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Cu(II) chelates of several sulfanilar-ide derivatives (Sulfa-Cu) were prepared and their effects on solubility, absorptivity in intestinal lumen, binding tendency with..serum protein and erythrocytes, concentration in rabbit blood, and ;acetylation rate were studied in comparison with their free ligand forms. For solubility concerned, the partition coefficients of Sulfa-Cu are decreased as following order: Sulfadimethoxine Copper chelate(SDM-Cu), Sulfamethoxypyridazine Copper chelate (SMP-Cu), Sulfamonomethoxine Copper chelate (SMM-Cu), Sulfathiazole Copper chelate (ST-Cu),Sulfadiazine Copper chelate (SD-Cu), Sulfamerazine Copper chelate (SM-Cu), Sulfaisoxazole Copper chelate (SIX-Cu). The partitio n coefficients of SDM-Cu and ST-Cu were much greater than those of ligands. This phenomenons accounts for the rapid absorption of SDM-Cu and ST-Cu in the rat small intestine (in situ). The Sulfa-Cu were absorbed at the intestinal lumen of a rat in the rate of first order and there was no difference between long acting sulfa drugs and their Cu-chelates in biological half lives. In binding expriments, sulfa-Cu binded with serum protein in lower ratio than their ligands except SIX-Cu. On other hand, acetylation rates of stilfa-Cu were higher than those of free-sulfa drugs and the acetylation rate were determined with a pigeon liver acetone powder. In a experiment on Sulfa-Cu concentration in rabbit blood, the half lives of SD-Cu, SIX-Cu, ST-Cu, and SM-Cu were longer than those of their ligands. Above all, the half life of SD-Cu appeared to be approximately 3.5 times longer than that of corresponding ligand, SD. When absorption of sulfa drugs or sulfa-Cu at the small intestinal lumen of a rat and the concentration in rabbit blood after absorption were compared, it was found that there was not always correlated.
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