Following feedback from the United States FDA for additional clinical data, the French drug marker Sanofi-Aventis lately withdrawn both US and EU marketing authorization applications for insomnia drug Eplivanserin (protected by the US Patent No. 5166416). Sanofi, which over the years occupied a major share in the branded insomnia market by its Ambien Franchise, was counting high on Eplivanserin, the drug that was likely to be the first drug in the class of serotonin receptor to reach the market, particularly following Sanofi’s discontinuation of another insomnia drug Volinanserin (protected by European Patent Nos. 0.208.235 and 0.531.410) in early 2009. Other serotonin receptors that are still running under development in different clinical phases are Pruvanserin (disclosed in WO01007435) by Eli Lilly and Pimavanserin (disclosed in WO0166521) by Acadia Pharmaceuticals.