SL651498 was identified as a drug development candidate from a research program designed to discover subtype-selective GABA(A) receptor agonists for the treatment of generalized anxiety disorder and muscle spasms. SL651498 displayed high affinity for GABA(A) receptors containing alpha(1) and alpha(2 subunits, and weaker affinity for alpha5-containing GABA(A) receptors, it behaved as a full agonist at recombinant t GABA(A) receptors containing alpha(2) and alpha(3) subunits, and as a partial agonist at recombinant GABA(A) receptors expressing alpha(1) and alpha(5) subunits. It was shown, that SL651498 represented a promising alternative to agents currently used for the treatment of anxiety disorders and muscle spasms without the major side effects seen with classical benzodiazepines).

PHA-543613 was discovered by Pfizer and has been under development primarily as a potential treatment of schizophrenia. PHA-543613 acts as an agonist to the Neuronal acetylcholine receptor protein alpha-7 subunit. A single human trial was conducted in healthy human volunteers, but the compound has been studied extensively in rat models for schizophrenia as well as Parkinson's disease and Alzheimer's disease.