Perospirone (SM-9018 free base) is an orally active antagonist of 5-HT2A receptor (Ki=0.6 nM) and dopamine D2 receptor (Ki=1.4 nM), and also a partial agonist of 5-HT1A receptor (Ki=2.9 nM). Perospirone is an atypical antipsychotic agent and has the potential for schizophrenic disease research[2].In Vitro: Perospirone (SM-9018 free base) possesses moderate affinities for α1, 5-HT1, and D1 receptors (Ki=17, 18 and 41 nM, respectively) .In Vivo: Perospirone (SM-9018 free base; 1.0-10.0 mg/kg/day; orally; for 14 consecutive days) significantly attenuates PCP-induced cognitive deficits in mice in a dose-dependent manner[2].