<unk>  (also known as (-)-phenserine or (-)-eseroline phenylcarbamate) is a synthetic drug which has been investigated as a medication to treat Alzheimer's disease (AD), as the drug exhibits neuroprotective and neurotrophic effects. The research of<unk> , initially patented by the National Institute on Aging (NIA), has been suspended since phase III of clinical trials in 2006, conducted right after the drug licenses were issued. The abandonment of the clinical trials led to disapproval by FDA. The retrospective meta-analysis of the<unk>  research proposed that its clinical invalidation was arisen from methodological issues that were not impeccably settled before proceeding to the subsequent clinical phases.<unk>  was introduced as an inhibitor of acetylcholinesterase (AChE) and demonstrated significant alleviation in numerous neuropathological manifestations, improving cognitive functions of the brain. The ameliorative mechanism involves both cholinergic and non-cholinergic pathways. The clinical translatable doses of<unk>  show relatively high tolerability and rarely manifest severe adverse effects. With respect to overdosing of the drug (20 mg/kg), a few cholinergic adverse effects were reported, including nausea and tremor which are not life-threatening. An administration form of<unk> , (-)-phenserine tartrate, which exhibits high bioavailability and solubility, is taken by mouth.<unk>  and its metabolites can readily access the brain with high permeability across the blood-brain barrier and sustain to act for a long duration with the relatively short half-life. Posiphen ((+)-phenserine), the enantiomer of (-)-phenserine, is also a potential drug by itself or synergically with (-)-phenserine, to mitigate the progression of neurological diseases, mainly Alzheimer's disease.
Phenserine
Nicotinamide
Glutamate 
Glutamine
Choline
Carnitine
Pyridinoline
Gamma-Amino-beta-hydroxybutyric acid