ANTHELMINTIC MACROCYCLIC LACTONE COMPOSITIONS

Abstract: A composition containing an anthelmintic chosen from the class of macrocyclic lactones including but not limited to the avermectins, ivermectin, doramectin, abamectin, milbemycin and moxidectin, together with a vegetable oil and a co-solvent chosen from the group comprising alcohols having four or more carbon atoms. The compositions of the invention may be formulated as injections, drenches or for topical administration and are suitable for treating helminthiasis in animals.

Description: Anthelmintic Macrocyclic Lactone Compositions TECHNICAL FIELD OF THE INVENTION This invention relates to compositions containing an anthelmintic chosen from the class of macrocyclic lactones including but not limited to the avermectins, ivermectin, doramectin, abamectin, milbemycin and moxidectin. BACKGROUND This class of anthelmintics are difficult to formulate. For example, the commercially available injectable antiparasitic agent based on an aqueous co-solvent formulation containing ivermectin, water and an organic co-solvent, has been shown to result in some precipitation of the ivermectin at the injection site, with the possibility of irritation to the animal, and possible loss of effectiveness as an anthelmintic. In pour-on formulations, water miscible formulations are diluted if there is rain after treatment. OBJECT It is an object of this invention to provide an improved injectable composition containing an anthelmintic, or one which will at least provide the public with a useful choice. STATEMENT OF INVENTION One aspect ofthe invention provides an injectable solution containing an anthelmintic chosen from the class of macrocyclic lactones including but not limited to the avermectins, ivermectin, doramectin, abamectin, milbemycin, and moxidectin, together with a vegetable oil and a co¬ solvent chosen from the group comprising alcohols having 4 or more carbon atoms. Preferred alcohols are benzyl alcohol, ethyl benzyl alcohol, phenethyl alcohol and other aromatic monohydric alcohols. The most preferred co-solvent is benzyl alcohol. More preferably the benzyl alcohol is present in the range of 1-30% by weight. Preferred vegetable oils are soya bean oil, sesame oil and corn oil. The most preferred oil is soya bean oil. Preferably the anthelmintic is chosen from the group comprising abamectin and ivermectin. More preferably the abamectin or ivermectin is present in the range from 0.5 - 5 % by weight ofthe formulation. Optionally, a wetting agent such as ethyl oleate may be used to assist in dissolving the anthelmintic in solution. Optionally, oil soluble vitamins may be added. In another aspect the invention provides a pour-on composition containing an anthelmintic chosen from the class of macrocyclic lactones including but not limited to the avermectins, ivermectin, doramectin, abamectin, milbemycin, and moxidectin, together with a vegetable oil and a co-solvent chosen from the group comprising alcohols having 4 or more carbon atoms. Preferred alcohols are benzyl alcohol, ethyl benzyl alcohol, phenethyl alcohol and other aromatic monohydric alcohols. The most preferred co-solvent is benzyl alcohol. More preferably the benzyl alcohol is present in the range of 1-30% by weight. Preferred vegetable oils are soya bean oil, sesame oil and corn oil. The most preferred oil is soya bean oil. Preferably the anthelmintic is chosen from the group comprising abamectin and ivermectin. More preferably the abamectin or ivermectin is present in the range from 0.5-5% by weight of the formulation. Optionally, a wetting agent such as ethyl oleate may be used to assist in dissolving the anthelmintic in solution. Optionally, oil soluble vitamins may be added. In another aspect the invention provides a solution suitable for oral administration containing an anthelmintic chosen from the class of macrocyclic lactones including but not limited to the avermectins, ivermectin, doramectin, abamectin, milbemycin, and moxidectin, together with a vegetable oil and a co-solvent chosen from the group comprising alcohols having 4 or more carbon atoms. Preferred alcohols are benzyl alcohol, ethyl benzyl alcohol, phenethyl alcohol and other aromatic monohydric alcohols. The most preferred co-solvent is benzyl alcohol. More preferably the benzyl alcohol is present in the range of 1-30% by weight. Preferred vegetable oils are soya bean oil, sesame oil and corn oil. The most preferred oil is corn oil. Preferably the anthelmintic is chosen from the group comprising abamectin and ivermectin. More preferably the abamectin or ivermectin is present in the range from 0.1-10% by weight of the formulation. Optionally, a wetting agent such as ethyl oleate may be used to assist in dissolving the anthelmintic in solution. Optionally, oil soluble vitamins may be added. DRAWINGS Figure 1 : is a chart showing Faecal Egg Counts prior to treatment and for two weeks after treatment (Trial 1 ). Figure 2: is a chart showing Faecal Egg Counts prior to treatment and for three weeks after treatment (Trial 2). DEFINITIONS FEC stands for Faecal Egg Counts FECR stands for Faecal Egg Count Reduction PREFERRED EMBODIMENTS These and other aspects of this invention, which should be considered and always novel aspects, will be apparent from the following examples. We have found that the particular formulations ofthe chosen anthelmintic, as set out in the following examples, can increase the length of activity ofthe anthelmintic on external and internal parasites. Avermectins, ivermectin, doramectin, abamectin, milbemycin and moxidectin oxidise and break down in water. Previous formulations of avermectin and ivermectin have been based on glycol solvents, glycerol formal, surfactants and/or water. These have had the disadvantage that the abamectin or ivermectin was rapidly released in the animal, giving a shorter activity which was also sometimes toxic. This resulted from the rapid absoφtion into the blood stream of the abamectin or ivermectin and excretion ofthe drug. It is particularly noted in the case of young animals, who have a low tolerance to these high levels of abamectin or ivermectin in the blood stream. Indeed, calves under ten weeks old cannot be treated with an injectable composition containing abamectin and a co-solvent as this may be toxic. Avermectins, ivermectin, doramectin, abamectin, milbemycin and moxidectin are sparingly soluble in oils such as sesame oil, soya bean oil and corn oil. Pure sesame oil has a relatively high viscosity, which makes it unsuitable for use as a solvent for injection using typical veterinary syringes. We have found that by using sesame oil, soya bean oil or corn oil together with a co-solvent chosen from the class of alcohols having four or more carbon atoms, and more preferably benzyl alcohol it is possible to make a stable solution containing avermectins, ivermectin, doramectin, abamectin, milbemycin or moxidectin which allows the avermectins, ivermectin, doramectin, abamectin, milbemycin or moxidectin to remain in solution even when stored in cold conditions, whilst at the same time allowing the controlled release ofthe drug into the animal's body, for use against both internal and external parasites. Solutions can be prepared which are suitable for injection, pour-on application and/or oral administration. Injectable Formulations: Example 1: Ivermectin 1% Benzyl Alcohol 20% Sesame Oil to 100% Example 2: Ivermectin 1% Benzyl Alcohol 20% Soya Bean Oil to 100% Example 3: Trial Solution 1 Abamectin 1% Benzyl Alcohol 20% Sesame Oil to 100% The abamectin was dissolved in a mixture of benzyl alcohol and sesame oil. Example 4: Ivermectin 1% Benzyl Alcohol 20% Soya Bean Oil to 100% Example 5 Ivermectin 1% Benzyl Alcohol 20% Ethyl Oleate 10% Sesame Oil to 100% le 6: Abamectin 1% Benzyl Alcohol 20% Ethyl Oleate 10% Soya Bean Oil to 100% Trial 1 Evaluation ofthe efficacy of Trial Solution 1 Injection in the control and treatment of naturally occurring infection with common pathogenic nematodes in cattle. TRIAL ACTIVITY AND DESIGN Day 1 Animals selected and allocated randomly: 15 cattle untreated control 100 cattle treated with Dectomax* 100 cattle treated with Trial Solution 1 Animals weighed Samples taken for the FEC from 15 control animals and 15 animals in each treated group. Animals giving samples identified so that they can be followed throughout the trial. Larval development test on group samples conducted. Animals treated as per treatment protocol. Day 7 Samples for the FEC from each of 45 identified animals taken If eggs are present in the faeces, conduct larval development test on group samples for confirmation ofthe species involved. Day 14 Samples for the FEC from each of 45 identified animals taken. If eggs are present in the faeces, conduct larval development test on group samples for confirmation ofthe species involved. Some ofthe animals in the control group treated due to high egg counts. (*Dectomax is a registered trade mark of Pfizer Pty Limited) PARASITOLOGY ANALYSIS Faecal samples will be analysed for gastrointestinal nematodes and lungworms. Larval differentiation test will also be performed whenever the eggs are present. Only initial larval differentiation results are available at the moment. RESULTS Mean FEC and % of reduction per group prior to treatment and for 2 weeks after the treatment: Day 1 Day 7 Day 14 abamectin 490* 0(100%) 3.3 (99.8%) doramectin 610* 10.7(98.9%) 350(86.8%) control 586* 1056.6 1896.6 *no statistical difference between the treatment Figure 1 shows the graphical representation of these results. Trial 2 Evaluation ofthe efficacy of Trial Solution 1 Injection in the control and treatment of naturally occurring infection with common pathogenic nematodes in cattle. TRIAL ACTIVITY AND DESIGN Day l Animals selected and allocated randomly: 100 cattle to each group: C = controls A = abamectin + copper injection B = doramectin + copper injection G = abamectin (Trial Solution 1) I = ivermectin + copper injection Animals weighed. Samples taken for the FEC. Larval development test on group samples conducted. Animals treated as per treatment protocol. Day 7 Samples for the FEC taken. Larval development test on group samples conducted. Day 14 Samples for the FEC taken. Larval development test on group samples conducted. Day 21 Samples for the FEC taken. Larval development tests on group samples conducted. PARASITOLOGY ANAL YSIS Faecal samples were analysed for gastrointestinal nematodes and lungworms. Larval differentiation test were performed whenever the eggs are present. RESULTS Mean FEC and % of reduction per group prior to treatment and for 3 weeks after the treatment: Day 1 Day 7 Day 14 Day 21 abamectin+ 340 0(100%) 0(100%) 0(100%) Cu abamectin 160 0(100%) 0(100%) 0(100%) doramectin 345 15(88.88%) 5(97.91%) 25(92.53%) ivermectin 170 5(96.29%) 25(89.58%) 40(88.05%) control 290 135 240 335 Figure 2 shows the graphical representation of these results. Trial 3 A trial was undertaken to assess the efficacy of Trial Solution 1 injection and Stand-by pour-on formulations against natural infections of gastro-intestinal nematode parasites of cattle. Twenty-four clinically healthy Friesian and Friesian cross male calves, 6-7 months of age, and of similar body condition, harbouring natural infections were restrictively randomised into 4 groups. Group 1 remain as the untreated control, Group 2 was injected subcutaneously in the left side ofthe neck with Abamectin L A (200μg kg), Group 3 was treated with the Stand-by pour-on formulation along the mid line ofthe back and Group 4 was treated with Ivomec* Pour-on formulation (500μg/kg) in accordance with the manufacturers recommendation (MSD AgVet). On days 7 and 8 post treatment the calves were necropsied for worm counts. At necropsy all the treated groups harboured significantly fewer adult, late 4 th and early 4 th stage worms ofthe main cattle parasites viz. Ostertagia spp. and Cooperia spp. as well as Haemonchus contortus (p<0.01). Only in the case of Cooperia spp was there a significant difference between treated groups there being fewer adult worms present in the group treated with injectable abamectin (p<0.01). There were also significantly fewer adult and late 4 th stage worms of Trichostrongylus axei in the treated groups but not early 4 stage worms. All three treated groups also showed significant efficacy against adult Dictyocaulus viviparus, Chabertia ovina (both p<0.01), Capillaria spp. and Trichuris spp. (both p<0.05). No adverse reactions to the treatments were observed at the time of their administration. There were no visible lesions at the injection site of Group 2 calves at slaughter 7 days after treatment. (*Ivomec is a registered trade mark of Merck & Co., Inc. and is used on compositions containing ivermectin) Experimental Procedures Animals: Twenty four clinically healthy Friesian and Friesian cross male calves, 6-7 months of age, and of similar body condition, harbouring natural infections of gastro-intestinal nematodes were obtained from commercial properties and held on pasture for 7 days prior to the commencement ofthe trial. The calves were individually identified by ear tags on arrival at WallaceviUe Animal Research Centre, weighed and sampled for faecal egg counts to ensure they were carrying adequate worm burdens. Animal Welfare: Animals handling procedures were in compliance with local regulations and conducted with the approval of the WallaceviUe Animal Ethics Committee - AEC No. 440. Parasite burdens: On arrival on day -7 the animals were weighed and faecal sampled and a bulk faecal culture was undertaken to identify the composition ofthe calves worm burdens. Treatments: On Day 0 the calves were re-weighed and randomly allocated to four treatment groups on the basis of faecal egg count, live weight and overall body condition (see Table 1). Treatments were administered according to individual live weights using disposable 5.0, 10.0 or 20.0 ml graduated plastic syringes (see Appendix 2 Table lb). Group 2 was injected in the left side ofthe neck near the base of the ear with Abamectin L.A. (200 μg/kg); Group 3 was treated with the Stand-by Pour-on formulation (500 μg/kg MSD Ag Vet) in accordance with the manufacturer's recommendation and Group 1 remained as the untreated control. Table 1: Treatment Allocation Group Count Anthelmintic Dose/Kg 1 n=6 Untreated Control - 2 n=6 Abamectin injectable Day 0 200μg/kg 3 n=6 Stand-by pour-on Day 0 4 n=6 Ivomec Pour-on Day 0 500μg kg Husbandry - Feed and water: The animals were maintained on pasture for the duration ofthe trial with ready access to drinking water. The groups treated with pour-on anmelmintics were kept on separate pastures for approximately 12 hours after treatment to avoid the transfer ofthe pour-on formulations to those in other groups. At all other times the calves were maintained as one herd. Reactions to treatments: All animals were observed for adverse reactions to the anthelmintics immediately after treatment and when they were returned to pasture. At time of slaughter Group 2 calves (Abamectin injectable) had the left side ofthe neck skinned in order to assess any reaction to the treatment. Faecal Sampling: All animals were faecal sampled on Day -7, Day 0 and Day 5. Faecal egg counts were carried out using a modified McMaster technique in which each egg counted represents 50 eggs per gram faeces. Necropsies: The calves were necropsied on Days 7 and 8 following anthelmintic treatment. The groups were arbitrarily divided into two with half of each group slaughtered on each day. The animals were euthanased by stunning with a captive bolt pistol followed by ex- sanguination and severing ofthe nerve chord. Worm counts ofthe gastro intestinal tracts and lungs were carried out using the method described by Brunsdon, (1972) and in accordance with the World Association for the Advancement of Veterinary Parasitology guidelines (Wood et al. (1995)). Lungs and the abomasal mucosa were processed using the techniques described by Downey (1981) and Oakley (1989). Briefly the lungs together with the heart and the gastrointestinal tract were removed and the abomasum, small intestine and large intestine ligatured and separated. The lungs were infused after the method of Oakley (1989) using mains pressure water directed through the pulmonary artery. Approximately 8 litres were passed through each lung. The bronchial tree was then opened with scissors and examined to ensure no worms remained. The total contents and washings ofthe abomasum and small intestine were also collected separately, made up to 8 litres and a 1/10 aliquot passed through a 45μ sieve and preserved with formalin for counting. The contents and washings ofthe abomasum and small intestine were also collected separately, made up to 8 litres and a 1/10 aliquot passed through a 45μ sieve and preserved with formalin for counting. The contents ofthe large intestine were made up to 8 litres and half passed through 635μ sieve and preserved with formalin for counting. The abomasal mucosa of each animal was incubated in 1.5 litres of physiological saline at 37°C over night (Downey, 1981) and then treated as with the contents. Nematode Counts: Nematodes present in the total contents ofthe washings from the lungs, the 1/2 aliquot sample ofthe large intestine, a 1/5 subsample ofthe abomasal contents, abomasal mucosa and a 1/10 subsample ofthe small intestine were identified to developmental stage and genus and counted. Counts were multiplied by the appropriate aliquot factor to give total numbers present in each organ. The first 20 adult male worms ofthe genera Ostertagia and Cooperia in each sample (depending on availability) were identified to species using the spicule morphology to determine the species composition ofthe respective worm population on a proportional basis. Statistical Methods: Data for both faecal egg counts and worm counts were transformed to Log e (X+100) to normalise their distributions before analyses were carried out. FEC's and worm counts were analysed by 1-way ANOVA's using the Minitab 10.5 statistical package. FEC's and worm counts given in tables are the back transformed values. The percentage efficacy were calculated as: (Mean of Control - Mean of Treatment Mean of Control) x 100 Results: Faecal culture: Results ofthe pre-treatment faecal culture indicated that the following genera of gastrointestinal nematodes were present in the experimental herd - Haemonchus contortus, Ostertagia spp., Trichostrongylus spp., Cooperia spp., and Oesophagostomum spp. (Table 2). Table 2: Generic composition of faecal egg output of trial animals pre-treatment. Genus L3 - Count Percent Trichostrongylus spp 5 2 Ostertagia spp. 23 12 Haemonchus contortus 6 3 Cooperia spp 162 81 Oesophagostomum spp 4 2 Total 200 100 Faecal egg counts (FEC's) Pre- and post- treatment FEC's and percentage faecal egg count reductions (FECR) are presented in Table 3. FEC's of all three treated groups of day 5 were significantly lower than the controls (pO.Ol) but not significantly different from one another. The FECR for the injectable formulation of abamectin was the higher than both ofthe pour-on treatments. Table 3: Faecal Egg Counts (Geometric means). Pre-treatment Post-treatment Group FEC 1- 8/02 FEC 2 - 15/02 FEC 3 - 20/02 FECR % 1 Control 546.0 733.3 673.7 a 2 Abamec LA 537.9 393.9 6.9 b 98.97 3 Stand-by P- 513.7 528.9 46.8° 93.05 on 4 Ivomec P-on 568.1 641.6 54.3° 91.94 FECR = Faecal egg count reduction for FEC3 on samples taken 5 days post treatment. Values for FEC 3 for 20/02 with different super scripts are significantly different (pO.Ol). Worm counts The geometric mean worm burdens recovered from the abomasum, small intestine, large intestine and the lungs and the percentage reduction are presented in Tables 4-7. A small number of parasites of sheep origin were present in the calves which had been in a mixed grazing management system. Treated animals had significantly fewer adult, late 4th and early 4th stage worms of Ostertagia spp, Haemonchus contortus, and Cooperia spp. Only in the case of Cooperia spp was there a difference between treatment groups there being significantly fewer adult and late 4th stage worms of Trichostrongylus axei in all treated groups but not early 4th stage larvae. Due to the trial design it cannot be verified that this is due to the lower efficacy ofthe treatments against this developmental stage at the calves may have acquired some larvae while grazing on pasture between the treatment date and the time of their slaughter. All three treatments also showed significant efficacy against adult Dictyocaulus viviparus, Chabertia ovina (both p<0.01) as well as Capillaria spp. and Trichuris spp. (both p<0.05). The efficacy ofthe treatments against a Nematodirus spp., and Oesophagostomum spp. could not be determined with any degree of accuracy as there were only present in small numbers. Table 4: Mean abomasal worm burdens (Geometric data). Mean worm count and % efficacy for treatment groups Genus & stage Group 1 Group 2 Group 3 Group 4 of development Ostertagia spp Adult (5th) 6921.2 a 33.4° (99.5) 6.9 b (99.9) 6.9 b (99.9) Late 4th 466.9 a 6.9° (98.5) 24.6° (94.7) 6.9° (98.5) Early 4th 1837.6 a 34.8° (98.1) 44.2° (97.6) 35.7° (98.1) Trichostrongy lus axei Adult 3259.7 a 20. l b (99.4) 23.2 b (99.3) 81.7 b (97.5) Late 4th 1087.7 a 20. l b (98.2) 28.5° (97.4) 61.9° (94.3) Early 4th 3252.6 822.5(74.7) 1023.2 (68.5) 1614.2 (50.4) Haemonchus contortus Adult (5th) 277. l a 0.0 b (100) 0.0 b (100) 0.0 b (100) Late 4th 312.3 3 0.0° (100) 28.5° (90.9) 0.0° (100) Early 4th 1360.3 3 49.7° (96.3) 54.3° (96.0) 39.9° (97.1 For rows values with different super scripts are significantly different (pO.Ol). Table 5: Mean small intestinal worm burdens (Geometric data). Mean worm count and % efficacy for treatment groups Genus & stage Group 1 Group 2 Group 3 Group 4 of development Cooperia spp Adult (5th) 51434.2 3 248.6° (99.5) 3479.6° (93.2) 3055.8° (94.1) Late 4th 7398.1 3 0.0° (100) 84.9° (98.8) 49.1° (99.3) Early 4th 23216.4 3 243.1° (98.9) 465.1 D (98.0) 462.3° (98.0) Trichostrongy lus spp 15.1 0.0 0.0 0.0 Adult (5th) Late 4th 12.2 0.0 0.0 0.0 Early 4th 30.8 0.0 0.0 0.0 Nematodirus spp 453.4 0.0 195.9 159.6 Adult (5th) Capillaria spp Adult (5th) 70.1 X o.o y o.o y 12.2 y For rows values with different super scripts are significantly different a, b (pO.Ol); x, y (p<0.05). Rows with non-annotated values are not significantly different. Table 6: Mean large intestinal worm burdens (Geometric data). Mean worm count and % efficacy for treatment groups Genus & stage Group 1 Group 2 Group 3 Group 4 of development Oesophagosto mum 1.3 0.0 0.0 0.0 Adult (5th) Trichuris spp Adult (5th) 24.8 X o.o y 2.3 y 1.3 y Chabertia vina ι.o a o.o b o.o b 0.0° Adult (5th) For rows values with different super scripts are significantly different a, b (pO.Ol); x, y (p<0.05). Table 7: Mean lungworm burdens (Geometric data). Mean worm count and % efficacy for treatment groups Genus & stage Group 1 Group 2 Group 3 Group 4 of development Dictyocaulus viviparus 10.9 3 0.0° (100) 0.0° (100) 0.0 b (100) Early 5th adults Values with different super scripts are significantly different (p<0.01). Species composition (Ostertagia and Cooperia). Four species of Ostertagia and three species of Cooperia were identified from the worm burdens ofthe calves in the trial - i.e. 0. ostertagi, O. lyrata, O. leptospicularis, O. kolchida, C. oncophora, C mcmasteri, and C. punctata. O. ostertagi and C. oncophora were the predominant species present representing approximately 60% and 75% ofthe respective genera (Table 8). All three anthelmintic treatments appeared equally effective against all species oϊ Ostertagia and similar proportions of all Cooperia species remained after treatment. Table 8: Species composition ofthe Ostertagia and Cooperia worm populations (based on the identification of adult males). Mean % species composition and range Species Group 1 Group 2 Group 3 Group 4 O. ostertagi 60.2 * * * (45-80) O. lyrata 27.6 * * * * (10-45) 0. leptospicularis 6.5 * * * (0.10) O. kolchida 5.7 * * * (0-10) 0. oncophora 74.4 77.0 75.0 78.3 (61-80) (75-78) (67-80) (70-88) O. mcmasteri 10.1 15.4 13.8 13.3 (4-28) (0-22) (0-29) (9-18) 0. punctata 15.5 7.6 11.2 8.4 (5-30) (0-25) (0-33) (0-15) * = No adult males found ** = Only adult male found Injection sites No adverse reaction to either the injectable or pour-on formulations was observed at the time of treatment. At the time of slaughter the injection sites of group 2 calves were examined by removing the skin from the neck of each animal. No reactions to treatment were found. We have found that we can produce long acting injectable solutions containing between 0.5-5% of an anthelmintic chosen from the class of monocyclic lactones including but not limited to avermectins, ivermectin, doramectin, abamectin, milbemycin, and moxidectin, by using from 1-30% benzyl alcohol and a vegetable oil such as sesame oil or soya bean oil, and by optionally using from 5-30% ofa wetting agent such as ethyl oleate. Optionally, oil soluble vitamins such as Vitamins A, D, E and K^ may be added. Oral Formulations: Example 6: Ivermectin 0.1% Benzyl Alcohol 10% Corn Oil to 100% Example 7: Abamectin 0.1% Benzyl Alcohol 10% Corn Oil to 100% Example 8: Doramectin 0.1% Benzyl Alcohol 10% Corn Oil to 100% Example 9: Milbemycin 0.1% Benzyl Alcohol 10% Corn Oil to 100% We have found that we can produce long acting solutions for oral administration containing between 0.1-5% of an anthelmintic chosen from the class of monocyclic lactones including but not limited to avermectins, ivermectin, doramectin, abamectin, milbemycin, and moxidectin, by using from 1-30% benzyl alcohol and a vegetable oil such as corn oil, sesame oil or soya bean oil, and by optionally using from 5-30% of a wetting agent such as ethyl oleate. Optionally, oil soluble vitamins such as Vitamins A, D, E and Kj may be added. Pour-on Formulations: Example 13: Abamectin 1.0% Benzyl Alcohol 20% Soya Bean Oil to 100% Example 14: - Ivermectin 1.0% Benzyl Alcohol 20% Soya Bean Oil to 100% Example 15: Moxidectin 1.0% Benzyl Alcohol 20% Soya Bean Oil to 100% Example 16: Abamectin 1.0% Benzyl Alcohol 20% Ethyl Oleate 10% Soya Bean Oil to 100% We have found that we can produce long acting pour-on solutions containing between 0.5-5% of an anthelmintic chosen from the class of monocyclic lactones including but not limited to avermectins, ivermectin, doramectin, abamectin, milbemycin, and moxidectin, by using from 1-30% benzyl alcohol and a vegetable oil such as sesame oil or soya bean oil, and by optionally using from 5-30% ofa wetting agent such as ethyl oleate. Optionally, oil soluble vitamins such as Vitamins A, D, E and Kj may be added. ADVANTAGES The relatively high viscosity of vegetable oils such as sesame oil makes them unsuitable for use as a solvent for injection using typical veterinary syringes. However, a co-solvent chosen from the class of alcohols having 4 or more carbon atoms, and preferably benzyl alcohol, decreases the viscosity ofthe vegetable oil such that the vegetable oil becomes a suitable solvent for injection. The active anthelmintic ingredient remains in solution in formulations of this invention even when stored for long periods or in cold conditions. The formulations of this invention also allow the controlled release ofthe active anthelmintic in the blood stream ofthe animal. INDUSTRIAL APPLICATION The formulations shown above are effective in the treatment of helmithiasis in cattle and other domestically important animals including, but not limited to, goats and pigs. VARIATIONS Whilst the above examples have concentrated on the use of ivermectin and abamectin, it will be appreciated that the same technique can be used to provide stable formulations for injectable, pour-on or oral administration containing an anthelmintic chosen from the group comprising avermectins, ivermectin, doramectin, abamectin, milbemycin, and moxidectin. Although we prefer to use sesame oil in these formulations other vegetable oils such as soya bean oil, corn oil and rape oil are possible as are other viscous vegetable oils. Benzyl alcohol is the preferred co-solvent, however other co-solvents may be used in some formulations. Finally it will be appreciated that various other alterations and modifications may be made to the forgoing without departing from the spirit or scope of this invention. REFERENCES Brunsdon. R.V.. 1972: Inhibited development of Ostertagia spp. and Cooperia spp. in naturally acquired infection in calves. N.Z. Veterinary Journal 20: 183-189) Downey. N.E.. 1981 : Recovery of Ostertagia from bovine abomasal mucosa by immersion in warm normal saline. In P. Nansen, R.J. Jorgenson, E.J.L. Soulsby, Eds Epidemiology and Control of Nematodiasis in Cattle. ECSC, EAEC, Brussels Luxembourg. Oakley. G.A.. 1989: The recovery of Dictycaulus viviparous from bovine lungs by lung perfusion: a modification of Inderbitzem's method. Research in Veterinary Science. 29, 395-6. Wood I.B.. Amaral N.K.. Bairden K. et al. 1995: World Association for the Advancement of Veterinary Parasitology (W.A.A.V.P) - Second Edition of Guidelines for Evaluating the Efficacy of Anthelmintics in Ruminants (bovine, ovine, caprine). Veterinary Parasitology 58: 181-213

Claims: CLAIMS: 1. A composition containing an anthelmintic chosen from the class of macrocyclic lactones, together with a vegetable oil and a co-solvent chosen from the group comprising alcohols having 4 or more carbon atoms. 2. A composition as claimed in claim 1, wherein the anthelmintic is chosen from the group comprising the avermectins, ivermectin, doramectin, abamectin, milbemycin, and moxidectin. 3. A composition as claimed in claim 1, wherein the co-solvent is chosen from the group comprising benzyl alcohol, ethyl benzyl alcohol, phenethyl alcohol, and other aromatic monohydric alcohols. 4. A composition as claimed in claim 3, wherein the co-solvent is benzyl alcohol. 5. A composition as claimed in claim 4, wherein the benzyl alcohol is present in the range of 1-30% by weight. 6. A composition as claimed in claim 1 wherein the vegetable oil is chosen from the group comprising sesame oil, soya bean oil, and corn oil. 7. A composition as claimed in claim 1 wherein the anthelmintic is present in the range of from 0.1-5% by weight of formulation. 8. A method of treating helminthiasis by injecting an animal with a composition as claimed in claim 1 at the rate of 100-300 μg/kg ofthe animal's live weight. 9. A method of treating helminthiasis by applying a topical pour-on composition as claimed in claim 1 at the rate of 200-600 μg/kg ofthe animal's live weight. 10. A method of treating helminthiasis by drenching an animal with a composition as claimed in claim 1 at the rate of 100-300 μg/kg of the animal's live weight.

Inventors: HARVEY COLIN MANSON, HARVEY, COLIN, MANSON
Applicants: ASHMONT HOLDINGS LTD, HARVEY COLIN MANSON, ASHMONT HOLDINGS LIMITED, HARVEY, COLIN, MANSON
Application year: 1996
Main classification: A61K31
IPC codes: A61K9, A61K31, A61K47