Assessment of the onset of lotilaner (Credelio\u2122) speed of kill of fleas on dogs

Daniela Cavalleri,Steve Nanchen,Wolfgang Seewald,Martin Murphy,Jason Drake

doi:10.1186/s13071-017-2474-0

Abstract

BackgroundLotilaner (Credelio™) is the newest member of the novel isoxazoline chemical class to be developed to treat canine ectoparasitism. Administered orally, lotilaner is rapidly absorbed with peak blood levels occurring within 2 h post-treatment. A study was undertaken to determine the earliest onset of lotilaner’s efficacy against existing flea infestations.MethodsFrom 72 Beagles, 64 qualifying dogs were ranked in descending order of flea counts from a Day -8 infestation and placed into eight blocks. Within blocks, eight dogs were randomly allocated among eight groups: Groups 1 to 4 were treated orally with lotilaner, at as close as possible to the minimum dose rate of 20 mg/kg within 30 (± 5) minutes after feeding; Groups 5 to 8 were untreated controls. All dogs were infested with 100 ± 5 fleas on Day -2, and whole-body flea counts were completed at 30 min and one, two and 8 h after treatment. Efficacy calculations were based on arithmetic and geometric means if an adequate infestation (at least six of eight untreated dogs with a flea retention of ≥ 50%) was demonstrated in the equivalent control group.ResultsAdequate infestations were established in all control groups. At 30 min and 1 h post-treatment, relative to the matching untreated control group, there were no significant reductions in mean flea counts in lotilaner-treated dogs, although moribund fleas were evident at 1 h post-treatment. At 2 h after treatment, compared with the equivalent control group, the geometric mean flea count reduction in the lotilaner group was 64.0% (t(7) = 2.86, P = 0.0242). At 8 h after treatment, lotilaner efficacy was 99.6%. There were no treatment-related adverse events.ConclusionThis study demonstrates that lotilaner flavored chewable tablets are well tolerated and begin to kill fleas within 2 h of treatment, achieving 99.6% efficacy within 8 h. Lotilaner can therefore be used to quickly alleviate the flea irritation that arises from existing infestations.

Highlights

Lotilaner (CredelioTM) is the newest member of the novel isoxazoline chemical class to be developed to treat canine ectoparasitism
The highest dose was greater than targeted, and so this dog was excluded from calculations so as to not bias the results towards any increased speed of kill related to higher doses
Adequacy of infestation in the control groups (Groups 5 to 8) was achieved at all assessment time points, as more than six of the eight dogs in each had a flea retention of ≥ 50%, and mean live flea counts ranged from 76.9 to 88.8

Summary

Introduction

Lotilaner (CredelioTM) is the newest member of the novel isoxazoline chemical class to be developed to treat canine ectoparasitism. From the time of launch of the spot-on products fipronil and imidacloprid in the mid-1990s, speed of kill (SOK) of existing flea infestations has been a desirable feature of any new flea control product. The importance of this feature has been attributed to the need to provide a dog with relief from the irritation of flea bites, for affirmation of a pet owner’s perception of a product’s performance, and to quickly eliminate the source of egg production [1]. Orally administered isoxazolines have emerged as rapid-onset products, as yet none appeared to match the high-efficacy, rapid SOK that has been established for the earlier oral products against existing flea populations.

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