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

Background: lotilaner (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. methods: from 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. results: adequate 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. conclusion: this 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. © 2017 the author(s).