Ramelteon (TAK-375) is a melatonin [
M1105] receptor agonist with both high affinity for melatonin MT
1 and MT
2 receptors, and high selectivity for MT
1 and MT
2 receptors compared to the MT
3 receptor. In addition, ramelteon showed no measurable affinity for a large number of ligand binding sites, including benzodiazepine receptors, dopamine receptors, opiate receptors, ion channels, and transporters. Ramelteon also does not interfere with the activity of a number of enzymes. The agonist activity at the MT
1 and MT
2 receptors has been reported to contribute to its sleep-promoting properties. And then, ramelteon currently is approved in the United States and Japan for the treatment of insomnia. (The product is for research purpose only.)