Antipsychotic efficacy: Relationship to optimal D2-receptor occupancy

Abstract Clinically important differences exist between antipsychotic agents and formulations in terms of safety and tolerability. Features of the biochemical interaction between the antipsychotic and the D 2 -receptor may underlie these differences. This article reviews current information on the relationship between antipsychotic receptor occupancy and clinical response. A literature search was performed using the keywords ‘antipsychotic or neuroleptic’, ‘receptor’ and ‘occupancy’ and ‘dopamine’ and ‘D 2 ’ supplemented by the authors’ knowledge of the literature. Imaging and clinical data have generally supported the hypotheses that optimal D 2 -receptor occupancy in the striatum lies in a ‘therapeutic window’ between ∼65 and ∼80%, however, pharmacokinetic and pharmacodynamic properties of a drug should also be taken into account to fully evaluate its therapeutic effects. Additional research, perhaps in preclinical models, is needed to establish D 2 -receptor occupancy in various regions of the brain and the optimal duration of D 2 -receptor blockade in order to maximise efficacy and tolerability profiles of atypical antipsychotics and thereby improve treatment outcomes for patients with schizophrenia.