2,2,5,5-Tetramethyl-4-thiazolidinecarboxylic Acid is an intermediate in the synthesis of D,L-Penicillamine O-Lactose Adduct (P223020), which is an impurity of D-Penicillamine (P223000), a Penicillin metabolite used in the treatment of Wilson’s disease, Cystinuria, Scleroderma and arsenic poisoning.