Further studies on the effect of niridazole on urinary and biliary excretion of copper.

Administration of niridazole to rats poisoned with copper caused a significant increase in both the urinary and biliary excretion of the metal. Although the urinary excretion of iron was increased by the drug, iron excretion was significantly decreased during the drug-induced excretion of copper after copper poisoning. Formation of a copper-niridazole chelate or chelates before excretion in the bile or urine may explain these findings. Polarity and molecular weights of the metal-drug chelates formed in vivo may be the directing forces not only in the selection of the metal for chelation, but also for its urinary or biliary excretion. The laboratory preparation of two copper-niridazole complexes lends support to these conclusions.