Generic Name: Succimer
Class: Heavy Metal Antagonists
ATC Class: V03AB
VA Class: AD300
Chemical Name: Meso 2,3-dimercaptosuccnic acid
Molecular Formula: C4H6O4S2
CAS Number: 304-55-2
Uses for Chemet
The AAP recommends succimer in the treatment of lead poisoning in children with blood lead concentrations of 45–70 mcg/dL who do not have symptoms of lead encephalopathy.5 Alternatively, parenteral therapy with edetate calcium disodium (calcium EDTA) alone is recommended.5
CDC and AAP do not recommend routine chelation therapy in pediatric patients with blood lead concentrations 25–45 mcg/dL.5 b However, oral chelation therapy with succimer may be recommended in certain patients (e.g., blood lead concentrations of 35–44 mcg/dL, children <2 years of age, evidence of toxicity or symptoms).5 b
The AAP currently states that patients with blood lead concentrations >70mcg/dL or with symptoms of lead encephalopathy require inpatient combined therapy with parenteral calcium EDTA and dimercaprol.4 5 8
Children may need to be hospitalized during initiation of therapy to monitor for adverse effects, ensure patient compliance, and allow time for implementation of environmental lead abatement procedures.5 6
Used in conjunction with a lead abatement program.a
Other Heavy Metal Poisoning
Chemet Dosage and Administration
When source for lead poisoning has been identified, remove patient from that source.a
Maintain adequate hydration to ensure renal excretion of chelating agents.a
In patients who cannot swallow capsules, administer by opening capsule and sprinkling beads on a small amount of soft food or by putting beads in a spoon and following with fruit drink.a
Blood Lead Concentration 45–70 mcg/dLOral
Mild Symptoms or Blood Lead Concentration 70–100 mcg/dLOral
Safety of uninterrupted dosing >3 weeks not established and not recommended.a
Safety of uninterrupted dosing >3 weeks not established and not recommended.a
No special population dosage recommendations at this time.a
Cautions for Chemet
Known hypersensitivity to succimer or any ingredient in the formulation.a
Not a substitute for the abatement of lead exposure.a
Risk of mild to moderate neutropenia, possibly resulting in infection.a
Perform CBCs, including differential and platelet counts, prior to and weekly during therapy.a Withhold therapy if ANC <1200/mm3; continue monitoring until ANC >1500/mm3 or recovery to patient’s baseline neutrophil count.a Rechallenge only if the benefit of therapy outweighs the risk of neutropenia and only with careful monitoring.a
Assess blood counts if infection is suspected.a
Possible allergic or mucocutaneous reactions; may occur with readministration as well as during initial course.a
Recurrent mucocutaneous vesicular eruptions affecting oral mucosa, external urethral meatus, and perianal area reported in one patient; reactions increased in severity with administration of each subsequent course and resolved between courses and upon discontinuance of therapy.a
Clinical experience is limited; careful observation recommended during therapy.a
Rebound Lead Toxicity
Risk of elevated blood lead concentrations and associated symptoms after discontinuance of drug due to redistribution of lead from bone stores to soft tissues and blood.a
After completion of therapy, monitor blood lead concentrations at least once weekly until stable.a Use the severity of lead intoxication (as measured by the initial blood lead concentration and the rate and degree of rebound of blood lead) as a guide for more frequent monitoring.a
Elevated Serum Transaminases
Not known whether succimer is distributed into milk; however, breastfeeding is contraindicated in women receiving succimer due to maternal lead poisoning and risk of exposing nursing infant to the toxic heavy metal.a e
Safety and efficacy not established in children <12 months of age.a
Use with caution; assess hepatic function prior to and periodically during therapy.a
Closely monitor patients with a history of liver disease.a
Use with caution; assess renal function prior to and periodically during prolonged therapy.a Adequately hydrate patients during therapy.a Limited data suggests that succimer is dialyzable, but the lead chelates are not.a
Common Adverse Effects
GI symptoms (nausea, vomiting, diarrhea, appetite loss, loose stools, metallic taste), elevated serum transaminases, rash, neutropenia.a
Interactions for Chemet
Concomitant administration with other chelating agents (i.e., edetate sodium dicalcium) is not recommended.c
May interfere with serum and urinary laboratory tests.a May cause false positive results for ketones in urine using nitroprusside reagents (e.g., Ketostix) and falsely decreased measurements of serum uric acid and CPK.a
Absorption is rapid and variable, with peak plasma concentrations obtained at 1–2 hours.a
Approximately 90% of absorbed dose is metabolized to mixed succimer-cysteine disulfides.a
Unabsorbed drug excreted principally in feces; absorbed drug excreted principally in the urine as metabolites.a
Approximately 2 days.a
Forms water soluble chelates with lead and increases urinary excretion of lead.a
Improves clinical symptoms (e.g., headache, colic) and biochemical indices of lead poisoning.a
Does not affect urinary elimination of iron, calcium, or magnesium; however, may double zinc excretion.a
Advice to Patients
For patients unable to swallow capsules, contents of capsules may be sprinkled on soft food just before administration or placed on a spoon for administration and taken with fruit juice.a
Importance of maintaining adequate fluid intake.a
Importance of informing clinicians if rash or infection occurs.a
Importance of completing full course of therapy.a
Importance of women informing clinicians if they are or plan to become pregnant or plan to breast-feed.a
Importance of keeping succimer out of reach of children.a
Importance of informing patients of other important precautionary information.a (See Cautions.)
Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.
Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.
AHFS DI Essentials. © Copyright 2017, Selected Revisions August 1, 2009. American Society of Health-System Pharmacists, Inc., 7272 Wisconsin Avenue, Bethesda, Maryland 20814.
1. McNeil Consumer Products Company. Chemet (succimer) capsules prescribing information. Fort Washington, PA; 1991 Feb.
2. McNeil Consumer Products Company. A summary of pharmacological and clinical data: Chemet (succimer). Fort Washington, PA: 1991.
3. McNeil, Fort Washington, PA: Personal communication.
4. US Department of Health and Human Services. Preventing lead poisoning in young children: a statement by the Centers for Disease Control October 1991. Atlanta, GA: Centers for Disease Control, Center for Environmental Health.
5. Committee on Drugs, American Academy of Pediatrics. Treatment guidelines for lead exposure in children. Pediatrics. 1995; 96:155-60. [IDIS 349805] [PubMed 7596706]
6. Committee on Environmental Health, American Academy of Pediatrics. Lead poisoning: from screening to primary prevention. Pediatrics. 1993; 92:176-83. [PubMed 8516071]
7. Mann KV, Travers JD. Succimer, an oral lead chelator. Clin Pharm. 1991; 10:914-22. [IDIS 288062] [PubMed 1663439]
8. Piomelli S, Rosen JF, Chisolm JJ Jr et al. Management of childhood lead poisoning. J Pediatr. 1984; 105:523-32. [IDIS 190925] [PubMed 6481529]
9. Food and Drug Administration. Orphan designations pursuant to Section 526 of the Federal Food and Cosmetic Act as amended by the Orphan Drug Act (P.L. 97-414), to June 28, 1996. Rockville, MD; 1996 Jul.
a. Schwarz Pharma Mfg. Chemet (succimer) capsules prescribing information. Seymour, IN; 2007 Apr.
b. Henretig FM. Lead. In: Flomenbaum NE, Goldfrank LR, Hoffman RS et al, eds. Goldfrank’s toxicologic emergencies. 8th ed. New York: McGraw-Hill; 2006:1308-24.
c. Howland MA. Succimer (2,3-dimercaptosuccinic acid). In: Flomenbaum NE, Goldfrank LR, Hoffman RS et al, eds. Goldfrank’s toxicologic emergencies. 8th ed. New York: McGraw-Hill; 2006:1325-30
d. Gracia RC, Snodgrass WR. Lead toxicity and chelation therapy. Am J Health-Syst Pharm. 2007; 64:45-53. [PubMed 17189579]
e. Briggs GC, Freeman RK, Yaffe SJ. Drugs in Pregnancy and Lactation. 7th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2005:1706-8.