Nootropic agents

The compounds used to palliate the mnemonic and cognitive decline associated with dementia include cerebral vasodilators and the so-called nootropic agents. These materials enhance cerebral metaboHsm. Agents which enhance neurotransmitter function are in most cases cholinergic. 

The mechanism of action of nootropic agents has been proposed to be their abiUty to faciUtate information acquisition, consoHdation, and retrieval (36). No one particular effect has been observed with any consistency for these agents, thus whereas a considerable amount of diverse preclinical pharmacological behavioral data has been generated using these compounds, the significance of these results in predicting clinical efficacy has not been established (43,44). Reviews on the biochemical and behavioral effects of nootropics are available (45—47). 

Other nootropic agents in some stage of clinical development include nebracetam (9), nefinacetam (10), and BMY 21502 (11). Nebracetam, an aminomethyl pyrrolidinone derivative, is expected to be approved in Japan in 1994 (73). In clinical studies involving patients having cerebrovascular or senile dementia of the Alzheimer s type, clinical symptoms such as spontaneous or emotional expression were enhanced in up to 71% of cases. Long-term treatment using nebracetam in patients with cerebral infarction also afforded marked improvement in most cases with few side effects (74). A review of this compound has beenpubUshed (75). 

There appear to be a number of clinical studies that support the efficacy of various nootropic agents in patients with some form or degree of dementia, but the results are not particularly convincing (50,51,57—59,63,74). 

Chemistry, pharmacology, and clinical efficacy of the Chinese nootropic agent huperzine A, alkaloid from Hupenia sermta with annulated 2-pyridone and l-amino-3-methyl-9-ethylidenebicyclo[3.3.l]nona-2,6-diene fragments 99ACR641. 

Rolziracetam (5.62), a nootropic agent, has a structure containing two fused lactam rings. This compound is stable in buffer solutions, but is rapidly metabolized in laboratory animals, yielding exclusively the ring-opened... 

Endogenous nucleotide + nootropic agent + neuro-immunotrophin... 

It improves the functioning of the brain involved in cognitive processes e.g. memory, thought, learning in normal and in subnormal conditions. It is categorized as nootropic agent (cognition enhancers). 

Only four inhibitors of AChE have been approved as therapeutic drugs for combating dementia diseases. The very first is tacrine or Cognex [Figure 2] from Parke-Davis8 and the second is aricept from Eisai [Japan] and Pfizer [U.S.].9 A third inhibitor available is huperzine A, a "nootropic" agent isolated from a Chinese folk medicine and used by Chinese for centuries to improve memory.10 Other known reversible AChE inhibitors... 

Nootropic agents, antihypoxic agents E.g. piracetam, amiracetam, pramiracetam, oxiracetam No evidence for efficacy in AD... 

Li, Y Hu, G. Y. Huperzine A, a nootropic agent, inhibits fast transient potassium current in rat dissociated hippocampal neurons. Neurosci Lett., 2002, 324(1) 25-28. 

Singh, M. Saraf, M. K. Platelet-activating factor a new target site for the development of nootropic agents. Drugs Future, 2001, 26 883-888. 

L-dopa, a precursor of the neurotransmitters norepinephrine and dopamine, was introduced into HE therapy by J.D. Parkes et al. in 1970. The results were good. As yet, there is still no accepted opinion on the use of this substance. Piracetam, as a nootropic substance, led to a clear improvement in typical electrical brain activities in animals displaying hepatic damage and symptoms of encephalopathy. Similarly, a double-blind randomized cross-over study with the nootropic agent centropheno-xine partly showed positive effects in psychometric testing. Bromocriptine, an agonist of the dopamine receptor, was also used in 1980 for chronic hepatic encephalopathy. (146,163) Application of L-carnitine (6 g/day orally, divided into two doses, for 4 weeks) leads to a marked reduction of hyperammonaemia and a clear improvement in clinical symptoms of HE in cirrhotic patients. (119) (s. p.49)... 

DE 019 bucillamine, deacetyllanatoside C deslanoside, deanol [ban] (norcholine N-dimethylethanolamine) is isolated from a Neurospora crassa strain and is a residue present in the alkaloids cassaine and cassaidine. It is a choline precursor and has been used to enhance central acetylcholine formation. It has been used as a CNS STIMULANT (nootropic agent) to enhance mental function, and as an ANTIDEPRESSANT,... 

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