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Table 3 Comparison of drug affinities for [ 3 H]clozapine binding sites in rat brain and cloned dopamine receptors

From: Clozapine: Selective Labeling of Sites Resembling 5HT6 Serotonin Receptors May Reflect Psychoactive Profile

Ligand D1 nMa,b D2 nMc D3 nMc D4 nMd [3H]Clozapine
SCH 23390 0.11 1,000
(+) Butaclamol 0.90 0.83 40 1,000
Ketanserin 190 >1,000 148
Spiperone 220 0.07 0.61 0.05 30
Apomorphine 210 24 20 4.1 50,000
Dopamine 2,500 474 25 28 500,000
Haloperidol 203 0.45 9.8 5.1 400
Bromocriptine 5.3 7.4 340 200
Domperidone 0.3 9.5 6,000
Thioridazine 3.3 7.8 12 30
Chlorpromazine 2.8 6.1 37 20
Raclopride 1.8 3.5 237 >10,000
Eticlopride 2.1 >10,000
Fluphenazine 46 20
Trifluoperazine 3 30
Clozapine 56 180 9 10
  1. All numbers represent Ki values from the literature as noted or [3H]clozapine to rat brain membranes. Values for drug potencies at [3H]clozapine binding sites are means of two to three determinations that varied less than 20%.
  2. aDeary et al. (16)
  3. bZhou et al. (17)
  4. cSokoloff et al. (18)
  5. dVan Tol et al. (9)