An animal trial was conducted to measure the concentrations of ivermectin occurring in abomasal and small intestinal contents and mucosa, and in the target parasites (Ostertagia ostertagi and Cooperia oncophora) following administration by subcutaneous, oral and pour-on routes. Twenty-five steers were infected with ivermectin-resistant isolates of O. ostertagi and C. oncophora and following patency randomly allocated to 3 treatment groups of 7 and 1 untreated control group of four. On day 0, animals in the treatment groups were administered ivermectin via the oral, injectable or pour-on routes. On days 1, 2, 3, 4, 5, 6 and 8, blood samples were collected from all live animals, one animal from each treatment group was euthanised and the abomasum and small intestine recovered. Control animals were euthanised on each of days 4, 5, 6 and 8. Samples of gastrointestinal tract organs, their contents, mucosa and parasites were collected and assayed for ivermectin concentration using HPLC. The highest plasma concentrations occurred following subcutaneous administration. In the gastrointestinal contents the highest levels occurred following oral administration, although one high value occurred following pour-on administration, which was attributed to self-licking by the treated animal. The lowest GI content levels followed subcutaneous injection. Ivermectin concentrations in the gastrointestinal mucosa were highest following subcutaneous injection. Drug levels in the abomasal parasite O. ostertagi were most closely correlated with levels in the abomasal mucosa whereas levels in the intestinal C. oncophora were most closely correlated with those in the intestinal contents. Thus, the maximun levels of drug reached C. oncophora in the small intestine following oral administration. In contrast, the highest levels of ivermectin in O. ostertagi followed subcutaneous injection. Therefore, route of administration is likely to influence the exposure to ivermectin for different parasite species.

进行了一项动物试验，以测量通过皮下、口服和浇注途径给药后在真胃和小肠内容物和粘膜以及目标寄生虫（Ostertagia ostertagi和Cooperia oncophora）中发生的伊维菌素浓度。25 头公牛感染了伊维菌素耐药的O分离株。ostertagi和Ç。锥体和以下通畅随机分配到 3 个治疗组 7 个和 1 个未治疗的对照组 4 个。在第 0 天，通过口服、注射或浇注途径给治疗组中的动物施用伊维菌素。在第 1、2、3、4、5、6 和 8 天，从所有活体动物中采集血液样本，每个处理组的一只动物被安乐死，并恢复真胃和小肠。在第 4、5、6 和 8 天的每一天对对照动物实施安乐死。收集胃肠道器官、其内容物、粘膜和寄生虫的样品，并使用 HPLC 分析伊维菌素浓度。皮下给药后血浆浓度最高。在胃肠内容物中最高水平出现在口服给药后，虽然在倾倒给药后出现了一个高值，这归因于接受治疗的动物的自我舔舐。最低 GI 含量水平出现在皮下注射之后。皮下注射后胃肠黏膜中的伊维菌素浓度最高。真胃寄生虫中的药物水平哦。ostertagi与皱胃粘膜中的水平最密切相关，而肠道中的水平C . oncophora与肠内容物中的最密切相关。因此，药物的最大水平达到C。口服给药后小肠中的肿瘤。相比之下，O 中最高水平的伊维菌素。ostertagi随后皮下注射。因此，给药途径可能会影响不同寄生虫物种对伊维菌素的暴露。