D2 antagonist (Ki = 72.7 nM in a ligand binding assay; apparent KB = 14.5 nM in a cAMP accumulation assay); displays preferential activity at central dopamine autoreceptors. Stimulates a marked acceleration of dopamine synthesis and turnover. Produces locomotor stimulation. Exhibits little or no activity at central noradrenalin and 5-HT receptors. Also D3 partial agonist. MW (observed): 391.51.