Racetam

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Racetams are a class of drugs that share a pyrrolidone nucleus.[1] Many, such as piracetam, but not all, are considered nootropics. Some such as oxiracetam and phenylpiracetam are also stimulants. Others such as levetiracetam and seletracetam are anticonvulsants.

Mechanism[edit]

There is no universally accepted mechanism of action for racetams. Racetams generally show negligible affinity for common central nervous system receptors, but modulation of central neurotransmitters, including acetylcholine and glutamate, has been reported. Although aniracetam and nebracetam show affinity for muscarinic receptors, only nefiracetam demonstrates nanomolar interactions. Modification of membrane-located mechanisms of central signal transduction is another hypothesis.[2]

Like some ampakines, some racetams such as piracetam and aniracetam are positive allosteric modulators of the AMPA receptor.[3]

Racetams are understood to work by activating glutamate receptors that are colocalized with cholinergic receptors, thus increasing the frequency of activation of the latter.[4] The racetams consequently increase memory capacity by a similar method as acetylcholinesterase inhibitors.[5]

In aged rats, piracetam potency was shown to be increased when administered in combination with choline.[6]

References[edit]

  1. ^ Löscher, W.; Richter, A. (2000). "Piracetam and levetiracetam, two pyrrolidone derivatives, exert antidystonic activity in a hamster model of paroxysmal dystonia". European journal of pharmacology 391 (3): 251–254. doi:10.1016/S0014-2999(00)00105-9. PMID 10729365.  edit
  2. ^ Gualtieri, F.; Manetti, D.; Romanelli, M. N.; Ghelardini, C. (2002). "Design and study of piracetam-like nootropics, controversial members of the problematic class of cognition-enhancing drugs". Current pharmaceutical design 8 (2): 125–138. doi:10.2174/1381612023396582. PMID 11812254.  edit
  3. ^ Ahmed, A. H.; Oswald, R. E. (2010). "Piracetam Defines a New Binding Site for Allosteric Modulators of α-Amino-3-hydroxy-5-methyl-4-isoxazole-propionic Acid (AMPA) Receptors". Journal of Medicinal Chemistry 53 (5): 2197–2203. doi:10.1021/jm901905j. PMC 2872987. PMID 20163115.  edit
  4. ^ Copani, A.; Genazzani, A. A.; Aleppo, G.; Casabona, G.; Canonico, P. L.; Scapagnini, U.; Nicoletti, F. (1992). "Nootropic drugs positively modulate alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid-sensitive glutamate receptors in neuronal cultures". Journal of neurochemistry 58 (4): 1199–1204. doi:10.1111/j.1471-4159.1992.tb11329.x. PMID 1372342.  edit
  5. ^ Koliaki, C. C.; Messini, C.; Tsolaki, M. (2012). "Clinical Efficacy of Aniracetam, Either as Monotherapy or Combined with Cholinesterase Inhibitors, in Patients with Cognitive Impairment: A Comparative Open Study*". CNS Neuroscience & Therapeutics 18 (4): 302–312. doi:10.1111/j.1755-5949.2010.00244.x. PMID 22070796.  edit
  6. ^ Bartus, R. T.; Dean Rl, 3.; Sherman, K. A.; Friedman, E.; Beer, B. (1981). "Profound effects of combining choline and piracetam on memory enhancement and cholinergic function in aged rats". Neurobiology of aging 2 (2): 105–111. doi:10.1016/0197-4580(81)90007-5. PMID 7301036.  edit