TIK-301 (PD-6735) is a chlorinated melatonin derivative and a potent, high-affinity and orally active melatonin MT 1 and MT 2 receptors agonist with K i s of 0.081 nM and 0.042 nM, respectively. TIK-301 is also a 5-HT 2B /5-HT 2C receptors antagonist with antidepressant action. TIK-301 has the potential for sleep disorders and other circadian rhythm disorders treatment.