The anecdata seem to indicate that the mode of delivery, that is whether or not systemic or local, doesn't seem to matter that much
Reactive O2 species molecules include peroxide (H2O2) and superoxide anions (O2 with unpaired electron) these molecules are very toxic to the cell
These include decreased drug transport, increased cellular detoxification because of increased glutathione (GSH), changes in DNA repair involving increased nucleotide excision repair and/or loss of mismatch repair, increased tolerance of DNA adducts, and alterations in the apoptotic cell death pathway (Andrews and Howell, 1990
Beyond its antioxidant prowess, NAC possesses unique biochemical properties that directly address the vascular and neurological pathologies of Long COVID
The Safety of Glutathione for G6PD Deficiency The question of safety often arises because people with G6PD deficiency are told to avoid "oxidizing agents." Since glutathione is an antioxidant, it is the opposite of an oxidizer