APD668 is a novel, highly potent and orally active glucose-dependent insulinotropic receptor (GDIR) agonist intended to more efficiently stimulate insulin release by beta cells in response to elevated blood glucose levels, and to avoid hypoglycemia. Ortho-McNeil's initial clinical studies evaluated healthy volunteers and patients with type 2 diabetes in randomized, double-blind, placebo-controlled trials evaluating the safety, tolerability, pharmacokinetics and pharmacodynamics of single and multiple (14 day) escalating doses of APD668. Based on the data from those studies, Ortho-McNeil has decided to put APD668 on hold and has advanced a potentially more potent Arena discovered GDIR agonist into preclinical development.

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).