Acetyltryptophan, L- functions readily as a component of the food in place of the free amino acid. Acetyltryptophan, L- is a neurokinin-1 receptor antagonist. It significantly improved motor and cognitive outcomes in models of Parkinson’s diseases, as well as reduced brain edema and axonal injury in experimental traumatic brain injury and stroke. It is a potent therapeutic agent for the treatment of amyotrophic lateral sclerosis.

L-822179 is a triazolophthalazine that selectively attenuates the effects of GABA at GABA(A) receptors containing an alpha5 subunit. It is an orally active, functionally selective compound, which enhances cognition in animals without anxiogenic or convulsant effects. The dose-limiting adverse event of L-822179 is dizziness and/or light-headedness. L-822179 does not improve cognitive performance in the elderly; indeed the dose of 4 mg actually significantly impairs performance. In this regard, it could therefore be considered that this study is a failed trial in so far as the positive control, lorazepam, does not show the anticipated effect.