A selective serotonin reuptake inhibitor (IC50 = 1.8 nM for 5-HT reuptake in rat brain synaptosomes); selective for 5-HT reuptake over that of dopamine and norepinephrine (IC50s = >6 mM); potentiates 5-hydroxy-L-tryptophan-induced headweaving and tremor in mice (ED50s = 0.61 and 0.66 mmol/kg, respectively); acts as an antagonist of nicotinic acetylcholine receptors (IC50 = 0.93 μM)