ALBENDAZOLE-RELATED DRUG RESIDUES IN MILK AND THEIR FATE DURING CHEESE-MAKING, RIPENING, AND STORAGE

The level and nature of the albendazole residues in milk of treated co ws were determined as a function of the time of milking (12-h interval s), and the fate of those residues during cheesemaking, ripening, and storage was examined when the obtained milk was used for making Teleme cheese. Ion-pair liquid chromatographic analysis with fluorescence de tection showed that the albendazole sulfoxide metabolite reached its m aximum (523 +/- 199 mu g/kg) at the Ist milking and declined below the detection limit by the 4th milking. The sulfone metabolite attained i ts highest level (812 +/- 99 mu g/kg) more slowly (at the 2nd milking) and declined below detection limit by the 13th milking. The 2-aminosu lfone metabolite, which was present in the milk obtained at the Ist mi lking, reached its maximum (128 +/- 36 mu g/kg) at the 3rd milking, an d slowly declined to a level below detection limit by the 15th milking . Whey and cheese analysis revealed that about 70% of each major metab olite initially present in milk could be distributed in the whey. The remaining 30% occurred in the cheese at residue levels higher than tho se initially present in the milk of the Ist or 2nd milking (688 versus 445 or 450 versus 230 mu g/kg for albendazole sulfoxide; 890 versus 6 08 or 1502 versus 783 mu g/kg for albendazole sulfone; 19 versus 15 or 161 versus 105 mu g/kg for albendazole 2-aminosulfone). Ripening and storage of the cheeses made from milks from the Ist or 2nd milkings re sults in a decrease of the sulfoxide metabolite (to 225 or 206 mu g/kg ), an increase of the sulfone metabolite (to 1,181 or 1,893 mu g/kg), and no effect on the 2-aminosulfone metabolite.