Clocapramine shows the lowest potency for D2-occupancy in vivo. 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).