MRK-409

MRK-409, also known as MK-0343, is a GABAA receptor partial agonist.

It was designed to be a non-sedative anxiolytic, however its development was halted because it produced sedation in humans.

Pharmacodynamics
Despite lacking the benzodiazepine chemical structure, MRK-409 acts on the benzodiazepine binding site, it is therefore a nonbenzodiazepine.

MRK-409 binds to the α1, α2, α3 and α5 subunits of the GABAA receptor.

In rats, it produces minimal to no sedation, however it produces sedation in humans at doses above 1 mg.