Rasmussen F
Acta Vet Scand. 1969;10(4):402-3. doi: 10.1186/BF03548272.
After administration of sulphanilamide to goats and cows, sulphanilamide is excreted into milk. The concentrations of sulphanilamide in ultrafiltrate of milk (M. Ultr.) and blood plasma (P. Ultr.) are equal and the ratio M. Ultr./P. Ultr. is 1.0. The pK of sulphanilamide is 10.4 and thus, sulphanilamide is un-ionized in both milk and blood plasma. Therefore, sulphanilamide is excreted into milk in accordance to the theory of passive diffusion of the non-protein-bound and un-ionized fraction in blood plasma ( 1958, 1966; 1967). A similar ratio was expected for acetylated sulphanilamide with a pK of 10.3. However, the concentration of the acetylated derivative is always found higher in milk than in plasma. This might be due to formation of acetylated sulphanilamide in the mammary tissue, as demonstrated by (1967) or active excretion of the compound just as in the case of N-acetylated p-aminohip-puric acid ( 1969).
给山羊和奶牛施用磺胺后，磺胺会排泄到牛奶中。牛奶超滤液（M. Ultr.）和血浆（P. Ultr.）中磺胺的浓度相等，M. Ultr./P. Ultr.的比值为1.0。磺胺的pK为10.4，因此，磺胺在牛奶和血浆中均呈非离子化状态。所以，磺胺是根据血浆中未结合且未离子化部分的被动扩散理论排泄到牛奶中的（1958年、1966年；1967年）。对于pK为10.3的乙酰化磺胺，预计会有相似的比值。然而，总是发现牛奶中乙酰化衍生物的浓度高于血浆中的浓度。这可能是由于乳腺组织中形成了乙酰化磺胺，如（1967年）所证明的，或者是该化合物的主动排泄，就像N - 乙酰化对氨基马尿酸的情况一样（1969年）。
