Deramciclane is a novel anxiolytic agent that binds with high affinity to 5-HT 2A / 2C receptors. The interactions of Deramciclane with the serotonin 5-HT 2C receptor are further characterized using receptor phosphoinositide hydrolysis assays and receptor autoradiography. Deramciclane antagonizes 5-HT 2C receptor mediated 5-HT-stimulated phosphoinositide hydrolysis with an IC 50 value of 168 nM. Deramciclane also decreases basal phosphoinositide hydrolysis by up to 33% (EC 50 = 93 nM) in a physiological system in the choroid plexus, suggesting that Deramciclane possesses inverse agonist properties at this receptor.