It is a very selective dopamine antagonist, while other APs bind serotonin and histamine receptors too. I guess this is why it can cause depression so easily and it lacks of antidepressants proprieties at high dose, but at really low dose it blocks auto receptors first (before blocking postsynaptic receptors) which are the ones that regulate how my dopamine is released by the neuron so it enhance dopamine neurotransmission. That's why a low doses it is used for dysthimia and negative symptoms, while at higher dosage it works like a very selective AP.