Distribution and elimination of sulphadimethoxine and its metabolites in treated chicken.

Sulphadimethoxine (SDM), and its metabolites, N4-acetyl SDM, N1-(2-methyl-6-hydroxy-4-pyrimidinyl) sulphanilamide (6-OH-SDM), N1-(6-methyl-2-hydroxy-4-pyrimidinyl) sulphanilamide (2-OH-SDM), N1-(2,6-dihydroxy-4-pyrimidinyl) sulphanilamide (2,6-diOH-SDM) and SDM N1-glucuronide in chicken tissues were extracted, partially purified by Bond Elute SCX cartridges, and assayed and identified by HPLC/LC-MS after administration of SDM to chickens. During the administration and 24 h after withdrawal, SDM and 6-OH-SDM were observed in almost all tissues and excreta. N4-Acetyl SDM and 2,6-diOH-SDM were observed in some tissues, but 2-OH-SDM and SDM N1-glucuronide were observed in a few limited tissues. Twenty four hours after withdrawal, SDM and its metabolites, except 6-OH-SDM, decreased. SDM and its metabolites were eliminated from all tissues within 48 h of withdrawal.