Adipiplon (developmental code name NG2-73) is an anxiolytic drug developed by Neurogen Corporation. It has similar effects to benzodiazepine drugs, but is structurally distinct and classed as a nonbenzodiazepine anxiolytic.
Adipiplon is a subtype-selective GABA<sub>A</sub> receptor partial agonist, which binds preferentially to the ñ<sub>3</sub> subtype. This is significant as while several previous nonbenzodiazepine drugs have been developed that are selective for ñ<sub>2/3</sub> over the other subtypes, adipiplon is one of the first drugs selected for clinical development which can discriminate between ñ<sub>2</sub> and ñ<sub>3</sub>, as well as showing a little affinity for the ñ<sub>1</sub> or ñ<sub>5</sub> subtypes â alpidem is selective for ñ<sub>3</sub> over ñ<sub>2</sub>, but still has moderate affinity for ñ<sub>1</sub>, whereas adipiplon is highly ñ<sub>3</sub>-selective with little affinity for either ñ<sub>1</sub>, ñ<sub>2</sub> or ñ<sub>5</sub>.
Adipiplon was being researched as a potential medication for the treatment of anxiety and insomnia, and in 2008 it was being used in Phase IIb trials. These trials were suspended after significant next-day side effects were discovered.