Discovery of dual orexin receptor antagonists (DORAs) for the treatment of insomnia.

Orexins are excitatory neuropeptides that have a critical role in maintaining wakefulness. Orexin receptor antagonists promote sleep in animals and humans. Indeed, small molecule orexin receptor antagonists have demonstrated clinical proof-of-concept in the treatment of primary insomnia. This review describes optimization of orexin receptor antagonists across diverse structural classes with a focus on how molecules were designed to optimize potency, physicochemical properties, pharmacokinetics, brain penetration, and in vivo activity.