2,3-Dimercaptosuccinic acid as an antidote for lead intoxication.

2,3-Dimercaptosuccinic acid (DMSA) is an orally effective drug more specific and with a wider therapeutic index than currently available drugs for lead intoxication. Eighteen men with elevated blood lead (BPb) concentrations received either 30, 20, or 10 mg/kg DMSA for 5 days in three divided daily doses. The mean BPb level decreased 72.5%, 58.3%, and 35.5% of the pretreatment values, with a simultaneous elevation in urinary Pb excretion. Clinical symptoms and biochemical indices of lead toxicity also improved. Red blood cell d-aminolevulinic acid dehydratase activity increased, while urinary excretion of d-aminolevulinic acid and coproporphyrin fell. DMSA was well tolerated; the only observed adverse drug reaction was a mild, transient elevation of serum SGPT levels in two subjects. DMSA appears promising and may greatly simplify the treatment of lead intoxication.