S1RA

S1RA, E-52862, or 4-(2-((5-methyl-1-(naphthalen-2-yl)-1H-pyrazol-3-yl)oxy)ethyl)morpholine is a selective sigma-1 receptor antagonist, with a reported binding affinity of Ki = 17.0 ± 7.0 nM, and more than 58 times selectivity over the sigma-2 receptor.

S1RA is has successfully completed Phase I clinical trials for the treatment of neuropathic pain, and is currently undergoing Phase II trials, making it the first selective sigma-1 receptor antagonist evaluated in humans for this condition.