Oikawa H, Nakamoto K, Hirota K, Katagiri K
Poult Sci. 1977 May;56(3):813-21. doi: 10.3382/ps.0560813.
Clearance of sulfamethoxazole (SMX, or sulfisomezole) in eggs and tissues of chicken after withdrawal of the drug which was medicated feed additively (at 0.2 or 0.4%) or administered intramuscularly (100 mg./kg., twice daily) for 5 successive days was determined using a fluorescamine reagent. Clearance patterns of SMX were found to be different between albumen and yolk. SMX level in albumen diminished linearly to below 0.1 p.p.m. (sensitivity level) by 5 days after the cessation of medication. On the other hand, SMX level in yolk remained at a plateau until 4 days, and thereafter decreased linearly to below 0.1 p.p.m. by 10 days. SMX levels in most tissues diminished below 0.1 p.p.m. by 3 days and those in kidney and skin by 4 days. Clearance patterns in tissue were quite similar to those in egg albumen. Proportion of acetylated-SMX to total-one in both albumen and yolk tended to increase up to 10% with the lapse of time after drug withdrawal. Acetylation was high in liver (36.5-43.6%), spleen skin and fat, but low in breast muscle and kidney (3.7-11%) in the groups of feed addition; while acetylation was low in liver of the group of intramuscular injection.
