Succimer is approved for the treatment of lead intoxication, where it is associated with increased urinary excretion of the metal and concurrent reversal of metal-induced enzyme inhibition. At moderately elevated blood lead concentrations, oral succimer is comparable with parenteral calcium EDTA (See EDTA, Calcium (Calcium Disodium EDTA, Calcium Disodium Edetate, Calcium Disodium Versenate))in decreasing blood lead concentrations. The efficiency of succimer in eliminating lead from the blood and tissues may somewhat decline at very high blood concentrations of lead (eg, >100 mcg/dL). Although succimer treatment has been associated with subjective clinical improvement, controlled clinical trials demonstrating therapeutic efficacy have not been reported. A recent large, randomized, double-blind placebo-controlled trial of succimer in children with blood lead concentrations between 25 and 44 mcg/dL found no evidence of benefit in clinical outcome or long-term blood lead reduction.