title: Assessment of the onset of action of afoxolaner against existing adult flea (Ctenocephalides felis) infestations on dogs.
abstract: The speed of kill of afoxolaner against experimental infestations by Ctenocephalides felis was evaluated after oral administration of afoxolaner in a soft chew (NEXGARD(®)) at a dose to achieve 2.5mg/kg bodyweight. Forty beagles were allocated to two treatment groups. Dogs in Treatment Group 1 were untreated controls. Dogs in Treatment Group 2 were treated on Day-0 with afoxolaner, according to their pre-treatment bodyweight. All dogs were infested with approximately 100 C. felis on Day-1. Live fleas were counted upon removal at 5 time points after treatment (i.e., 2, 4, 8, 12 and 24h after treatment). For each time point, counts were performed on 4 dogs from each of the treated and the untreated groups. Early curative flea killing efficacy was evaluated with respect to the untreated control group. The afoxolaner treated group had significantly fewer fleas than the untreated control group at 8, 12, and 24h (p<0.001). The percent efficacies of orally administered afoxolaner were 15.0%, 87.8%, 99.5%, 100.0%, and 100.0% at 2, 4, 8, 12, and 24h, respectively. In this study, afoxolaner began killing fleas by 2h after treatment with increasing efficacy at subsequent time points and had >99.5% efficacy at 8, 12, and 24h after treatment demonstrating an early onset of action.
authors.affiliation: Merial Limited, 3239 Satellite Boulevard, Duluth, GA 30096, USA.
authors.forename: Bruce N
authors.initials: BN
authors.lastname: Kunkle
authors.affiliation: Merial Limited, 3239 Satellite Boulevard, Duluth, GA 30096, USA.
authors.forename: Marlene D
authors.initials: MD
authors.lastname: Drag
authors.affiliation: Merial Limited, 3239 Satellite Boulevard, Duluth, GA 30096, USA.
authors.forename: Theodore S
authors.initials: TS
authors.lastname: Chester
authors.affiliation: Merial Limited, 3239 Satellite Boulevard, Duluth, GA 30096, USA.
authors.forename: Diane L
authors.initials: DL
authors.lastname: Larsen
mesh_terms: D000284:Administration, Oral; D000818:Animals; D000977:Antiparasitic Agents / Q000008:administration & dosage / Q000494:pharmacology*; D058251:Ctenocephalides / Q000187:drug effects*; D004283:Dog Diseases / Q000188:drug therapy; D004285:Dogs; D005260:Female; D058267:Flea Infestations / Q000188:drug therapy / Q000662:veterinary*; D007555:Isoxazoles / Q000008:administration & dosage / Q000494:pharmacology; D008297:Male; D009281:Naphthalenes / Q000008:administration & dosage / Q000494:pharmacology; D011897:Random Allocation; D013995:Time
chemical_list: D000977:Antiparasitic Agents; D007555:Isoxazoles; D009281:Naphthalenes; C000589002:afoxolaner
keywords: Afoxolaner; Ctenocephalides felis; Curative efficacy; Dog; Speed of kill