Acetylcysteine serves as a prodrug to L-cysteine.

L-cysteine is a precursor to the biologic antioxidant glutathione. Hence administration of acetylcysteine replenishes glutathione stores.^[60]

– Glutathione, along with oxidized glutathione (GSSG) and S-nitrosoglutathione (GSNO), have been found to bind to the glutamate recognition site of the NMDA and AMPA receptors (via their γ-glutamyl moieties), and may be endogenousneuromodulators.^[61][62] At millimolar concentrations, they may also modulate the redox state of the NMDA receptor complex.^[62] In addition, glutathione has been found to bind to and activate ionotropic receptors that are different from any other excitatory amino acid receptor, and which may constitute glutathione receptors, potentially making it a neurotransmitter.^[63] As such, since N-acetylcysteine is a prodrug of glutathione, it may modulate all of the aforementioned receptors as well.

– Glutathione also modulates the NMDA receptor by acting at the…