Acetylcysteine (also known as N-acetylcysteine or N-acetyl-L-cysteine or NAC) is primarily used as a mucolytic agent and in the management of acetaminophen poisoning. Acetylcysteine likely protects the liver by maintaining or restoring the glutathione levels, or by acting as an alternate substrate for conjugation with, and thus detoxification of, the reactive metabolite. Nacystelyn (NAL), a recently-developed lysine salt of N-acetylcysteine (NAC) is known to have excellent mucolytic capabilities and is used to treat cystic fibrosis (CF) lung disease. NAC as a precursor to the antioxidant glutathione modulates glutamatergic, neurotrophic, and inflammatory pathways. The potential applications of NAC to facilitate recovery after traumatic brain injury, cerebral ischemia, and in treatment of cerebrovascular vasospasm after subarachnoid hemorrhage. Acetylcysteine serves as a prodrug to L-cysteine, which is a precursor to the biologic antioxidant, glutathione, and hence administration of acetylcysteine replenishes glutathione stores. L-cysteine also serves as a precursor to cystine, which in turn serves as a substrate for the cystine-glutamate antiporter on astrocytes hence increasing glutamate release into the extracellular space. Acetylcysteine also possesses some anti-inflammatory effects possibly via inhibiting NF-κB through redox activation of the nuclear factor kappa kinases thereby modulating cytokine synthesis. NAC is associated with reduced levels of inflammatory cytokines and acts as a substrate for glutathione synthesis. These actions are believed to converge upon mechanisms promoting cell survival and growth factor synthesis, leading to increased neurite sprouting.

N-Acetylglucosamine (N-acetyl-D-glucosamine, or GlcNAc,) is a monosaccharide and a derivative of glucose. It is part of a biopolymer in the bacterial cell wall, built from alternating units of GlcNAc and N-acetylmuramic acid (MurNAc), cross-linked with oligopeptides at the lactic acid residue of MurNAc. This layered structure is called peptidoglycan (formerly called murein). GlcNAc is the monomeric unit of the polymer chitin, which forms the outer coverings of insects and crustaceans. It is the main component of the radulas of mollusks, the beaks of cephalopods, and a major component of the cell walls of most fungi. It is lnsown, that the breakdown of glycosaminoglycans is an important consequence of inflammation at mucosal surfaces, and inhibition of metalloprotease activity may be effective in treating chronic inflammation. GlcNAc directly incorporates into glycosaminoglycans and glycoproteins, as a substrate for tissue repair mechanisms. It was shown, that GlcNAc was promising substance for treatment of chronic inflammatory bowel disease, with a mode of action which is distinct from conventional treatments. In experiments on rabbits with osteoarthritis, was found chondroprotective effects of aminomonosaccharide glucosamine, but no statistically significant difference was found between study groups. It was also investigated for the treatment of Multiple sclerosis, however, as a drug development target, GlcNAc had significant limitations. GlcNAc has poor membrane permeability, requiring high concentrations for biological effects.

Aceglutamide (INN, JAN) (brand name Neuramina), or aceglutamide aluminum (JAN, USAN) (brand name Glumal), also known as acetylglutamine, is a psychostimulant, nootropic, and antiulcer agent that is marketed in Spain and Japan. Aceglutamide functions as a prodrug to glutamine with improved potency and stability. Aceglutamide is used as a psychostimulant and nootropic, while aceglutamide aluminum is used in the treatment of ulcers. Aceglutamide can also be used as a liquid-stable source of glutamine to prevent damage from protein energy malnutrition.

N-Acetyltyrosine is an acetylated derivative of the amino acid L-tyrosine. Ordinary L-tyrosine is less stable and also less soluble in water, which may result in reduced bioavailability. Acetylation enhances the solubility and stability of certain amino acids. N-Acetyltyrosine is commonly used in place of tyrosine in parenteral nutrition. It converts to tyrosine and then can be used in neurotransmitter treatment as a precursor of cathecholamine. N-Acetyltyrosine supports brain function by supporting the synthesis of the catecholamines norepinephrine and dopamine (neurotransmitters). N-Acetyltyrosine supplements are used to improve memory and cognitive performance in humans while they are experiencing psychological stress.