 Tumor cell GSH concentration may be among the determinant of the cytotoxicity of many chemotherapeutic agents and of radiation, and an increase in GSH concentration appears to be at least one of the mechanisms of acquired drug resistance to chemotherapy.Therapeutic elevation of normal cell GSH levels has also been investigated as a means to reduce the toxicity associated with a wide variety of compounds of both endogenous and exogenous origin.GSH may be increased by different methods including delivery of L-Cystine, a rare limiting amino acid in GSH synthesis.