Abstract
BackgroundLotilaner (Credelio™, Elanco), a novel isoxazoline, is a systemic insecticide and acaricide that is rapidly absorbed following oral administration to dogs and has a half-life of 30 days. As part of a development program, studies were undertaken to investigate lotilaner’s initial and sustained efficacy and speed of kill against fleas.MethodsFour studies were conducted to evaluate the onset of lotilaner’s speed of flea knockdown at the time of treatment, and to determine the sustained speed of flea kill (SOK) up to 35 days post-treatment. Each study assessed one or two specific time points (4, 6, 8 and 12 h) post-treatment and following weekly re-infestations. In each study, dogs were randomised to a lotilaner or an untreated group based on pre-administration flea counts, and before treatment were infested with adult Ctenocephalides felis. Dogs randomised to a lotilaner group received a single treatment on Day 0, at the minimum recommended dose rate of 20 mg/kg, 30 (± 5) minutes after being fed. Efficacy was calculated using geometric, and arithmetic mean flea counts in treated versus untreated groups.ResultsOn Day 0, lotilaner efficacy was 89.9% at 4 h, 99.2% at 6 h, 99.9% at 8 h, and 100% at 12 h post-treatment. At each weekly assessment, lotilaner efficacy at 4 h remained at > 97%, at 8 h remained at > 99%, and at 12 h remained at 100% through Day 35. Across all studies, there were no treatment-related adverse events.ConclusionLotilaner’s rapid flea knockdown immediately following treatment and sustained SOK through 35 days post-treatment offers a new solution for helping to eliminate the health risks that accompany flea infestations on dogs. The consistency of the rapid, sustained flea SOK demonstrated in these studies generates confidence that monthly use of lotilaner in dogs can be valuable in disrupting the flea life cycle in a contaminated environment, and that newly acquired fleas will die quickly, thereby reducing the discomfort of flea bites. The sustained lotilaner SOK also provides confidence that there will be no “end-of-dose” resurgence in flea burdens with the potential accompanying consequence of flares in flea-bite hypersensitivity.
Highlights
Lotilaner (CredelioTM, Elanco), a novel isoxazoline, is a systemic insecticide and acaricide that is rapidly absorbed following oral administration to dogs and has a half-life of 30 days
Study 1 Within 4 h after treatment, geometric mean flea counts had been reduced by 89.9% in lotilaner-treated dogs; and following all subsequent infestations, four-hour flea count reductions in both geometric and arithmetic means were within the efficacy range of 97.1 to 100% (Table 1)
Moribund fleas were present on lotilanergroup dogs on all days, except on Day 14 when there were no fleas classified as either live or moribund
Summary
Lotilaner (CredelioTM, Elanco), a novel isoxazoline, is a systemic insecticide and acaricide that is rapidly absorbed following oral administration to dogs and has a half-life of 30 days. The emergence of orally administered flea-killing products has brought attention to other potential shortcomings of topical products. These include concern about household pesticide exposure, the requirement for careful application by owners directly to a pet’s skin, and the decline in skin concentrations over the month following treatment, which may vary from animal to animal, and be unpredictable under different climatic or water exposure conditions [3]. The first monthly oral flea adulticide product for dogs, spinosad, has been shown to provide a rapid onset of flea knockdown while providing a month of flea-killing activity [4]. The rapid killing of fleas was seen as desirable, to break the flea life cycle by preventing flea egg production, and to quickly remove a source of irritation from biting fleas, a cause of allergic dermatitis, and to quickly kill fleas that are known to transmit a number of infectious agents such as Dipylidium caninum, Acanthocheilonema reconditum, Bartonella spp. and Rickettsia spp. [5]
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