The third term is the loss of cysteine in the reaction catalyzed by GCS that makes glutamyl-cysteine and the fourth term represents the loss of cysteine to other pathways (for example to sulfate and taurine)
That is why we provide lipotropic injections that contain a specially formulated blend of compounded amino acids, vitamins and minerals to help encourage the breakdown of fat in the liver
Vol 6, Supplement 2 (December 2017): Annals of Palliative Medicine A selective review of medical cannabis in cancer pain management Review Article Alexia Blake, Bo Angela Wan, Leila Malek, Carlo DeAngelis, Patrick Diaz, Nicholas Lao, Edward Chow, Shannon OHearn Foods
Factor in the cost of bacteriostatic water, syringes, alcohol swabs, and third-party testing
For dietary supplements, including many glutathione products, I note the FDA doesnt require pre-market approvalonly that ingredients are generally recognized as safe (GRAS)