Nielsen P, Rasmussen F
Res Vet Sci. 1977 Mar;22(2):205-8.
The half-lives, apparent volume of distribution and protein-binding of 11 sulphonamides were determined in 89 experiments on 49 cows. The estimations of half-lives indicated the presence of a distribution phase (alpha-phase) for all the sulphonamides investigated with the exception of sulphachloropyridazine. The elimination half-life (beta-phase) of the sulphonamides in plasma varied from 70 to 1000 min and was positively correlated with the solubility of the compounds in organic solvents. This was explained by the greater reabsorption of the more fat-soluble compounds in the kidneys. All the sulphonamides except sulphadimidine had a shorter half-life in cows than previously reported from human investigations. The apparent volume of distribution was about one for sulphanilamide and lower for all the other sulphonamides investigated. The protein-binding estimated in vitro agreed well with the in vivo results. It was slightly lower than in humans and the degree of protein-binding decreased with increasing sulphonamide concentration in plasma.
在对49头奶牛进行的89次实验中，测定了11种磺胺类药物的半衰期、表观分布容积和蛋白结合率。半衰期估计表明，除磺胺氯哒嗪外，所有研究的磺胺类药物均存在分布相（α相）。磺胺类药物在血浆中的消除半衰期（β相）为70至1000分钟，与化合物在有机溶剂中的溶解度呈正相关。这是因为脂溶性更强的化合物在肾脏中的重吸收更多。除磺胺二甲嘧啶外，所有磺胺类药物在奶牛体内的半衰期均比先前人类研究报告的要短。磺胺的表观分布容积约为1，而所有其他研究的磺胺类药物的表观分布容积更低。体外估计的蛋白结合率与体内结果吻合良好。它略低于人类，且蛋白结合程度随血浆中磺胺类药物浓度的增加而降低。
