Excretion of some sulphonamides by buffaloes

ABSTRACT

Sodium salts of sulphadiazine, sulphadimidine and sulphamerzine were infused intravenously into healthy and lactating buffaloes at a does of 100 mg/kg. So as to maintain a constant plasma concentration over 3 hours. Blood, milk and urine samples were obtained 1.2, 2.5, and 3.5 h. after the start of infusion Sulphamerazine attained the highest plasma concentration [280 ug/ml], whereas concentrations of sulphadimidine and sulphadiazine were lower [247 and 212 ug/ml, respectively]. Sulphadimidine was highly excreted into buffalo's milk [95 ug/ml] as compared to both sulphamerzine [33 ug/ml] and sulphadiazine [30 ug/ml]. The drugs tested were extensively excreted via kidneys. A relationship was observed between the rate of excretion of the sulphonamides in urine and their pKa values. The plasma protein binding showed close. Similarity [18-20%] among the three sulphonamides. On comparing the urinary clearance of sulphonamides with both creatinine and urea clearances, sulphadiazine had the highest ratio, sulphamerzine a lower and sulphadimidine the lowest one. The percentages of acetylated products of the three sulphonamides in plasma were similar [8.2-9.4%]. However, the concentrations of acetylated metabolites in the milk and urine varied distinctly