Department of Pharmacology and Toxicology, Faculty of Veterinary Medicine, Adnan Menderes University, Isikli Koyu, 09100 Aydin, Turkey.
Vet Parasitol. 2010 May 28;170(1-2):120-6. doi: 10.1016/j.vetpar.2010.01.041. Epub 2010 Feb 4.
Pour-on formulations of endectocides decrease the risk of injury for both user and animal, and are particularly convenient for animal owners who can apply the product. This study was designed to investigate the plasma disposition and efficacy of ivermectin (IVM) following pour-on, per os and intravenous administrations. Eighteen female horses weighing 510-610 kg were used in this study. The animals were allocated into three groups (per os, pour-on and intravenous groups). The equine paste, bovine pour-on and bovine injectable formulations of IVM were administered orally, topically and intravenously at the dose rates of 0.2, 0.5 and 0.2mg/kg bodyweight, respectively. Heparinized blood samples and hair samples were collected at various times between 1h and 40 days. The samples were analysed by high performance liquid chromatography with fluorescence detector. Faecal strongyle egg counts (EPG) were performed by a modified McMaster's technique before and at weekly intervals during 10 weeks after treatment. The results indicated that the plasma concentration and systemic availability of IVM was lower but the plasma persistence was prolonged after pour-on administration compared with per os route. IVM (paste) reduced the EPG by >95% for 10 weeks, whereas the reduction in pour-on group varied from 82 to 97%. EPG reduction in pour-on group was lower than that of per os group. Degradation on the application site, cutaneous biotransformation, binding of IVM to the haircoat and/or sebum are probably responsible for the relatively lower bioavailability of IVM in horses after pour-on administration. In conclusion, the poor plasma availability observed after pour-on administration could result in subtherapeutic plasma concentrations, which may promote the development of drug resistance in parasites.
经皮给药剂型的驱虫剂降低了使用者和动物受伤的风险，对动物主人尤其方便，因为他们可以使用这种产品。本研究旨在研究伊维菌素（IVM）经皮、口服和静脉给药后的血浆处置和疗效。本研究使用了 18 匹体重为 510-610kg 的母马。这些动物被分配到三组（口服组、经皮组和静脉组）。以 0.2、0.5 和 0.2mg/kg 体重的剂量率，分别给马用膏剂、牛用经皮滴剂和牛用注射液经口、经皮和静脉给药。在 1 小时至 40 天的不同时间采集肝素化血液样本和毛发样本。用高效液相色谱法-荧光检测器分析样品。在治疗后 10 周内每周进行一次改良麦克马斯特技术的粪便强中卵计数（EPG）。结果表明，与口服途径相比，经皮给药后 IVM 的血浆浓度和全身利用率较低，但血浆持久性延长。IVM（膏剂）可将 EPG 减少>95%，持续 10 周，而经皮给药组的减少范围为 82-97%。经皮给药组的 EPG 减少低于口服组。在应用部位的降解、皮肤生物转化、IVM 与毛被和/或皮脂的结合可能是 IVM 在经皮给药后在马中相对较低生物利用度的原因。总之，经皮给药后观察到的血浆利用率低可能导致治疗性血浆浓度降低，从而促进寄生虫对药物产生耐药性。
