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PubMed1979

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↗
PubMed1975

Influence of anthelmintic treatment on the liveweight of outwintered ewe hoggs.

Three systems of outwintering ewe hoggs are normally practised on Scottish hill farms. A series of field trials involving some 2000 different animals was conducted to determine the response in liveweight from anthelmintic treatment for roundworms. The results suggest that, under field conditions, a strategic dosing programme using a modern anthelmintic can prevent liveweight loss in ewe hoggs wintered either on the hill or "inbye". The best response may be expected from a two dose regime--one in early winter (mid October to mid November) and the other in winter (mid January to mid February). In away-wintered hoggs, the kinder climate, better pssture, and, in the vast majority of cases, less contaminated ground, appear to outweigh the advantages of dosing after the late autumn.

Animals↗
PubMed1975

[Committee on anthelmintics. Residual group].

A number of the older and a few recent anthelmintics are enumerated or briefly discussed. Moreover some attention is paid to anthelmintics, used for nematodes and trematodes which have a limited effect on cestodes.

Animals↗
PubMed1975

The resistance of a field strain of Haemonchus contortus to five benzimidazole anthelmintics in current use.

Using artificially infected sheep, the response of a laboratory strain of Haemonchus contortus, which had not been subjected to anthelmintics for three years, was compared with that exhibited by a parbendazole resistant field strain following treatment with each of seven anthelmintics, the laboratory strain proved fully susceptable to thiabendazole, parbendazole, cambendazole, mebendazole, fenbandazole, levamisole and haloxon, in contrast to the field strain which showed a moderate to marked resistance to all five benzimidazoles, but was fully susceptible to levamisole and haloxon.

Animals↗
PubMed1979

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↗
PubMed1978

The dose response of several benzimidazole anthelmintics against resistant strains of Haemonchus contortus and Trichostrongylus colubriformis selected with thiabendazole.

Dose response lines for eight benzimidazole anthelmintics and thiophanate were determined, using standardised strains of thiabendazole selected and resistant Haemonchus contortus and Trichostrongylus colubriformis. Against H contortus, thiophanate, thiabendazole, parbendazole and oxibendazole were inactive. Mebendazole was inactive at dose rates of 6.26 and 12.5 mg/kg, although significant activity occurred at 25 mg/kg. Fenbendazole, cambendazole, oxfendazole and albendazole demonstrated significant activity at dose rates equal to or greater than the recommended therapeutic level. Thiophanate was inactive against resistant T colubriformis. The remaining compounds only showed significant activity when used at dose rates in excess of the recommended therapeutic level. These results show that a side resistance exists among the benzimidazole anthelmintics and suggests that changes in dose response lines could be expected to occur if resistant strains are selected with benzimidazoles other than thiabendazole.

Animals↗
PubMed1976

Anthelmintic treatment of young beef cattle in the Wallum region of south-eastern Queensland.

An anthelmintic treatment trial on 125 Brahman-British crossbred 2 to 4 month old calves was undertaken on Wallum country in south eastern Queesland. The calves were divided into 5 experimental groups, grazed together and treated as follows for 17 months: Group 1--Untreated controls; Group 2--Monthly levamisole--niclosamide on 4 occasions; Group 3--Monthly levamisole until 1 month after weaning; Group 4--Levamisole 3 to 6 weeks after saturating rains; Group 5--No levamisole--niclosamide as for Group 2. The mean body weight gains for cattle in Groups 1 to 5 were 95, 124, 105, 121 and 97 kg respectively. Four cattle were lost from each of Groups 1 and 3 and five from Group 5. Most of these losses occurred towards the end of the second summer rainfall season. Faecal egg count maxima were recorded around weaning in untreated groups and during the summer rainfall period of both the first and second summer in all groups. The most prevalent nematode species encountered were H. placei, Cooperia spp and O. ostertagi. It is recommended that in this region cattle under 2 years of age should receive anthelmintic treatment at least in autumn and spring.

Animals↗
PubMed1992

Reduced growth of Lucilia cuprina larvae fed serum from sheep treated with anthelmintics.

The effect of three commonly used anthelmintics, levamisole hydrochloride, ivermectin and closantel, on the development of the sheep blowfly, Lucilia cuprina, was determined. Sheep were treated with each anthelmintic using the manufacturers' recommended dose for helminth control. Both ivermectin and closantel significantly (p < 0.05) reduced the growth rate of larvae of L cuprina cultured in vitro on serum from these sheep. Levamisole hydrochloride had no effect. Ivermectin was effective for less than 6 days after treatment, whereas closantel significantly reduced larval growth 21 days after treatment. Dose-response experiments showed that lower concentrations of both ivermectin and closantel were not as effective in reducing larval growth.

Animals↗
PubMed1976

The anthelmintic efficacy of fenbendazole against thiabendazole-resistant strains of Haemonchus contortus and Trichostrongylus colubriformis in sheep.

The anthelmintic efficacy of fenbendazole (methyl 5-(phenylthio)-2-benzimidazole carbamate) was tested in sheep against standardised strains of Hcaemonchus contortus and Trichostrongylus colubriformis, known to be resistant to thiabendazole (LD90 for thiabendazole against H ontortus was 200 mg/kg bodyweight and against T colubriformis was 150 mg/kg). Fenbendazole at dose rates of 5, 10 and 20 mg/kg per os reduced total worm counts in H contortus infected sheep by 66, 90 and 100 per cent respectively, with similar reductions recorded for worm egg outputs. For the thiabendazole resistant strain of T colubriformis, fenbendazole reduced total worm counts in infected sheep by 4, 44 (40-48), 79 (75-83), 96 and 100 per cent at dose rates of 5, 10, 20, 40 and 80 mg/kg per os. Significant suppression of worm-egg production by thiabendazole resistant T colubriformis was obtained with fenbendazole at dose levels of 5 mg/kg and above. The implications of these results are discussed in the light of the increasing occurrence of strains of trichostrongylid nematodes resistant to currently available benzimidazole anthelmintics.

Animals↗
PubMed1977

Anthelmintic dihydroquinoxalino[2,3-b]quinoxalines.

A series of dihydroquinoxalino[2,3-b]quinoxalines was synthesized and tested for anthelmintic activity in a model assay. The most promising compound, 5,12-diacetyl-5,12-dihydroquinoxalino[2,3-b]quinoxaline, was orally effective in sheep at a dose of 200 mg/kg against a broad range of helminths.

Animals↗
PubMed1977

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↗
PubMed1979

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↗
PubMed1979

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↗
PubMed1977

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↗
PubMed1978

Studies with Brugia pahangi. 20. An investigation of 23 anthelmintics using different screening techniques.

23 anthelmintics were tested against Brugia pahangi microfilariae and infective larvae in vitro and in Aedes aegypti infected with B. pahagi and jirds (Meriones unguiculatus) infected with a B. pahangi/patei hybrid. There was little correlation between the results obtained in vitro and in infected insects and the results obtained in these tests gave no indication of the activity in jirds. Three of the compounds were macrofilaricidal in jirds and these were tested in cats infected with B. pahangi. One of these--5-benzamido-2(4-thiazolyl)-benzimidazole--was macrofilaricidal in cats and it is suggest that it should be tested in other filarial systems. It is concluded that the insect and in vitro tests are not good primary screens for filaricidal activity.

Aedes↗
PubMed1979

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↗