Laboratory evaluations of the immediate and sustained efficacy of lotilaner (Credelio™) against four common species of ticks affecting dogs in North America

Abstract

BackgroundEffective control of tick infestations on dogs is important to reduce the risk of transmission of bacterial, viral, and protozoal pathogens. Laboratory studies were initiated to determine the efficacy of lotilaner against common ticks infesting dogs in the United States.MethodsEight studies investigated the efficacy of lotilaner against ticks. In two studies dogs were infested with both Dermacentor variabilis and Rhipicephalus sanguineus: one additional study was completed for each of these species. Two studies assessed infestations with Amblyomma americanum and two with Ixodes scapularis. In all studies, dogs were ranked and blocked by counts from pre-treatment infestations and randomly allocated, at least eight per group, to be treated orally with lotilaner (minimum dose rate 20 mg/kg), or to be untreated controls. Treatments were administered on Day 0, within 30 min after dogs were fed. In all studies, infestations were performed with 50 adult ticks on Days -2, 7, 14, 21 and 28, and also on Day 35 for R. sanguineus, D. variabilis and I. scapularis. Tick counts were completed 48 h after treatment or after each subsequent challenge. An adequate infestation was defined as at least 25% of the infestation dose recovered from each of at least six control animals at each evaluation. Efficacy calculations for the primary objective were based on geometric means.ResultsIn all studies, lotilaner was 100% effective against existing infestations. For post-treatment assessments, on only two occasions did efficacy fall below 99%: in one D. variabilis study efficacy was 98.0% on Day 35 and in one I. scapularis study efficacy on Day 16 was 98.4%. Only mild and transient adverse events were observed, and none were considered to be related to treatment.ConclusionLotilaner was completely effective against existing infestations with four common species of ticks, D. variabilis, R. sanguineus, A. americanum and I. scapularis, that affect dogs in North America, with at least 4 weeks efficacy of 98.0% or more against subsequent challenge infestations. These results show that lotilaner is a highly effective isoxazoline that offers sustained efficacy against ticks through and beyond the one-month end-of-dose treatment interval.Electronic supplementary materialThe online version of this article (10.1186/s13071-017-2476-y) contains supplementary material, which is available to authorized users.

Laboratory evaluation of the efficacy of lotilaner (Credelio™) against Amblyomma cajennense (sensu lato) infestations of dogs

“…A report of a series of studies involving experimental infestations with commonly occurring European ticks showed that lotilaner efficacy remained at least 95% through 35 days post-treatment and a field study across three European countries subsequently confirmed lotilaner effectiveness against field challenge [ 18 , 23 ]. Similar efficacy was reported following induced infestations of commonly occurring ticks in North America [ 24 ]. As in this study, experimental infestation studies typically involve assessments at 48 h post-treatment, and 48 h after subsequent weekly challenges.…”

“…For instance, there are only two reports of afoxolaner efficacy against A. americanum - in one of these at 24 h post-infestation afoxolaner efficacy was less than 80% from Day 14 through Day 30 while under the same conditions sarolaner efficacy remained at greater than 90% until Day 28 [ 22 ]. Studies assessing lotilaner efficacy against A. americanum at 48 h post-treatment and post infestation have demonstrated efficacy of 100% throughout, except at nine days post-treatment when efficacy was 99% [ 19 ].…”

“…Following oral administration under fed conditions, peak lotilaner concentrations are reached within two hours, with a corresponding rapid onset of activity against fleas and ticks [ 15 – 17 ]. Lotilaner efficacy has been demonstrated against a number of tick species including, but not limited to, Rhipicephalus sanguineus ( sensu lato ), Dermacentor reticulatus , Dermacentor variabilis , Ixodes scapularis , Ixodes ricinus and Amblyomma americanum [ 18 , 19 ]. With a half-life of 30 days, lotilaner has been shown to provide at least a month of activity against infesting ticks [ 15 , 17 – 19 ].…”

“…Lotilaner efficacy has been demonstrated against a number of tick species including, but not limited to, Rhipicephalus sanguineus ( sensu lato ), Dermacentor reticulatus , Dermacentor variabilis , Ixodes scapularis , Ixodes ricinus and Amblyomma americanum [ 18 , 19 ]. With a half-life of 30 days, lotilaner has been shown to provide at least a month of activity against infesting ticks [ 15 , 17 – 19 ]. To further expand the understanding of the activity of lotilaner flavored chewable tablets against ticks, a study was initiated to investigate efficacy in eliminating existing burdens of A. cajennense ( s.l .)…”

Distinct molecular targets for macrocyclic lactone and isoxazoline insecticides in the human louse: new prospects for the treatment of pediculosis

“…Whereas 10 µM ivermectin treatment killed 100% of adult lice after 24h, we obtained the same result with 10 µM lotilaner in only 3 hours following exposure. This fast activity is in accordance with the 4h-12h needed to kill ticks and fleas in lotilaner treated dogs [79,80]. In contrast, neither ivermectin nor lotilaner were found to have a pediculicidal activity on nits.…”