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Nippostrongylus brasiliensis infection in the rat: effect of iron and protein deficiency on the anthelmintic efficacy of mebendazole, pyrantel, piperazine, and levamisole.

The benzimidazole anthelmintics mebendazole and fenbendazole have been shown to be much less effective against Nippostrongylus brasiliensis infections in the rat on a combined iron and protein deficient diet. In the present experiments it was shown that the anthelmintic efficacy of mebendazole was significantly impaired in the rat on either an iron deficient or a protein deficient diet. Furthermore, iron and protein deficiency reduced the efficacy of the anthelmintics pyrantel and piperazine but not levamisole. The finding that nutritional deficiencies reduce anthelmintic efficacy may well be relevant to worm eradication programmes in iron deficient and protein calorie malnourished populations.

Anemia, Hypochromic

Anthelmintic efficacy of oxfendazole in calves.

Oxfendazole, methyl [5-(Phenylsulfinyl)-1H-benzimidazol-2-yl]carbamate given to calves at dose level of 2.5 mg/kg as a paste, as a bolus, or as a drench resulted in excellent (97 to 100%) anthelmintic efficacy against mature Ostertagia ostertagi, Trichostrongylus axei, Cooperia oncophora, C mcmasteri, C pectinata, C punctata, Nematodirus helvetianus, Trichostrongylus longispicularis, Chabertia ovina, and Oesophagostomum radiatum. Against the early 4th stage larvage of O ostertagia and N helvetianus, these formulations had anthelmintic efficacies of 71% to 87% and 21% to 65%, respectively. As the result of differences in drug intake by individual calves, a pelleted feed additive given as top dress on chopped alfalfa hay gave an unsatisfactory mean anthelmintic response. Anthelmintic action in individual calves ranged from none to 98--100%.

Administration, Oral

Levamisole: anthelmintic activity in calves following dermal application.

A series of seven experiments designed to evaluate the anthelmintic efficacy of levamisole (1-tetramisole) by dermal application is described. This work involved use of 181 artificially infested calves. The drug was formulated at a concentration of 10% m/v levamisole base in a solvent system promoting dermal absorption and was applied to both sides of the spine in the lumber region at a dose rate of 10 mg levamisole base per kg livemass. A consistent performance was achieved in these investigations, the results from all of which were based upon necropsy findings. Efficacy of treatment was assessed against the third and fourth larval stages and fifth stage larvae/adult worms of six nematode species; the respective efficacies obtained were Haemonchus placei 72,0%; 99,3%; and 100%: Ostertagia ostertagi 85,5%; 38,1% and 74,5%: Cooperia spp. 98,9%; 99,9% and 100%: Bunostomum phlebotomum 83,0%; 100% and 98,5%: Oesophagostomum radiatum 47,4%; 94,9% and 99,6% and Dictyocaulus viviparus 79,5%; 94,1%; 90.9% (fifth stage larvae) and 93,8% (adult worms). The anthelmintic efficacy of levamisole in these experiments is of the same order as that achieved by orthodox methods of administration at dose rates between 7,5 and 10,0 mg levamisole HC1 per kg livemass. These findings add a new dimension to the use of levamisole and to anthelmintic therapy in general.

Administration, Topical

Genomic landscape of drug response reveals mediators of anthelmintic resistance.

Like other pathogens, parasitic helminths can rapidly evolve resistance to drug treatment. Understanding the genetic basis of anthelmintic drug resistance in parasitic nematodes is key to tracking its spread and improving the efficacy and sustainability of parasite control. Here, we use an in vivo genetic cross between drug-susceptible and multi-drug-resistant strains of Haemonchus contortus in a natural host-parasite system to simultaneously map resistance loci for the three major classes of anthelmintics. This approach identifies new alleles for resistance to benzimidazoles and levamisole and implicates the transcription factor cky-1 in ivermectin resistance. This gene is within a locus under selection in ivermectin-resistant populations worldwide; expression analyses and functional validation using knockdown experiments support that cky-1 is associated with ivermectin survival. Our work demonstrates the feasibility of high-resolution forward genetics in a parasitic nematode and identifies variants for the development of molecular diagnostics to combat drug resistance in the field.

Ivermectin

Discovery of Human PIM Kinase Inhibitors as a Class of Anthelmintic Drugs to Treat Intestinal Nematode Infections.

Soil-transmitted helminth (STH) infections affect one-fourth of the global population and pose a significant threat to human and animal health, with limited treatment options and emerging drug resistance. Trichuris trichiura (whipworm) stands out as a neglected disease, necessitating new drugs to address this unmet medical need. We discovered that several different chemical series of related human Provirus Integration sites for Moloney murine leukemia virus (PIM) family kinase inhibitors possess potent anthelmintic activity by using whole-worm motility assays. Systematic structure-activity relationship (SAR) studies based on the pan-PIM kinase inhibitor CX-6258 were conducted to identify compounds displaying improved in vitro motility inhibition of both adult hookworm (Ancylostoma ceylanicum) and adult whipworm (Trichuris muris) nematodes. A broad kinase selectivity screen of >450 human kinases confirms PIM1 kinase and others as potential targets for CX-6258 and analogues thereof. In addition, we demonstrated that CX-6258 significantly reduced worm burden and egg counts in the T. muris infection model of mice, establishing it as a new oral small molecule anthelmintic therapeutic.

Animals

Anthelmintic efficiency of oxfendazole, fenbendazole and levamisole against naturally acquired infections of Ostertagia ostertagi and Trichostrongylus axei in cattle.

The anthelmintic efficiencies of oxfendazole, fenbendazole and levamisole, each at 4 dose rates spanning the manufacturers' recommended dosages were compared in beef cattle with naturally acquired infections of Ostertagia ostertagi and Trichostrongylus axei. In 8 of the 9 cases tested there was no significant increase in anthelmintic efficiency due to increased dose rates of any of the drugs. Percentage efficiencies and their standard errors, calculated from mean worm counts of pooled data for adult worms, developing 4th stage and early 4th stage larvae of O. ostertagi, were respectively, 86.9+/-4.2, 77.4+/-6.1, 74.5+/-7.3 for oxfendazole, 93.7+/-2.0. 80.7+/-6.8, 59.6+/-13.9 for fenbendazole and 69.7+/-6.9, 39.4+/-14.8, 31.2+/-22.6 for levamisole. Counts of O. ostertagi from cattle treated with oxfendazole and fenbendazole were not significantly different, but both were significantly lower than those from cattle given levamisole. Efficiency against T. axei exceeded 99% for all drugs. Practical implications for therapy and preventative control of ostertagiasis are discussed.

Animals

The efficacy of amidantel, a new anthelmintic, on hookworms and ascarids in dogs.

Amidantel is a new anthelmintic from a new chemical class with an interesting anthelmintic spectrum. In dogs amidantel is highly effective in a single oral dose of 25 mg/kg against both hookworm species, Ancylostoma caninum and Unicinaria stenocephala. In Toxascaris leonina infected dogs a complete cure rate was achieved with a single oral dose of 50 mg/kg. Similar results were obtained with 8 mg/kg administered three times per day. The most sensitive parasite to amidantel was found to be Toxocara canis with a 100 per cent cure rate after a single oral treatment with 10 mg/kg. In preliminary trials amidantel was also effective against hookworms and ascarids after subcutaneous administration. All hookworms and almost all of the ascarids were eliminated with the faeces within 2 days after treatment. Amidantel was tolerated in all dosages tested by all the dogs without any symptoms.

Ancylostoma

Mutagenicity studies with praziquantel, a new anthelmintic drug: tissue-, host-, and urine-mediated mutagenicity assays.

Praziquantel, a new anthelmintic drug with activity against all species of schistosomes pathogenic to man, and against a wide range of Cestodes, was tested for mutagenic potential. For the detection of both base substitutions and frameshift mutations, Salmonella typhimurium TA 100 and TA 98 were used as tester strains. Using the plate assay with and without added S-9, host-mediated assay and urine-mediated assay without and after incubation with beta-glucuronidase/arylsulfatase, no mutagenic activity could be detected.

Administration, Oral

Oxfendazole--anthelmintic activity in Egyptian goats artificially infected with gastrointestinal nematodes.

The recently developed benzimidazole anthelmintic, oxfendazole, was tested against artificial nematode infestations in Egyptian goats using oral dosing at 4.5 and 2.8 mg/kg. A 100% clearance of mature and immature Haemonchus contortus, Trichostrongylus axei, Ostertagia circumcincta, Coopera curticei, Bunostomum trigonocephalum and Chabertia ovina was obtained at the 4.5 mg/kg level. Very high levels of clearance against the mature worms were obtained at 2.8 mg/kg but the drug was less effective against immature worms at the lower dose rate. PCV, hemoglobin concentration and total erythrocyte counts declined after infection but became significantly (P less than 0.001) raised in treated animal.

Animals

Enhancement of in vitro binding and some of the pharmacological properties of diazepam by a novel anthelmintic agent, Avermectin B1a.

A novel macrocyclic lactone disaccharide anthelmintic agent, Avermectin B1a (AVM) has been found to cause a concentration-dependent increase in the in vitro binding of 3H-diazepam to rat and mouse brain membranes. The increase in binding is manifested as both an increase in the affinity and number of bindings sites for 3H-diazepam. Preliminary in vivo studies demonstrate that AVM can also enhance some of the pharmacological actions of diazepam.

Animals

Mutagenicity tests on anthelmintics: microsomal activation of viprynium embonate to a mutagen.

Eight anthelmintic preparations readily available in Australia were tested for mutagenicity in the Salmonella typhimurium test system. A slightly modified version of the procedure recommended by Ames et al. [2] was adopted, in that the test samples were placed in "wells" cut out of the agar of a plate previously seeded with the appropriate tester strain. Addition of a mixture of rat liver microsomal enzymes and appropriate co-factors ("S-9 mix") to one of the two wells on a single plate allowed a possible requirement for metabolic activation to be recognised. Using this procedure, viprynium embonate was found to be non-mutagenic. It was however, activated by the rat liver microsome preparation to a mutagen capable of causing both base-pair substitution (detected with strain TA100) and frameshift (detected with strain TA98) mutations. The other seven compounds tested all gave negative results in this system.

Animals

The anthelmintic effects of flubendazole on Brugia pahangi.

The anthelmintic effects of flubendazole (methyl [5-(4-fluorobenzoyl)-1-H-benzimidazol-2-yl] carbamate) (Janssen Pharmaceutica) were evaluated in jirds (Meriones unguiculatus) and cats (Felis cattus) infected with Brugia pahangi. Flubendazole was macrofilaricidal at 5 x 2.5 mg/kg and 1 x 25 mg/kg in jirds and 1 x 100 mg/kg in cats when administered by subcutaneous injection. It also killed developing larvae in jirds. It was not microfilaricidal.

Animals

Effectiveness of anthelmintic treatments against levamisole-resistant Ostertagia.

Adult worms from a population of Ostertagia consisting of 88% O. circumcincta and 12% O. trifurcata were found to survive a double drench (14 mg/kg) of levamisole. An anthelmintic assay on this population found that against levamisole the LD50 was 11.95 mg/kg and the LD99 was 67.75 mg/kg. Three benzimidazoles were also tested against this population and the LD50 and LD99 were respectively thiabendazole 11.8 and 144.9 mg/kg, oxfendazole 0.17 and 6.10 mg/kg and albendazole 0.08 and 2.55 mg/kg. The percentage of worms killed by the recommended dose rate was levamisole 24%; thiabendazole 91%; oxfendazole 99% and albendazole 99%.

Animals

Avermectins, new family of potent anthelmintic agents: producing organism and fermentation.

The avermectins are a complex of chemically related agents which exhibit extraordinarily potent anthelmintic activity. They are produced by a novel species of actinomycete, NRRL 8165, which we have named Streptomyces avermitilis. The morphological and cultural characteristics which differentiate the producing organism from other species are described. The avermectins have been identified as a series of macrocyclic lactone derivatives which, in contrast to the macrolide or polyene antibiotics, lack significant antibacterial or antifungal activity. The avermectin complex is fully active against the gastrointestinal nematode Nematospiroides dubius when fed to infected mice for 6 days at 0.0002% of the diet. Fermentation development, including medium modification and strain selection, resulted in increasing the broth yields from 9 to 500 mug/ml.

Anthelmintics

Avermectins, new family of potent anthelmintic agents: isolation and chromatographic properties.

The avermectins, a family of new anthelmintic agents, were isolated from the mycelia of Streptomyces avermitilis. Four closely related major components and four homologous minor components were separated from the complex. Solvent extraction, solvent partition, and adsorption methods were used to isolate and purify the complex; novel partition chromatography systems using Sephadex LH-20 were used to separate the components. A reverse-phase high-pressure liquid chromatography assay for the quantitative determination of all components was used extensively to monitor the purification methods.

Anthelmintics