Elimination profile of methylthiouracil in cows after oral administration†

Abstract

In addition to methods for the determination of residues, there is an important need for knowledge of the fate and excretion of growth promoting substances in fattening animals. In court, often simple questions are asked, such as, over what period of time can the drug be detected?, is it possible to find residues after 2 months, etc. These questions can only be answered by conducting animal experiments. Data on excretion and distribution of thiouracils in cows are rather scarce. At the beginning of the 1980s, animal experiments with methylthiouracil (MTU) were carried out in the Laboratory of Chemical Analysis. These experiments showed that treatment of cows with MTU results in the rapid appearance of the drug in plasma, urine and milk, whereas MTU selectively accumulates in the thyroid gland. The results of these experiments were only published in media with limited access (thesis, abstracts) and also there has been a considerable improvement in data handling with computer programs in the last 15 years. This investigation reinterprets the ‘old’ analytical data from animal experiments using a pharmacokinetic software package.

References

1. EEC Directive 96/22/EG, No. 125/3, 1996.
2. P. Batjoens, H. F. De Brabander and L. T'Kindt, Anal. Chim. Acta, 1993, 275, 335.
3. H. F. De Brabander and R. Verbeke, J. Chromatogr., 1977, 138, 131.
4. P. Batjoens, H. F. De Brabander and L. T'Kint, in Proceedings of the Euroresidue II Conference, Veldhoven, 3–5 May 1993, ed. N. Haagsma, A. Ruiter and P. B. Czedik-Eysenberg, 1993, pp. 176–180.
5. M. L. Desbarats-Schonbaum, L. Endrenyi, E. Kours, E. Schonbaum and E. A. Siller, Eur. J. Pharmacol., 1972, 19, 104.
6. A. Ermens, Master's Thesis, University of Ghent, 1982.
7. H. F. De Brabander, PhD Thesis, University of Ghent, 1986.
8. R. VerbekeH. F. De Brabander and A. Ermens, in Proceedings of the 30th European Meeting of Meat Research Workers, Bristol, 1984, ed. S. Taylor, pp. 385–386.
9. H. J. Proost and D. K. F. Meyer, Comput. Biol. Med., 1992, 22, 155.
10. H. F. De Brabander and R. Verbeke, J. Chromatogr., 1975, 108, 141.
11. H. F. De Brabander, P. Batjoens and J. Van Hoof, J. Planar Chromatogr., 1992, 5, 124.
12. J. Borner, Clin. Chem. Biochem., 1979, 17, 474.
13. H. Bartels, M. Böhmer and C. Heierte, Clin. Chim. Acta, 1972, 37, 139.
14. R. E. Erb., A. H. Surve, R. E. Randel and A. H. Garverick, J. Dairy Sci., 1977, 60, 1057.
15. J. J. Bezem, G. J. Van Esch and H. C. Peer, Landbouwtijdschrift, 1949, 61, 946.
16. T. Böhnel, Inaugural Dissertation, Universität, München, 1966.
17. R. E. Ely, K. J. Olson and E. P. Reinecke, J. Dairy Sci., 1947, 30, 577.
18. J. Pohlschmidt and E. Forschner, Fleischwirtschaft, 1979, 59, 253.
19. G. Pottie, Fleischwirtschaft, 1979, 59, 248.
20. H. F. De Brabander, unpublished data.
21. C. Gissel and M. Schaal, Arch. Lebensmittelhyg., 1974, 1, 8.
22. P. Batjoens, H. F. De Brabander and K. De Wasch, J. Chromatogr., 1996, 750, 127.
23. B. Le Bizec, F. Monteau, D. Maume, M.-P. Montrade, C. Gade and F. André, Anal. Chim. Acta, 1997, 340, 201.
24. G. Y. F. Yu, E. J. Murby and R. J. Wells, J. Chromatogr., 1997, 703, 159.
25. W. J. Blanchflower, P. J. Hughes, A. Cannavan, M. A. McCoy and D. J. Kennedy, Analyst, 1997, 122, 967.
26. K. De Wasch, H. F. De Brabander, L. A. van Ginkel, A. Spaan, S. S. Sterk and H. D. Meiring, J. Chromatogr., 1998, 819, 99.