Oral Succimer Dosing for Lead Poisoning (BLL 45-69 μg/dL)
For children with blood lead levels between 45-69 μg/dL, administer succimer 10 mg/kg (or 350 mg/m²) orally every 8 hours for 5 days, then reduce to 10 mg/kg (or 350 mg/m²) every 12 hours for an additional 14 days. 1
Standard Dosing Regimen
The FDA-approved dosing protocol consists of two phases:
Initial High-Dose Phase:
- 10 mg/kg or 350 mg/m² every 8 hours for 5 days (total daily dose: 30 mg/kg/day or 1,050 mg/m²/day) 1, 2
- This represents the most effective dose for enhancing urinary lead excretion, superior to either 10 or 20 mg/kg/day regimens 2
Maintenance Low-Dose Phase:
- 10 mg/kg or 350 mg/m² every 12 hours for 14 additional days (total daily dose: 20 mg/kg/day or 700 mg/m²/day) 1
- This extended phase was designed to prevent or blunt the rebound in blood lead concentration that occurs from redistribution of lead from bone stores 2
Alternative Dosing Strategy
An acceptable alternative approach involves two 5-day courses of high-dose therapy (10 mg/kg every 8 hours) separated by a 1-week treatment-free interval 2, 3. This strategy:
- Allows redistribution of lead from bone to soft tissues and blood during the treatment-free period 2
- May be equally efficacious as the standard 19-day regimen 2, 3
- Showed comparable blood lead reductions (33 to 23 μg/dL) versus standard therapy (33 to 27 μg/dL) in comparative studies 3
Clinical Considerations for This Blood Lead Range
Chelation Indication:
- Blood lead levels >45 μg/dL warrant chelation therapy in children 4
- This range (45-69 μg/dL) falls well above the threshold requiring treatment but below levels typically requiring parenteral therapy
Expected Response:
- Blood lead concentrations typically fall to 50% or less of pretreatment levels over a 5-day course 2
- Mean daily urinary lead excretion increases 5- to 20-fold above baseline 2
- Maximum enhancement of urinary lead elimination occurs with the first dose 2
- Most symptomatic patients report improvement after 2 days of treatment 2
Important Caveats
Rebound Phenomenon:
- Blood lead levels commonly rebound after chelation due to redistribution from bone stores 1, 2
- Multiple courses of chelation may be required 1
- Monitor blood lead levels closely after treatment completion
Common Adverse Effects:
- Nausea, vomiting, diarrhea, appetite loss, and loose stools occur frequently and may relate to the drug's unpleasant mercaptan odor 1
- Transient modest transaminase elevation occurs in up to 60% of patients but is not clinically significant 2
- Skin reactions occur in approximately 6% of patients and are occasionally severe 2
Capsule Administration:
- For children unable to swallow capsules, the contents can be sprinkled on soft food or administered via spoon 1
Concurrent Source Removal: