ORM-10103 is a specific inhibitor of the Na+/Ca2+ exchanger (NCX), which decreases the NCX current with estimated IC50s of 55 and 67 nM at -80 and at 20 mV, respectively[1][2]. IC50: 55 (NCX -80 mV ), 67 nM (NCX 20 mV)[2]
[1]. Jost N, et al. ORM-10103, a novel specific inhibitor of the Na+/Ca2+ exchanger, decreases early and delayed afterdepolarizations in the canine heart. Br J Pharmacol. 2013 Oct;170(4):768-78. [2]. Kohajda Z, et al. The Effect of a Novel Highly Selective Inhibitor of the Sodium/Calcium Exchanger (NCX) on Cardiac Arrhythmias in In Vitro and In Vivo Experiments. PLoS One. 2016 Nov 10;11(11):e0166041.