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

Table 1 Drug effect on [ ³ H]clozapine binding in rat brain membranes

Drug	K_i (nM)
Histamine H1 Triprolidine	1,000
Adrenergic α 1 Prazosin	>10,000
Muscarinic Cholinergic
Scopolamine	0.8
Atropine	1.0
Butyrophenones Pipamperone	400
Spiperone	30
Phenothiazines Fluphenazine	20
Trifluoperazine	30
Thioridazine	30
Chlorpromazine	20
Tricyclic Antidepressants Nortriptyline	30
Imipramine	150
Amitriptyline	30
Ergot Alkaloids Ergotamine	10
Dihydroergotamine	20

Increasing concentrations of the indicated compounds were used to inhibit the binding of 1 nM [³H]clozapine to rat brain membranes. K_i values were determined from the IC₅₀’s by the method of Cheng and Prusoff (15). Results are the means of at least two experiments run in duplicate.

ISSN: 1528-3658