Aripiprazole (OPC-14597) is an antipsychotic agent that is structurally related to piperazines and quinolones. It is a partial agonist of SEROTONIN RECEPTOR, 5-HT1A and DOPAMINE D2 RECEPTORS, where it also functions as a post-synaptic antagonist, and an antagonist of SEROTONIN RECEPTOR, 5-HT2A.

5-HT1A:4.2 nM(Ki)

Aripiprazole exhibits the highest affinity for h5-HT(2B), hD(2L), and hD(3) dopamine receptors but also demonstrates significant affinity (5-30 nM) for various other 5-HT receptors (5-HT(1A), 5-HT(2A), 5-HT(7)), as well as α(1A)-adrenergic and hH(1)-histamine receptors. Aripiprazole acts as an inverse agonist at the 5-HT(2B) receptor and displays partial agonist activity at 5-HT(2A), 5-HT(2C), D(3), and D(4) receptors. It binds with high affinity to both G protein-coupled and uncoupled states of these receptors. Additionally, Aripiprazole effectively activates D2 receptor-mediated inhibition of cAMP accumulation.

Aripiprazole administration at doses of 0.1 mg/kg and 0.3 mg/kg significantly increased dopamine release in the hippocampus of rats. A dose of 0.3 mg/kg slightly, yet significantly, enhanced dopamine release in the medial prefrontal cortex, without affecting dopamine levels in the nucleus accumbens. Additionally, 0.3 mg/kg of Aripiprazole transiently amplified dopamine release in the medial prefrontal cortex induced by 0.1 mg/kg of Haloperidol, but it inhibited dopamine release in the nucleus accumbens. Higher doses of 3.0 mg/kg and 10 mg/kg distinctly decreased dopamine release in the nucleus accumbens, without impacting the medial prefrontal cortex. Aripiprazole reduced the extracellular concentration of 5-HIAA in the medial prefrontal cortex and striatum of drug-naïve rats, but this effect was not observed in rats with chronic Aripiprazole pretreatment.