Almorexant

Almorexant (ACT-078573) is a competitive OX1 and OX2 orexin receptor antagonist with IC50 of 13 and 8 nM, respectively. It is rapidly absorbed and distributed and shows no tendency to accumulate with repeated dosing. Preclinical studies in rats and dogs have demonstrated a sleep-promoting effect which resembles physiological sleep; this could be quickly reversed upon sensorimotor stimulation and yet allow resumption of sleep upon its cessation. Almorexant’s (ACT-078573) sleep-promoting effects were confirmed in volunteers and patients with primary insomnia. It dose-dependently increased sleep efficiency and decreased sleep latency and wake time after sleep onset.