MRK-016 is a selective, orally bioavailable inverse agonist of the GABAA α5 receptor.

GABAA α1β3γ2 (human):0.83 nM (Ki), GABAA α5:3 nM (EC50), GABAA α3β3γ2 (human):0.77 nM (Ki), GABAA α2β3γ2 (human):0.85 nM (Ki), GABAA α5β3γ2 (human):1.4 nM (Ki)

MRK-016 is a selective, orally bioavailable inverse GABAA α5 receptor agonist (EC50 of 3 nM for GABAA α5, and Kis of 0.83, 0.85, 0.77, and 1.4 nM for human GABAA α1β3γ2, GABAA α2β3γ2, GABAA α3β3γ2, and GABAA α5β3γ2, respectively) [1].

MRK-016 (0.3, 1, or 3 mg/kg p.o.) shows cognition-enhancing activity in the delayed matching-to-position version of the Morris water maze. MRK-016 (1, 3, or 10 mg/kg i.p.) does not produce kindling in mice[2]. MRK-016 (3 mg/kg, i.p.) protects against LPS-induced learning/memory decrements in mice[3].