In the December 8 issue of the holy journal known as the Lancet (1), an article was published regarding the sassy cousin of ramelteon, tasimelteon. Ramelteon selectively binds to the melatonin receptors in the suprachiasmatic nuclei of the hypothalamus (m1 & m2 specifically). At present the drug is FDA approved for the treatment of primary insomnia.
Enter tasimelteon, which is in phase III clinical trials and is being studied for circadian rhythm sleep disorders (jet-lag and shift-work being the most common). I don't know a lot about the pharmacological properties of tasimelteon, but as far as I can tell, it offers no advantage over ramelteon since they affect the same brain receptors and have a similar half-life (I believe ramelteon is more potent).
Just like all the SSRI's that followed Prozac, this drug appears to offer nothing in the way of improved effectiveness or safety over ramelteon, however, I am making the prediction that when the drug does hit the market, it will cost a pretty penny (2, 3).
Here is what the Medical Letter had to say about ramelteon when it was released, "Ramelteon (Rozerem), a melatonin receptor agonist, is not a controlled substance and apparently has no potential for abuse, but its hypnotic effect is not impressive. In clinical trials, it produced small, statistically significant improvements in sleep latency, but had little effect on sleep maintenance." You can substitute the name tasimelteon for ramelteon and the Medical Letter statement still holds true.
The study published in the Lancet was funded by Vanda Pharmaceuticals Inc., the company responsible for the development of tasimelteon. Sure the article talks about safety and tolerability, how it beat placebo, and blah blah blah (placebo actually did pretty well too), but this article is a simple marketing ploy, nothing more. Think of it as a movie trailer, which is released months before the actual movie, in order to generate buzz, because the actual product has no substance (e.g., Valkyrie). The cool part is, the articles that talk about this drug, act as if ramelteon does not exist. Tasimelteon is portrayed as a break through drug (4, 5), which it's not.
So, should this drug actually make it to market, it will be advertised for circadian rhythm sleep disorders. I might be as bold as to say it will be advertised as the first drug approved for these types of sleep disorders, even though there are already many effective ways to managed these sleep problems.