RESEARCH MONOGRAPH · KDC-MN-235
Aripiprazole
Aripiprazole (Abilify) was the first third-generation antipsychotic, approved by the FDA in 2002. The mechanistic novelty is partial agonism at the dopamine D2 receptor: rather than fully blocking dopamine signaling like first- and second-generation antipsychotics, it sits in the receptor and produces about 30 percent of dopamine's normal signal. The functional result is region-dependent: where dopamine signaling is excessive (mesolimbic, in psychosis) it acts as a brake; where dopamine signaling is deficient (prefrontal, in negative symptoms) it acts as a mild stimulator. That property makes aripiprazole much less prone to causing the prolactin elevation and metabolic burden of older antipsychotics, although akathisia (motor restlessness) is its signature side effect. Used in schizophrenia, bipolar, depression augmentation, and irritability in autism. Not stocked by Kodiac. This monograph is provided for research and educational reference.
Intrigue 0–100 blends mechanism novelty, evidence strength, and translational potential. Kodiac editorial, not peer-reviewed.
D2/D3 partial agonist atypical antipsychotic
A piperazinyl-quinolinone partial agonist at D2 and 5-HT1A receptors; the prototype third-generation antipsychotic.
Abstract
Aripiprazole (7-[4-[4-(2,3-dichlorophenyl)piperazin-1-yl]butoxy]-3,4-dihydroquinolin-2(1H)-one; CAS 129722-12-9; molecular formula C23H27Cl2N3O2; molecular weight 448.39) is a piperazinyl-quinolinone D2 partial agonist developed at Otsuka and approved by the FDA in 2002 under the trade name Abilify. Distinct from earlier antipsychotics by partial agonism: D2 affinity is high (Ki approximately 0.34 nM) but intrinsic activity is approximately 30 percent, producing antagonism in regions of high dopaminergic tone (mesolimbic, treating psychosis) and agonism in regions of low tone (mesocortical, mitigating negative symptoms; nigrostriatal, reducing extrapyramidal effects). Additional 5-HT1A partial agonism (Ki approximately 1.7 nM, intrinsic activity approximately 70 percent) and 5-HT2A antagonism complete the profile. The metabolic risk is intermediate (lower than olanzapine or clozapine). Plasma half-life is 75 hours; metabolism is via CYP3A4 and CYP2D6. Approved for schizophrenia, bipolar I disorder, MDD adjunctive, autism-associated irritability, and Tourette syndrome. Long-acting injectable formulations (Abilify Maintena, Aristada) provide monthly administration. Used as the reference D2 partial agonist in mechanism studies.
Mechanism of action
D2 partial agonist (intrinsic activity approximately 30 percent), 5-HT1A partial agonist, 5-HT2A antagonist. Region-dependent dopaminergic effect.
Reported research dose ranges
Clinical 2 to 30 mg per oral administration daily. Long-acting injectable 300 to 400 mg monthly. Rodent studies 0.3 to 10 mg/kg/day.
References
- Burris KD, et al. Aripiprazole, a novel antipsychotic, is a high-affinity partial agonist at human dopamine D2 receptors. J Pharmacol Exp Ther 2002.
- Tamminga CA. Partial dopamine agonists in the treatment of psychosis. J Neural Transm 2002.
- Pae CU, et al. Aripiprazole augmentation for major depressive disorder. CNS Drugs 2011.
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FOR RESEARCH USE ONLY. Not for medical, diagnostic, or therapeutic purposes. Not for human consumption. All information is provided for research and educational purposes only.