Atypical

Second-generation: D2 antagonism combined with strong 5-HT2A antagonism — except aripiprazole, which is a D2 partial agonist and therefore behaves unlike everything else under the heading. Atypical is a generation, not a mechanism. Within it the members diverge sharply: quetiapine and olanzapine sedate heavily through H1 and carry the heaviest metabolic burden, risperidone and paliperidone raise prolactin, ziprasidone leans on QT, and clozapine requires blood monitoring because it can suppress the white cell count.

The 5-HT2A component is why this group is what tends to be reached for to end a psychedelic experience, and what comes with it is everything else they do: dopamine blockade nobody asked for, movement effects, and orthostatic hypotension that adds to alcohol and other depressants. Quetiapine also circulates on its own account, for the sedation.