Ampakine

Ampakines are a class of compounds that take their name from the glutamatergic AMPA receptor with which they strongly interact. The AMPA receptor, in turn, gets its name from AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid), which selectively binds to it.

They are currently being investigated as potential treatment for a range of conditions involving mental disability and disturbances such as Alzheimer's disease, Parkinson's disease, schizophrenia, treatment-resistant depression (TRD) or neurological disorders such as Attention Deficit Hyperactivity Disorder (ADHD), among others.

More recently developed ampakine compounds are much more potent and selective for the AMPA receptor target, and while none of the newer selective ampakine compounds have yet come onto the market, one compound CX717 is currently in Phase II clinical trials as of 2008.

Five structural classes of ampakine drugs have been developed so far:

Additionally, as of 2017 the rapid antidepressant action exerted by tianeptine is thought to be exerted through positive allosteric AMPA receptor modulation, making it the first and currently only approved antidepressant with this mechanism of action. Even though it does not exhibit the properties typical of this class, the compound is chemically a tricyclic antidepressant (TCA), and therefore belongs to neither of the five major ampakine classes listed above.

The parent compound in which the AMPA modulating activity was first characterised was the well known nootropic drug aniracetam. Several drugs in the racetam family have been reported as producing ampakine effects, but while this has been well established for some compounds such as aniracetam and pramiracetam, it is unclear if all of the racetam family act in this way, as the racetam drugs appear to have multiple modes of action.

Since the discovery of the ampakine mode of action as one of the means by which the racetams produce their nootropic effects, a wide range of more selective ampakine drugs have been developed by Cortex Pharmaceuticals, which hold patents covering most medical uses of this class of drugs. The best known compounds that have come out of the Cortex drug development program are CX-516 (Ampalex), CX-546, CX-614, CX-691 (Farampator) and CX-717. Org 26576 was invented by Cortex but then licensed to Organon for development.

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