Aripiprazole's unique receptor pharmacology that distinguishes it from first and most second-generation antipsychotics is its action as a:

• A D4 receptor full antagonist sparing D2 receptors in the striatum
• B D2 receptor partial agonist with high intrinsic activity in hypodopaminergic and low intrinsic activity in hyperdopaminergic states ✓
• C D1/D5 receptor partial agonist in prefrontal cortex improving working memory
• D Dopamine-serotonin stabilizer acting primarily through 5-HT7 agonism

Explanation

Aripiprazole is a D2 receptor partial agonist with approximately 25–30% intrinsic activity relative to dopamine. In mesolimbic pathways where dopamine is excessive (producing positive symptoms), aripiprazole acts as a functional antagonist by competing with dopamine and producing less receptor activation; in nigrostriatal and mesocortical pathways where dopamine tone is relatively low, it provides partial agonism preventing complete dopamine deprivation. This functional antagonism/agonism duality explains its low EPS rate, absence of hyperprolactinemia, and minimal negative-symptom worsening. It also has 5-HT1A partial agonism and 5-HT2A antagonism contributing to its profile.

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

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Written and medically reviewed by the StethoPrep medical team.