in animals: 1 mg/kg of a 1 mg/ml solution in 50% polyethylene glycol 300 was administered after overnight food deprivation to either male Sprague-Dawley rats (∼300 g; n = 6), female beagle dogs (∼12 kg; n = 3), or male rhesus monkeys (∼4 kg; n = 3)

MRK-016 is clearly an GABAA α5-selective inverse agonist, it has much greater efficacy at the α5 subtype (maximal efficacy, −55%) compared with the α1, α2, or α3 subtypes respective maximal efficacy values, −16, +6, and −9%, respectively). Most notably, however, the efficacy of MRK-016 at the α5 subtype (−55%) is greater than that observed for α5IA (−40%) and is comparable with the α5 inverse agonism of the nonselective full inverse agonist DMCM (−57%)