In vitro activity: Tasimelteon (also known as BMS-214778; VEC-162; brand name: Hetlioz), a novel circadian regulator, is the first product for the treatment of Non-24-hour Sleep-Wake Disorder (Non-24) approved by either the FDA or the European Medicines Agency (EMA). Tasimelteon is a potent and specific melatonin (MT1 and MT2) receptor agonist with 2 - 4 times greater affinity for the MT2 receptor. Long-term tasimelteon administration was safe and well-tolerated. This is supported by placebo-controlled data in both Non-24 and insomnia patients.

Kinase Assay: Tasimelteon is a selective dual melatonin receptor (MT1/MT2) agonist with 2.1-4.4 times greater affinity for the MT2 receptor believed to mediate circadian rhythm phase-shifting (Ki = 0.0692 nM and Ki = 0.17 nM in NIH-3T3 and CHOeK1 cells, respectively), than for the MT1 receptor (Ki = 0.304 nM and Ki = 0.35 nM, respectively).