Benzimidazole anthelmintics, veterinary

The discovery of parbendazole stimulated a vigorous search for better benzimidazole anthelmintics in different pharmaceutical companies of the world. Soon a number of drugs (14-22) were introduced in veterinary and humans medicine. All these benzimidazole anthelmintics may be regarded as the 5(6)-derivatives of car-bendazim (10) which per se is an effective pesticide rather than an anthelmintic [12]. A novel non-carbamate benzimidazole fasciolicide, triclabendazole (23) [13] and a benzimidazole-2-carbamate anthelmintic, ricobendazole (24) [14] have been introduced recently (Table 1). 

Thiabendazole. This benzimidazole derivative (12) is an effective oral drug used in the treatment of intestinal roundworms and selected tissue parasites. Infections with S. stercorahs are commonly treated with thiabendazole for two days. Disseminated strongyloidiasis is treated for at least five days. Satisfactory results have been reported when used for T. spirahs infections however, its effectiveness on encapsulated muscle larvae has not been clinically demonstrated. Extensively used in veterinary medicine, thiabendazole was the first broad-spectrum benzimidazole anthelmintic. It is widely used in the United States. The mechanism of action is not clearly understood, but it has been shown that thiabendazole inhibits the enzyme fiima.ra.te reductase, which is found specifically in the mitochondria of helminths (31). 

Other Anthelmintics — Efforts directed primarily toward the development of anthelmintics for veterinary use (Chapter lij-b) have recently yielded a variety of active nematocldes of potential usefixlness in man. Among them, various benzimidazoles,tetramisole (XXVIIl) and relatives, ... 

Bantenol (5-Benzoyl-1H-benzimidazol-2-yl)oarbamic acid methyl ester 5-Benzoyl-2-benzimidazoiecarbamic acid methyl ester Besantin CCRIS 4479 EINECS 250-635-4 Equi-Vurm Plus Equivurm Plus HSDB 3232 Lomper MBDZ Mebendazol Mebendazole Mebendazolum Mebenvet Mebutar Methyl 5-benzoyl-2-benzimidazolecarbamate Noverme NSC 184849 Ovitelmin Panteimin R 17635 Telmin Vermex Vermicidin Vermirax Vermox Verpanyl, Anthelmintic. Targets nematodes. Used as a veterinary anthelmintic, especially with horses. Ciystals mp = 288.5" insoluble in H2O, EtOH, EtzO, CHCI3 soluble in formic acid LDso (sheep orl) > 80 mg/kg, (mus, rat, chk) > 40 mg/kg. Janssen Chimica Janssen Pharm. Ltd. 

Examples of synthetically produced and biologically active benzimidazoles are the fungicides methyl l-butylcarbamoyl-2-benzimidazole carbamate (benomyl) 5 and 2-(4 -thiazolyl)benzimidazole (thiabendazole) 6. The latter is used extensively as a preservative for fruit (E 233) and as an anthelmintic in veterinary medicine ... 

Veterinary anthelmintics. Among the most used drugs are pyrantel 6.38) the organic phosphates [such as metrifonate 6,28) and dichlorvos 13,29) and the benzimidazoles, particularly thiabendazole 6,36) which has a wide range of activity against both adult and immature worms in cattle, horses, pigs, and sheep. It is so selective, and so rapidly eliminated, that animals can safely be slaughtered, and milk from cows used, soon after administration. 

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