Anthelmintics and antifungals

Anthelmintic (deworming) compounds control parasitic infections. Benzimida-zoles are anthelmintics that contain a common 1,2-diaminobenzene nucleus; most of them also have a carbamate functional group. Albendazole and fenbendazole are common drugs in this class. These drugs protect against roundworms and flukes by inhibiting the processes necessary for parasitic mitochondrial production of ATP [11]. The use of fenbendazole (Figure 2) can also increase the rate of weight gain in growing and finishing swine.

Avermectins are anthelmintics isolated from Streptomyces avermitilis. Ivermec-tin, doramectin and eprinomectin are avermectin compounds that may be administered to cattle to combat parasitic infections such as roundworms, lungworms and mites, among others [12]. Approvals have been granted for injectable or oral (bolus) dosage forms for some of these drugs in cattle, but it is common for these drugs to be applied topically. Ivermectin and doramectin are not approved for lactating dairy cattle. Some avermectins, including emamectin, have also been shown to be effective for the treatment of fishfin diseases such as sea lice in farm-raised salmon. Moxidectin is a synthetic milbemycin drug with similar properties to the avermectins; it has been approved for use in dairy cattle.

Levamisole (Figure 2) is another anthelmintic that is used for the control of lungworms and gastrointestinal nematodes in cattle, sheep and swine. It can be administered orally, topically, via injection or in a medicated feed. Other compounds such as the tetrahydropyrimidines (i.e., pyrantel or morantel) are administered to swine for the treatment of parasites and are considered broad-spectrum anthelmintics in ruminants. Organophosphates (i.e., dichlorvos and coumaphos) can also be considered anthelmintics in food animals, as well as being an effective external pest control.

Triphenylmethane dyes are effective fungicides and are used illegally in food production facilities for that purpose. Malachite green, in particular, is added to the water of aquaculture ponds to treat fungal infections. An analogous compound, crystal violet, has also been reported to have been used for aquaculture as well as in chicken feed to prevent fungal growth.

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