Since pure glutathione IV treatments arent feasible due to its instability in large fluids, it is typically: Added to an IV infusion with hydration, vitamin C, NAC, and other nutrients to enhance absorption
Radoigraphics 31: 1863, 2011
Because its actually fairly easy to supplement with selenium (provided you are using the right dose) and to replace low levels in your body
Redox Biology;2015 Jul Guoyao Wu, Yun-Zhong Fang, Sheng Yang, Joanne R Lupton, Nancy D Turner
Symptoms and Health Implications : Reduced glutathione levels are associated with increased susceptibility to oxidative stress, chronic diseases, and compromised immune function
Additionally, cells are well equipped with defense mechanisms to rapidly quench and/or metabolize RCS and repair RCS damage