For the many people who have used it, it has proved safe and effective, according to the FDA
Chemical Information: TB-4 Fragment (Ac-SDKP)
Using them in the morning can help protect your skin from environmental damage due to their antioxidant properties, while nighttime use can enhance your skin's natural repair process
TRN, tegmental reticular nucleus
Isolation of a mixed disulphide of glutathione and cysteinylglycine from a partial [PMID: 13087249] Laboratory literature summary: Isolation of a mixed disulphide of glutathione and cysteinylglycine from a partial hydrolysate of glutathione
J Allergy Clin Immunol 118 : 12181225 Fitzpatrick AM, Teague WG, Holguin F, Yeh M, Brown LA, Severe Asthma Research Program 2009 Airway glutathione homeostasis is altered in children with severe asthma: evidence for oxidant stress