Which drug is described as having high affinity for D2 and D3, as well as 5-HT1A and 5-HT2A receptors?

• A. Clozapine
• B. Risperidone
• C. Aripiprazole
• D. Ziprasidone

Answer: (C)

This profile reflects a distinctive antipsychotic with a balanced, modulatory effect on dopamine and serotonin systems. It binds strongly to D2 and D3 receptors, but unlike many typical antipsychotics that simply block D2, it acts as a partial agonist at D2. That means it can stimulate dopamine receptors when dopamine levels are low and dampen signaling when dopamine is high, which helps control psychotic symptoms while reducing extrapyramidal side effects and prolactin elevation.

On the serotonin side, it behaves as a partial agonist at 5-HT1A receptors, which can contribute to anxiolytic and antidepressant effects, and as an antagonist at 5-HT2A receptors, which helps mitigate EPS and may improve certain negative symptoms. This combination—high affinity for D2/D3 plus 5-HT1A partial agonism and 5-HT2A antagonism—is the hallmark of aripiprazole's pharmacology.

Other drugs may share one or two of these actions (for example, strong D2 and 5-HT2A antagonism), but they don’t combine all four receptor interactions to the same extent, nor do they exhibit the same partial agonist activity at D2 and 5-HT1A.