伊维菌素脂质体的急性毒性试验

为了解伊维菌素脂质体的毒性，将伊维菌素脂质体给试验小鼠按一定浓度一次腹腔注射，连续观察7-14d，用改良寇氏法计算半数致死量（LD50）及95％的可信限，并在同一方法和条件下与伊维菌素注射剂相比较。结果表明，伊维菌素脂质体（脂质体组）的LD50（92．1516mg／kg．BW）显著高于伊维菌素注射剂（原药组）的LD50（24．2493mg／kg．BW），是原药组的3．80倍。证明伊维菌素脂质体的毒性更低，刺激性更小，安全范围更广。     

Ivermectin is an effective treatment for bovine cutaneous papillomatosis

This study aimed to evaluate the effectiveness of ivermectin on the treatment of bovine cutaneous papillomatosis. Twenty-four Holstein calves between 9 and 17 months of age with cutaneous papillomatosis were placed into three groups with six in group I, and nine in groups II and III. Group I served as a control group and received no treatment. Ivermectin at a dose of 0.2mg/kg was administered subcutaneously as a single dose to the animals in Group II and twice with 15 days intervals to animals in Group III. The first ivermectin application was considered as the 0th day Animals were monitored at 15 days intervals up to 3 months. No remission was observed in the control group (Group I). In Group II eight out of nine animals (88.8%) and in Group III seven out of nine animals (77.7%) showed complete recovery within 3 month observation period. It was concluded that ivermectin, as either single or double dose applications, is effective as a treatment for cutaneous papillomatosis.     

双波长紫外分光光度法测定伊维菌素注射液中伊维菌素的含量

建立伊维菌素注射液中伊维菌素的含量测定方法。采用双波长分光光度法测定伊维菌素的含量,测定波长为245 nm,参比波长为270 nm。结果表明,伊维菌素在1~100μg/mL范围内线性关系良好(r=0.9993),平均回收率为102.96%,RSD为4.19%(n=6)。该方法简便,结果准确可靠,适合伊维菌素注射液中伊维菌素的含量测定。     

伊维菌素泼背剂对牦牛寄生虫的驱除效果试验

为选择适应于高寒牧区放牧牦牛大群驱除体内外寄生虫的理想荆型,在青海大通种牛场通过粪检选60头牦牛,随机分为3组,每组20头,试验1组用伊维菌素泼背荆接0.5 mg/kg体重剂量经背部皮肤浇泼给药,试验2组用伊维菌素注射剂按0.2 mg/kg体重剂量经皮下注射给药,试验3组为空白对照组.分析了三组不同寄生虫卵转率、虫卵减少率及驱虫率指标的变化,同时对药物的安全性进行了观察.结果试验1组消化道线虫虫卵转阴率、减少率分别为90%和99.1%,原圆科线虫幼虫转阴率、减少率分别为80%和92.8%;线虫成虫、寄生阶段幼虫的总计驱虫率分别为99.3%和98.8%;试验2组相应指标分别为90%和98.7%、80%和92.9%、99.4%和99.2%;1.2组对牛颚虱杀虫率均达100%,但对莫尼茨绦虫无效,对照组体内外寄生虫均无明显变化.表明伊维菌素泼背剂0.5 mg/kg剂量安全,驱虫效果可信,可在青海高寒地区牦牛体内外寄生虫驱虫工作中推广应用.     

伊维菌素驱除香猪体内外寄生虫的试验

应用进口伊维菌素对刚从贵州引进的20头香猪进行了驱虫试验,以400μgkg体重剂量皮下注射,两周后重复一次,驱虫后8天粪中线虫虫卵转阴率为94.74%,虫卵减少率为100%;驱虫后4周体表血虱及其虫卵全部转阴。     

伊维菌素干混悬剂对羊狂蝇蛆的驱杀效果试验

选择自然感染羊狂蝇蛆绵羊131只,分别按体重0.1,0.2和0.3mg/kg剂量口服伊维菌素干混悬剂,进行驱除效果观察,同时设空白对照组。结果表明,口服伊维菌素干混悬剂0.2,0.3mg/kg剂量组绵羊的羊狂蝇蛆驱净率和驱虫率均达100%。口服0.1mg/kg剂量组绵羊的羊狂蝇蛆驱净率93.9%、驱虫率98.6%。试验证明伊维菌素干混悬剂对羊狂蝇蛆驱虫效果明显,临床使用0.2mg/kg体重剂量高效安全。     

伊维菌素和阿维菌素对中华鰟鮍的急性毒性效应

[目的]探讨伊维菌素和阿维菌素对中华鰟鮍(Rhodeus sinensis Gunther)的急性毒性效应。[方法]采用急性毒性试验方法测定了伊维菌素、阿维菌素2种常见杀虫药对中华鰟鮍的半致死浓度(LC50)及安全浓度。[结果]含量为6%的伊维菌素对中华鰟鮍的24、48、72、96 h LC50分别为71.68、45.04、37.81、35.69μg/L,安全浓度为0.001 3μg/L;含量为1%的阿维菌素对中华鰟鮍的LC50分别为129.35、77.35、47.54、34.63μg/L,安全浓度为0.000 2μg/L。[结论]中华鰟鮍对伊维菌素和阿维菌素2种大环内酯类杀虫药较敏感,在使用过程中要注意用量,否则极易出现药害。     

Potential environmental consequences of administration of anthelmintics to sheep

Anthelmintics, veterinary medicines for the control of endoparasites, enter into the environment largely through faeces of the treated animals. Sheep dung is a patchily distributed, ephemeral resource, with a functionally important decomposer community. The nature of this community and the pharmacokinetics of anthelmintics in sheep mean that the ecotoxic impacts of these drugs in sheep dung may differ markedly from those in cattle dung, where most research has been focussed. The period of maximum residue excretion is generally more transient in sheep than cattle dung, but low-level excretion may continue for longer, giving the potential for extended sub-lethal effects. Here, the environmental impacts of sheep anthelmintics, as well as alternative endoparasite control methods are reviewed. Impacts are discussed in terms of the potential for residues to enter into the environment, the toxicity and the impact on ecosystem functioning at an appropriate scale. Future research priorities are also discussed; these include the need for studies of the functional contributions of dung-colonising species, as well as the development of higher-tier ecotoxicological methods bridging the gap between laboratory and field experiments. Large-scale and long-term studies, including the development of appropriate models, are necessary to allow the consequences of anthelmintic administration to be assessed, particularly within the remit of sustainable animal production.     

Acaricide treatment prevents adrenocortical hyperplasia as a long-term stress reaction to psoroptic mange in cattle

In cattle, infestation with Psoroptes ovis mites may cause severe dermatitis (psoroptic mange) which compromises the health and welfare of the animals and may lead to significant economic losses. To investigate yet undocumented effects of psoroptic mange mite infestations and how successful therapy promotes animal health, the present study examined alterations of the skin, lymph nodes and adrenal glands of P. ovis infested Fleckvieh (Simmental) bulls treated with either ivermectin long-acting injection (IVM LAI; IVOMEC^® GOLD, Merial; 3.15% ivermectin w/v) or saline (n = 16 each). Approximately 8 weeks subsequent to experimental infestation with P. ovis, the bulls had developed mange and were administered either IVM LAI or saline once at 1 mL/50 kg body weight by subcutaneous injection. Mite counts were conducted in weekly intervals for determination of efficacy of treatment, and following humane euthanasia of the animals 8 weeks after treatment, skin samples from affected (mangy or previously mangy) and unaffected areas, prescapular lymph nodes and adrenal glands were collected for gross and pathohistological examination. In addition, four age-matching, uninfested Simmental bulls were sampled as controls for comparison.No P. ovis mites were detected on any IVM LAI-treated bull after 28 days following treatment whereas saline-treated bulls maintained infestation throughout the study. At sampling (approximately 16 weeks after experimental infestation and 8 weeks following saline or IVM LAI treatment), saline-treated bulls displayed a severe, exsudative dermatitis with significantly increased skin thickness and inflammatory cell infiltration, significantly enlarged, hyperplastic prescapular lymph nodes, as well as significantly increased adrenal gland weights and volumes as compared to P. ovis-infested, IVM LAI-treated bulls and uninfested controls. Quantitative stereological analysis revealed that the adrenal gland enlargement in P. ovis-infested, saline-treated bulls was due to a selective increase of the volume of the zona fasciculata in the adrenal cortex. Compared to uninfested controls and P. ovis-infested, IVM LAI-treated bulls, the number of epithelial cells in the zona fasciculata was significantly increased in P. ovis-infested, saline-treated bulls, while the zona fasciculata cell volumes did not differ between the three groups of cattle. While the single point determination of serum cortisol concentrations did not reveal significant differences between the three groups of cattle at tissue sampling, the hyperplastic growth of the adrenal cortex in the P. ovis-infested, saline-treated bulls provides morphologic evidence that a chronic stress reaction is one consequence of mange mite infestations that can be prevented by efficacious acaricidal treatment.     

An ivermectin tablet for sheep: Efficacy against gastro-intestinal nematodes and a bioavailability comparison with a liquid ivermectin formulation

An ivermectin tablet for o ral administration to sheep was developed for use in countries where it is customary to treat sheep with anthelmintic tablets. Tablets require no special administration equipment, and offer convenience for storage and transport. The ivermectin tablet, which delivers 10 mg of ivermectin (200 μg kg⁻¹ in a 50 kg sheep), had similar bioavailability to a liquid formulation of ivermectin (IVOMEC^® Liquid for Sheep) as determined by peak plasma ivermectin concentrations and area under the concentration curve in plasma (P>0.10). In dose confirmation trials in which nematode infections were induced in helminth-naive sheep, animals treated with the ivermectin tablet had significantly fewer adult and fourth-stage larval nematodes than untreated control sheep P<0.01 with efficacies >99% against all nematode species tested. In six field trials evaluating the efficacy of the ivermectin tablet in 240 Merino sheep, the reductions in faecal nematode egg counts ranged between 98 and 100%, as determined by comparison of pre- and post-treatment counts for the ivermectin-treated group.