However, it is rapidly degraded by dipeptidyl peptidase-4 (DPP-IV) and other serum proteases, giving it a half-life of only 10-20 minutes
Iowa City, Iowa: University of Iowa Press

Major Ingredients [Glutathione Niacinamide Body Wash] Aqua(Water), Sodium Laureth Sulfate, Centella Asiatica Leaf Water, Glycerin, Propylene Glycol, Cocamide MEA, Lauramide DEA, Cocamidopropyl Betaine, Sodium Benzoate, Citric Acid, Chlorphenesin, Sodium Chloride, 1,2-Hexanediol, Glutathione, Niacinamide, Polyquaternium-10, Styrene/Acrylates Copolymer, Disodium EDTA, Butylene Glycol, Dipropylene Glycol, Squalane, Beta-Glucan, Asiaticoside, Madecassic Acid, Asiatic Acid, Caprylic/Capric Triglyceride, Hippophae Rhamnoides Fruit Extract, Melaleuca Alternifolia Leaf Extract, Hydrolyzed Collagen, Hydrogenated Lecithin, Artemisia Annua Extract, Nelumbium Speciosum Flower Extract, Oryza Sativa Extract, Saccharomyces Ferment, Sodium Hyaluronate, Solanum Melongena Fruit Extract, Glyceryl Stearate, Xanthan Gum [Glutathione Niacinamide Body Lotion] Aqua(Water), Centella Asiatica Leaf Water, Glycerin, Cetyl Ethylhexanoate, Cetearyl Alcohol, Glyceryl Stearate, PEG-100 Stearate, Cyclopentasiloxane, 1,2-Hexanediol, Dimethicone, Saccharide Hydrolysate, Sorbitan Stearate, Palmitic Acid, Cyclohexasiloxane, Stearic Acid, Glyceryl Stearate SE, Chlorphenesin, Carbomer, Glutathione, Caprylyl Glycol, Niacinamide, Xanthan Gum, Potassium Hydroxide, Disodium EDTA, Butylene Glycol, Dipropylene Glycol, Caprylic/Capric Triglyceride, Arachidic Acid, Myristic Acid, Squalane, Beta-Glucan, Asiaticoside, Madecassic Acid, Asiatic Acid, Hippophae Rhamnoides Fruit Extract, Melaleuca Alternifolia Leaf Extract, Hydrolyzed Collagen, Hydrogenated Lecithin, Artemisia Annua Extract, Nelumbium Speciosum Flower Extract, Oryza Sativa Extract, Saccharomyces Ferment, Sodium Hyaluronate, Solanum Melongena Fruit Extract Ingredients subject to change at manufacturer's discretion

This remains the most direct explanation offered by the people reporting it
Research Considerations by Study Population Fat metabolism research often accounts for study population as a variable, since hormonal baselines differ between male and female subjects and can influence how a given peptides mechanism is observed and measured
One study summarizes investigations of memantine, riluzole, ketamine, D-cycloserine, glycine, NAC, topiramate, and lamotrigine