Laboratory evaluation of the efficacy and speed of kill of lotilaner (Credelio™) against Ixodes ricinus ticks on cats

Abstract

Background: Lotilaner, approved for dogs as a chewable tablet formulation, has separately been developed for oral use in cats (Credelio™ chewable tablets for cats), to meet the need for an easy to use, safe and rapidly effective parasiticide. It is a valid cat- and owner-friendly alternative to topical products. This manuscript describes three pivotal laboratory studies assessing the efficacy and speed of kill of lotilaner in cats against Ixodes ricinus ticks following a single oral administration, at a dose rate close to 6 mg/kg. Methods: In Studies 1 and 2, efficacy and safety were evaluated 48 h after treatment and post-treatment weekly infestations in 16 cats, against untreated controls, for 35 days. In Study 3, efficacy and safety were assessed in 8 lotilaner-treated cats until Day 35, before and after 24 h incubation of the female live ticks removed from the animals 12, 18 and 24 h after dosing and subsequent weekly infestations. Results: Efficacy was > 99% on days 23 and 37, and 100% on all other timepoints in Study 1. In Study 2 it was > 98% on Days 9 and 37, and 100% on all other days. In Study 3, on Day 0, lotilaner was > 90% efficacious, pre- and post-incubation at all time-points. On Day 7, at 12 hours after infestation, efficacy was 100%, pre- and post-incubation. On Day 14, there was a 66.5% reduction in geometric mean live tick counts in treated cats compared to controls, increasing, after incubation, to 94.4%. Afterwards, efficacy decreased below 90% while tick counts in the treated groups remained significantly lower compared to controls. At 18 hours, lotilaner was ≥ 90% efficacious through Day 37, increasing to 100% at 24 hours, on all study days, with the exception of Day 28 (98.9 and 99.1% pre- and post-incubation, respectively). There were no treatment-related adverse events. Conclusions: At the minimum dose rate of 6 mg/kg, lotilaner was efficacious against I. ricinus ticks. In addition, lotilaner was effective against this tick within 12 hours of treatment, reaching 100% efficacy within 24 hours. Lotilaner sustained a rapid kill of newly infesting I. ricinus through 35 days. By quickly killing ticks that infest cats, lotilaner has the potential to contribute to the reduction of tick-borne pathogens transmission.