Eisai gets Lunesta approval in Japan, launches Fostoin

Japanese drug major Eisai (TYO: 4523) this week received approval from Japan's Ministry of Health, Labor and Welfare (MHLW) to market Lunesta (eszopiclone), a product the company has been developing in Japan, as a treatment for insomnia.

Lunesta, originally discovered and developed by Sunovion Pharmaceuticals; a US subsidiary of Dainippon Sumitomo Pharma, has been marketed in the USA since April 2005. The drug generated US sales of $787 million in the 12 months to September 2010. The agent was approved as the first insomnia treatment not to have restrictions on its length of use, and is widely used by individuals suffering from insomnia. Eisai has been pursuing the development of Lunesta since acquiring the exclusive rights to develop and market it in Japan from Sunovion (at the time known as Sepracor) in July 2007. The company submitted a marketing authorization application to the MHLW in November 2010.

Lunesta is a non-benzodiazepine type GABAA agonist that is believed to enhance GABA activity while exerting hypnotic and sedative effects. Results from clinical studies conducted in Japan and overseas demonstrated that the agent is effective in those patients who have trouble falling asleep or wake up often during the night, two major symptoms of insomnia. A distinctive feature of Lunesta is that patients do not experience clinically problematic issues such as dependency or carry-over effects or develop a tolerance (experience diminished efficacy) with long-term use.