Background:

Clocapramine is an antagonist of the D2, 5-HT2A receptors.

Clocapramine has a moderate affinity for D2-receptors in vitro. Clocapramine shows higher affinity for 5-HT2A than for D2-receptors in vitro[1].

Clocapramine shows the lowest potency for D2-occupancy in vivo[1]. An in vivo receptor binding technique is used to evaluate the binding profiles of typical and atypical antipsychotic drugs to striatal dopamine-D2 and frontal serotonin-5-HT2 receptors in a rat brain using more specific ligands. Clocapramine produces ratios of potency in occupying 5-HT2 versus D2 receptors that fall between these two groups (ED50 of 14.5 mg/kg for D2, 4.9 mg/kg for 5-HT2)[2].

[1]. Schotte A, et al. In vitro receptor binding and in vivo receptor occupancy in rat and guinea pig brain: risperidone compared with antipsychotics hitherto used. Jpn J Pharmacol. 1995 Dec;69(4):399-412. [2]. Sumiyoshi T, et al. Atypicality of several antipsychotics on the basis of in vivo dopamine-D2 and serotonin-5HT2 receptor occupancy. Neuropsychopharmacology. 1995 Feb;12(1):57-64.