Objective: To determine the short-term efficacy of meso-2,3-dimercaptosuccinic acid (DMSA) in mild to moderately lead poisoned children.
Methods: Medical records of all pediatric patients receiving 19 days of DMSA between June 1991 and May 1993 were reviewed retrospectively. Patients were included if their pretreatment blood lead concentration (BPb) was 1.21 to 2.36 mumol/L (25 to 49 micrograms/dL) and excluded if they: received DMSA through participation in a pharmaceutical company-sponsored drug study; underwent chelation therapy in the previous 28 days; or received another chelating agent concomitantly with DMSA; or if noncompliance was documented. Homes were inspected and abated of major hazards before chelation therapy. BPb and blood zinc protoporphyrin concentration (ZnP) were obtained at baseline. DMSA was administered in a dose approximating 10 mg/kg per dose every 8 hours for 5 days, followed by 10 mg/kg per dose every 12 hours for 14 days. Baseline laboratory studies were repeated weekly while the patients were receiving therapy and for 2 weeks after therapy, then monthly unless chelated again.
Results: Of the 46 children who were treated with DMSA, 18 were excluded from the analysis. In the remaining 28 children, the mean +/- SD pretreatment BPb and ZnP were 1.79 +/- 0.33 mumol/L (37 +/- 6.9 micrograms/dL) and 1.26 +/- 0.64 mumol/L (71 +/- 36.1 micrograms/dL), respectively. The percent reduction (mean +/- SD) in BPb compared with baseline was -43% +/- 20.8%, -26% +/- 16.9%, and -31% +/- 20.2% on mean days 18, 30, and 80, respectively, whereas the changes in ZnP were -12% +/- 21.7%, -20% +/- 18.1%, and -31% +/- 21.9%, respectively. Eighty percent of patients had 20% or more reduction in their pretreatment BPb and/or ZnP after completion of DMSA therapy (95% confidence interval, 61, 92%). No significant adverse effects were observed except for neutropenia (absolute neutrophil count of 0.752 x 10(9)/L) in one patient.
Conclusion: Our findings support the short-term efficacy of DMSA in children with BPb of 2.36 mumol/L (49 micrograms/dL) or less.