Aripiprazole is a second generation, atypical antipsychotic medication used in the treatment of schizophrenia, schizo-affective disorder, and acute bipolar mania. The mechanism of action of this drug is not entirely known; however, it has been shown to have high affinity agonistic activity at D₂ dopamine and serotonin 5-HT_1A receptors, and antagonistic activity at serotonin 5-HT_2A receptors. Other affinities noted in premarketing studies [1] demonstrated moderate affinities for dopamine D₄, serotonin 5-HT_2C, histamine H₁, and α₁-adrenergic receptors.