Dual Orexin Receptor Antagonists (DORA) bind to both the Orexin 1 and 2 receptors. High resolution crystal structures of the Orexin 1 and 2 receptors, both class A GPCRs, were not available at the time of this study, and thus, ligand-based analyses were invoked and successfully applied to the design of DORAs. Computational analysis, ligand based superposition, unbound small-molecule X-ray cryst...