Anthelmintic combination

The present invention relates to compositions for controlling parasites, comprising a combination of ivermectin, abamectin, albendazole sulphoxide and trichlorfon and the use of such compositions in the preparation of a medicament for controlling parasites.

Endoparasites commonly cause clinical disease in especially in livestock animals and have significant adverse economic effects on farming economies when present at subclinical levels. 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 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.

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.

Meanwhile the problem has arisen that some parasites develop a resistance to antiparasitic drugs like ivermectin. The resistance occurs when a strain of a parasite is able to tolerate 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 several reports on resistant endoparasites in sheep, cattle and goats were published. 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 endoparasites, especially in ruminants and delaying the occurrence of resistant strains. Avermectins are well known anthelmintic compounds, belonging to the class of macrocyclic lactones. The avermectins are isolated from fermentation products of 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 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.

Albendazole sulphoxide (also known as ricobendazole) is a benzimidazole carbamate which is used as a broad spectrum anthelmintic in veterinary medicine. The preparation and certain uses of albendazole sulphoxide are disclosed in U.S. Pat. No. US 3,915,86. It is also the metabolite of two other veterinary drugs: netobimin and albendazole. Albendazole is the generic name for [5-(propylthio)-1 H- benzimidazol-2-yl)]carbamic acid methyl ester. The preparation and certain uses of albendazole are disclosed in U.S. Pat. No. 3,915,986.

Trichlorfon (O,O-dimethyl-(2,2,2-trichloro-1-hydroxyethyl)-phosphonale dimethyl 2,2,2,2-trichloro-1-hydroxyethyl-phosphonate, also called metrifonate is an organophosphorous compound having potent anticholinesterase activity and is administered topically as an ectoparasiticide or orally as an anthelmintic.

Examples of other organophosphates as antiparasitic agents are e.g. dichlorvos, coumaphos, crufomate or haloxon. Organophosphates act as cholinesterase inhibitor by irreversible inactivation of acetylcholinesterase, leading to excessive cholinergic activity at relevant sites.

It has now been found that the combination of ivermectin, abamectin, albendazole sulphoxide and trichlorfon result in such a broad-spectrum anthelmintic composition with activity against resistant nematode species.

The present invention concerns an anthelmintic composition, which comprises a combination of ivermectin, abamectin, albenazole sulphoxide and trichlorfon.

In one embodiment the present invention provides an antiparasitic composition, which comprises as active ingredient, an effective amount of a combination of ivermectin, abamectin, albendazole suphoxide and trichlorfon in the following concentrations: 0.02-1.0% or 0.05- 0.25% w/w ivermectin, 0.01-0.5%, or 0.05-0.25%

w/w abamectin, 0.3 - 15%, or 1.0% - 2.5% w/w albendazole sulphoxide and 10-70 %, or 15- 60% w/w trichlorfon.

The invention includes pharmaceutically acceptable salts of the compounds.

Pharmacologically intolerable salts which can initially be obtained, for example, as process products in the production of the compounds according to the invention on the industrial scale, are converted into the pharmacologically tolerable salts by processes known to the person skilled in the art.

In order to form the composition according to the invention the active ingredients may be present in the dosage form as true mixtures, but they may also be administered individually in separate dosage forms and form mixtures only when they are in the host animal.

The pharmaceutical composition can be in a form suitable for oral or intraruminal administration, as a solid dosage form, a liquid suspension, or a paste. Conventional liquid formulations for oral administration are usually solutions, suspensions or emulsions of the active ingredients together with suitable diluents, solvents, flavours and colours to form a dosage form.

In one embodiment the composition is in the form of a powder for extemporaneous suspension. This powder is suspended in water or in a suspension containing active ingredients before oral administration to the animal.

The particular amount of the anthelminthic compound required for a particular treatment will vary, depending upon the species, age and weight of the animal being treated, the particular parasite to be guarded against, or treated, as well as the specific organophosphate compound selected for the treatment, the route and the frequency of administration. Anthelminthics are frequently delivered to ruminants in the form of oral drenches directly into the rumen.

By "w/v" is meant weight/weight, i.e. "1 % w/v" means 1 g in 100 g of the composition, "v/v" means volume per volume, and 1% v/v means 1 ml, in a total of 100 ml.

Good results were obtained with a composition comprising 0.1% ivermectin, 0.05% abamectin, 20% trichlorfon and 1.5% albendazole sulphoxide. A recommended

dosage is 2 ml of the aqueous suspension based on the powder formulation described above per 5 kg body weight of the animal.

The novel compositions according to the invention have proven good efficacy against internal parasites, especially in sheep and goats. The novel compositions according to the invention result in a unique formulation which controls parasites resistant to ivermectin and doramectin, like, Cooperia spp. and Haemonchus spp.

The compositions of the invention may be used for the preparation of a medicament for controlling parasites in and on host animals, particularly in ruminants such as sheep, cattle and goats.

EXAMPLES: Suspension formulation

Example 1 :

A B

Trichlorfon 50.Og 5Og

Albendazole sulphoxide 3.Og 3.Og

Ivermectin 0.1g 0.2g

Abamectin 0.1g 0.1 g

Method to manufacture formulation 1 :

The following ingredients are introduced sequentially into a vessel containing water and with the stirring: methylparaben, propylparaben, sodium laurylsulfate or other wettable surfactant, aluminum hydroxide dry, Aerosil 200, albendazole sulphoxide, ivermectin and abamectin. Stir until getting homogeneous suspension. Trichlorfon is added at the moment of using.

Example 2

A B

Trichlorfon 25g 25%

Albendazole sulphoxide 1.5g 1.5%

Ivermectin 0.1g 0.2%

Abamectin 0.1g 0.1 %

Method to manufacture formulation 2:

The following ingredients are introduced sequentially into a vessel containing water and with stirring: polysorbate, propyleneglycol, Albendazole sulphoxide, ivermectin and abamectin. Add methylparaben and propylparaben in ethanol and antifoam. Stir until get homogeneous suspension and add hydroxyethylcellulose hydrated. Trichlorfon is added at the moment of using.

Example 3:

A B

Trichlorfon 5Og 25g

Albendazole sulphoxide 3.Og 1.5g

Ivermectin 0.2g 0.1g

Abamectin 0.1 g 0.05g

Method to manufacture formulation 3:

The following solid ingredients are introduced sequentially into a vessel containing water and with the stirring: methylparaben, propylparaben. Aerosil 200, albendazole sulphoxide, ivermectin and abamectin. Stir until getting homogeneous suspension and add the mixture of water, polysorbate, antifoam and ethanol. Trichlorfon is added at the moment of using.

Example 4

AA B

Trichorfon 20.0% 50%

Albendazole sulphoxide 1.5% 3.0%

Ivermectin 0.1 % 0.2%

Abamectin 0.05% 0.1 % Method to manufacture formulation 4

The following ingredients are introduced sequentially into a vessel containing water and with the stirring: sodium citrate, Carboxymethylcellulose, Polyvinylpyrrolidone and Aerosil 200. Stir until getting homogenous dispersion and add a solution of methylparaben and propylparaben dissolved in benzyl alcohol. Stir and add albendazole sulfoxide, abamectin and ivermectin. Trichlorfon is added at the moment of using.

Experiment 1

An field trial experiment conducted in naturally infected sheep demonstrated that the combination of ivermectin, abamectin, albendazole sulphoxide and trichlorfon according to the invention showed a higher anthelminthic efficacy compared to TRIMIX, Merial containing 200 mcg/kg ivermectin, 7,5 mg/kg levamisole, 5 mg/kg albendazole and CYDECTIN injectable, Fort Dodge Animal Health, containing Moxidectin, both commercial formulations, against the following species of endoparasites: Haemonchus contortus (both Trimex and Cydectin) and S.papillosus (Cydectin), All formulations showed a 100% efficacy against the other species on the 14th day post treatment for C. pectinata, C. curticei, C. spatulata, T. axei, O. columbianum and Trichuris ovis.

Experiment 2 An field trial experiment conducted in naturally infected sheep demonstrated that the combination of ivermectin, abamectin, albendazole sulphoxide and trichlorfon according to the invention showed a higher anthelminthic efficacy, when compared to TRIMIX of Merial, containing 200 mcg/kg ivermectin, 7,5 mg/kg levamisole, 5 mg/kg albendazole and CYDECTIN oral, Fort Dodge Animal Health containing Moxidectin, both commercial formulations, against the following species of endoparasites: Haemonchus contortus (Cydectin) , T. axei (Cydectin) and S.papillosus (Cydectin),

All formulations showed a 100% efficacy against the other species on the 14th day post treatment for C. curticei, C. bovis, O. columbianum and Trichuris ovis.

Experiment 3

An field trial experiment conducted in naturally infected goat demonstrated that the combination of ivermectin, abamectin, albendazole sulphoxide and trichlorfon showed a higher anthelminthic efficacy, when compared to TRIMIX of Merial and CYDECTIN injectable, Fort Dodge Animal Health, containing Moxidectin, both

commercial formulations, against the following species of endoparasites: T. ovis (Cydectin), C. bovis (Cydectin).

All formulations showed a 100% efficacy against the other species on the 14th day post treatment for H. contortus, T. axei, T. columbriformis, O. columbianum.

Experiment 4

An field trial experiment conducted in naturally infected goat demonstrated that the combination of ivermectin, abamectin, albendazole sulphoxide and trichlorfon showed a higher anthelminthic efficacy, when compared to TRIMIX of Merial containing 200 mcg/kg ivermectin, 7,5 mg/kg levamisole, 5 mg/kg albendazole and CYDECTIN oral, Fort Dodge Animal Health, containing Moxidectin, both commercial formulations, against the following species of endoparasites: Haemonchus contortus (both Trimex and Cydectin), T. ovis (Cydectin) and S.papillosus (Cydectin),

All formulations showed a 100% efficacy against the other species on the 14th day post treatment for C. curticei, C. spatulata, T. axei, T. colubriformis and O. columbianum.

Experiment 5

Efficacy on e.p.g. reduction in sheep The efficacy of a combination of 0.1 % ivermectin, 0.1 % abamectin, 3% albendazole sulphoxide and 50% trichlorfon was compared with ivermectin, abamectin, albendazole sulphoxide and trichlorfon alone in 4 animals per group

The combination according to the invention showed a egg per gram (e p g) reduction in sheep on Day 3 of 97.0 % compared with 84% for trichlorfon, 66.1 % for albendazole sulphoxide, 63.8% for ivermectin and 30% for abamectin alone.

Experiment 6

Efficacy on e.p.g. reduction in sheep

Efficacy on e.p.g. reduction in sheep was evaluated for the combination of 0.1 % ivermectin, 0.1% abamectin, 3% albendazole sulphoxide and either 20% or 25% trichlorfon compared with the commercial product TRIMIX of Merial containing 200 mcg/kg ivermectin, 7,5 mg/kg levamisole, 5 mg/kg albendazole .

The combination with 20% Trichlorfon showed a e.p.g. reduction in sheep on Day 3 of 99.5% % and 100% for Trichlorfon 25 % compared with 92.2% for TRIMIX.