In-vivo effects of ivermection onRhipicephalus appendiculatus: the influence of tick feeding patterns and drug pharmacokinetics

Abstract

Sublethal effects seen amongst Rhipicephalus appendiculatus feeding on ivermectin-treated rabbits were diverse and dependent both on drug dose, pharmacokinetics and tick feeding patterns: changes in drug formulation, the time of infestation relative to treatment, and the tick instar used, profoundly influenced acaricidal activity. Death was a sequel to paralysis only if tick feeding was interrupted for sufficient time to produce irreversible dehydration. Concurrent pharmacokinetic investigations revealed that, for the larvae of R. appendiculatus, the mean critical lethal dose of ivermectin imbibed over a 5-day engorgement period was 3500 micrograms/kg. This quantity of ivermectin was achieved in the blood-meals of larvae feeding on rabbits treated subcutaneously with a single dose of Ivomec injection (MSD)* greater than or equal to 800 micrograms/kg, provided infestation took place within 24 h of treatment. At lower drug doses, or if larval infestations were delayed for greater than 24 h post-treatment, the quantity of circulating ivermectin (and thus imbibed by the tick larvae) fell below 3500 micrograms/kg and an increasing percentage of larvae successfully engorged and detached. More than 90% of such larvae moulted to the nymphal stage. Nymphae and larvae exhibited similar susceptibility to ivermectin on treated rabbits which could be explained by similar feeding patterns. However, adult female and male ticks were markedly less susceptible and interpretation of ivermectin-induced effects was more complex.

Repellency and Antifeedant of Ticks Through Ethno Plant Extracts and Ivermectin on Buffalo Calves

“…Helen and Chesterman, (2005) described that the tick (adult male and female) and nymphs were markedly susceptible on ivermectin. The results of present study was also similar to the findings of Helen and Chesterman (2005), that the effect of ivermectin is found more potent drug against tick infestation and provide 100% results within limited time against parasites. John, (2002) reported in natural history of ticks with the investigation ethno-veterinary method practiced by the owners for the treatment of common disorders of digestive tract (indigestion, colic and diarrhea), respiratory tract (cold/rhinitis, pneumonia) as well as against ectoparasites (mange, ticks, lice and flies).…”

Dermatologic problems of rabbits

“…Ivermectin (0.4 mg/kg SC) has been recommended for killing ticks feeding on rabbits, 2 although the drug's efficacy may depend on the tick species and feeding pattern and on the dose received. 15 Amitraz can be used in the topical treatment of tick and mite infestation. 5 As stated previously, fipronil is not recommended for use in rabbits.…”

Validated capillary electrophoretic method for the analysis of ivermectin in plasma after intragastric administration in pigs and horses

“…Ivermectin was detected in plasma between 12 h and 35 days post administration of drug (Lifschitz et al, 1999). Furthermore, many other analytical methods have been described to be used in pharmacokinetic studies of ivermectin in cattle (Wilkinson et al, 1985;Toutain et al, 1997;Gayrard et al, 1999;Lifschitz et al, 1999a), pigs (Scott and McKellar, 1992;Lifschitz et al, 1999b;Craven et al, 2002), horses (Baggot, 1992;Perez et al, 1999Perez et al, , 2002Gokbulut et al, 2001), sheep (Ali and Hennessy, 1996;Cervenik et al, 2002), dogs (Lo et al, 1985) and rabbits (Jackson and Chesterman, 1989). Unfortunately, the presented methods are complicated; time-consuming multiple extraction and cleanup involve the use of procedures which are impracticable for routine application.…”