Combined chelation therapy in reducing tissue lead concentrations in suckling rats

The very young are more prone to lead poisoning than adults, and the treatm ent with chelating agents, either as monotherapy or combined treatment, is still a matter of dispute, The purpose of this work was to evaluate the eff iciency of three chelating agents administered either as monotherapies or a s combined treatments in sucklings. Lead acetate (5 mg: Pb kg(-1) i.p.) was administered to the 7-day-old rat pups in eight litters on experimental da y 1 and chelating agents on experimental days 2 and 3, Pups were divided in to six groups: (1) untreated control; (2) EDTA (calcium disodium ethylendia minetetraacetate, 0.3 mmol kg(-1) i.p. at 4 p.m.); (3) meso-DMSA (meso-2,3- dimeracaptosuccinic acid, 0.5 mmol kg(-1) p,o, at 10 a.m.); (4) rac-DMSA (r acemic-2,3-dimeracaptosuccinic acid, 0.5 mmol kg(-1) p,o, at 10 a.m.); (5) EDTA+meso-DMSA; and (6) EDTA+rac-DMSA, Rats were killed on experimental day 5, Tissue element concentrations were analyzed by atomic absorption spectr ometry. Treatment with EDTA did not affect tissue Pb, but it reduced Zn in the carcass and liver. Meso-DMSA reduced Pb in the kidneys and brain, and i t did not affect organ essential elements, Rac-DMSA most efficiently reduce d Pb concentrations in the carcass, kidneys and brain, but it also reduced Zn and Cu in the liver and Zn in the kidneys. Combined treatments with EDTA . never improved the efficiency of either DR ISA isoform in decreasing tiss ue Pb but they did reduce tissue Zn concentrations. All treatments caused t he same decrease in the carcass Ca concentrations. The results do not suppo rt combined treatment in this age group, which is especially sensitive to t race element deficiencies, and suggest that meso-DMSA might be the treatmen t of choice in acute lead poisoning in infants. Copyright (C) 1999 John Wil ey Br Sons, Ltd.