The effect of increasing the time interval between acute
zinc exposure and
chelation therapy was studied in male Swiss mice.
Cyclohexanediaminetetraacetic acid (
CDTA), and diethylenetriaminepentaacetic
acid (
DTPA) were administered ip at 0, 0.25, 0.5, 2, 12, or 24 hr after ip administration of 0.40 mmol/kg of
zinc acetate dihydrate.
Chelating agents were given at doses equal to 1/3 of their respective LD50 values. Effectiveness of
chelation therapy was determined by measuring the ability of the
chelators to increase the elimination of
zinc and decrease the concentration of the
metal in various tissues. Treatment with
DTPA or
CDTA increased significantly the urinary and fecal excretion of
zinc when the
chelators were administered at various times following
zinc exposure. The greatest antidotal efficacy of the
chelating agents was observed at 0.50 hr after
zinc injection. Nevertheless, the effectiveness of
DTPA and
CDTA was decreasing when the
chelators were administered later.
DTPA was more effective than
CDTA in the prevention of acute
zinc intoxication.
CDTA would be considered as a possible alternative.