Exzolt is a unique parasiticide for chickens that provides potent efficacy against poultry red mites via a convenient oral solution for administration in the drinking water.
- Treatment with Exzolt provides fast, convenient and potent acaricidal efficacy, with a proven safety profile for chickens and the users of the product.
- Exzolt is approved for treatment of poultry red mite (Dermanyssus gallinae) infestation in pullets, breeders, and layer hens when provided in drinking water at 0.5 mg fluralaner/kg Body Weight, administered twice 7 days apart.
- Exzolt has a zero-day withdrawal period for eggs and a 14-day withdrawal period for meat and offal, with no contraindications, known adverse effects or known interactions.
Mode of Action
Fluralaner (carbamoyl-benzamide-phenyl-isoxazoline), the active ingredient of Exzolt, is a member of the novel antiparasitic compound class of isoxazoline-substituted benzamide derivatives. Once ingested by a mite feeding on a treated chicken, fluralaner acts as a potent inhibitor of parts of the arthropod nervous system by acting antagonistically on ligand-gated chloride channels (GABA-receptor and glutamate-receptor).
The compound has demonstrated high activity on various heterologous GABA-receptors but shows no activity on the tested mammalian GABA-receptor.2 In vitro bio-assays have shown that fluralaner is effective against parasites having proven field resistance, including organophosphates (tick, mite), pyrethroids (tick, mite), and carbamates (mite).3
Fast, Potent Efficacy
Treatment of the host with Exzolt is an innovative approach to targeting mite parasites. Convenient treatment of poultry with Exzolt causes effective levels of the acaricide to be systemically distributed within all birds, ready to kill mites when the parasites extract a blood meal from their hosts.
Efficacy against D. gallinae begins within 4 hours after exposure of mites to treated chickens, and any mites feeding on treated chickens for at least 2 weeks after the first Exzolt administration will be killed.
With Exzolt, the mite life cycle is disrupted due to:
- Rapid onset of fluralaner activity
- High mite-killing efficacy (duration of at least 2 mite life cycles)
- Absence of egg production from female mites exposed to treated chickens
Exzolt also contributes toward long-term control of mite populations in a poultry house when used in conjunction with implementation of proper biosecurity measures.
Safety profile for Chickens and People
Fluralaner offers high selectivity for arthropods like poultry mites, and the formulated product has a large safety margin demonstrated in chickens1. Safety studies demonstrated that Exzolt is well tolerated in chicks, layers and breeders. Exzolt has a zero-day withdrawal period for eggs, which is essential for large poultry units.
Exzolt also minimises the potential for exposure to chemicals by humans and reduces the workload compared to spraying. With Exzolt, house workers do not have to:
- Remove birds and/or eggs
- Repeat spray applications
- Wear extensive safety equipment
- Meet application license requirements
Fight Resistance with Exzolt
The development of resistance by mites to control agents is an ongoing concern, as with most medicinal or chemical interventions used for animal health (e.g., antimicrobials, anthelmintics, insecticides, etc.). However, fluralaner is an agent introduced in poultry veterinary medicine only in 2017 and resistance is not expected to develop for a long time due to its dual mode of action.
The Exzolt Difference
Isoxazolines like fluralaner act at previously unrecognized activity sites without cross-resistance to other chemotypes, and effects differ between insects and mammals so toxicity is selective4. In vitro bioassays have indicated that fluralaner offers efficacy against parasites with known field resistance to various chemical classes, including:
- Organophosphates (tick, mite)
- Pyrethroids (tick, mite)
- Carbamates (mite)
During dose confirmation and field studies conducted in support of Exzolt approval, 12 mite isolates were collected in 2014 and 2015 from 12 chicken houses in France, Germany and Spain. The collected isolates were tested for in vitro acaricide sensitivity to fluralaner (11 isolates) and several other acaricides (not all tested for each isolate), with the following outcomes for various agents6:
- Fluralaner: Isolates were highly susceptible to fluralaner with LC90 < 15.63 ppm.
- Phoxim: Demonstrated variable sensitivity as 6 of 11 isolates had LC90 greater than the recommended concentration for chicken houses (2,000 ppm). The average LC90 for the 11 recent isolates was 3 dilutions higher than an older isolate collected in 2011.
- Deltamethrin: 3 of 3 isolates tested had LC90 exceeding the recommended concentration for chicken houses (250 ppm).
- Propoxur: 2 of 2 isolates tested had LC90 > 1,000 ppm.
- Spinosad: 1 of 11 isolates tested had LC90 (> 4000 ppm) higher than the highest recommended concentration in the field (4000 ppm).
The Exzolt dosage regime was designed to ensure effective treatment and elimination of all mite development stages that take a blood meal from the flock, which limits resistance development. In addition, research showed that female mites dying after a blood meal from a fluralaner-treated hen were unable to lay any eggs, suggesting that the development of less sensitive mite stages from eggs is unlikely6. Correct use of Exzolt according to label directions cannot be overemphasized, such as providing the full-approved dose regime and estimating bird weights as closely as possible.
- Angella Prohaczik et al. Safety of fluralaner oral solution, a novel systemic antiparasitic treatment for chickens, in laying hens after oral administration via drinking water. Parasites & Vectors (2017) 10:363 DOI 10.1186/s13071-017-2291-5.
- Gassel M, Wolf C, Noack S, Williams H, Ilg T. The novel isoxazoline ectoparasiticide fluralaner: selective inhibition of arthropod γ-aminobutyric acid- and L-glutamate-gated chloride channels and insecticidal/ acaricidal activity. Insect Biochem Molec Biol 2014; 45:111-124.
- European Public Assessment Report (EPAR) for Exzolt. European Medicines Agency.
- Casida JE. Golden age of RyR and GABA-R diamide and isoxazoline insecticides: common genesis, serendipity, surprises, selectivity, and safety. Chem Res Toxicol 2015; 28:560-566.
- Thomas E, Zoller H, Heckeroth AR, Liebisch G, Flochlay Sigognault A. Comparative In Vitro Susceptibility Of Dermanyssus gallinae Field Isolates To Fluralaner, Phoxim, Spinosad, Deltamethrin And Propoxur- Proceedings of the WVPA 2017 Congress. Edinburgh, September 2017.
- Data on file. MSD Animal Health.