Fluvoxamine selectively inhibits the reuptake of serotonin (Ki = 6.2 nM in rat hypothalamus) with comparatively little effect on noradrenaline reuptake (Ki = 1,100 nM), resulting in decreased serotonin turnover in the brain. By potentiating the pharmacological effects of serotonin and its precursor, 5-hydroxy tryptophan, in the central nervous system, fluvoxamine is known to exhibit antidepressant effects. At higher concentrations, fluvoxamine can block the activity of HERG channels (IC50 = 3.8 μM), which carry the delayed rectifier potassium current that is important for repolarization of ventricular action potentials over the course of normal cardiac functioning. It also has been reported to exhibit cardioprotective effects by stimulating the σ1 receptor.
