A randomized, controlled field study to assess the efficacy and safety of lotilaner flavored chewable tablets (Credelio™ CAT) in eliminating fleas in client-owned cats in the USA
Authors: Chappell Kimberly , Paarlberg Tandy , Seewald Wolfgang , Karadzovska Daniela , Nanchen Steve 
Published: March 2021

Abstract
Background
Studies show that the novel isoxazoline, lotilaner (Credelio™ CAT; Elanco Animal Health), which is administered orally to cats, provides rapid and sustained flea kill for least 1 month following administration with a wide safety margin. A clinical trial was undertaken to confirm its efficacy, impact on flea allergy dermatitis (FAD) and safety under field conditions.

Methods
A total of 343 cats were enrolled in the study at 11 veterinary clinics in the USA. Upon inclusion, cat households were randomized at a ratio of 2:1 to receive lotilaner tablets at the recommended dose (minimum 6 mg/kg) or a topical formulation containing fipronil + S-methoprene (Frontline® Plus for cats; Boehringer Ingelheim), administered per label. Owners were dispensed treatments for administration on days 0, 30 and 60; all household cats were administered the same treatment. Flea counts were made on primary cats (1 cat per household) on days 0 (pre-treatment), 30, 60 and 90. Flea allergy dermatitis was assessed on days 30, 60 and 90 for all cats with signs of FAD on day 0. Lotilaner-treated cats were also assessed for their acceptance of oral tablet administration by the pet owner, and safety was assessed for all cats in both groups.

Results
Lotilaner efficacy was 98.3, 99.9 and 99.9% on days 30, 60 and 90, respectively, while the efficacy of fipronil + S-methoprene was 61.6, 75.4 and 84.7%, respectively (P < 0.0001, within both groups and all days). Flea counts were significantly lower in the lotilaner group than in the fipronil + S-methoprene group (P < 0.0001) on each assessment day. On day 90, 98.3% of lotilaner-treated cats and 28.8% of fipronil + S-methoprene-treated cats were free of fleas. Owners successfully administered 99.5% of tablets to their cats. Total FAD score was reduced significantly following treatment in both groups by day 30 (lotilaner: P < 0.0001; fipronil + S-methoprene: P = 0.0041) and continued to decrease following multiple treatments. Total FAD scores were also significantly lower in the lotilaner group than in the fipronil + S-methoprene group on day 90 (P = 0.0006 for FAD total score). Pruritus scores were significantly lower in the lotilaner group on all assessment days.

Conclusion
A single lotilaner treatment, administered by the pet owner, was > 98% efficacious in reducing flea counts within 30 days. Three consecutive monthly lotilaner treatments resulted in nearly 100% reduction in flea infestation. In the evaluations of flea counts, number of cats free from fleas and pruritus FAD score, lotilaner was shown to be superior to fipronil + S-methoprene at all time points. Lotilaner was more efficacious than fipronil + S-methoprene and was associated with greater reduction in FAD signs. Lotilaner flavored tablets were well accepted by cats. Adverse reactions were mild and infrequent, confirming the safety of lotilaner tablets in client-owned cats.

Graphical Abstract