A potent 5-HT2A receptor antagonist; selective for 5-HT2A over 5-HT1 receptors (IC50s = 0.9 nM and >1000 nM, respectively); has 39-, 77-, 107-, and 166-fold lower affinity for H1, D2, α1-adrenergic, and α2-adrenergic receptors, respectively; blocks 5-hydroxy tryptophan-induced head twitches in rats at a dose of 10 mg/kg