MRK-623 (Compound 14k) is a potent, orally active agonist of the GABA A receptor, exhibiting high affinity for subunits α1, α2, α3, and α5 with Ki values of 0.85 nM, 3.7 nM, 4.0 nM, and 0.53 nM, respectively. Notably, MRK-623 demonstrates anxiolytic effects [1].