A 5-HT2A inverse agonist (IC50 = 1.86 nM; Ki = 0.5 nM); selective for 5-HT2A over a panel of 65 ion channels, enzymes, and receptors (Kis = >100 nM); reduces DOI-induced head-twitch behavior and prepulse inhibition deficits in rats at doses of 3 mg/kg, p.o. and 1-10 mg/kg, s.c., respectively; exhibits antipsychotic-like activity, reducing (+)-MK-801-induced hyperactivity in mice; acts synergistically with haloperidol or risperidone to suppress (+)-MK-801-induced hyperactivity and attenuates haloperidol- and risperidone-induced catalepsy in rats