharmacy, Paul Scherrer Institute, Villigen, Switzerland.
Lin
S
S
Bläuenstein
P
P
Hasler
P
P
Schubiger
P A
PA
Maier
A
A
Lichtensteiger
W
W
Oettli
R
R
Bekier
A
A
Weder
B
B
D000368:Aged; D000818:Animals; D001552:Benzazepines / Q000031:analogs & derivatives* / Q000378:metabolism / Q000493:pharmacokinetics; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D007457:Iodine Radioisotopes; D008297:Male; D008875:Middle Aged; D051381:Rats; D017208:Rats, Wistar; D017447:Receptors, Dopamine D1 / Q000037:antagonists & inhibitors*; D014018:Tissue Distribution; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*
C049558:8-iodo-2,3,4,5-tetrahydro-3-methyl-5-phenyl-1H-3-benzazepine-7-ol; D001552:Benzazepines; D007457:Iodine Radioisotopes; D017447:Receptors, Dopamine D1