SB-206553SB-206553 is a drug which acts as a mixed antagonist for the 5-HT2B and 5-HT2C serotonin receptors.UsageIt has anxiolytic properties in animal studies and interacts with a range of other drugs. It has also been shown to act as a positive allosteric modulator of α7 nicotinic acetylcholine receptors. Modified derivatives of SB-206553 have been used to probe the structure of the 5-HT2B receptor.DevelopmentSB-206553 was under development by GlaxoSmithKline for the treatment of anxiety disorders in the 1990s. However, its development was discontinued in 1996.