Serum and Milk Concentrations of Several Sulphonamides and their N⁴-Acetyl Metabolites Following Oral Administration to Cows

Abstract

Serum and milk concentrations of sulphonamides following oral administration of three commercial sulphonamide products to dairy cows were studied. The fate of the N⁴-acetyl derivatives of the compounds was also monitored. Sulfadimidine was found to have the slowest oral absorption rate compared to sulfametoxypyridazine, sulfa-phenazole and sulfanilamide. Sulfaphenazole was least absorbed. Excretion of the different sulfonamides into the milk was by passive diffusion and was best for the least ionized sulfanilamide followed by sulfadimidine and sulfamethoxypyridazine. The most ionized sulfaphenazole was not found in milk. Sulfanilamides was found to be readily acetylated (and sulfaphenazole to a lesser degree). N⁴-acetyl-sulfanilamide seemed to be actively secreted from blood into milk in the cow.

Sammanfattning

Serum och mjölkkoncentrationer av sulfonamider efter oralt bruk av tre kommerciella sulfonamidprodukter på mjölkkor undersöktes. Likaledes kartlades händelseförloppet hos komponenternas N⁴-acetyl-derivativer. Sulfadimidin befanns uppvisa det långsammaste orala ab-sorptionsförloppet jämfört med sulfametoxypyridazin, sulfafenazol och sulfanilamid. Sulfafenazol absorberades minst.

Avsöndring av de olika sulfonamiderna i mjölken var genom passiv diffusion högst hos det lägst-ioniserade sulfanilamid, därniäst sulfadimidin och sulfamethoxypyridazin. Det högst ioniserade sulfafenazol förekom inte i mjölken. Endasit sulfanilamid (sulfafenazol i mindre grad) visade sig vara lätt acetylerat. N⁴-acetylsulfanilamid tycks ut-söndras aktivt från blodet tili mjölken hos kon.