The metabolism of four sulphonamides in cows

Article abstract of DOI:10.1042/bj1361039

The metabolism of sulphanilamide, sulphadimidine (4,6 dimethyl 2 sulphanilamido pyrimidine), sulphamethoxazole (5 methyl 3 sulphanilamidoisoxazole) and sulphadoxine (5,6 dimethoxy 4 sulphanilamidopyrimidine) given by intravenous injection has been examined in cows. The sulphonamides were present mainly as unchanged drugs in blood samples collected 2 hr after administration. The sulphonamides were excreted in the milk partly as unchanged drugs and partly as conjugated metabolites whereas only small amounts were excreted as the N⁴ acetyl derivatives. The unchanged drug and the N⁴ acetyl derivative were the major constituents in urine samples after administration of sulphanilamide, sulphamethoxazole and sulphadoxine. Besides the unchanged drug, the N⁴ acetyl derivative and the conjugated metabolites, three further metabolites of sulphadimidine were isolated from urine samples and identified. They were 5 hydroxy 4,6 dimethyl 2 sulphanilamidopyrimidine, 4 hydroxymethyl 6 methyl 2 sulphanilamido pyrimidine and sulphaguanidine.