Version July 2025
Note: Consultation with a clinical toxicologist or an expert in the treatment of heavy metal poisoning is highly recommended.
Arsenic poisoning (off-label use): Dosing is based on the use of succimer for the treatment of lead poisoning (Ref). Consultation with a clinical toxicologist or poison control center is highly recommended in patients who are being considered for chelation therapy.
Oral: 10 mg/kg 3 times daily for 5 days followed by 10 mg/kg twice daily for 14 days (Ref).
Lead poisoning (off-label use): Available guidelines recommend chelation therapy with blood lead levels (BLL) >50 mcg/dL and significant symptoms; chelation therapy may also be indicated for most patients with BLL ≥80 mcg/dL and all patients with BLL ≥100 mcg/dL and/or symptoms (Ref). Selection of chelating regimen should be made in consultation with a clinical toxicologist or expert in the treatment of heavy metal poisoning.
Oral: 10 mg/kg 3 times daily for 5 days followed by 10 mg/kg twice daily for 14 days (Ref).
Note: Treatment courses may be repeated, but 2-week intervals between courses is generally recommended because lead re-equilibrates between the extravascular storage sites (eg, bone) and the vascular compartment. High initial blood lead levels (eg, >100 mcg/dL) or presence of lead encephalopathy may indicate the need for more prompt retreatment (Ref); consultation with a clinical toxicologist or poison control center is highly recommended.
Mercury poisoning (off-label use): Dosing is based on the use of succimer for the treatment of lead poisoning (Ref). Consultation with a clinical toxicologist or poison control center is highly recommended in patients who are being considered for chelation therapy.
Oral: 10 mg/kg 3 times daily for 5 days followed by 10 mg/kg twice daily for 14 days (Ref).
There are no dosage adjustments provided in the manufacturer's labeling; use with caution. Succimer is dialyzable; however, the lead chelates are not.
Hepatic impairment prior to treatment: There are no dosage adjustments provided in the manufacturer's labeling; has not been studied. More frequent monitoring of serum transaminases may be required in patients with a history of liver disease due to the risk of transient increases.
Hepatotoxicity during treatment: AST or ALT >5 times ULN: Interrupt therapy or reduce dose.
ANC <1200 mm3: The manufacturer recommends withholding treatment; treatment may be cautiously resumed when ANC returns to baseline or >1500/mm3. May rechallenge if benefits outweigh risk and with more frequent CBC monitoring. Discontinue succimer if signs and symptoms of infection occur.
Refer to adult dosing.
(For additional information see "Dimercaptosuccinic acid (succimer): Pediatric drug information")
Dosage guidance:
Dosing: Dosing is presented in both mg/kg and mg/m2; use caution.
Arsenic poisoning: Limited data available: Note: Dosing is based on the use of succimer for the treatment of lead poisoning (Ref). Experts recommend dosing for children <5 years of age should be based on body surface area (Ref). Consultation with a clinical toxicologist, poison center, or an expert in the treatment of heavy metal poisoning is highly recommended.
Children <5 years: Oral: 350 mg/m2/dose every 8 hours for 5 days followed by 350 mg/m2/dose every 12 hours for 14 days; maximum dose: 500 mg/dose; round dose to the nearest 100 mg (Ref).
Children ≥5 years and Adolescents: Oral: 10 mg/kg/dose or 350 mg/m2/dose every 8 hours for 5 days followed by 10 mg/kg/dose or 350 mg/m2/dose every 12 hours for 14 days; round dose to the nearest 100 mg; maximum dose: 500 mg/dose (Ref).
Lead poisoning, mild and asymptomatic:
Note: For the treatment of high blood lead levels (BLL) in children, the CDC recommends chelation treatment when BLL >45 mcg/dL (Ref). The AAP recommends succimer as the drug used for initial management in asymptomatic children when BLL >45 mcg/dL and <70 mcg/dL; children with BLL ≥70 mcg/dL or symptomatic lead poisoning should be treated with parenteral agents (Ref). Selection of chelating regimen should be made in consultation with a clinical toxicologist or expert in the treatment of heavy metal poisoning. Assess baseline blood lead concentration, CBC (ensure neutrophils >1,500/mm3), liver transaminases (AST, ALT), and kidney function (BUN, SCr, urine protein).
Children and Adolescents:
Weight or BSA-directed dosing: Oral: Initial: 10 mg/kg/dose or 350 mg/m2/dose every 8 hours for 5 days followed by 10 mg/kg/dose or 350 mg/m2/dose every 12 hours for 14 days; round doses to the nearest 100 mg; maximum dose: 500 mg/dose; maximum daily dose: 1,500 mg/day. Note: Some experts recommend dosing for children <5 years of age should be based on body surface area (Ref).
Weight-band dosing: Oral: Dosing based on weight-directed dosing (10 mg/kg/dose) rounded to nearest 100 mg.
|
Weight-band |
Dose |
Frequency |
|---|---|---|
|
8 to <16 kg |
100 mg |
Administer dose every 8 hours for 5 days followed by the same dose every 12 hours for 14 days |
|
16 to <24 kg |
200 mg | |
|
24 to <35 kg |
300 mg | |
|
35 to <45 kg |
400 mg | |
|
≥45 kg |
500 mg |
Repeat courses: Assess BLL at completion (Day 19) of succimer treatment course and weekly until stable. Treatment courses may be repeated with similar BLL monitoring; however, a minimum interval of 2 weeks between courses is generally recommended to identify lead redistribution from extravascular storage sites (eg, bone) to the vascular compartment.
Mercury poisoning: Limited data available: Note: Dosing is based on the use of succimer for the treatment of lead poisoning (Ref). Experts recommend dosing for children <5 years of age should be based on body surface area (Ref); round doses to the nearest 100 mg. Consultation with a clinical toxicologist, poison center, or an expert in the treatment of heavy metal poisoning is highly recommended.
Children <5 years: Oral: 350 mg/m2/dose every 8 hours for 5 days followed by 350 mg/m2/dose every 12 hours for 14 days; maximum dose: 500 mg/dose; round dose to the nearest 100 mg (Ref).
Children ≥5 years and Adolescents: Oral: 10 mg/kg/dose or 350 mg/m2/dose every 8 hours for 5 days followed by 10 mg/kg/dose or 350 mg/m2/dose every 12 hours for 14 days; maximum dose: 500 mg/dose.
Dosing adjustment for toxicity: Children and Adolescents: ANC <1,200/mm3: The manufacturer recommends withholding treatment; treatment may be cautiously resumed at previous dose when ANC returns to baseline or >1,500/mm3. Consult a clinical toxicologist to determine the risk versus benefit of withholding treatment or rechallenge in patients who develop neutropenia.
Children and Adolescents: There are no dosage adjustments in the manufacturer's labeling; use with caution and monitor closely; patients with a history of kidney impairment may require more frequent monitoring. Succimer is dialyzable; however, the lead chelates are not.
Children and Adolescents: Suspend or reduce succimer dosing if ALT or AST >5 × ULN. More frequent monitoring of serum transaminases may be required in patients with a history of liver disease due to the risk of transient increases.
The following adverse drug reactions and incidences are derived from product labeling unless otherwise specified. Adverse reactions reported in pediatric patients.
>10%: Gastrointestinal: Gastrointestinal signs and symptoms (12%; including decreased appetite, diarrhea, hemorrhoids, metallic taste, nausea, vomiting)
1% to 10%:
Dermatologic: Papular rash (≤3%), pruritus (≤3%), skin rash (4%), vesicular eruption (mucocutaneous; including oral, perianal, urethral) (≤3%)
Endocrine & metabolic: Hypercholesterolemia (≤4%)
Gastrointestinal: Abdominal cramps (≤5%), stomach pain (≤5%)
Hematologic & oncologic: Eosinophilia (≤1%), neutropenia (≤1%), thrombocytosis (≤1%)
Hepatic: Increased serum alanine aminotransferase (6% to 10%), increased serum alkaline phosphatase (≤4%), increased serum aspartate aminotransferase (6% to 10%)
Infection: Candidiasis (≤5%), herpetic lesion (≤3%)
Nervous system: Chills (≤5%), fatigue (≤5%), headache (≤5%), heavy headedness (≤5%), neurological signs and symptoms (1%; including dizziness, drowsiness, paresthesia, sensorimotor neuropathy)
Neuromuscular & skeletal: Back pain (≤5%), rib pain (≤5%)
Ophthalmic: Cloudy vision (cloudy film in eye) (≤1%), watery eyes (≤1%)
Renal: Flank pain (≤5%)
Respiratory: Flu-like symptoms (≤5%), pulmonary signs and symptoms (4%; including cough, nasal congestion, pharyngitis, rhinorrhea)
Miscellaneous: Fever (≤5%)
Postmarketing: Hypersensitivity: Hypersensitivity reaction (including angioedema)
History of hypersensitivity (eg, angioedema, mucocutaneous vesicular eruptions, urticaria) to succimer or any component of the formulation.
Concerns related to adverse effects:
• Hematologic effects: Succimer may cause neutropenia.
• Hepatic effects: Elevations in serum transaminases (ALT/AST) have been reported.
• Hypersensitivity reactions: Hypersensitivity, including angioedema and urticaria, and dermatologic reactions, including mucocutaneous vesicular eruptions, have been reported. Reactions have been reported with repeat administration and may increase with each treatment course. Interrupt therapy if rash or mucocutaneous vesicular eruptions occur; consider rechallenge if lead levels are elevated enough to require treatment.
Disease-related concerns:
• Encephalopathy: Succimer does not cross blood-brain barrier and should not be used to treat encephalopathy associated with lead toxicity.
• Lead poisoning: Investigate, identify, and remove sources of lead exposure prior to treatment; do not permit patients to reenter the contaminated environment until lead abatement has been completed. Consultation with a clinical toxicologist or an expert in the treatment of heavy metal poisoning is highly recommended before initiating chelation therapy. Succimer is not used to prevent lead poisoning. A rebound rise in serum lead levels may occur after treatment as lead is released from storage sites into blood. The severity of rebound may guide the frequency of future monitoring and the need for additional chelation therapy. In a small prospective, randomized, open-label trial, succimer was shown to improve clinical signs and symptoms of lead poisoning and to reduce blood lead levels more effectively than edetate calcium disodium (Sakthithasan 2018).
• Liver impairment: Use with caution in patients with liver impairment.
• Renal impairment: Use with caution in patients with renal impairment. Succimer is dialyzable; however, the lead chelates are not.
Other warnings/precautions:
• Hydration: Adequate hydration should be maintained during therapy.
Excipient information presented when available (limited, particularly for generics); consult specific product labeling.
Capsule, Oral:
Chemet: 100 mg
No
Capsules (Chemet Oral)
100 mg (per each): $26.44
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Oral: If unable to swallow whole, capsule may be separated and contents sprinkled on a small amount of soft food, or the contents placed on a spoon and administered followed by fruit drink.
Oral : Capsules: Swallow capsule whole. Ensure adequate patient hydration.
Oral administration on soft food: For patients who cannot swallow the capsule whole, may open the capsule(s) and sprinkle the medicated beads into a small amount of juice or on a small amount of apple sauce, ice cream, or soft food or placed on a spoon and followed with fruit drink to mask the odor. Prepare immediately prior to dose.
Lead poisoning: Treatment of lead poisoning in pediatric patients ≥1 year of age with blood lead levels >45 mcg/dL.
Lead poisoning; Mercury poisoning; Arsenic poisoning
None known.
There are no known significant interactions.
Pregnancy testing is recommended prior to succimer use in patients who may become pregnant. Patients who could become pregnant should use effective contraception during therapy and for 14 days after the last dose of succimer.
Consider chelation therapy in patients of child-bearing potential with blood lead levels 45 to 70 mcg/dL, with or without clinical symptoms, to reduce the risk of in utero lead exposure in future pregnancies (WHO 2021).
Adverse events were observed in animal reproduction studies.
Lead poisoning: Data related to the use of succimer during pregnancy are limited (CDC 2010; Shannon 2003; WHO 2021). Lead crosses the placenta in amounts related to maternal plasma levels. Prenatal lead exposure may be associated with adverse events such as spontaneous abortion, preterm delivery, decreased birth weight, and impaired neurodevelopment. Some adverse outcomes may occur with maternal blood lead levels <10 mcg/dL. In addition, pregnant patients exposed to lead may have an increased risk of gestational hypertension. Consider chelation therapy in pregnant patients with confirmed blood lead levels ≥45 mcg/dL (pregnant patients with blood lead levels ≥70 mcg/dL should be considered for chelation regardless of trimester); consultation with experts in lead poisoning and high-risk pregnancy is recommended. Encephalopathic pregnant patients should be chelated regardless of trimester (CDC 2010; WHO 2021). An agent other than succimer may be preferred when a chelating agent is needed during the first trimester (WHO 2021).
It is not known if succimer is present in breast milk.
When treating lead poisoning, the amount of lead in breast milk may range from 0.6% to 3% of the maternal serum concentration. Lactating patients with confirmed blood lead levels ≥40 mcg/dL should pump and discard breast milk until blood lead levels are <40 mcg/dL. Monitor infant blood lead levels; if rising or not falling, temporarily discontinue breastfeeding if maternal breast milk is found to be the source (CDC 2010). Calcium supplementation may reduce the amount of lead in breast milk.
Blood lead levels (baseline and 7 to 21 days after completing chelation therapy); kidney function (baseline and periodically during prolonged treatment); serum transaminases (baseline and weekly during treatment; may require more frequent monitoring in patients with a history of liver disease); CBC with differential and platelets (baseline, and weekly during treatment); hemoglobin or hematocrit, iron status, free erythrocyte protoporphyrin or zinc protoporphyrin; neurodevelopmental changes; mucocutaneous eruptions, including oral, perianal, urethral, especially with repeated doses; signs/symptoms of infection. Pregnancy testing prior to use in patients who may become pregnant.
Succimer is an analog of dimercaprol. It forms water soluble chelates with heavy metals which are subsequently excreted renally. Succimer binds heavy metals; however, the chemical form of these chelates is not known.
Absorption: Rapid but incomplete
Distribution: Primarily extracellular (Aposhian 1992)
Protein binding: >95% primarily to albumin (Aposhian 1992)
Metabolism: Rapidly and extensively to mixed succimer cysteine disulfides
Half-life elimination: ~3 hours (Aposhian 1992)
Time to peak, serum: ~1 to 2 hours
Excretion: Urine (~25%) with peak urinary excretion between 2 to 4 hours (90% as mixed succimer-cysteine disulfide conjugates, 10% as unchanged drug); feces (as unabsorbed drug)
Molecular weight: 182.2.
