SB-408124 is a drug which is a non-peptide antagonist selective for the orexin receptor subtype OX1, with around 70x selectivity for OX1 over OX2 receptors, and improved oral bioavailability compared to the older OX1 antagonist SB-334867. It is used in scientific research into the function of orexinergic neurons in the body.[1][2]
↑"Orexin-A modulates glutamatergic NMDA-dependent spinal reflex potentiation via inhibition of NR2B subunit". American Journal of Physiology. Endocrinology and Metabolism295 (1): E117-29. July 2008. doi:10.1152/ajpendo.90243.2008. PMID18477704.