Transfer and distribution profiles of dietary sulphonamides in the tissues of the laying hen

The five sulphonamides, sulphadiazine (SDZ), sulphadimidine (SDD), sulphamethoxazole (SMX), sulphamonomethoxine (SMM) and sulphaquinoxaline (SQ), were fed to laying hens at a dietary concentration of 100 mg kg(-1), respectively. On the 7th day after the start of feeding, the drug concentrations in the plasma, muscle and the main tissues involved in egg formation, the liver, and ovary and oviducts (magnum and isthmus plus shell grand) were determined by high-performance liquid chromatography. Dietary sulphonamides were distributed throughout the above tissues. SQ was found at the highest concentration in all tissues, while the reverse was true for SDD. The ratio of SDD concentrations in the main tissues involved in egg formation to that in the plasma were greater than those for the other drugs.