Structure-activity relationships of phenylalkylamines as agonist ligands for 5-HT2A receptors

Agonist activation of central 5-HT2A receptors results in diverse effects, such as hallucinations and changes of consciousness. Recent findings indicate that activation of the 5-HT2A receptor also leads to interesting physiological responses, possibly holding therapeutic value. Selective agonists are needed to study the full therapeutic potential of this receptor. 5-HT2A ligands with agonist profiles are primarily derived from phenylalkylamines, indolealkylamines, and certain piperazines. Of these, phenylalkylamines, most notably substituted phenylisopropylamines, ore considered the most selective agonists for 5-HT2 receptors. This review summarizes the structure-activity relationships (SAR) of phenylalkylamines as agonist ligands for 5-HT2A receptors. Selectivity is a central theme, as is selectivity for the 5-HT2A receptor and for its specific signaling pathways. SAR data from receptor affinity studies, functional assays, behavioral drug discrimination as well as human studies are discussed.