WO2009023014A1

WO2009023014A1 - Emamectin compositions and methods

Info

Publication number: WO2009023014A1
Application number: PCT/US2007/023277
Authority: WO
Inventors: John Stephen Clark
Original assignee: Alpharma, Inc.
Priority date: 2007-08-13
Filing date: 2007-11-05
Publication date: 2009-02-19

Abstract

Disclosed is a multiparticulate in- feed additive composition comprising Emamectin or a salt thereof, a method of manufacturing the multiparticulate in- feed additive composition, a medicated fish- feed comprising the multiparticulate in- feed additive composition, and a method of eliminating or reducing or preventing parasites in a fish population.

Description

EMAMECTIN COMPOSITIONS AND METHODS

BACKGROUND

[0001] The control of sea lice (e.g., Lepeophtheirus salmonis and Caligus elongatus) infestations in commercial fish farming operations, for example, is largely dependent on the use of chemical treatments. Typically, in fish farming operations, infestations are chemically treated by immersion bath treatments to reduce parasites. Immersion bath treatments, however, are very labor intensive, costly and cause considerable stress to fish. Furthermore, such treatments may not be feasible on exposed sites and during adverse weather conditions. An alternative to immersion bath treatments is in-feed treatment. In-feed treatment allows medication during adverse weather conditions and on exposed sites, and permits simultaneous medication of all cages on a site and all sites in a lake, reservoir or loch system or in a single bay, thus reducing any cross infestation that may occur during the several days necessary to apply bath treatments to all cages on a site.

[0002] Emamectin, 4'-deoxy-4' epimethylaminoavermectin Bi, has been shown to be effective for in-feed treatments against sea lice. A commercially available Emamectin composition is SLICE^® (Emamectin benzoate 0.2% Aquaculture Premix), produced by Schering-Plough Animal Health. SLICE^® is indicated for the treatment and prevention of lice infestations in salmonids caused by Lepeophtheirus salmonis, Caligus elongatus, Caligus teres and Caligus rogercressyi.

BRIEF SUMMARY

[0003] The above-described and other drawbacks are alleviated by the in-feed additive composition comprising Emamectin or a salt thereof described herein.

[0004] hi one embodiment, a multiparticulate in-feed additive composition comprises a plurality of granular cores, a first coating disposed on the granular cores comprising a hydrogel-forming polymer and Emamectin or a salt thereof, and a third coating disposed on the first coating comprising a film-forming polymer and a taste-masking polymer. [0005] In another embodiment, a method of making a multiparticulate in-feed additive composition, comprises coating a plurality of granular cores with a first coating comprising a hydrogel forming polymer and Emamectin or a salt thereof to form a plurality of first coated granular cores, and coating the plurality of first coated granular cores with a third coating comprising a film- forming polymer, and a taste-masking polymer or an enteric polymer.

[0006] In another embodiment, there is provided a medicated fish feed comprising the multiparticulate in-feed additive composition described herein.

[0007] In yet another embodiment, there provided a method of eliminating or reducing parasites in a fish population comprising administering to a fish population the multiparticulate in feed additive composition described herein.

[0008] The above-described and other features will be appreciated and understood by those skilled in the art from the following detailed description and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 illustrates the Feed Conversion Ratio ("FCR") in test fish (Sea Bass, Lates calcarifer). Control refers to fish fed with a fish feed containing no multiparticulate in- feed additive composition, while Test refers to fish fed with a medicated fish feed containing a multiparticulate in-feed additive composition described herein. The medicated fish feed is administered on a seven day on, seven day off regimen.

[0010] Figure 2 illustrates the reduction of sea lice infestations in test fish (Sea Bass, Lates calcarifer) administered a medicated fish feed containing a multiparticulate in-feed additive composition described herein.

[0011] Figure 3 is a scanning electron micrograph of a conventionally prepared Emamectin benzoate premix at 50X magnification.

[0012] Figure 4 is a scanning electron micrograph of an inventive Emamectin benzoate composition at 50X magnification. DETAILED DESCRIPTION

[0013] Disclosed herein are improved Emamectin in-feed additive compositions suitable for aquaculture applications. The Emamectin in-feed additive composition comprises a multiparticulate in-feed additive composition. The term multiparticulate is intended to refer broadly to small particles regardless of their composition or the manner in which they are formed. The particles generally are of a mean diameter of about 50 to about 1000 μm, specifically about 100 to about 500 μm.

[0014] hi one embodiment, the multiparticulate in-feed additive composition comprises a plurality of granular cores having disposed thereon Emamectin or a salt thereof. The granular cores comprises cores generally acceptable for veterinary medicine or pharmaceuticals, e.g., granular cores are non-toxic, do not react with the Emamectin or its salts that is coated thereon. Suitable granular cores include water soluble and water insoluble cores such as, for example, sugar spheres, beads, pharma beads, Nonpareils (e.g., pharma beads), ion-exchange resin beads, spheroids, microspheres, seeds, pellets, granules, microcrystalline cellulose spheres, other multiparticulate materials, and combinations comprising one or more of the forgoing cores.

[0015] The granular cores comprise 50 wt% to 90 wt%, specifically 60 wt% to 90 wt% of the total weight of the multiparticulate Emamectin in-feed additive composition.

[0016] The granular cores are coated with one or more coatings comprising the Emamectin or salt thereof and other coating components to impart the desired properties to the multiparticulate in-feed additive composition. For example, the coatings provide the multiparticulate in- feed additive composition with desired release profile of the Emamectin in the digestive system of a target organism, taste-masking properties, and/or other desired properties.

[0017] The granular cores of the multiparticulate in-feed additive composition have disposed thereon a first coating composition comprising Emamectin or a salt thereof and a hydrogel-forming polymer.

[0018] Emamectin (4'-deoxy-4' epimethylaminoavermectin B i), which can be prepared as described in U.S. Pat. No. 5,288, 710 or 5,399,717, is a mixture of two homologues, 4'-deoxy-4'-epi-methylaminoavermectin BIa and 4'-deoxy-4'-epi- methylaminoavermectin BIb. In one embodiment, a salt of Emamectin is employed. Non- limiting examples of salts of Emamectin which may be used include the salts described in U.S. Pat. No. 5,288,710, incorporated herein by reference. Suitable salts include, for example, salts derived from benzoic acid, substituted benzoic acid, benzenesulfonic acid, citric acid, phosphoric acid, tartaric acid, maleic acid, and the like, and combinations comprising one or more of the foregoing salts. In a specific embodiment, the Emamectin salt comprises Emamectin benzoate.

[0019] The first coating also comprises a hydrogel-forming polymer. Hydrogel- forming polymers are polymers that form an insoluble network that swells in aqueous solutions. Both natural and synthetic hydrogel-forming polymers that are capable of swelling and releasing the Emamectin or salt thereof in the gastrointestinal tract may be employed. Suitable hydrogel-forming polymers include, for example, alginate, carrageenan, agar, agarose, polysaccharides, natural gum, fucoidan, furcellaran, laminaran, hypnea, gum arabic, gum ghatti, gum karaya, gum tragacanth, locust bean gum, pectin, amylopectin, gelatin, casein, albumen, a hydrophilic colloid, polyvinyl alcohol, sodium polyacrylate, acrylate polymers and copolymers with hydrophilic groups, and combinations comprising one or more of the foregoing hydrogel-forming polymers. In one embodiment, the hydrogel-forming polymer comprises alginate.

[0020] The first coating optionally comprises one or more pharmaceutically acceptable excipients such as, for example, a binder. Exemplary binders include, for example, polyvinyl pyrrolidone, hydroxypropyl cellulose, hydroxypropyl methylcellulose, methylcellulose and hydroxyethyl cellulose, sugars, modified starch, gelatin, albumen, caseins, polyvinyl alcohol, and combinations comprising one or more of the foregoing binders.

[0021] The Emamectin or salt thereof in the first coating comprises 0.05 wt% to 1 wt%, specifically 0.1 wt% to 0.5 wt% of the total weight of the multiparticulate Emamectin in- feed additive composition. The hydrogel-forming polymer in the first coating comprises 0.01 wt% to 12 wt%, specifically 0.05 wt% to 10 wt% of the total weight of the multiparticulate Emamectin in-feed additive composition. The optional excipient comprises 0 wt% to 10 wt % of the total weight of the multiparticulate Emamectin in-feed additive composition.

[0022] A second coating comprising a barrier material is optionally disposed on the first coating. A "barrier material" is a material that separates the first coating from subsequent coatings. In one embodiment, the barrier material imparts hydrophobicity to the coating without compromising digestibility. Suitable barrier materials include, for example, naturally occurring gums, e.g., gum acacia or gum tragacanth; naturally occurring phosphatides, e.g., lecithin or soybean lecithin; condensation products of ethylene oxide with e.g., a fatty acid, a long chain aliphatic alcohol, or a partial ester derived from fatty acids and a hexitol or a hexitol anhydride, for example polyoxyethylene stearate; polyoxyethylene sorbitol monooleate; polyoxyethylene sorbitan monooleate etc., and combinations comprising one or more of the foregoing. In one embodiment, the barrier material comprises lecithin. The barrier material of the optional second coating comprises 0 to 10 wt%, specifically 0 wt% to 6 wt% of the total weight of the multiparticulate Emamectin in- feed additive composition.

[0023] There are some specific advantages in the use of lecithin in the second coating. First, the use of lecithin improves lipid absorption rates and efficiencies through emulsification. Second, lecithins are excellent sources of phosphorus, choline, and inositol, which are advantageous in the fish feed compositions.

[0024] hi one embodiment, third coating suitable to provide taste-masking and gastric bypass is disposed on the first coating or the optional second coating. In one embodiment, the third coating comprises a film-forming polymer; and a taste-masking polymer or an enteric polymer. Suitable film- forming polymers include, for example, methylcellulose, ethylcellulose, hydroxypropyl cellulose, hydroxypropyl methylcellulose, hydroxybutyl methylcellulose, cellulose acetate, cellulose propionate (lower, medium or higher molecular weight), cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate phthalate, carboxymethyl cellulose, cellulose triacetate, cellulose sulphate sodium salt, poly(methyl methacrylate), poly (ethyl methacrylate), poly (butyl methacrylate), poly (isobutyl methacrylate), poly (hexyl methacrylate), poly (phenyl methacrylate), poly (methyl acrylate), poly (isopropyl acrylate), poly (isobutyl acrylate), poly (octadecyl acrylate), poly (ethylene), poly (ethylene) low density, poly (ethylene)high density, (poly propylene), poly (ethylene glycol poly (ethylene oxide), poly (ethylene terephthalate), poly( vinyl alcohol), polyvinyl isobutyl ether), poly(viny acetate), poly (vinyl chloride), polyvinyl pyrrolidone, and combinations comprising one or more of the foregoing polymers. In one embodiment, the film-forming polymer comprises ethylcellulose.

[0025] In one embodiment, the taste-masking polymer is soluble in gastric fluid at pHs less than or equal to 5. Suitable taste-masking polymers include a butyl methacrylate-(2- dimethylaminoethyl methacrylate)-methyl methacrylate copolymer (1 :2:1) available under the tradename Eudragit^® E-IOO (Rohm & Haas GmbH, Germany), and a 1 :2:1 (butyl methacrylate-co-(2-dimethylaminoethyl)methacrylate-co-methyl methacrylate), having an average molecular weight of about 150,000, available under the tradename Eudragit^® E PO (Rohm & Haas GmbH, Germany), acrylic and/or methacrylic ester polymers, butyrates or propionates or copolymers of acrylates or methacrylates having a low quaternary ammonium content, and the like. The taste-masking polymer improves palatability of the multiparticulate in-feed additive composition. In one embodiment, the taste masking polymer comprises Eudragit^® E and/or Eudragit^® EPO.

[0026] In another embodiment, the composition comprises an enteric polymer that is soluble at pHs greater than or equal to 7. Suitable enteric polymers include, for example, methacrylic esters (Eudragit^® L and S) copolymer, cellulose

[0027] The third coating provides gastric bypass and taste-masking. In one embodiment, the third coating forms a substantially completely coat on the particle. In those embodiments, each individual unit of the plurality of granular cores comprising the Emamectin is substantially completely coated. The term "substantially completely coated" means that the third coating substantially shields the Emamectin or salt thereof from contact with the outside environment. The substantially complete third coating helps ensure that the taste buds of an animal are not exposed to an objectionable- tasting material.

[0028] The film-forming polymer in the third coating comprises about 5 wt% to about 15 wt%, specifically about 8 wt% to about 12 wt% of the total weight of the multiparticulate Emamectin in-feed additive composition. The taste-masking polymer or enteric polymer comprises about 5 wt% to about 15 wt%, specifically about 8 wt% to about 12 wt% of the total weight of the multiparticulate in- feed additive composition. [0029] The third coating optionally comprises a plasticizer. Suitable plasticizers include, for example, polyethylene glycol, triacetin, vinylpyrrolidone, diethyl phthallate, dibutylsebacate, or a citric acid ester, and combinations thereof. Generally, the amount of plasticizer included in a coating is based on the total weight of the polymer contained in the coating, for example, typically about 0 wt% to about 50 wt% of the total weight of the polymer. Amounts of the plasticizer, however, can be determined by routine experimentation.

[0030] In another embodiment, instead of a third coating, the composition comprises a third and a fourth coating disposed on the first coating or the optional second coating. In one embodiment, the third coating comprises a film- forming polymer and a fourth coating comprises a taste-masking polymer; or the third coating comprises a taste-masking polymer and a fourth coating comprises a film-forming polymer.

[0031] Each of the coatings individually optionally comprises additional excipients such as, for example, plasticizers (e.g., propylene glycol); anti-adhesives such as, for example, colloidal silicium dioxide (fumed silica), talc, and magnesium stearate; colorants (e.g., titanuim dioxide); free flow agents (e.g., Sipernat^® 22S, available from The Cary Company); glazing agents e.g., Quick Shine from Alfred L. Wolff; materials that preserve the shelf life of the Emamectin, such as, for example, antixidants (e.g., potassium metabisulfite, ascorbic acid, butylhydroxytoluene, butylhydroxyanisole, tocopherol), and combinations comprising one or more of the forgoing excipients.

[0032] The multiparticulate in-feed additive composition described herein is simple to manufacture, cost-effective, and can be made with conventional tabletting machines and coating equipment.

[0033] The plurality of granular cores of the multiparticulate in-feed additive composition is prepared by techniques well known in the art such as, for example, rotary bed granulation, extrusion, or granulation and treatment in a intensive mixer. The application of the coatings is performed in a fiuidized bed or by other suitable coating techniques such as pan coating, spray-drying, electrostatic coating, and the like. [0034] Granular cores, for example, spheroids or Pharma beads, coated with Emamectin or its salts are prepared, for example, by dissolving/suspending the Emamectin or salt thereof and a hydrogel-forming polymer (e.g., sodium alginate), then spraying the solution/suspension onto the granular cores to form a first coating. Suitable solvents include, for example, water, propylene glycol, ethanol, acetone, and combinations comprising one or more of the foregoing solvents. In one embodiment, the first coating is dried before applying a subsequent coating, for example, with an inlet temperature of 57°C. The mean particle size after applying the first coating should not be too small, e.g., less than 50 microns; typically, the mean particle size is about 150-300 microns.

[0035] The resulting material is optionally overcoated with a second coating comprising a barrier material to separate the Emamectin or its salt from additional coatings. The barrier material is dissolved/suspended in a solvent, and sprayed onto the cores comprising the first coating. The cores coated with the optional second coating are optionally dried, for example at a temperature of 55-57°C, prior to deposition of the third coating coating.

[0036] Subsequently, a third coating comprising a film- forming polymer and a taste- masking polymer is disposed on the first or second coating. The film-forming polymer and taste-masking polymer are dissolved/suspended in a solvent, and sprayed onto the cores comprising the first coating and optionally the second coating. The third coating is dried at a temperature of 55-57°C.

The mean particle size after the coating steps should not be too small, e.g. less than 50 microns; typically, the mean particle size after the coating steps is 150 to 400 microns, hi one embodiment, it is preferred that the particles remain in a non-agglommerated form so as to facilitate homogeneity during feed ingredient mixing.

[0037] The multiparticulate in-feed additive composition is administered orally in the form of powders, tablets, capsules, pastes, granules, crumbles, pellets, and the like, either as such or in admixture with a basal fish feed to make a medicated fish feed.

[0038] hi one embodiment, the multiparticulate in- feed additive is admixed with a basal fish feed. A basal fish feed refers to prepared or artificial diets that promote fish growth and health. Suitable diets include complete diets that contain the required nutrition for fish, e.g., protein, lipid, carbohydrate, ash, phosphorus, water, vitamins and minerals; and supplemental diets that are intended to help support the natural food (e.g, insects, algae, small fish) normally available to fish in ponds, tanks, cages , or outdoor raceways.

[0039] A medicated fish feed is a fish feed comprising a multiparticulate in-feed additive composition comprising Emamectin or a salt thereof and a basal fish feed. The medicated fish feed can be prepared by incorporating a suitable amount of the multiparticulate in-feed additive composition comprising Emamectin or a salt thereof into a basal fish feed to achieve the desired dosing levels. The amount of the in-feed additive composition comprising Emamectin or a salt thereof incorporated into the fish feed will depend on the rate at which the fish are fed. For fish fed at the rate of 0.2% to 4% of biomass/day, the medicated fish feed specifically contains 0.5 to 100 mg of the Emamectin or a salt thereof per kg of medicated fish feed, more specifically, 1 to 50 mg the Emamectin or a salt thereof per kg of medicated fish feed, and most specifically, 5 to 15 mg the Emamectin or a salt thereof per kg of medicated fish feed.

[0040] Several embodiment of fish feed processing may be employed. In one embodiment, a fish feed pelleting operation is employed. Conventionally, raw materials are passed through a hammer mill or pulverizer until >98% of the particles are reduced to sizes of 250microns and below. These raw materials are then passed to a ribbon mixer, where sensitive materials are added, especially vitamins, carotenoids and products such as Emamectin Benzoate. Approximately 2% moisture is sprayed into this mixture to maximize pellet durability. The complete feed mix is then pelleted by compression at a die temperature of approximately 90°C. The finished pellets are dried to remove excessive moisture, then cooled, sieved and bagged.

[0041] In another embodiment, a fish feed extrusion operation is employed. Conventionally, raw materials are passed through a hammer mill or pulverizer until >98% of the particles are reduced to sizes of 250 microns and below. These raw materials are then passed to a ribbon mixer, where sensitive materials are added, especially vitamins, carotenoids and products such as Emamectin Benzoate. Approximately 2-7% moisture is sprayed into this mixture to maximize pellet durability. The complete feed mix is then extruded by expansion at a die temperature of approximately 140°C. The finished pellets are dried to remove excessive moisture, then cooled, sieved and bagged.

[0042] In yet another embodiment, a feed mill top dressing operation is employed. Conventionally, raw materials are passed through a hammer mill or pulverizer until >98% of the particles are reduced to sizes of 250microns and below. These raw materials are then passed to a ribbon mixer, ready for extrusion. Approximately 2-7% moisture is sprayed into this mixture to maximize pellet durability. The incomplete feed mix is then extruded by expansion at a die temperature of approximately 140°C. The finished pellets are then passed to a fat coating device (spray nozzle facing into a rotating mixer) for addition of sensitive materials like Emamectin Benzoate. The mix contains only fish oil, vitamins and the EB active substance. After oil absorption, pellets are dried to remove excessive moisture, then cooled, sieved and bagged.

[0043] In another embodiment, an on-site, e.g., farmer, top dressing operation is employed. Many farmers do not trust feed mills to carry out such operations to their satisfaction, preferring instead to top-dress finished feed they purchase. They will buy their own mixers, and using fish oil or egg white, alginates or gelatin, they will mix the Emamectin with the binder and spray the resultant suspension onto the pellets. Pellets will then be sun dried and re-bagged. There is little high temperature exposure in this type of operation.

[0044] The multiparticulate Emamectin in-feed additive composition is employed to eliminate or reduce many types offish parasites, including ectoparasites, as well as endoparasites. Examples of endoparasites that can be eliminated or reduced include, but are not limited to: Lepeophtheirus, Caligus, Pseudocaligus,, Ergasilus,Argulus, Salmincola,Cruoricola, Pearsonellum, Cardicola, Paradeontacylix, Lernanthropus, Ceratothoa and Lernaea as well as Isopods (Alitropus.Rhexanella and Nerocilά).

[0045] The multiparticulate Emamectin in-feed additive compositions disclosed herein are particularly effective as a treatment for sea lice, that is, parasites belonging to the Subclass Copepoda, Order Caligidea, especially those belonging to the genera Lepeophtheirus and Caligus. [0046] Fresh water and salt-water fish species are treated with Emamectin to eliminate and/or reduce parasites. Examples of suitable fish for treatment include, but are not limited to: salmon, trout, catfish, sea bass, tuna, halibut, arctic charr, sturgeon, turbot, flounder, sole, carp, tilapia, striped bass, eel, sea bream, yellowtail, amberjack, grouper, milkfish, and combinations comprising one or more of the foregoing fish species.

[0047] The dose of Emamectin that is effective for reducing, eliminating, or preventing parasites is routinely determined, and varies depending on the species offish treated, the particular parasites involved, and the degree of infestation. In specific embodiments, Emamectin or a salt thereof is administered at a dose of about 25 μg to about 400 μg per kg of fish biomass per day, more specifically, about 25 μg to about 100 μg per kg of fish biomass per day, most specifically, about 50 μg to about 75 μg per kg of fish biomass per day.

[0048] The Emamectin multiparticulate in-feed additive composition or a medicated fish feed is administered daily, for a period of 3 to 14 days, specifically for 7-14 days, most specifically for 1 week. The multiparticulate Emamectin in-feed additive composition is effective in reducing parasite infection, for example, when sea bass is treated with the multiparticulate Emamectin in-feed additive composition, 90.0-99.5 % of sea lice infection is eliminated. The Emamectin multiparticulate in-feed additive can be administered as a prophylactic measure to prevent the occurrence of parasites.

[0049] The invention is further illustrated by the following non-limiting examples.

EXAMPLES

[0050] Example 1. Manufacture process of a multiparticulate in- feed additive composition containing Emamectin benzoate

[0051] Excipient beads (e.g., Pharma Beads) were added to a fluid bed drier and fluidized. A first coating material containing Emamectin benzoate(2 grams) and sodium alginate (2.5 grams) were dissolved in 80 grams Polyethylene Glycol and 100 grams water and the solution was sprayed onto the Pharma Beads to form a first coating under a fluidised air flow controlled at 55- 57⁰C, maintaining a product temperature of 37-4O⁰C. The first coated beads were dried at 57 ⁰C and sieved so that the resulting beads had an average size of about 150 to 300 microns.

[0052] 20 grams of powdered lecithin (Emulpur N, Lucas Meyer GmBH) was dissolved in 300 grams water. The resulting solution was sprayed onto the Pharma Beads containing the first coating to form a second coating; the inlet temperature was 55-57°C.

[0053] Next, solutions containing Eudragit^® E 100 (or Eudragit^® E PO, Rohm & Haas GmbH, Germany) and ethylcellulose were prepared. 4 grams of Eudragit^® E 100 and 40 grams of ethylcellulose were dissolved in ethanol, and the resulting solutions were sprayed onto the twice coated Pharma Beads to form a third coating. The beads were dried and sieved to give an average size of less than 400 microns.

[0054] Table 1 shows the composition of a multiparticulate in- feed additive composition containing 0.2% Emamectin benzoate manufactured according to the above- described process.

Table 1

* The amount represents wt% of an ingredient in the total weight of the multiparticulate in- feed additive composition.

[0055] Example 2. Performance study: palatability and efficiency of the in-feed additive composition containing Emamectin benzoate

[0056] A palatability study was performed for 4 months. Two different types offish feed were used in the study. Each fish feed had three fish test groups. [0057] Sea Bass (Lates calcarifer) fingerlings (1,000) each were placed in sea cages of 5x5x2m and fed for 16 weeks. Each cage was supplied with natural seawater at ambient temperature (25-32 ⁰C) and salinity (25-35 ppt), at flow rates according to tidal fluctuation. Fish were observed daily for behaviour and adverse drug reactions. Fish mortalities, weights, feed intake, FCR, bacterial counts, viral pathogens, fluke numbers, lice numbers and the occurrence of gross sea lice damage were also recorded.

[0058] The control fish were fed with a fish feed containing no Emamectin benzoate (the Control) and the test fish were fed with a fish feed contained 0.2% of the multiparticulate in- feed additive composition containing Emamectin benzoate (the Test) to give a dietary level of 50 micrograms Emamectin benzoate/Kg fish/Day. Test fish were fed on a 7-day on, 7 day off regimen.

[0059] The test fish gained weight during the experimental period, illustrating that there were no palatability problems during the 16-week test period. In addition, the test fish had a lower Feed Conversion Ratio ("FCR") compared to the control fish (Figure 1). FCR is calculated from the number of kilograms of feed that are used to produce one kilo of whole fish. Specifically, FCR is the mass of the food eaten divided by the body mass gain, over a specified period of time (e.g., the 16-week test period). Thus, the test fish used the feed more efficiently.

[0060] Furthermore, efficacy of the Emamectin benzoate composition was high as evidenced in Figure 2, since sea lice numbers fall drastically (e.g., sea lice number of the test fish was down over 99 % compared to the control fish) upon commencement of treatment and maintained at that low level during the whole 16-week period.

[0061] Particle sizes were measured by electron microscopy. The particle size of the inventive compositions is more consistent than the prior art SLICE^® pre-mix. Figures 3 and 4 illustrate the differences between SLICE^® and the Emamectin benzoate composition disclosed herein.

In Figure 3, SLICE^® can be seen to be a rudimentary pre-mix in which the active ingredient (Emamectin benzoate) can be exposed to the rigours of heat, moisture, trace element interaction and storage currently seen in manufactured feed rations. The prior art pre-mix, being dusty, may cause irritation to humans in the confined environment of the feedmill. The pre-mix is then further exposed to moisture (water) on the farm, can be readily lost to water and sediments in the natural environment thereby causing potential negative environmental contamination and leads naturally towards a tendency to overdose causing potential resistance build up in the pathogen. Figure 4, in contract, shows an electron micrograph of an inventive Emamectin benzoate composition. The inventive composition, wherein the active ingredient is protected from these effects by a triple coating, does not suffer from the the disadvantages of the prior-art pre-mix.

[0062] The multiparticulate Emamectin in-feed additive composition disclosed herein provides an improved delivery system of the Emamectin that is particularly suitable for aquaculture applications. For example, the in-feed additive composition is resistant to water and acid, and provides gastric bypass after ingestion by a fish. Additionally, the in- feed additive composition is resistant to the high temperatures up to 14O⁰C under which a medicated fish-feed is manufactured.

[0063] Advantages of the compositions disclosed herein include low dust content, therefore inhalation exposure is considerably reduced compared to prior art compositions. Also, particle size is substantially more uniform than prior art compositions, and the coating ensures there is a pronounced barrier between the active substance and the environment. It is expected that the compositions disclosed herein will have a reduced environmental impact when compared to prior art compositions such as Slice . Environmental concerns are paramount, especially in salmonid producing countries.

[0064] The use of the terms "a" and "an" and "the" and similar referents (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms first, second etc. as used herein are not meant to denote any particular ordering, but simply for convenience to denote a plurality. The terms "comprising", "having", "including", and "containing" are to be construed as open-ended terms (i.e., meaning "including, but not limited to") unless otherwise noted. Recitation of ranges of values are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. The endpoints of all ranges are included within the range and independently combinable. All methods described herein can be performed in a suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., "such as"), is intended merely to better illustrate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention as used herein.

[0065] While the invention has been described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims. Any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.

[0066] All cited patents, patent applications, and other references are incorporated herein by reference in their entirety.

Claims

CLAIMS:

1. A multiparticulate in-feed additive composition comprising:

a plurality of granular cores, and

a first coating disposed on the plurality of granular cores comprising a hydrogel-forming polymer and Emamectin or a salt thereof,

a third coating disposed on the first coating comprising a film- forming polymer; and a taste-masking polymer or an enteric polymer.

2. The composition of claim 1, further comprising a second coating disposed between the first coating and the third coating, wherein the second coating comprises a barrier material.

3. The composition of claim 1, wherein the film- forming polymer comprises ethylcellulose.

4. The composition of claim 1 , wherein the plurality of granular cores comprise nonpareils.

5. The composition of claim 1, wherein the Emamectin salt is Emamectin benzoate.

6. The composite of claim 1, wherein the hydrogel-forming polymer comprises sodium alginate.

7. The composition of claim 1, wherein the composition comprises a taste-masking polymer that is soluble in gastric fluid at pHs less than or equal to 5.

8. The composition of claim 1, wherein the composition comprises an enteric polymer that is soluble at a pH of greater than 7.0.

9. The composition of claim 1, wherein the Emamectin or a salt thereof comprises about 0.05 wt% to about 1 wt% of the total weight of the multiparticulate in-feed additive composition.

10. The composition of claim 1 , wherein the plurality of granular cores comprise about 50 wt% to about 90 wt% of the total weight of the multiparticulate in- feed additive composition.

11. The composition of claim 1 , wherein the hydrogel-forming polymer comprises about 2 wt% to about 12 wt% of the total weight of the multiparticulate in- feed additive composition.

12. The composition of claim 1, wherein the taste-masking polymer or enteric polymer comprises about 5 wt% to about 15wt% of the total weight of the multiparticulate in-feed additive composition.

13. The composition of claim 1 , wherein the film- forming polymer comprises about 5 wt% to about 15wt% of the total weight of the multiparticulate in- feed additive composition.

14. The composition of claim 2, wherein the barrier material comprises lecithin.

15. The composition of claim 2, wherein the barrier material comprises 0 to about 10 wt% of the total weight of the multiparticulate in- feed additive composition.

16. A medicated fish- feed comprising the multiparticulate in- feed additive composition of claim 1 and a basal fish- feed.

17. The medicated fish-feed of claim 16, wherein the multiparticulate in- feed additive composition further comprises a second coating disposed between the first coating and the third coating, wherein the second coating comprises a barrier material.

18. A method of reducing, eliminating, or preventing parasites in a fish population, comprising: feeding the multiparticulate in-feed additive composition of claim 1 to the fish population at a daily dose of Emamectin about 25 μg to about 400 μ g per kg of fish biomass per day for a period of 3-14 days.

19. A method of making a multiparticulate in-feed additive composition, comprising:

coating a plurality of granular cores with a first coating comprising a hydrogel- forming polymer and Emamectin or a salt thereof to form a plurality of first-coated cores, and

coating the plurality of first coated cores with a third coating comprising a film-forming polymer; and a taste-masking polymer or an enteric polymer.

20. The method of claim 19, further comprising, prior to coating with the third coating,

coating the plurality of first coated cores with a second coating comprising a barrier material.