Potent and selective μ opioid receptor antagonist (Ki values are 0.96 and >10,000 nM for μ and δ receptors respectively). Causes behavioral effects on central administration in vivo. Also increases K+ currents in rat locus ceruleus neurons in vitro via a μ receptor independent mechanism.

BTRX-335140 is a potent and selective, orally active κ opioid receptor (KOR) antagonist, has antagonist activity for κOR, μOR and δOR with IC50 values of 0.8 nM, 110 nM, and 6500 nM, respectively.

High affinity ligand for the NOP site (Ki = 1.5 nM). Antagonizes nociceptin-stimulated GTP binding in rat brain and the chronotropic effect of nociceptin on rat cardiomyocytes. However, displays potent agonist properties in vivo, inhibiting locomotor activity in mice.