The intravenous and oral pharmacokinetics of lotilaner in dogs

Efficacy and Safety of Lotilaner Ophthalmic Solution (0.25%) for the Treatment of Demodex Blepharitis: A GRADE Assessed Systematic Review and Meta-Analysis of Observational & Experimental Studies

PURPOSE

Several treatments have been in use for Demodex blepharitis, before the discovery of lotilaner, like tea tree oil and antibiotics; however, they either have irritable effects or systemic adverse effects, respectively. Lotilaner, a novel ectoparasiticide, has been proposed as a treatment for patients grappling with Demodex blepharitis. This review aims to assess the safety and efficacy of lotilaner in the treatment of Demodex blepharitis.

DESIGN

Systematic review and meta-analysis.

METHODS

An extensive search was conducted on PubMed, Cochrane Library, Scopus, and Google Scholar to find relevant literature till July 31, 2023 following the PRISMA guidelines. A total of 143 articles were retrieved by database searching, out of which 6 studies met the inclusion criteria and were included in the review. Four randomized controlled trials were included in the meta-analysis of mite eradication incidence. The review is registered with PROSPERO: CRD42023459997.

RESULTS

Lotilaner is effective in eradicating Demodex mites in individuals suffering from Demodex blepharitis according to RR for the intervention versus the control group of 3.55 (95% confidence interval [CI]: 2.87-4.40, P < .00001, I2 = 0%). The meta-analysis of clinically meaningful collarette score revealed the summary RR for the intervention versus the control group was 3.15 (95% CI: 2.56-3.89, P < 0.00001, I2 = 27%). In conclusion, the results of the included studies were comparable and consistent.

CONCLUSIONS

Our results indicated that lotilaner is an effective, well-tolerated, and promising drug in treating patients with Demodex blepharitis. Lotilaner administration and cost-effectiveness should now be contemplated for the study population as these constituents have a vital impact on its treatment success.

Comparative speed of kill provided by lotilaner (Credelio™), sarolaner (Simparica Trio™), and afoxolaner (NexGard™) to control Amblyomma americanum infestations on dogs

BACKGROUND

Canine acaricides with rapid onset and sustained activity can reduce pathogen transmission risk and enhance pet owner experience. This randomized, complete block design, investigator-masked study compared the speed of kill of Amblyomma americanum provided by three monthly-use isoxazoline-containing products.

METHODS

Eight randomized beagles per group were treated (day 0), per label, with sarolaner (combined with moxidectin and pyrantel, Simparica Trio™), afoxolaner (NexGard™), or lotilaner (Credelio™), or remained untreated. Infestations with 50 adult A. americanum were conducted on days - 7, - 2, 21, and 28, and tick counts were performed on day - 5 (for blocking), and at 4, 8, 12, 24, 48, and 72 h following treatment and subsequent infestations. Efficacy calculations were based on geometric mean live tick counts. A linear mixed model was used for between-group comparisons.

RESULTS

On day 0, only lotilaner significantly reduced an A. americanum infestation by 12 h (43.3%; P = 0.002). Efficacy of lotilaner and afoxolaner at 24 h post-treatment was 95.3% and 97.6%, respectively, both significantly different from sarolaner (74%) (P = 0.002, P < 0.001, respectively). On day 21, at 12 h postinfestation, lotilaner efficacy (59.6%) was significantly different from sarolaner (0.0%) (P < 0.001) and afoxolaner (6.3%) (P < 0.001). At 24 h, lotilaner efficacy (97.4%) was significantly different (P < 0.001) from sarolaner and afoxolaner (13.6% and 14.9%, respectively). On day 28, at 12 h postinfestation, lotilaner efficacy (47.8%) was significantly different from sarolaner (17.1%) (P = 0.020) and afoxolaner (9.0%) (P = 0.006). At 24 h, lotilaner efficacy (92.3%) was significantly different from sarolaner 4.9% (P < 0.001) and afoxolaner (0.0%) (P < 0.001). Speed of kill for sarolaner and afoxolaner, but not lotilaner, significantly declined over the study period. Following reinfestation on day 28, neither sarolaner nor afoxolaner reached 90% efficacy by 48 h. By 72 h, sarolaner efficacy was 97.4% and afoxolaner efficacy was 86.3%. Only lotilaner achieved ≥ 90% efficacy by 24 h post-treatment and 24 h postinfestation on days 21 and 28. Time to ≥ 90% efficacy following new infestations consistently occurred 24-48 h earlier for lotilaner compared with sarolaner or afoxolaner.

CONCLUSIONS

Credelio (lotilaner) has a more rapid onset of acaricidal activity against A. americanum than Simparica Trio (sarolaner-moxidectin-pyrantel) and NexGard (afoxolaner). Only lotilaner's speed of tick kill is sustained throughout the dosing period.

Recent United States Developments in the Pharmacological Treatment of Dry Eye Disease

Dry eye disease (DED) can arise from a variety of factors, including inflammation, meibomian gland dysfunction (MGD), and neurosensory abnormalities. Individuals with DED may exhibit a range of clinical signs, including tear instability, reduced tear production, and epithelial disruption, that are driven by different pathophysiological contributors. Those affected often report a spectrum of pain and visual symptoms that can impact physical and mental aspects of health, placing an overall burden on an individual's well-being. This cumulative impact of DED on an individual's activities and on society underscores the importance of finding diverse and effective management strategies. Such management strategies necessitate an understanding of the underlying pathophysiological mechanisms that contribute to DED in the individual patient. Presently, the majority of approved therapies for DED address T cell-mediated inflammation, with their tolerability and effectiveness varying across different studies. However, there is an emergence of treatments that target additional aspects of the disease, including novel inflammatory pathways, abnormalities of the eyelid margin, and neuronal function. These developments may allow for a more nuanced and precise management strategy for DED. This review highlights the recent pharmacological advancements in DED therapy in the United States. It discusses the mechanisms of action of these new treatments, presents key findings from clinical trials, discusses their current stage of development, and explores their potential applicability to different sub-types of DED. By providing a comprehensive overview of products in development, this review aims to contribute valuable insights to the ongoing efforts in enhancing the therapeutic options available to individuals suffering from DED.

Why Certain Repurposed Drugs Are Unlikely to Be Effective Antivirals to Treat SARS-CoV-2 Infections

Most repurposed drugs have proved ineffective for treating COVID-19. We evaluated median effective and toxic concentrations (EC50, CC50) of 49 drugs, mostly from previous clinical trials, in Vero cells. Ratios of reported unbound peak plasma concentrations, (Cmax)/EC50, were used to predict the potential in vivo efficacy. The 20 drugs with the highest ratios were retested in human Calu-3 and Caco-2 cells, and their CC50 was determined in an expanded panel of cell lines. Many of the 20 drugs with the highest ratios were inactive in human Calu-3 and Caco-2 cells. Antivirals effective in controlled clinical trials had unbound Cmax/EC50 ≥ 6.8 in Calu-3 or Caco-2 cells. EC50 of nucleoside analogs were cell dependent. This approach and earlier availability of more relevant cultures could have reduced the number of unwarranted clinical trials.

Long-Term Outcomes of 6-Week Treatment of Lotilaner Ophthalmic Solution, 0.25%, for Demodex Blepharitis: A Noninterventional Extension Study

PURPOSE

The aim of this study was to evaluate the long-term outcomes of lotilaner ophthalmic solution, 0.25%, in the treatment of Demodex blepharitis.

METHODS

This observational, extension study included patients with Demodex blepharitis (N = 239) who completed the Saturn-1 study and presented for the day 180 visit. All participants were assessed at days 180 and 365 after the initiation of 6-week treatment with the study drug or its vehicle.

RESULTS

The proportion of patients with 0 to 2 collarettes (grade 0) was significantly higher in the study group (N = 128 patients) than in the control group (N = 111 patients) (39.8% vs. 2.7% at day 180 and 23.5% vs. 2.9% at day 365; P < 0.0001). Similarly, the proportion of patients with ≤10 collarettes (collarette grade 0-1) in the study group was significantly higher than in the control group (70.3% vs. 18.0% at day 180 and 62.6% vs. 21.9% at day 365; P < 0.0001). In the study group, erythema continued to improve even after completion of the 6-week lotilaner treatment. No serious ocular adverse events were observed in the study group, and there was 1 treatment-related ocular adverse event in the study group, which was considered mild.

CONCLUSIONS

After 6-week treatment with lotilaner ophthalmic solution, 0.25%, for Demodex blepharitis, no long-term concerns were observed during 1 year of follow-up. A high proportion of patients with 0 to 2 collarettes (grade 0) or ≤10 collarettes (collarette grade of 0 or 1) was observed throughout 1 year of follow-up, indicating that the efficacy of lotilaner ophthalmic solution, 0.25%, against Demodex blepharitis may last well after completion of therapy.

Treatment of Demodex Blepharitis: A Prospective, Randomized, Controlled, Double-Masked Clinical Trial Comparing Topical Lotilaner Ophthalmic Solution, 0.25% Eyedrops to Vehicle

PURPOSE

To evaluate the efficacy and safety of lotilaner ophthalmic solution, 0.25% eyedrops compared to vehicle for the treatment of Demodex blepharitis.

METHODS

In this randomized, controlled, double-masked clinical trial, 54 participants were randomly assigned in a 1:1 ratio to receive either lotilaner ophthalmic solution, 0.25% (study group) or the vehicle (control group) bilaterally, twice daily for 42 days. Outcome measures were collarette cure (collarette grade 0, upper eyelid), mite eradication (mite density of 0 mites/lash), and composite cure (grade 0 for collarettes and erythema).

RESULTS

The proportion of participants achieving collarette cure (80.0% vs 15.8%; p < .001), mite eradication (73.3% vs 21.1%, p = .003) and composite cure (73.3% vs 10.5%, p < .001) at Day 42 was statistically significantly higher in the study group than the control group.

CONCLUSION

Twice-daily 42-day treatment with novel lotilaner ophthalmic solution, 0.25% is safe and effective for the treatment of Demodex blepharitis compared to the vehicle control. (Registry number: ACTRN12620000320954, dated 09/03/2020).

Lotilaner Ophthalmic Solution, 0.25%, for the Treatment of Demodex Blepharitis: Results of a Prospective, Randomized, Vehicle-Controlled, Double-Masked, Pivotal Trial (Saturn-1)

PURPOSE

The purpose of this study was to evaluate the safety and efficacy of lotilaner ophthalmic solution, 0.25%, compared with vehicle for the treatment of Demodex blepharitis.

METHODS

In this prospective, randomized, controlled, double-masked, phase 2b/3 clinical trial, 421 patients with Demodex blepharitis were randomly assigned in a 1:1 ratio to receive either lotilaner ophthalmic solution, 0.25% (study group), or vehicle without lotilaner (control group) bilaterally, twice daily for 43 days. Patients were evaluated at days 8, 15, 22, and 43. Outcome measures were complete collarette cure (collarette grade 0), clinically meaningful collarette cure (grade 0 or 1), mite eradication (0 mites/lash), erythema cure (grade 0), composite cure (grade 0 for collarettes/erythema), and drop comfort. Adverse events were also evaluated.

RESULTS

At day 43, the study group achieved a statistically significantly higher proportion of patients with clinically meaningful collarette cure (81.3% vs. 23.0%; P < 0.0001), complete collarette cure (44.0% vs. 7.4%; P < 0.0001), mite eradication (67.9% vs. 17.6%; P < 0.0001), erythema cure (19.1% vs. 6.9%; P = 0.0001), and composite cure (13.9% vs. 1.0%; P < 0.0001) than the control group. Nearly 92.0% of patients rated the study drop as neutral to very comfortable. All ocular adverse events in the study group were mild, with the most common being instillation site pain.

CONCLUSIONS

Twice-daily treatment with a novel lotilaner ophthalmic solution, 0.25% for 43 days, is safe and effective for the treatment of Demodex blepharitis compared with the vehicle control.

Efficacy of lotilaner against myiasis caused by Cochliomyia hominivorax (Diptera: Calliphoridae) in naturally infested dogs

BACKGROUND

The New World screwworm fly, Cochliomyia hominivorax, is widely distributed across South America. This parasitic insect is a significant cause of primary myiasis in animals, including dogs. There is an urgent need for a rapid and efficient treatment to improve the recovery of affected animals. In the present study we evaluated the potential of lotilaner for the treatment of myiasis caused by C. hominivorax larvae in naturally infested dogs. Lotilaner belongs to the isoxazoline class of chemical compounds and is marketed as Credelio™ for use against ticks and fleas in dogs and cats.

METHODS

Eleven dogs with naturally acquired myiasis were enrolled in this study based on the severity of lesions and the number of identified larvae. All animals received a single oral administration of lotilaner at a minimum dose of 20.5 mg/kg body weight. After treatment, the number of expelled larvae, live or dead, was determined at 2, 6 and 24 h, and the larval expulsion rate, larvicidal effect and overall efficacy were calculated. After 24 h, the remaining larvae were removed, counted and identified. The lesions were cleaned, and palliative treatment was administered when necessary, according to the animal's health status.

RESULTS

All larvae were identified as C. hominivorax. The larval expulsion rate was 80.5% and 93.0% at 2 and 6 h post-treatment, respectively. Lotilaner showed an overall efficacy of 100% at 24 h post-treatment.

CONCLUSIONS

Lotilaner demonstrated a rapid onset of action and a high efficacy against C. hominivorax. We therefore recommend lotilaner for the effective treatment of myiasis in dogs.

The Effects of Feed Intake and Water Hardness on Fluralaner Pharmacokinetics in Layer Chickens

Background

Fluralaner is a novel drug belonging to the isoxazoline class that acts on external parasites of domestic animals. It is used systemically via drinking water, especially against red poultry mite in layer chickens. Fluralaner is frequently used in layers infected with D. gallinae. However, no study to date has investigated the effects of feed intake and water hardness.

Objectives

This study aimed to investigate the effects of variable water hardness and feed intake on the pharmacokinetic profile of fluralaner.

Methods

Layer chickens were divided into four groups (n = 8): fed + purified water (Group 1), feed restricted + purified water (Group 2), feed restricted + hard water (Group 3), and feed restricted + soft water (Group 4). After administering a single dose of the drug with drinking water, the blood samples were collected for 21 days. Fluralaner concentrations in plasma samples were determined by liquid chromatography/tandem mass spectrometry. The maximum plasma concentration (C_max), time to reach maximum plasma concentration (t_max), area under the concentration–time curve values (AUC_0-21d), half-life (t_1/2), and other pharmacokinetic parameters were calculated.

Results

Although the highest maximum plasma concentration (C_max) was determined in Group 1 (fed + purified water), no statistically significant difference was found in the C_max, t_max, t_1/2, MRT_{0-inf_obs}, Vz/F_obs, and Cl/F_{_obs} parameters between the experimental groups.

Conclusions

It was concluded that the feed intake or water hardness did not change the pharmacokinetic profile of fluralaner in layer chickens. Therefore, fluralaner could be used before or after feeding with the varying water hardness in poultry industry.

Safety and Efficacy of Topical Lotilaner Ophthalmic Solution 0.25% for the Treatment of Demodex Blepharitis: A Pilot Study

Purpose

Evaluate safety and efficacy of topical lotilaner ophthalmic solution, 0.25% for the treatment of Demodex blepharitis. Patients and Methods. 15 patients with Demodex blepharitis, defined as >10 collarettes on the upper lid, lid margin erythema, and Demodex density of ≥1.5 mites/lash on microscopy, were treated bid for 28 days with lotilaner ophthalmic solution, 0.25%. Contact lens wear, artificial eyelashes, and lid structural abnormalities were among the exclusion criteria. No other antibacterial, antiparasitic, or anti-inflammatory treatment or lid hygiene products were permitted. Patients were assessed on Days 7, 14, 28, 60, and 90. Outcome measures were changes in collarette grade and mite density on Day 28. Adverse events and changes in intraocular pressure (IOP), corrected distance visual acuity (CDVA), and slit-lamp biomicroscopy were assessed.

Results

Mean collarette grade (upper lids) improved from 3.07 ± 0.21 to 0.79 ± 0.19 on Day 28; the change was statistically significant for both upper and lower lids from Day 14 on. Mean mite density per lash decreased from 2.28 ± 0.16 at baseline to 0.14 ± 0.05 at Day 28 (p < 0.0001). Mite eradication (0 mites) was documented in 57.1% of eyes. The effects were durable through Day 90. There were no adverse events and little to no change in CDVA or IOP. The drop was well tolerated, with no discontinuations due to ocular irritation.

Conclusion

Topical lotilaner ophthalmic solution, 0.25% for 4 weeks, showed promising efficacy for the treatment of Demodex blepharitis. This novel treatment appears to be safe and well tolerated. Randomized controlled studies are needed to confirm the results.

Safety and efficacy of lotilaner ophthalmic solution, 0.25% for the treatment of blepharitis due to demodex infestation: A randomized, controlled, double-masked clinical trial

PURPOSE

To evaluate the safety and efficacy of lotilaner ophthalmic solution, 0.25% for the treatment of blepharitis due to Demodex infestation compared to vehicle control.

METHODS

In this phase II, randomized, controlled, double-masked clinical trial, 60 eligible participants with Demodex blepharitis were randomly assigned in a 1:1 ratio to receive either topical lotilaner ophthalmic solution, 0.25% (Tarsus Pharmaceuticals, Inc., Irvine, CA) (study group) or the vehicle without lotilaner (control group) bilaterally twice a day for 28 days. Participants were followed at Days 7, 14, 28, 60 and 90. The efficacy parameters were change in collarette grade and Demodex density at Day 28. Safety parameters were adverse events, changes in corrected distance visual acuity (CDVA), intraocular pressure (IOP) and slit-lamp biomicroscopy.

RESULTS

The study group showed a statistically significant decrease in collarette grade compared to the control group beginning at Day 14 (p = 0.003) in the upper eyelid and at Day 28 (p = 0.003) in the lower eyelid. Decreases in both lids were maintained through Day 90 (p < 0.001). At Day 28, mite eradication was achieved in 66.7% and 25.9% of eyes in the study and control group (p = 0.005); at Day 90, these proportions were 68.2% and 18.5% (p = 0.001), respectively. No serious adverse events or clinically significant changes in CDVA and IOP were observed.

CONCLUSION

For Demodex blepharitis, treatment with lotilaner ophthalmic solution, 0.25% for 4 weeks is safe and effective. The improvement in collarette grade and mite density observed during the treatment period persisted for at least two months following treatment cessation.

Early onset of pre-lethal effects of lotilaner (Credelio®) on Amblyomma americanum ticks on experimentally infested dogs

Background

The speed with which acaricides paralyze and kill ticks is relevant to impeding pathogen transmission. The objective of this study was to assess early-onset lotilaner effects on the motility and weights of Amblyomma americanum ticks collected from treated dogs.

Methods

Twelve healthy dogs were randomized between two groups to receive either lotilaner (Credelio^®) on Day 0 or to be sham treated. On Day 7, 25 male and 25 female A. americanum were placed under bandages, two on each flank of each dog. After 30 or 45 min, all unattached ticks were removed and T = 0 was set. At T = 2, 4, 8 and 24 h post attachment, 5 attached ticks removed from each bandage on each dog were weighed, assessed by blinded observers for righting ability and movement recorded.

Results

After the infestation period significantly fewer treated than control dogs had 20 ticks attached (50.0% versus 91.7%, P = 0.0015). At 24 h post attachment, mean weights of ticks from treated dogs (males 1.69 mg; females 2.72) were significantly less than ticks from controls (males 2.66 mg; females 4.67) (P_male = 0.0002; P_female < 0.0001). Mean tick weights from the treated group were significantly lower at 24 h than at earlier time points (P_male < 0.0307; P_female = 0.0021). At 4 and 8 h, significantly fewer ticks from treated (14.3%, 0.0%, respectively) than from control dogs could right (73.3%, 70.0%) (P_4h < 0.0001; P_8h = 0.0024) (at 24 h, all ticks from treated dogs were dead), and distance moved was significantly less at all time points (P_2h = 0.0413; P_4h, P_8h < 0.0001). Mean and maximum velocity of ticks from treated dogs were significantly lower, relative to controls, at 4 and 8 h (P ≤ 0.0001). Within the treated group, collected ticks had significantly lower mean and maximum velocities at 4 and 8 h compared to 2 h (P_mean < 0.0042; P_max < 0.0194).

Conclusion

The observed changes indicate that lotilaner may disrupt tick attachment. In ticks that attached, a progressive impairment of neuromuscular processes began within 2 h. Those irreversible changes could substantially reduce the risk of pathogen transmission from tick to host.

Long-term and acute safety of a novel orally administered combination drug product containing milbemycin oxime and lotilaner (Credelio® Plus) in juvenile and adult dogs

BACKGROUND

The combination of milbemycin oxime (MO) and lotilaner (Credelio® Plus) is a novel systemic endectocide that provides month-long effectiveness in dogs after a single oral treatment. The safety of Credelio® Plus flavored chewable tablets was investigated in three target animal safety studies. Two studies (one in juveniles and one in adults) evaluated the long-term safety, and one study evaluated the acute safety of the product when administered orally at the upper end of the recommended dose range (0.75-1.53 mg/kg MO and 20-41 mg/kg lotilaner) and multiples of this dose.

METHODS

The objectives of these studies were to determine the long-term and acute safety of MO and lotilaner flavored chewable tablets in healthy dogs. All three studies were randomized, blinded, parallel-group design studies in healthy Beagle dogs. In each of the two long-term studies, 32 dogs were randomized among four groups to untreated controls or to treated groups at target doses of 1X, 3X, or 5X. Treatment was administered on seven (adult dogs) or nine (juvenile dogs) occasions with dosing every 4 weeks. In the acute study, 48 dogs were randomized among four groups to untreated controls or to treated groups at 1X, 3X, or 6X. In all three studies, the control group was administered placebo tablets. All dogs were fed 30 to 45 min prior to treatment and the assessment of safety was based on health observations, complete physical/neurological examinations, and food consumption. For the long-term safety studies, safety assessments also included clinical pathology evaluations (hematology, clinical chemistry and urinalysis), body weight, pharmacokinetic blood collections, and macroscopic and microscopic examinations of collected tissues.

RESULTS

MO and lotilaner did not induce any treatment-related adverse effects based on health observations, physical/neurological examinations, or food consumption in the long-term or acute studies. Additionally, in the long-term studies, MO and lotilaner did not induce any treatment-related effects on clinical pathology, body weight, and macroscopic and microscopic examinations.

CONCLUSIONS

These three studies demonstrate that Credelio® Plus has a wide safety margin when administered at monthly intervals to puppies and dogs at the high end of the commercial dose band.

Current review of isoxazoline ectoparasiticides used in veterinary medicine

The isoxazolines are a novel class of ectoparasiticides with potent inhibitory activity on glutamate- and gamma-aminobutyric acid-gated chloride channel located in nervous system of invertebrates. In recent years, studies have been performed to evaluate the efficacy and safety of isoxazolines against various types of ectoparasites, including fleas, ticks, and mites. As more single and combined isoxazoline products have been approved by the United States Food and Drug Administration and European Medicines Agency, a more comprehensive understanding of isoxazolines becomes essential for veterinary clinical practitioners. This article provides a complete review of isoxazolines with respect to pharmacodynamics, pharmacokinetics, ectoparasiticidal efficacy, and safety, which will provide veterinarians information to allow them to make the best choice of ectoparasiticide for their clients' specific needs.

Discovery, development, chemical diversity and design of isoxazoline-based insecticides

Isoxazoline is a 5-membered heterocycle present in the active compounds of many commercial veterinary anti-ectoparasitic products. The molecular target of isoxazolines is the inhibition of GABA-gated chloride channels in insects. These facts have inspired the use of the isoxazoline scaffold in the design of novel insecticide compounds. The main strategies used for isoxazoline synthesis are either the 1,3-dipolar cycloaddition between a nitrile oxide and an alkene or the reaction between hydroxylamine and an α,β-unsaturated carbonyl compound. This review highlights the utilization of isoxazoline as insecticide: its mode of action, its commercial preparations and its consideration in the design of novel insecticides. Similarity analyses were performed with 235 isoxazoline derivatives in three different cheminformatic approaches - chemical property correlations, similarity network and compound clustering. The cheminformatic methodologies are interesting tools to use in evaluating the similarity between commercial isoxazolines and to clarify the main features explored within their derivatives.

Efficacy of lotilaner (Credelio™) against the adult cat flea, Ctenocephalides felis and flea eggs following oral administration to dogs

BACKGROUND

A blinded, randomized, negative controlled laboratory study was conducted to evaluate the efficacy of lotilaner (CredelioTM, Elanco) when administered orally to dogs, against experimentally induced adult flea infestations and flea egg production.

METHODS

Twenty dogs were selected for the study and allocated to two treatment groups. Ten dogs were treated with lotilaner (at the lower half of the recommended dose range of 20-43 mg/kg) on Day 0. Ten dogs treated with placebo tablets served as the control group. Each dog was infested with 100 unfed adult C. felis fleas on days -1, 6, 13, 20 and 29. At 24 h post-treatment or post-infestation, each dog was combed for the removal and counting of adult live fleas. Flea eggs were also collected and counted from the pan under each dog cage.

RESULTS

Dogs in the lotilaner treated group received a mean dose of 22.6 mg/kg (range 20.2-25.9 mg/kg) and no adverse events were observed in any dog in this study. At each evaluation time point, the lotilaner group provided 100% efficacy against adult live flea counts as compared to the placebo control group. Egg production from lotilaner treated dogs was reduced by 98.5% (geometric mean; 97.4% arithmetic mean) 24 h post-treatment (and 48 h post-flea infestation). No eggs (100% efficacy) were available for collection following infestations on Day 6 onwards from the lotilaner treated dogs. At each evaluation time point, adult live flea counts from the lotilaner treated dogs were significantly lower (P < 0.0001) than from the placebo control group.

CONCLUSIONS

In dogs treated with a single dose of lotilaner (mean dose 22.6 mg/kg), 100% of adult fleas were killed within 24 h post-treatment or post-subsequent infestations as compared to the placebo control group, thereby demonstrating that lotilaner kills fleas before they can lay eggs thus preventing subsequent flea infestations for 30 days after treatment. There were no reported adverse events in any dogs, demonstrating that lotilaner tablets were well tolerated at the dose rates assessed in this study.

Optimising systemic insecticide use to improve malaria control

Background

Long-lasting insecticidal nets and indoor residual sprays have significantly reduced the burden of malaria. However, several hurdles remain before elimination can be achieved: mosquito vectors have developed resistance to public health insecticides, including pyrethroids, and have altered their biting behaviour to avoid these indoor control tools. Systemic insecticides, drugs applied directly to blood hosts to kill mosquitoes that take a blood meal, offer a promising vector control option. To date, most studies focus on repurposing ivermectin, a drug used extensively to treat river blindness. There is concern that overdependence on a single drug will inevitably repeat past experiences with the rapid spread of pyrethroid resistance in malaria vectors. Diversifying the arsenal of systemic insecticides used for mass drug administration would improve this strategy’s sustainability.

Methods

Here, a review was conducted to identify systemic insecticide candidates and consolidate their pharmacokinetic/pharmacodynamic properties. The impact of alternative integrated vector control options and different dosing regimens on malaria transmission reduction are illustrated through mathematical model simulation.

Results

The review identified drugs from four classes commonly used in livestock and companion animals: avermectins, milbemycins, isoxazolines and spinosyns. Simulations predicted that isoxazolines and spinosyns are promising candidates for mass drug administration, as they were predicted to need less frequent application than avermectins and milbemycins to maintain mosquitocidal blood concentrations.

Conclusions

These findings will provide a guide for investigating and applying different systemic insecticides to achieve more effective and sustainable control of malaria transmission.

In-home assessment of flea control and dermatologic lesions in dogs provided by lotilaner (Credelio®) and spinosad (Comfortis®) in west central Florida

Post-launch field investigations of recently-approved flea control products establish an efficacy baseline and in subsequent years can detect any efficacy decline suggestive of emerging resistance. As part of a continuing program of yearly assessment of flea control products in west central Florida, this study, using client-owned dogs, investigated the efficacy of lotilaner and spinosad in controlling fleas and in alleviating dermatologic signs likely associated with flea infestations. Forty-four qualifying households were randomized to either a lotilaner (Credelio®) (minimum dose rate 20 mg/kg) or a spinosad (Comfortis®) (30 mg/kg) group, with 33 and 36 dogs in each group, respectively. On Days 0 and 28 (±2) all dogs in each household were treated with the allocated product according to label directions, and all household cats received spinetoram (Cheristin®). On Day 0 and at weekly intervals through Day 56 (±2), on-animal and premises flea burdens were enumerated, a veterinary dermatologist scored integumental changes using canine atopic dermatitis extent and severity index (CADESI)-4 and flea allergy dermatitis (FAD) scales, and owners scored pruritus using the validated canine pruritus severity scale (CPSS). At study entry geometric mean flea counts were 33.2 and 29.9 in the lotilaner and spinosad groups, respectively. For both groups, reductions in flea counts were > 99% at the first post-treatment assessment (Week 1), and 100% from Week 6 through the final assessment (Week 8) when all study dogs were flea-free. For both groups, at each timepoint, flea counts on dogs and in traps were significantly reduced compared to the initial assessment (p < 0.001), as were improvements in median CADESI-4, FAD and CPSS scores (p ≤ 0.001). At Week 4, the geometric mean flea count on dogs in the lotilaner group (0.1) was significantly lower than that of dogs in the spinosad group (0.6) (p = 0.027), significantly fewer dogs in the lotilaner group were found to have fleas (p = 0.034), and mean owner-rated pruritus scores were significantly lower (p = 0.025). Under field conditions favoring heavy flea challenge, two consecutive monthly treatments of dogs with either lotilaner or spinosad produced a 100% reduction in canine flea infestations and dramatic improvements in dermatologic lesions and pruritus, based on scoring by a veterinary dermatologist and by dog owners. Household flea burdens were driven to extinction in all but one home in each treatment group.

Laboratory evaluation of the efficacy of lotilaner (Credelio™) against Amblyomma cajennense (sensu lato) infestations of dogs

BACKGROUND

The ixodid tick Amblyomma cajennense (sensu lato) complex, widespread throughout South and Central America, is also present in Mexico, Texas and Florida. As a vector of Rickettsia rickettsii, and potentially of other pathogens, infestations with A. cajennense present a substantial health risk to humans, dogs and other mammals. Oral administration of lotilaner flavored chewable tablets (CredelioTM, Elanco) to dogs was previously shown to rapidly provide killing activity of infesting ticks. This study investigated lotilaner's efficacy against A. cajennense (s.l.).

METHODS

Twenty purpose-bred Beagles (10 male and 10 female) were ranked by Day -5 burdens of nymphal A. cajennense (s.l.) and randomized to either treatment with lotilaner or to a sham-treated control group. On Day 0, dogs were fed within approximately 30 min prior to oral lotilaner administration at as close as possible to 20 mg/kg, the minimum dose rate. For efficacy assessments, tick counts were completed 48 h post-treatment or 48 h after experimental challenge infestations with 200 nymphal A. cajennense (s.l.) on Days -7, -2, 7, 14, 21 and 28.

RESULTS

Tick infestations in the control group dogs ranged from a low of 43 to 95, with the average infestation remaining above 25% at each assessment, thereby meeting the requirement for efficacy comparison with the treated group. Lotilaner efficacy was 100% within 48 h post-treatment, and at nine days post-treatment. Efficacy was greater than 99% at all subsequent assessments through Day 30. No treatment-related adverse events were observed.

CONCLUSION

The results demonstrate that lotilaner, administered orally to dogs at a minimum dose of 20 mg/kg is well tolerated, provides rapid reduction of existing A. cajennense (s.l.) tick infestations, and provides sustained residual protection for at least 30 days against subsequent infestation by A. cajennense (s.l.).

Laboratory evaluations of the 3-month efficacy of oral lotilaner (Credelio™) against experimental infestations of dogs with the Australian paralysis tick, Ixodes holocyclus

BACKGROUND

From three days following host attachment, the Australian paralysis tick, Ixodes holocyclus, secretes a neurotoxin that annually causes paralysis in approximately 10,000 domestic pets. Lotilaner, a novel isoxazoline formulated in a chewable flavoured tablet (CredelioTM), produces rapid onset of acaricidal activity in dogs, with an efficacy duration of at least one month. Two studies were performed to determine the efficacy of lotilaner against I. holocyclus infestations over 3 months.

METHODS

Both studies included 16 dogs, ranked according to I. holocyclus counts on Day -5 (from infestations on Day -8) and blocked into pairs. One dog in each pair was randomized to be a sham-treated control, the other to receive lotilaner at a minimum dose rate of 20 mg/kg on Day 0. Dogs were dosed in a fed state. Infestations were performed in both studies on Days -8 (to determine the tick carrying capacity of each dog) -1, 28, 56, 70, 77 and 84, and additionally in Study 1 on Day 91, in Study 2 on Days 14 and 42. In Study 1, ticks were counted and assessed as alive or dead at 24, 48 and 72 h post-initial infestation and post-subsequent re-infestations. In study 2, ticks were counted at 24, 48 and 72 h post-dosing or post-re-infestation. Efficacy was determined by the percent reduction in live attached tick counts in the lotilaner group compared to control.

RESULTS

Within 48 h post-treatment in Study 1 and within 72 h post-treatment in Study 2 all lotilaner-group dogs were free of live ticks. By 72 h post-infestation, efficacy in Study 1 remained at 100% through Day 87, except on Day 31 when a single tick was found on one dog, and through Day 59 in Study 2. Efficacy exceeded 95% through the final assessment in each study (Days 94 and 87 in Studies 1 and 2, respectively).

CONCLUSION

These results demonstrate that lotilaner quickly kills existing I. holocyclus infestations. By providing 95.3-100.0% protection through at least 87 days post-treatment, lotilaner can be a valuable tool in reducing the risk of tick paralysis in dogs.

Laboratory evaluation of the efficacy of lotilaner (Credelio™) against Haemaphysalis longicornis infestations of dogs

Background

Throughout Japan, Korea and China, Haemaphysalis longicornis ticks are vectors of Babesia gibsoni, which causes severe and progressive anemia in dogs. This study evaluated the efficacy of a single administration of lotilaner flavored chewable tablets (Credelio^TM) against experimental canine H. longicornis infestations.

Methods

Twenty-two healthy Beagles were ranked in descending order of counts of H. longicornis completed 48 h after challenge on Day -7. The 16 dogs with the highest live tick counts were blocked into pairs and within pairs randomized to either lotilaner-treatment at a minimum dose rate of 20 mg/kg or sham-treated controls. Treatment was administered within 30 ± 5 min following feeding on Day 0. Infestations with 50 unfed adult H. longicornis were completed on Days -2, 7, 14, 21, 28 and 35. Elizabethan collars were placed for 48 (± 2) h after each infestation and a T-shirt was placed on each dog to facilitate attachment. Ticks were counted in situ 12 and 24 h post-treatment and counted and removed after an additional 24 h (48 h after treatment) and 48 h after each post-treatment infestation. Dogs were sedated for tick challenges and counts. Live attached ticks on each dog were counted for efficacy assessments. Lotilaner was considered effective if the average tick attachment rate in the control group was at least 20%, if there was a statistically significant difference (P < 0.05) in mean tick counts between treated and control groups, and if the lotilaner-treated group had a calculated efficacy of at least 90%.

Results

Average control group retention of the H. longicornis challenge exceeded 20% at each assessment. Lotilaner started killing H. longicornis ticks quickly, achieving 57.4% efficacy within 12 h. At 48 h post-treatment, and following each subsequent infestation, between-group differences in mean H. longicornis counts were significant (P < 0.0001). From 48 h post-treatment, through the final assessment on Day 37, lotilaner efficacy remained greater than 95%, including on Day 37 when efficacy was 98.4%.

Conclusion

Lotilaner, administered to dogs orally at a minimum dose rate of 20 mg/kg is well tolerated, provides rapid reduction of existing H. longicornis tick infestations, and provides sustained residual protection for at least 35 days.

Pharmacokinetics of lotilaner following a single oral or intravenous administration in cats

BACKGROUND

CredelioTM (lotilaner) is an oral ectoparasiticide from the isoxazoline class developed for the treatment of flea and tick infestations in cats. It is formulated as a pure S-enantiomer in flavoured chewable tablets. The pharmacokinetics of lotilaner were investigated after intravenous or oral administration and under fed or fasted conditions in cats. Twenty-six adult cats were enrolled in a pharmacokinetic study evaluating either intravenous or oral administration of lotilaner. Following the oral administration at a dosage of 6 mg/kg, under fed or fasted conditions, or intravenous administration of 3 mg/kg, blood samples were collected up to 35 days after treatment. Lotilaner blood concentrations were measured using a validated liquid chromatography/tandem mass spectrometry method. Pharmacokinetic parameters were calculated by non-compartmental analysis. In addition, in vivo enantiomer stability of lotilaner was evaluated in a separate bioanalytical study.

RESULTS

Following oral administration in fed cats, lotilaner was readily absorbed and peak blood concentrations reached within four hours. The terminal half-life was 33.6 days. Food enhanced the absorption, providing close to 100% oral bioavailability and reduced the inter-individual variability. Following intravenous administration, lotilaner had a low clearance of 0.13 l/kg/day, large volumes of distribution Vz and Vss of 5.34 and 5.37 l/kg, respectively and a terminal half-life of 28.7 days. In addition, there was no in vivo racemization of lotilaner.

CONCLUSIONS

The pharmacokinetic properties of lotilaner administered orally as a flavoured chewable tablet (CredelioTM) were studied in detail. With a Tmax of 4 h and a terminal half-life of 33.6 days under fed conditions, lotilaner provides a rapid onset of flea and tick killing activity with consistent and sustained efficacy for at least one month in cats.

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

BACKGROUND

With the geographical expansion of tick species and increased recognition of pathogens they transmit, there is a requirement for safe and rapidly effective control measures for dogs. Lotilaner, a novel isoxazoline, is rapidly absorbed following administration of a flavored chewable tablet formulation (Credelio™), providing at least 98% efficacy for at least 1 month following assessments at 48 h post-treatment, and following subsequent challenges. A study was conducted to determine the speed with which lotilaner kills ticks.

METHODS

From 38 dogs, the 32 with the highest Ixodes ricinus counts from a Day -4 infestation were randomized among four groups: two groups were untreated controls, two received lotilaner tablets at a minimum dose rate of 20 mg/kg. Infestations with I. ricinus were performed on Days -2, 7, 14, 21, 28 and 35. Counts were completed 4 and 8 h post-treatment (Day 0), and 8 and 12 h following subsequent infestations. All live ticks were incubated for 24 h following removal from study dogs.

RESULTS

At 4 h post-treatment, there was a 69.8% reduction in geometric mean live tick counts in treated dogs compared to controls. After incubation, the reduction increased to 97.2%. At 8 h after treatment, pre- and post-incubation reductions were 99.2 and 100%, respectively. Following post-treatment challenges, post-incubation efficacy through Day 28 at 8 and 12 h was at least 94.3 and 98.0%, respectively, and was 85.7 and 94.2% at 8 and 12 h after the Day 35 challenge. Mean live tick counts in the lotilaner groups were significantly lower than in the control groups at all assessments through Day 35 at 8 (t ₍₇₎ ≥ 9, P < 0.0001, Days 0 to 28; t ₍₇₎ = 3.54, P ≤ 0.0095, Day 35) and 12 h post-treatment and after subsequent infestations (t ₍₇₎ ≥ 10, P < 0.0001, all days). There were no treatment-related adverse events.

CONCLUSION

Lotilaner at a minimum dose rate of 20 mg/kg began to kill ticks on dogs within 4 h of treatment and efficacy was 100% within 8 h. Lotilaner sustained a rapid kill of newly infesting I. ricinus through 35 days. By quickly killing ticks that infest dogs, lotilaner has potential to help limit the transmission of tick-borne pathogens.

Laboratory evaluations of the immediate and sustained effectiveness of lotilaner (Credelio™) against three common species of ticks affecting dogs in Europe

BACKGROUND

There is a continuing need for novel approaches to tick control in dogs. One such approach lies in the ability of lotilaner (Credelio™), an isoxazoline with a rapid onset of action, to provide sustained efficacy against ticks. Two studies were undertaken to confirm lotilaner's efficacy, at the minimum dose rate of 20 mg/kg, against the three most common tick species in Europe.

METHODS

In each of two studies, 16 Beagle dogs, at least 6 months old, were ranked and blocked by tick counts from infestations placed approximately 1 week before treatment. Within blocks, dogs were randomized to receive either lotilaner flavoured chewable tablets at as close as possible to, but not less than the minimum dose rate of 20 mg/kg, or to be sham-treated controls. Study 1 assessed lotilaner efficacy against concurrent infestations with 50 (± 6) Rhipicephalus sanguineus and 70 (± 6) Ixodes ricinus; Study 2 infestations were with 50 (± 2) Dermacentor reticulatus. Infestations were performed on Day -2 with counts on Day 2, 48 (± 2) hours post-treatment. Post-treatment infestations were performed on Days 7, 14, 21, 28 and 35, and ticks were counted 48 (±2) hours post-infestations. Efficacy was determined by the percent reduction in mean live tick counts.

RESULTS

Control group infestations for each tick species were adequate for assessing lotilaner efficacy at all assessment times. On Day 2 no live ticks were found on any lotilaner-treated dog. For subsequent counts, in Study 1 lotilaner was 100% effective in eliminating live I. ricinus and R. sanguineus on all but two occasions for each tick; on each of those occasions efficacy was sustained at greater than 98.0%. In Study 2, except for a single unattached live tick found on Day 16, efficacy against D. reticulatus was 100% at every post-treatment assessment.

CONCLUSION

The high and sustained efficacy against the three common species of ticks in Europe, R. sanguineus, I. ricinus and D. reticulatus, demonstrates that lotilaner can be a valuable tool in the treatment of canine tick infestations. Lotilaner flavoured chewable tablets were well tolerated and effectiveness was sustained through at least 35 days.

Safety evaluation of lotilaner in dogs after oral administration as flavoured chewable tablets (Credelio™)

BACKGROUND

Lotilaner (Credelio™, Elanco) is a novel isoxazoline that provides rapid speed of flea and tick knockdown which is sustained for at least 1 month following oral administration to dogs. The safety of lotilaner flavoured chewable tablets was investigated in a randomized, blinded, parallel-group design study in healthy Beagle puppies starting at 8 weeks of age. Lotilaner was administered orally once a month over 8 months at one, three and five times the upper level of the recommended dose range (of 20 to 43 mg/kg).

METHODS

The objective of this study was to determine the safety of lotilaner flavoured chewable tablets in healthy dogs when administered monthly over an extended time period at the highest recommended dose rate, i.e. 1× and at elevated dose rates, i.e. 3× and 5×. Sixteen male and 16 female healthy 8-week-old puppies, weighing ~1.5 to 3.0 kg, were randomized among four groups to be untreated controls or to receive lotilaner at dose rates of 43 mg/kg (1×), 129 mg/kg (3×), or 215 mg/kg (5×) on eight occasions - every 4 weeks over 8 months. The control group was sham-dosed. Study dogs were fed within 30 min prior to treatment. Assessment of safety was based on general health observations, detailed clinical observations, complete physical/neurological examinations, including ophthalmological examinations and clinical pathology evaluations (haematology, clinical chemistry and urinalysis), food and water consumption, body weight, pharmacokinetic blood collections, macroscopic and microscopic examinations.

RESULTS

Blood concentrations of lotilaner confirmed systemic exposure of all study dogs with the exception of the control group. Lotilaner did not induce any treatment-related effects on body weight, food consumption, opthalmoscopic, physical/neurological and electrocardiographic examinations. For clinical pathology, no changes related to treatment were noted. There were no treatment-related changes in gross examinations. After microscopic examinations, minor findings recorded in kidneys were of no toxicological relevance. Changes in the reproductive tissues were attributed to the peri-pubertal age and growth of the animals.

CONCLUSIONS

Lotilaner was well-tolerated in healthy puppies at 8 week of age when administered once monthly on eight occasion over 8 months at the highest recommended dose and at three and five-fold overdose.

A randomised, blinded, controlled field study to assess the efficacy and safety of lotilaner tablets (Credelio™) in controlling fleas in client-owned dogs in European countries

Background

Lotilaner is a novel isoxazoline developed for oral administration to dogs. In laboratory studies, lotilaner was shown to be safe and to produce a rapid flea and tick knockdown, with a sustained speed of kill for at least a month post-treatment. A study was undertaken to demonstrate the efficacy, safety and palatability of three monthly doses of lotilaner flavoured chewable tablets (Credelio™, Elanco) in controlling fleas under field conditions in Europe.

Methods

Dogs were enrolled at 17 veterinary clinics across Germany, Hungary and Portugal. Qualifying households having no more than three dogs and one primary dog with at least five fleas was randomised 2:1 to a lotilaner (minimum dose rate 20 mg/kg) or a topical fipronil group (administered per label). There were 128 and 64 households allocated to the lotilaner and fipronil groups, respectively. Treatments were dispensed to owners on Days 0, 28 and 56; supplementary household dogs received the same treatment as the primary dog. Post-enrollment flea counts and flea allergy dermatitis (FAD) assessments were made on primary dogs on Days 14, 28, 56 and 84. Efficacy calculations were based on geometric mean percent reductions of live flea counts versus pre-treatment counts on Day 0. The safety and palatability of lotilaner tablets were also assessed.

Results

Lotilaner efficacy was 99.1, 99.5, 99.9 and 99.8% on Days 14, 28, 56 and 84, respectively. Corresponding reductions for fipronil were 93.4, 91.2, 94.4 and 97.0%. Lotilaner was superior to fipronil at all post-Day 0 assessments (t₍₁₈₆₎ ≥ 3.43, P ≤ 0.0007). At every post-treatment assessment, at least 90% of lotilaner-treated dogs were flea-free (98.4% on Day 84); fewer than 90% of fipronil group dogs were flea-free on the same time points. Lotilaner flavoured chewable tablets were palatable, and both products were well tolerated. Lotilaner alleviated or eliminated clinical signs of FAD, including pruritus.

Conclusions

Under field conditions in Europe, lotilaner flavoured chewable tablets were greater than 99% effective in eliminating fleas from dogs at the first post-treatment assessment (Day 14). Efficacy was maintained through Day 84, with corresponding improvements in FAD. Lotilaner tablets were palatable and safe and provided superior flea control to fipronil.

Electronic supplementary material

The online version of this article (10.1186/s13071-017-2479-8) contains supplementary material, which is available to authorized users.

Laboratory evaluations of the immediate and sustained efficacy of lotilaner (Credelio™) against four common species of ticks affecting dogs in North America

BACKGROUND

Effective control of tick infestations on dogs is important to reduce the risk of transmission of bacterial, viral, and protozoal pathogens. Laboratory studies were initiated to determine the efficacy of lotilaner against common ticks infesting dogs in the United States.

METHODS

Eight studies investigated the efficacy of lotilaner against ticks. In two studies dogs were infested with both Dermacentor variabilis and Rhipicephalus sanguineus: one additional study was completed for each of these species. Two studies assessed infestations with Amblyomma americanum and two with Ixodes scapularis. In all studies, dogs were ranked and blocked by counts from pre-treatment infestations and randomly allocated, at least eight per group, to be treated orally with lotilaner (minimum dose rate 20 mg/kg), or to be untreated controls. Treatments were administered on Day 0, within 30 min after dogs were fed. In all studies, infestations were performed with 50 adult ticks on Days -2, 7, 14, 21 and 28, and also on Day 35 for R. sanguineus, D. variabilis and I. scapularis. Tick counts were completed 48 h after treatment or after each subsequent challenge. An adequate infestation was defined as at least 25% of the infestation dose recovered from each of at least six control animals at each evaluation. Efficacy calculations for the primary objective were based on geometric means.

RESULTS

In all studies, lotilaner was 100% effective against existing infestations. For post-treatment assessments, on only two occasions did efficacy fall below 99%: in one D. variabilis study efficacy was 98.0% on Day 35 and in one I. scapularis study efficacy on Day 16 was 98.4%. Only mild and transient adverse events were observed, and none were considered to be related to treatment.

CONCLUSION

Lotilaner was completely effective against existing infestations with four common species of ticks, D. variabilis, R. sanguineus, A. americanum and I. scapularis, that affect dogs in North America, with at least 4 weeks efficacy of 98.0% or more against subsequent challenge infestations. These results show that lotilaner is a highly effective isoxazoline that offers sustained efficacy against ticks through and beyond the one-month end-of-dose treatment interval.

Assessment of the speed of flea kill of lotilaner (Credelio™) throughout the month following oral administration to dogs

Background

Lotilaner (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.

Methods

Four 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.

Results

On 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.

Conclusion

Lotilaner’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.

Electronic supplementary material

The online version of this article (10.1186/s13071-017-2466-0) contains supplementary material, which is available to authorized users.

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.

Electronic supplementary material

The online version of this article (10.1186/s13071-017-2474-0) contains supplementary material, which is available to authorized users.