CO-EXTRUSION OF MULTI-COMPONENT ECTOPARASITICIDAL PET COLLARS

Abstract: Co-extruded insectidical pet collars contain one or more active insecticidal components in a desired relationship to the skin of the animal. The outside layer (away from the skin) contains carbamate, organo-phosphate chlorinated hydro­ carbon or other insecticide that is irritating to the skin, or a cholinesterase inhibitor. The inside layer acts as a barrier to the insecticide. The layers of a multi-layered collar which is prepared by extrusion may also contain different insecticidal systems. A co-extruded collar is prepared by preparing two blends which have varying concentrations of active and/or inert ingredients, depending on the end product which is desired. Each of the blends is fed into an extruder wherein the polyvinyl chloride is fused. The melt blend from extruder B is then transferred to the die of extruder A where it becomes an integral part of the extruded strip from extruder A.

Description: This invention relates to devices suitable for protecting domestic animals against ectoparasites, e.g., ticks and fleas, and more particularly relates to a flea and tick collar for providing protection to an animal. Previously commercially marketed flea and tick collars have been manufactured from a monolithic matrix containing either one or two insecticides, these insecticides being dispersed uniformly throughout the polymeric matrix. In many such devices, the insecticide containing polymer matrix is in direct contact with the skin of the cat or dog, and if two insecticides are utilized, both insecticides are dispersed together within the matrix. This construction can result in several problems: 1) because of the high degree of contact by an organophosphate or carbamate insecticide, abnormally high depression of cholinesterase or irritation of the skin of the animal occurs; 2) if the insecticides are mixed within the matrix, changes in the morphology of the plastic are caused so that the plastic becomes tacky with a distasteful odour. Such mixing also results in release rates which are not optimum for the insecticides, resulting in a less efficacious collar; 3) because a monolithic matrix requires a high concentration of insecticides to produce an effective collar, it is not economical to use a non-cholinesterase inhibiting, safer insecticide, such as the synthetic pyrethroids. U.S. Patent 4,224,901 discloses a combination flea-tick collar for animals having an outer protective collar having a recess housing an insecticide impregnated material and points out that the reason for this combination is to avoid direct contact of the skin of the animal with the chemicals in the flea and tick collars. DE-A-3300579 discloses anti-parasite collars for animals made from two laterally bonded strips, one strip containing an insecticide with the other having a C₁₈₋₂₂ unsaturated fatty acid. In Example 8 in mixture B the two strips are extruded side by side so that both strips will be next to the animal's skin. U. S. Patent 3,978,820 is also directed toward solving the problem of direct contact of an animal's skin with the insecticide by providing a collar which holds an insecticide-impregnated strip while providing a physical barrier between the strip and the hair of the animal and the hair and skin of the animal. U. S. Patent 4,150,109 and U. S. Patent 4,189,467 disclose an animal collar containing a polyurethane plus an insecticidal active compound and point out that it is possible to prepare animal collars based purely on polyurethane and then further states that in some cases it is desirable to impregnate and/or coat a suitable carrier (for example, a fabric made of natural material, such as cotton, and/or synthetic fibres, leather, imitation leather, or a porous or homogenous plastic sheet) with the polyurethane. It is also stated that carriers are worn on the outside of the collar, and the coating containing the polyurethane and the ectoparasiticide is on the inside of the collar. U. S. Patent 3,904,746 is directed to a flea collar and teaches that a hollow band can be produced by extrusion or by joining two flat bands of low thickness by welding or by sewing. In the latter instance, one of the two bands, for example, that are intended to face the neck of the animal can be of an inert nature such as, for example, gauze, leather, or a polymer-like material. U. S. Patent 4,141,322 teaches a collar which has a strip of resin containing a solid pesticidal composition, this strip being laced through loops on the exposed surface of the collar which can be plastic. The object of this invention is to prepare collars by co-extrusion, thereby eliminating many difficulties. The preferred co-extrusion methods are as follows: 1) co-extrusion of a collar in which an outside layer (away from the skin) contains carbamate, organophosphate, chlorinated hydrocarbon or other insecticide that is irritating, or a cholinesterase inhibitor; and 2) co-extrusion of a multi-layered collar in which the different layers contain different insecticidal systems. The object of this invention is to prepare collars by co-extrusion, thereby eliminating many such difficulties. According to the invention, there is provided an animal collar for controlling ectoparasites such as fleas and ticks on an animal, the collar comprising a first plastics matrix containing at least one insecticide, the first plastics matrix being co-extruded with a second plastics matrix containing at least one insecticide and at least part of one matrix is located between the animal's skin and the other matrix. The invention further enables the provision of a multi-layered collar by co-extrusion in which the different layers contain different insecticidal systems. The general procedure for preparing a monolithic polyvinyl chloride insecticide collar is to prepare a dry blend of materials containing all the inert and active ingredients and then to extrude the blend through a die into a cooling bath. The resulting plastic strip is cut, buckled, and packaged. The general procedure for preparing a co-extruded collar is to prepare two blends which have varying concentrations of active and inert ingredients, depending on the end product which is desired. Each of the blends is fed into an extruder (A or B) wherein the polyvinyl chloride (for example) is fused. The melt blend from extruder B is then transferred to the die of extruder A where it becomes an integral part of the extruded strip from extruder A. The term "insecticide" as used herein means "extoparasiticide", particularly a compound having insecticidal and/or acaricidal activity. For a better understanding of the present invention and to show how it may be put into effect, reference will now be made by way of example to the accompanying drawings, in which: Figure 1 is a schematic flow sheet for making a co-extruded collar; Figure 2 is a schematic flow sheet for making another co-extruded collar; and Figures 3a and 3b show schematically lateral sections giving two configurations of some co-extruded collars which are as follows: Figure 3a: A. Plastic matrix with insecticide system, and B. Plastic matrix with second insecticide system, Figure 3b: A. Plastic matrix with insecticide system, and B. Plastic matrix with second insecticide system. Insecticides which may be used are carbamates, organo-phosphorous compounds, organo-chlorine compounds, pyrethroids and mixtures thereof. Carbamates useful in the compositions of the present invention are represented by the formula: wherein R² represents hydrogen or lower alkyl, R³ represents lower alkyl and R¹ represents aryl, substituted aryl, heterocyclic or substituted heterocyclic groups. The term "lower alkyl" as used herein refers to an alkyl group, branched or straight chain, having a chain length of one to six carbon atoms. The term "aryl" as used herein refers to an aryl group such as phenyl or naphthyl. The term "substituted aryl" as used herein refers to a phenyl or naphthyl group substituted with one or more groups such as lower alkyl, halogen, lower alkoxy, lower alkylamino, lower dialkylamino or lower alkylthio. The term "heterocyclic" as used herein refers to an organic cyclic group having an oxygen atom, sulphur atom or nitrogen atom in the nucleus thereof and containing up to 12 carbon atoms. The term "substituted heterocyclic" as used herein refers to a heterocyclic group substituted with one or more groups such as lower alkyl, lower alkoxy, lower alkylthio, lower alkylamino, lower dialkylamino or halogen. Typical of the carbamates which can be used in the present invention are: 2,2-dimethyl-1,3-benzodioxal-4-ol methyl carbamate, 2-isopropylphenyl N-methyl carbamate, 2-isopropoxyphenyl N-methyl carbamate, 3-(1-methylbutyl)phenyl N-methyl carbamate, 3-(1-ethylpropyl)phenyl N-methyl carbamate, 6-chloro-3,4-xylenyl N-methyl carbamate, 4-methylthio-3,5-xylenyl N-methyl carbamate, 1-naphthyl N-methyl carbamate, 1-naphthyl N-ethyl carbamate, 1-naphthyl N-isopropyl carbamate, 1-naphthyl N-butyl carbamate, 1-naphthyl N-hexyl carbamate, 1-(4-chloronaphthyl) N-methyl carbamate, 1-(5,6-dihydronaphthyl) N-methyl carbamate, 1-(5,8-dihydronaphthyl) N-methyl carbamate, 4-benzothienyl N-methyl carbamate, 1-phenyl-3-methylpyrazol-5-yl N,N-dimethyl carbamate, dimethyl carbamate, 2-(N,N-dimethyl carbamyl)-3-methylpyrazol-5-yl N,N-dimethyl carbamate, and mixtures thereof. The preparation of carbamates of the above formula has been previously described. See, for example, U. S. Patent Nos. 2,903,478 and 3,203,853. Some useful alkyl-, alkaryl-, aralkyl- and heterocyclic carbamates are m-(1-ethylpropyl) phenyl methylcarbamate, m-(1-methylbutyl) phenyl methyl carbamate, 2-dimethylamino-5, 6-dimethylpyrimidin-4-yl dimethylcarbamate, 4-methylthio-3, 5 xylyl-N-methyl carbamate, 2-(1,3-dixolan-2 yl) phenyl-N-methylcarbamate, 3-isopropyl-5-methylphenyl-N-methylcarbamate, 4-dimethylamino-3-tolyl-N methylcarbamate. Useful organo-phosphorous compounds are phosphoric acid esters of the formula: wherein R₁ represents a member selected from the group consisting of alkyl, alkenyl, alkoxylalkyl and alkyl-mercapto-alkyl radicals, R₂ represents a member selected from the group consisting of hydrogen, lower alkyl and lower alkenyl radicals, R₃ and R₄ represent lower alkyl radicals, X represents oxygen or sulphur, and Y represents a direct link or sulphur. Specific organo-phosphorous compounds are: The composition according to the invention comprises 2-25% by weight of the insecticidal agent and more usually 2-15%. The following examples furnish comparative data for co-extruded collars having the configuration of Figure 3a and containing insecticides, extruded monolayer collars containing comparable insecticides, and extruded monolayer collars without insecticides and tested as placebos. Ingredients in the blends of each formula are on weight basis. Comparative Example 1 Two sets of insecticide-containing collars were prepared by utilizing the formula shown in Table 1. Collar V was prepared by co-extruding Blends A and B in the ratio of one part of Blend B to 6.92 parts of Blend A. Collar VI was prepared by extruding Blend A, including the insecticides. Six of each of these collars were placed on 12 dogs, and the dogs were infested with 100 fleas on eight different occasions. The dead fleas found in the pans under the animals were counted 24 hours after the infestations. The results are shown in Table 2. As can be seen from Table 2, co-extruded collar V had greater efficacy than the conventional matrix collar VI. Example 2 Collar IX was prepared by co-extruding Blend A and Blend B in the weight ratio of 9.5 to 1.0, using the blend shown in Table 4 . Six collars of collar IX type were placed on six cats, and six placebo collars prepared according to Table 3 were placed on six additional cats. One hundred fleas were placed on each cat once a week for four weeks. The number of dead fleas in the pans under the cats were determined six hours after infestation, and the number of live fleas on the cats was determined on the fifth day following infestation. The results shown in Tables 5 and 6 indicate that collar IX was effective in controlling fleas. In the process of co-extruding the polymers used as matrices and barrier layers, it is only necessary that the temperatures used be above the melting points of both polymers and that the polymers be compatible with each other. The preferred temperature range is 150-180 o C. Table 7 shows the extruder conditions used for extruding collars V, VI and IX that are described the Examples. Although polyvinyl chloride was used in the examples for the insecticidal blends, other polymers known in the art, such as polymers and copolymers of vinyl chloride, vinyl acetate, vinyl acetals, vinyl alcohol, vinylbenzene and divinylbenzene and vinylidene chloride are satisfactory. The copolymers may contain additional components such as ethylenic, propylenic, butadienic, isopronic, acrylic and methacrylic components. Preferably, the polymer or copolymer of a vinyl compound is a polyvinyl halide and contains one or more plasticizers. The plasticizers are usually liquid esters with a vapour pressure of less than 0.001 mm/Hg at 25 o C. Some non-restrictive examples of plasticizers are: diethyl, dimethyl, dipropyl, dibutyl, dihexyl, dioctyl,and didecyl phthalate, dibutyl, diamyl, dinonyl, dioctyl, and didecyl adipate, dipropyl, dibutyl, dibenzyl and dioctyl sebacate, diethyl, dipropyl and dibutyl citrate, triphenyl and tricresyl phosphate and the triglycerides. The preferred plasticizers are dioctyl phthalate, diisodecyl phthalate and dioctyl adipate. Suitable stabilizers include all those known from diazinone, of which the following can be mentioned: epoxides such as epichlorohydrin, calcium, magnesium, zinc, tin, barium, cadmium or potassium stearate, the laurates and palmitates of these same metals, chlorinated terphenyls and butoxy-propylene-glycol. The preferred stabilizers are calcium or zinc stearate and epoxidized soya bean oil.

Claims: An animal collar for controlling ectoparasites such as fleas and ticks on an animal, the collar comprising a first plastics matrix containing at least one insecticide, the first plastics matrix being co-extruded with a second plastics matrix, characterised in that the second plastics matrix contains at least one insecticide and at least part of one matrix being between the animal's skin and the other matrix. A collar as claimed in Claim 1, wherein the first plastics matrix containing the first insecticide surrounds the second plastics matrix containing the second insecticide on three sides. A collar as claimed in Claim 1 wherein the second plastics matrix containing the second insecticide surrounds the first plastics matrix containing the first insecticide on three sides. A collar as claimed in Claim 1 wherein the second plastics matrix containing the second insecticide surrounds the first plastics matrix containing the first insecticide on four sides.

Inventors: ATKINSON, EARL RANDOLPH, JR., CORRIGAN, EUGENE JAMES
Applicants: CONAGRA PET PRODUCTS, INC.
Application year: 1985
Main classification: A01K27
IPC codes: B29C47, A01N25, B32B27, A01K27, B29K105, A01M1, B29L31