Striatal and extrastriatal dopamine D 2 receptor occupancy by the partial agonist antipsychotic drug aripiprazole in the human brain: a positron emission tomography study

Rationale Second-generation antipsychotics demonstrate clinical efficacy with fewer extrapyramidal side effects compared with first-generation antipsychotics. One of the proposed explanations is the hypothesis of preferential extrastriatal dopamine D2 receptor occupancy (limbic selectivity) by antipsychotics. In the present study, we focused on aripiprazole, which has a unique pharmacological profile with partialagonismatdopamineD2receptorsandtheminimalrisk of extrapyramidal side effects. Previous positron emission tomography (PET) studies using high-affinity radioligands for dopamine D2 receptors have reported inconsistent results regarding regional differences of dopamine D2 receptor occupancy by aripiprazole.