Lactose conjugation of sulphonamide drugs in the lactating dairy cow.
1. 14C-Sulphamethazine (4-amino-N-(4,6-dimethyl-2-pyrimidinyl)benzene-[U-14C]-sulphonamide; 220 mg/kg of body weight) was given orally or i.v. to lactating dairy cows. Milk collected from 0-48 h after dosing accounted for 2.0% (oral dose) and 1.1% (i.v. dose) of the total 14C-activity administered. 2. Sulphamethazine accounted for 70-79% (oral dose) and 54-75% (i.v. dose) of the total 14C in milk samples collected from 0-48 h after dosing. N4-acetylsulphamethazine accounted for 1-2% (oral dose) and 1-4% (i.v. dose) of the 14C in milk. 3. The major 14C-labelled metabolite in the milk was isolated and identified as the N4-lactose conjugate of sulphamethazine, a unique type of metabolite not previously reported. This metabolite accounted for 10-14% (oral dose) and 9-20% (i.v. dose) of the 14C-activity in the milk collected from 0-48 h after dosing with 14C-sulphamethazine. 4. N4-lactose conjugates of sulphapyridine, sulphamerazine, sulphathiazole, sulphadimethoxine and sulphaquinoxaline were present in the milk from cows orally dosed with these five sulphonamide drugs.
Paulson
G D
GD
Biosciences Research Laboratory, US Department of Agriculture, Fargo, ND 58105.
Feil
V J
VJ
Giddings
J M
JM
Lamoureux
C H
CH
D000818:Animals; D002250:Carbon Radioisotopes; D002417:Cattle / Q000378:metabolism*; D005260:Female; D007774:Lactation; D007785:Lactose / Q000378:metabolism*; D008892:Milk / Q000737:chemistry*; D013449:Sulfonamides / Q000378:metabolism*
D002250:Carbon Radioisotopes; D013449:Sulfonamides; D007785:Lactose