indication

For the treatment of lead poisoning in pediatric patients with blood lead levels above 45 µg/dL. May also be used to treat mercury or arsenic poisoning.

pharmacology

Succimer is an orally active, heavy metal chelating agent. It forms water soluble chelates and, consequently, increases the urinary excretion of lead. Succimer is not to be used for prophylaxis of lead poisoning in a lead-containing environment. In addition, the use of succimer should always be accompanied by identification and removal of the source of the lead exposure.

mechanism of action

Succimer is a heavy metal chelator. It binds with high specificity to ions of lead in the blood to form a water-soluble complex that is subsequently excreted by the kidneys. Succimer can also chelate mercury, cadmium, and arsenic in this manner.

toxicity

Oral LD₅₀ in mice is over 5011 mg/kg. Doses of 2300 mg/kg in the rat and 2400 mg/kg in the mouse produced ataxia, convulsions, labored respiration and frequently death. No case of overdosage has been reported in humans. Limited data indicate that succimer is dialyzable.

biotransformation

Chemical analysis of succimer and its metabolites (primarily mixed disulfides of L-cysteine) in the urine showed that succimer was rapidly and extensively metabolized however the specific site of biotransformation is not known.

absorption

Rapid but variable.

half life

48 hours

route of elimination

Unabsorbed drug is excreted primarily in feces and absorbed drug is excreted primarily in the urine as metabolites.