Anticoccidial and other

Tire major anticoccidial and other antiprotozoal drugs have no common chemical structure and therefore no group tests can be used to screen for residues in animal-derived foods. This is in complete contrast to the antibacterials previously discussed, which can be detected, although not identified, on the basis of their biological activity. 

ANTICOCCIDIAL AND OTHER ANTIPROTOZOAL DRUGS Halofuginone Halofuginone Bovine... 

Table 29.11 Physicochemical Methods for Anticoccidial and other Antiprotozoal Drugs in Edible Animal Products... 

The FDA first approved use of a polyether ionophore as a feed additive for catde ia 1975. Ionophores were first isolated from bacteria generally of the Streptomjces genus, but are produced commercially by bacterial fermentation (qv). Monensia [17090-79-8] and other ionophores are being fed to over 90% of feedlot cattle grown for beef (53) to enhance efficiency of gain improvements of 5—10% are common. Ionophores also are used as anticoccidial dmgs ia poultry production and have similar, but lesser, effects ia mminants (54). 

The heterocyclic complexes incorporating other main group element atoms have been prepared via the reaction of RBiBr2 with an appropriate difunctional salt or chelating ligand (see equations 7 and 8). The compound (21) is reported to have anticoccidial and insecticidal properties, as do other RBi(SR)2 compounds. 

Previous Literature. As the importance of resistance has become apparent, a steadily increasing amount of research has been done to understand and combat it. Excellent summaries of earlier work, with extensive references to the original literature, are available in recent books and review articles, some dealing with all areas of agrochemistry (5-4), and others addressing specific classes of pests (insects, 9-11 fungi, 12,14 weeds, 14). Information on resistance to rodenticides, antibiotics, and anticoccidial drugs, which are not covered in this volume, is available in two of the references (2/5). 

Syntheses of some 8-aminoquinoline derivatives were reported by Armer et al. [20]. Novel analogues were screened for both in-vitro and in-vivo anticoccidial activity. Pentyl group at 8 position of quinoline ring showed better anticoccidial activity. Other analogues were less potent in-vitro or in-vivo or both. Also, an exploration of the terminal nitrogen substitution has revealed the tetrahydropyran group to be optimal. 

Metliylbenzoquate is probably the most potent among the anticoccidial quinolone derivatives. It is often used at 8.35 ppm in the feed in conjunction with other coccidiostats, especially clopidol, for prophylaxis of coccidiosis in chickens and turkeys. 

Other anticoccidials for which immunoassays have been developed include the polyethers salinomycin and lasalocid, and the quinazoline drug halofuginone. Concern over the potential toxicity of salinomycin has led to development of two competitive ELISAs for detecting and measuring salinomycin residues in poultry tissues. In the first ELISA (96), 16 monoclonal antibodies were prepared and evaluated for their ability to produce a rapid and low-cost screening procedure for residues of salinomycin in poultry liver. In the second (97), the antibodies produced showed cross-reactivity with narasin but not with lasalocid, madura-... 

Despite almost 10 years of intensive use in the production of broilers, this drug is remarkably free of resistance problems. Other ionophores have been tested and found to possess anticoccidial activity. Lasalocid (64) is in commerical use whilst salinomycin (65) and narasin (66) have recently been evaluated in field trials. 

---