AU2004281551B2

AU2004281551B2 - Compositions for controlling parasites comprising a combination of abamectin and ivermectin

Info

Publication number: AU2004281551B2
Application number: AU2004281551A
Authority: AU
Inventors: Hyun Sun Cho; Alvimar Jose Da Costa; Edival Junior Santos
Original assignee: Intervet International BV
Current assignee: Intervet International BV
Priority date: 2003-10-17
Filing date: 2004-10-15
Publication date: 2009-10-29
Anticipated expiration: 2024-10-15
Also published as: CN1867341B; ZA200603931B; TR200601608T1; CN1867341A; WO2005037294A8; WO2005037294A1; NZ546340A; BRPI0415366A; AU2004281551A1

Description

WO 2005/037294 PCT/EP2004/052554 1 COMPOSITIONS FOR CONTROLLING PARASITES COMPRISING A COMBINATION OF ABAMECTIN AND MILBEMYCIN The present invention relates to long acting compositions for controlling parasites, comprising a combination of ivermectin and abamectin in a slow release vehicle, the 5 use of such compositions in the preparation of a medicament for controlling parasites. Avermectins are well known anthelmintic compounds, belonging to the class of macrocyclic lactones. The avermectins are isolated from fermentation products of 10 Streptomyces avemitilis and ivermectin is a compound which is a semisynthetic chemical compound formed by modification of avermectin. The basic structure of the avermectins is a 16-membered lactone ring to which are appended three main substituent groups: a hexahydrobenzofuran group, a disaccharide group (at C-13) and a spiroketal ring (C-17 to C-28). The avermectin series of compounds, including 15 ivermectin, abamectin, doramectin, eprinomectin and selamectin, are potent anthelmintic and antiparasitic agents against internal and external parasites (endectocides). The natural product avermectins are disclosed in US-A-4,310, 519 to Albers Schonberg et al., and the 22,23-dihydro avermectin compounds are disclosed in Chabala et al, US-A- 4,199, 569. 20 Endoparasites cause widespread disease found in many animals. The most frequently encountered endoparasites are the group of worms referred to as nematodes. The nematodes are found in the intestinal tract, heart, lungs, blood vessels and other body tissues of animals and are a primary cause of anemia, weight 25 loss and malnutrition in the infected animals. The nematodes most commonly found to be the infecting agents of ruminants include Haemonchus and Ostertagia generally found in abomasum; Cooperia, Trichostrongylus and Nematodirus generally found in the intestinal tract, and Dictyocaulus found in the lungs. Ectoparasites commonly infecting warm-blooded animals are arthropods such as 30 ticks (e.g. Boophilus microplus), mites, lice, fleas, blowfly, and migrating dipterous larvae such as Hypoderma sp. in cattle. Treatment of animals to prevent infestation by any of the above-mentioned parasites, or to reduce or control the proliferation of these parasites in animals is thus important. 35 Meanwhile the problem has arisen that some parasites develop a resistance to drugs like ivermectin. The resistance occurs when a strain of a parasite is able to tolerate WO 2005/037294 PCT/EP2004/052554 2 doses of an active ingredient that is efficacious against other populations of parasites of the same species. This characteristic is inheritable. After the use of macrocyclic lactones for almost two decades in cattle in Brazil the 5 first reports on resistant parasites in cattle were published. In 2001 in Rio Grande do Sul State, Martins & Furlong observed low efficacy of doramectin, ivermectin and moxidectin against a strain of Boophilus microplus. In 2001 in Santa Catarina State, Souza et.al tested the efficacy of bovine anthelmintic on 7 farms (egg counting). Resistance to ivermectin was detected in 4 of 10 them (3 to Cooperia and 1 to Haemonchus), In vitro trials demonstrated resistance of H. placei and C. punctata to ivermectin in Sao Paulo State. The resistance to Cooperia and Haemonchus was also shown in other trials (CARDOSO et al., 2002). The endoparasites of the genus Cooperia and Haemonchus showed resistance to 15 ivermectin in bovines in 11 farms of 12 evaluated in Sao Paulo State (SOUTELLO et al, 2003). These trials demonstrated that the problem of bovine parasites resistant to avermectins, particularly to ivermectin, might soon become as serious as it is in ovine species. 20 The discovery of novel anti-parasitics with equal or better qualities than macrocyclic lactones seems to be a distant reality in the veterinary pharmaceutical industry. Therefore, the chemical groups available nowadays must be used in a rational way, with a view to achieving high percentages of efficacy against parasites and delaying 25 the occurrence of resistant strains (GEARY & THOMPSON, 2003). The avermectins have similar modes of action. Nevertheless, small differences in their structures affect their therapeutic efficiency. Where ivermectin resistant parasites will usually still be vulnerable to abamectin, abamectin has the 30 disadvantage that it cannot be used at higher concentrations since it is toxic at higher concentrations. The use of low concentrations of abamectin however, has the disadvantage that the formulations based on abamectin only are short acting. Many different concepts of prolonged release of pharmaceutical compositions in 35 animals have been described, e.g. use of low water soluble forms or complexes of active ingredients, use of liposomes, microspheres and lipospheres formulations, polymer formulations, oil based formulations, gel formulations etc. Some of them WO 2005/037294 PCT/EP2004/052554 3 have been proposed for the use with endo and / or ectoparasitic compounds. Several oil formulations have been suggested in prior art for long acting formulations, e.g. ethyl oleate or sesam oil formulations. 5 A combination of ivermectin and abamectin for antiparasitic use in bovines has been mentioned in Brazilian Patent Application No. PI 0104761-2, that was filed on August 8, 2001 and published on August 12, 2003. This document does not disclose any specific amounts and ratio of the compounds of the combination that allows the composition to release ivermectin and avermectin in a way to show the desired effect 10 even in parasites that are resistant to certain macrocyclic lactone compounds. It would therefore be desirable to have a long acting composition available that allows the release of an effective amount of the specific combination of ivermectin and avermectin over a prolonged time period that are suitable to control parasites 15 that show resistance to certain macrocyclic lactone compounds. It has now been found that the combination of ivermectin and abamectin in defined concentration ranges in a long acting vehicle comprising castor oil result in such a broad-spectrum antiparasitic composition with long acting activity. 20 The present invention concerns a long acting composition for controlling parasites in and on animals, which comprises in a slow release vehicle a combination of ivermectin and abamectin, characterized in that the total percentage w/v of ivermectin and abamectin equals or exceeds 3% w/v and the concentration of 25 ivermectin is higher than the concentration of abamectin. In one embodiment the present invention provides a composition for controlling endo and ecto- parasites in and on animals, which comprises as active ingredient, an effective amount of a combination of ivermectin and abamectin in the following 30 concentrations, 1.75-5% w/v ivermectin, 0.5-2% w/v abamectin, the composition further comprising 30-60 % w/v castor oil, a suitable amount of a solvent for the active ingredients, optionally other pharmaceutically acceptable ingredients, and up to 100 % v/v of a diluent. 35 By "w/v" is meant weight/volume, i.e. "1% w/v" means 1 g in 100 ml of the composition. "v/v" means volume per volume, and 1% v/v means 1 ml, in a total of 100 ml.

WO 2005/037294 PCT/EP2004/052554 4 Good results were obtained with a composition comprising 2.25% ivermectin and 1.25% abamectin, together amounting to a total concentration of 3.5% w/v of active ingredient. When benzyl alcohol is used as the solvent in a composition comprising 2.25% w/v ivermectin and 1.25% w/v abamectin, 5 Preferably the composition comprises a long acting vehicle that employs castor oil. Castor oil (ricinus oil, oleum ricini, ricinoleum, tangantangan) is a triglyceride of fatty acids. The fatty acid composition is approximately ricinoleic acid (87%); oleic acid (7%), linoleic acid (3%); palmitic acid (2%); stearic acid (1%) and trace amounts of 10 dihydroxy stearic acid. Castor oil is the fixed oil obtained by cold-expression of the seeds of Ricinus communis Linne (Fam. Euphorbiaceae). (Rowe R C et al: Handbook of Pharmaceutical Excipients, London, Pharmaceutical Press, GB, page 104-105). 15 The concentration of castor oil in the compositions according to the invention is between 30 and 60 %w/v. By raising or lowering the amount of the castor oil in the formulation the viscosity of the formulation is adjusted and the slow release effect is influenced. For example, by raising the concentration of castor oil, the viscosity is increased and the rate at which the active ingredients are released from the depot is 20 lowered. Good results were obtained with concentrations of castor oil of 50.4% w/v (52.5 ml on a total of 100 ml) and 33,6 %w/v (35 ml on a total of 100 ml). As shown in a pharmacokinetics study in example 4 and 5, although both sesame and castor oil are prolonged action vehicles, the castor oil based formulation provides 25 a better long acting profile for a macrocyclic lactone based formulation. Each oil promoted a different ivermectin and abamectin release pattern that is possible to verify by Tmax and t1 /2 values, which are 229.70h and 261.70h for formulation using castor oil and 63.43h and 197.87h for formulation using sesame oil These results suggest that the castor oil formulation has longer persistency when compared to the 30 sesame oil formulation what affects the residual efficacy of the product against parasites. The novel compositions according to the invention have proven long action and good efficacy against internal and external parasites, especially in bovines. The novel 35 compositions according to the invention result in a unique formulation which controls parasites resistant to ivermectin and doramectin, like, Cooperia and Haemonchus. It WO 2005/037294 PCT/EP2004/052554 5 is worth mentioning that these two nematode species account for approximately 90% of the parasites found in Brazilian cattle. The diluent preferably is a vegetable oil. The vegetable oil used in the formulation 5 may be any suitable vegetable oil of a pharmaceutical grade, such as soy bean oil, sesame oil, olive oil, sunflower oil and/or corn oil. Such vegetable oils may be used alone or in combinations. Preferably corn oil and/or olive oil is used, either alone or in combination. 10 The compositions according to the invention comprise a solvent for the active ingredient. Suitable solvents are, for example, benzyl alcohol, or caprylic/ capric acid triglyceride. The amount of solvent used should be adjusted to match the amount of active ingredients present in the composition. Preferably the solvent is benzyl alcohol. The concentration of benzyl alcohol preferably is 7.3 % w/v. 15 An experiment conducted in cattle demonstrated that the association ivermectin + abamectin (3.5%) showed a higher anti-helminthic efficacy, when compared to a high concentration (3.15%) Ivermectin commercial formulation, against four species of endoparasites: Haemonchus placei, Cooperia punctata, C. spatulata and Trichuris 20 discolor. Both formulations showed a 100% efficacy against the others four species on the 14th DPT, 18 bovine hosts, divided into three groups of six animals each that were necropsied. Eight nematode species were identified. Further pharmaceutically acceptable ingredients may be added such as an 25 antioxidant. An antioxidant that is particularly useful for use in vegetable oils is tocopherol acetate, but other suitable antioxidants known in the art may also be used. The compositions of the invention may be used for the preparation of a medicament 30 for controlling parasites in and on host animals, particularly in bovines The compositions according to the invention can be used in injectable formulations. The composition of the invention may be delivered to the animal by injection, preferably subcutaneously, for example in the neck. The oily formulations of the 35 invention will form a depot underneath the skin resulting in a slow release of the active ingredients.

WO 2005/037294 PCT/EP2004/052554 6 The amount of the composition injected into a target animal depends on the body weight of the animal. Good results were obtained when 1 ml of a composition was administered per 50 kg bodyweight. When a composition is used comprising 2.25% w/v ivermectin and 1.25% w/v abamectin, this results in 450 microgram/kg 5 bodyweight for ivermectin and 250 microgram/kg bodyweight for abamectin. Alternatively the composition according to the invention can be used in pour-on formulations i.e. the parasiticidal active agents may be applied by a localised application to the outer surface of an animal, whereby the active ingredient migrates 10 as to protect the whole external surface of the animal. By "localised" application it is meant that the active ingredient is only applied to a minor portion of the outer surface of the animal, generally as a line or spot on the animals back. For such a pour on formulation a non-aqueous solvent as spreading agent may be 15 added to the composition according to the invention in order to help dispersing the active ingredients so that they reach all parasites of the animal and control the level of skin penetration. Suitable spreading agents are e.g. Crodamol@ CAP and Crodamol PMP of Croda 20 Chemicals Europe, East Yorkshire, United Kingdom which is an oil soluble emollient comprising fatty acid esters, produced by the direct esterification of natural fatty acids and alcohols. Suitably pour on formulations normally include a colouring agent to enable the user 25 to visually monitor the application of the composition to the animal, The nature of the coloring agent is unimportant and a wide variety of suitable dyes and pigments will be known to the skilled person. A suitable pour-on formulation is disclosed in Example 3. 30 WO 2005/037294 PCT/EP2004/052554 7 EXAMPLES: EXAMPLE 1: Method to produce formulation 1 5 FORMULATION 1 IVERMECTIN 2.25g ABAMECTIN 1.25g BENZYL ALCOHOL 7.OmL CASTOR OIL 52.5mL 10 TOCOPHEROL ACETATE 0.05g CORN OIL up to 1 OOmL Method to manufacture formulation 1: In a suitable recipient provided with stirrer and nitrogen bubbling system, add 15 abamectin, ivermectin and benzyl alcohol. Heat until 50 o C under agitation and stirring until the solubilization of active ingredients occurs. Add castor oil and mix during 30-60 minutes under heating (50 o C).Turn off the heat and diminish the temperature until 30-400C. Then, add acetate tocopherol and corn oil and mix until to get homogeneous solution (around 60-90 minutes) 20 Filter the solution through suitable filter cartridge and sterilized in 0.22 m cartridge to obtain sterile solution. Alternative method to manufacture formulation 1: PART 1: In a suitable recipient provided with stirrer and nitrogen bubbling system, 25 add abamectin, ivermectin and benzyl alcohol. Heat until 50 o C under agitation and stirring until the solubilization of active ingredients occurs. PART 2: In another recipient add castor oil heat until 50 o C under stirring. Transfer the part 1 to part 2 and mix during 30-60 minutes and then turn off the heat and diminish the temperature until 30-400C. Then, add acetate tocopherol and corn 30 oil and mix until to get homogeneous solution (around 60-90 minutes) Filter the solution through suitable filter cartridge and sterilized in 0.22 m cartridge to obtain sterile solution.

WO 2005/037294 PCT/EP2004/052554 8 EXAMPLE 2: Method to produce formulation 2 FORMULATION 2 IVERMECTIN 2.25g 5 ABAMECTIN 1.25g BENZYL ALCOHOL 7.OmL CASTOR OIL 35mL TOCOPHEROL ACETATE 0.05g CORN OIL 35mL 10 OLIVE OIL up to 100mL PART 1: In a suitable recipient provided with stirrer and nitrogen bubbling system, add abamectin, ivermectin and benzyl alcohol. Heat until 50 o C under agitation and stirring until the solubilization of active 15 ingredient occurs. PART 2: In another recipient add castor oil and corn oil, and mix during 30 minute under 50 o C. Transfer the part 1 to part 2 and mix during 30-60 minutes and then turn off the heat and diminish the temperature until 30-40oC. Then, add acetate tocopherol and olive 20 oil and mix until to get homogeneous solution (around one minute) Filter the solution through suitable filter cartridge and sterilized in 0.22 m cartridge to obtain sterile solution. EXAMPLE 3: Pour-on formulation 25 IVERMECTIN ABAMECTIN Vehicle: BENZYL ALCOHOL, CAPCIC/ CAPRYLIC ACID TRIGLYCERIDE, ISOPROPYLALCOHOL, CASTOR OIL 30 WO 2005/037294 PCT/EP2004/052554 9 EXAMPLE 4: Comparison of Ivermectin plasma concentrations after administration in different long acting vehicles by sc administration to cattle Material and Methods: The pharmacokinetic profile of an 1% ivermectin formulation 5 comprising 35% (v/v) castor oil was assessed in this study by a parallel comparison with an 1% ivermectin formulation in 72.2% (w/w) sesame oil. The formulations were administered at a single dose subcutaneous (sc) into the neck of cattle. Blood samples were collected by jugular venipuncture at times 0, 0.5, 1, 1.5, 2, 3, 5, 7, 10, 15, 20, 30, and 40 days after drug administration. The concentration of 10 ivermectin in the plasma samples was determined by HPLC. Results: Figure 1 shows bovine plasma ivermectin concentrations (individual animals in ng/mL) after single sc administration of the formulations. The results obtained show that the castor oil based long acting formulation maintained therapeutic blood 15 levels for 40 days compared to 20 days for the sesame oil based formulation. EXAMPLE 5: Comparison of Abamectin plasma concentrations after administration in different long acting vehicles by sc administration to cattle 20 Material and Methods: The pharmacokinetic profile of an 1% abamectin formulation comprising 35% (v/v) castor oil was assessed in this study by a parallel comparison with an 1% abamectin formulation in 72.2% (w/w) sesame oil. The formulations were administered at a single dose subcutaneous (sc) into the neck of cattle. Blood samples were collected by jugular venipuncture at times 0, 0.5, 1, 1.5, 2, 3, 5, 7, 10, 25 15, 20, 30, and 40 days after drug administration. The concentration of ivermectin in the plasma samples was determined by HPLC. Results: Figure 2 shows bovine plasma abamectin concentrations (individual animals in ng/mL) after single sc administration of the formulations. The results obtained 30 show that the castor oil based long acting formulation maintained therapeutic blood levels for 30 days compared to 15 days for the sesame oil based formulation.

Claims

1. A long acting composition for controlling parasites in and on animals, which comprises in a slow release vehicle a combination of ivermectin and abamectin, characterized in that the total percentage w/v of ivermectin and abamectin equals or 5 exceeds 3% w/v and the concentration of ivermectin is higher than the concentration of abamectin

2. The composition according to claim 1 characterised in that the slow release vehicle comprises 30 to 60% w/v of castor oil, a solvent and up to 100 % v/v of a 10 diluent.

3. The composition according to any of claims 1 or 2, characterised in that it comprises 1.75- 5% w/v ivermectin and 0.5- 2% w/v abamectin. 15

4. The composition according to any of claims 1 to 3, characterized in that it comprises 2.25% ivermectin and 1.25% abamectin.

5. The composition according to any of claims 1 to 4, characterised in that the diluent is a vegetable oil. 20

6. The composition according to any of claims 1 to 5, characterised in that the vegetable oil is selected from corn oil or olive oil or a combination of corn oil and olive oil. 25

7. The composition according to any of claims 1 to 6, characterised in that the solvent is benzyl alcohol.

8. Use of a composition according to any of claims 1 to 7 for the preparation of a medicament for controlling parasites in and on host animals. 30

9. Use according to claim 8 characterized in that the composition is administered to the host animal by injection or as pour-on.

10. Use according to claim 8 or 9, characterized in that the host animal is bovine. 11

11. A method for controlling parasites in and on host animals, which comprises administering a composition according to any one of claims I to 7 to a host animal in need thereof.

12. The method according to claim I1 wherein the composition is 5 administered to the host animal by injection.

13. The method according to claim 12 wherein the composition is administered to the host animal as pour-on.

14. The method according to any one of claims 11 to 13 wherein the host animal is bovine. 10

15. The method according to any one of claims 11 to 14 wherein the parasites include one or more of Haemonchus placei, Cooperia punctata, Cooperia spatulata and Trichuris discolor.

16. A long acting composition for controlling parasites in and on animals as defined in claim I and substantially as hereinbefore described with reference to any one is of Examples 1 to 3.

17. A method of producing a composition as defined in claim 1 which method is substantially as herein described with reference to Example 1 or 2. Dated 30 September, 2009 Akzo Nobel N.V. 20 Patent Attorneys for the Applicant/Nominated Person SPRUSON & FERGUSON