Fananserin is an effective, selective and oral active antagonist of 5-HT2 (Ki = 0.37 nM for the rat 5-HT2A). Fananserin is an antagonist of human D4 receptor (Ki = 2.93 nM).

5-HT2 receptor:0.37 nM （ki）, D4 receptor:2.93 nM （ki）

Fananserin displays low to moderate affinity for α1-adrenoceptors, dopamine D2 receptors and histamine H 1 receptors[1]. Fananserin displaces [3H]spiperone binding to recombinant human dopamine D 4 receptors with a Ki of 2.93 nM[3]. Fananserin is relatively selective for 5-HT2 receptor with lower affinity for the 5-HT1A receptor and very low affinity for the 5-HT3 receptor[3].

Fananserin shows a moderate affinity for alpha 1-adrenoceptors in the rat thalamus with an IC50 of 14 nM and for H1 receptors in the guinea-pig cerebellum with an IC50 of 13 nM[1]. Fananserin displaces [125I]AMIK from 5-HT2 receptors with an IC50 of 0.21 nM in the rat frontal cortex[1]. Fananserin (0.5, 1, 2 and 4 mg/kg; p.o.) dose-dependently increases the duration of deep nonrapid eye movement (NREM) sleep at the expense of wakefulness[2].