Melatonergic drug: Ramelteon and its therapeutic applications in insomnia

Abstract

The efficacy of melatonin in promoting and maintaining sleep has been demonstrated in most of the clinical studies. However, because of its short half-life, its sustained effect in improving sleep quality could not be demonstrated uniformly in all the studies that have been undertaken so far. The development of slow-release melatonin preparation Circadin has been found effective in reducing sleep onset time and also for improving sleep quality. This was followed by the introduction of another melatonergic drug ramelteon a melatonin receptor agonist that has high selectivity for MT1 receptors than MT2 receptors and therefore targets sleep onset more specifically than melatonin. Clinical trials undertaken in different countries of European region and Japan have conclusively demonstrated that ramelteon in various doses (from 4 to 32 mg/day) reduced sleep onset latency, increased total sleep time, and sleep efficiency and quality in patients suffering from chronic insomnia. Besides acting as a sedative-hypnotic drug, ramelteon also demonstrated its ability as a drug with chronobiotic properties and has been found useful in resetting the disturbed circadian rhythms. The action of ramelteon in improving sleep efficiency is dose independent and hence acts differently from melatonin. It has a promising value in treating patients with chronic insomnia as it does not have any of the adverse effects like next-day hangover and dependence associated with the usage of other conventional hypnotic drugs.