Determination and metabolism of dithiol chelating agents. IV. Urinary excretion of meso-2,3-dimercaptosuccinic acid and mercaptosuccinic acid in rabbits given meso-2,3-dimercaptosuccinic acid.

The water-soluble dithiol chelating agents meso-2,3-dimercaptosuccinic acid (DMSA) and 2,3-dimercaptopropane-1-sulfonic acid (DMPS) are becoming of increasing importance for the treatment of lead, arsenic and mercury poisoning. There is, however, a paucity of data about their metabolic transformation. Male rabbits were given DMSA (0.20 mmol/kg) i.m., and urine was collected over a 6-hr period. Monobromobimane derivatization, HPLC separation, and fluorescence detection, along with [U-14C]DMSA data, demonstrated that the total 14C found in the urine was distributed as 73% unaltered DMSA, 7% mercaptosuccinic acid and 6 and 14% of two unknowns. Electrolytic reductive treatment of the urine did not increase the urinary content of DMSA, indicating that oxidative biotransformation is not a major pathway for DMSA in the rabbit. This latter result is strikingly different from that for DMPS in rabbit.