THEREOF

FIELD OF THE INVENTION

This invention relates to the treatment of cattle especially in large herds.

BACKGROUND OF THE INVENTION

Treatment of cattle to prevent and control parasite infection is an important aspect of modern farming, especially the treatment of roundworm.

Typical roundworm parasite known to infect cattle include parasite belonging to the following genera: Haemonchus, Trichostrongylus, Ostertagia, Nemaodirus, Cooperia, Ascaris, Bunostomum, Oesophagostomum, Chabertia, Trichuris, Strongylus, Trichonema, Dictyocaulus, Capillaria, Heterakis, Toxocara, Ascaridia, Oxyuris, Ancylostoma, Unicinaria, Toxascaris and Parascaris. Certain of these, such as Nematodirus, Cooperia and Oesophagostomum attack primarily the intestinal tract while others, such as Haemonchus and Ostertagia, are more prevalent in the stomach while others such as Dictyocaulus are found in the lungs. Still other parasites may be located in other tissues such as the heart and blood vessels, subcutaneous and lymphatic tissue and the like. The effect on cattle health and well-being can be significant, and can range from mild ill- health through to death. In adult cattle even sub-clinical parasitism can result in productivity loss through reduced body condition, reduced weight gain and reduced milk production.

Typically these parasites are controlled by specific chemical agents developed to meet certain criteria. These criteria include:

- High effectiveness against the target parasites - this could either be via broad- spectrum efficacy in which a wide range of parasites are controlled or alternatively via narrow spectrum of activity in which a more limited selection of parasites are controlled. - Wide margin of safety to the host animal

Low potential to cause toxic residues that could cause harm to humans consuming meat or milk products from the animal Over the past 50-60 years there have been 5 major classes of broad-spectrum anthelmintic developed that can be used to provide treatment of livestock for parasitism. These 5 classes are as follows:

Benzimidazoles.

The first chemical class of modern anthelmintics developed was the benzimidazoles (BZD). The first drug in this class, thiabendazole (TBZ) was introduced in 1961. Other members of the benzimidazole class includes fenbendazole, albendazole and oxfendazole.

Benzimidazole based anthelmintics interfere with the worm's energy metabolism on a cellular level. The molecule binds to a specific building block called beta tubulin and prevents its incorporation into certain cellular structures called microtubules, which are essential for energy metabolism. Interfering with energy metabolism is a much more basic mode of activity than that which occurs with other classes of anthelmintics. For this reason, benzimidazoles are also able to kill worm eggs. Benzimidazoles have a wide margin of safety and broad spectrum activity.

Nicotinic agonists

Nicotinic agonists comprise the secod class of anthelmintics. They include imidazothiazoles and tetrahydropyrimidines . The imidazothiazole group includes levamisole, while the tetrahydropyrimidine group includes pyrantel pamoate, pyrantel tartrate, and morantel tartrate.

The tetrahydropyrimidines mimic the activity of acetylcholine, a naturally occuring neurotransmitter that initiates muscular contraction. Upon exposure to the active ingredient, the worm is unable to feed and quickly starves. Tetrahydroyrimidines only affect adult populations of worms. They do not have activity against the larval stages and are ineffective against cestodes (tapeworms) and trematodes (liver flukes). Imidazothiaoles have a similar mode of action causing spastic paralysis of the worms. The group includes the drug levamisoie discovered in 1966.

Compared to other anthelmintics, levamisoie has the narrowest margin of safety, though toxicity is usually the result of excess dosage. Levamisoie has a broad spectrum of activity and is effective against many larval stages of parasites; though not arrested larvae.

Macrocyclic lactones

The next anthelmintic class to be developed was the macrocyclic lactones (MLs) developed from the Streptomyces genus of soil dwelling-organisms. The first drug of the class, ivermectin, was introduced in the early 1980s. Macrocyclic lactones consist of two closely related chemical groups: avermectins and milbemycins. The avermectins include abamectin, ivermectin doramectin and eprinomectin. The milbemycin group is represented by milbemycin oxime and moxidectin, introduced in 1997.

All of the macrocyclic lactone anthelmintics have the same mode of action. They interfere with GABA-mediated neurotransmission, causing paralysis and death of the parasite. Macrocyclic lactones are the most potent killer of worms and are more persistent in their effect. The duration of persistent activity varies according to the drug and formulation.

Macrocyclic lactones have the unique quality of also killing several types of external parasite such as lice, mites, and ticks. Because of this they are also known as "endectocides" (end- ecto-cides), meaning control of internal and external parasites. Generally, the macrocyclic lactones have a wide margin of safety in treated livestock and are effective against all stages of worms, including inactive forms. Amino-acetonitrile derivatives

In 2009, the first of this new class of anthelmintics was introduced. "Monepantel" acts by paralyzing worms by attacking a previously undiscovered receptor HCO-MPTL-1, present only in nematodes. Spiroindoles

In 2010 Derquantel (2- deoxoparaherquamide), the first of yet another new class of anthelmintic was introduced.

Some of these anthelmintic types have been used to treat adult dairy cattle. Over the years, there have been anthelmintic formulations from at least the benzimidazole, nicotinic agonist and macrocyclic lactone classes that have been used to fulfil this requirement. Formulation types have included slow-release bolus formulations, oral drenches and in-feed materials and, more recently, topical or "pour-on" formulations of the macrocyclic lactone class of chemicals. It is this latter class that has now become the de-facto norm for treatment of lactating dairy cows. "Nil-milk" or zero-milk withholding period pour-on formulations have been developed with all of the commercially available macrocyclic lactone active ingredients including; abamectin, ivermectin, doramectin, eprinomectin and moxidectin.

The chemical structure of each of these active ingredients is as follows: Abamectin (AvermectinBlaBlb)

Ivermectin B _la & Ivermectin B _lb

Eprinomectin

In each case, the pour-on formulation consists of a quantity of the macrocydic lactone active dissolved in one or more organic solvents. This is then applied topically to the back of the animal from where it is absorbed through the skin. The dose rate typically applied is 500mcg/kg at a dose volume of around lmL/lOkg or lmL/20kg. In New Zealand, such formulations have been the only nil-milk treatments available for at least the past 20 years. This has been due to their supposed convenience and the absence of alternative treatment forms and methods of treatment. In large dairy herds, it can be difficult to treat cows with an anthelmintic due to the design of modern dairy sheds and the lack of effective formulations designed for use in such situations.

The need for speed in milking has led to advances in the design of milking installations making it difficult to treat cows using conventional pour on, drenching or injection techniques. Each cow typically weighs in excess of 500kg making it impractical to manipulate them, particularly when the farmer may be treating 500 or more cows at a time. Most milking installations use either herringbone configuration sheds, or rotary milking platforms.

Treatment with an injectable formulation is desirable as when compared to the topical delivery route. Injectable formulations are capable of delivering much higher blood levels of the drug. Injectable anthelmintic formulations (designed for injection to the anterior neck portion of a cow) containing a macrocyclic lactone anthelmintic are usually formulated to deliver 200mcg/kg of the drug. Typically, this is administered from a 1% formulation via a lmL/50kg dose rate. This size of injectable anthelmintic dose is very impractical for such large animals. If a typical injectable were administered a 500kg cow would generally be given a dose of around lOmls. This would mean a standard 500mL pack would only be capable of treating 50 cows. On many large farms, a rotary platform holds 70-80 cows. In addition, lOmL is a relatively large dose that would take a reasonable period of time to inject. There is also a tendency for doses of this size to leak from the injection site, particularly when the injection is administered subcutaneously. The design of the rotary platform makes it difficult for the farmer to access the anterior portion of the neck where such treatments are typically administered. Attempting to reach between or across cows to reach the anterior neck portion could also be highly dangerous and subject the farmer to possible injury. The time taken to do this would also make it impracticable.

There is at present no nil-milk withholding injectable anthelmintic formulations currently available. This means that it is only possible to treat cows at a time of year when lactation is not occurring.

In New Zealand, the rotary cow shed has become the most popular form of milking parlour. This is due to the high speed at which large groups of cows can be milked. Unlike older walk through and herringbone designs, the flow of cows through a rotary cow shed is continuous. As shown in figure 1, the un-milked cows walk into stalls on to a large platform, which moves in a gradual circular movement around a central point. It is important to note that the cows are facing toward the centre with their posterior end toward the outside of the platform. Such a positioning means that it is easy for the milker standing at position X to place the milking machine "cups" on the teats of the cow.

As the platform gradually rotates, the cow is milked. At the end of the rotation the cups are removed either automatically, or by a second milker standing at position Y. After cup removal the cow then backs off the platform.

Due to speed and convenience, this style of shed is very popular with farmers milking large herds of 500 cows or more. Farmers prefer to treat their cows with an anthelmintic while they are located or moving on a rotary platform. Treatment may for example take place while the cows are being milked or when the cows are specifically brought on to the rotary platform for some other purpose such as administration of intramammary antibiotics, vaccines etc. If they are to be treated whilst lactating then the treatment has to have an approved "nil milk withholding time" (MWT).

In some other cases, the farmer may alternatively treat the cows while they are moving down a race or while they are stationery within the race. Even in such situations the large numbers of animals means that is desirable that the time taken to treat each animal is relatively fast.

Because of various factors, including the use of rotary sheds, very large animal numbers, and safety to the farmer, pour-on type formulations have become the preferred form of anthelmintic delivery as they:

Do not require the farmer to access the head or neck parts of the cow, which can be very difficult or in some cases very dangerous to access.

Enables the cow to be easily treated while it is on a milking platform.

To keep up with the speed of the milking platform each cow should be able to be treated in a similar period of time to what it would take the farmer to put the milking machine cups on the teats of the cow. If treatment were to take longer than this time the farmer would not keep up with the speed at which the platform is moving.

Pour- On formulations permit this but they do have limitations. These limitations include:

Relatively low levels of drug delivered into the blood when compared to other formulation types

Susceptibility to poor delivery due to effect of rain, UV and run-off

- Tendency to run-off the back of the cow; this problem is particularly so with dairy breed animals as they tend to have very smooth coats which do not act as a very effective barrier to the movement of the anthelmintic solution.

Such factors would make it desirable that farmers have an alternative means of treatment specifically designed to enable them to effectively treat large herds, and in particular lactating dairy cows at a speed sufficient to keep up with the movement of a rotary milking shed platform. OBJECT OF THE INVENTION

It is an object of the invention to provide a method or a formulation which can be used to treat cattle effectively and quickly, typically while located or moving on a rotary platform or at least provide the public with a useful choice.

STATEMENT OF INVENTION

In one aspect, the invention provides a method of treating cattle by injecting an animal at an injection site at or near the rear of the animal with an anthelmintic injectable formulation comprising eprinomectin in a suitable liquid carrier.

More preferably, the invention provides a method of treating cattle by injecting an animal at an injection site at or near the rear of the animal with a nil milk withholding time approved anthelmintic injectable formulation comprising eprinomectin in a suitable liquid carrier, wherein the concentration of eprinomectin is greater than 1% w/v.

Preferably, the injection site is chosen from the group comprising: the base of the tail, the tail fold, and the depressions on either side of the tail head of the cow.

Preferably, the liquid carrier is an organic solvent and anthelmintic injectable formulation comprises eprinomectin dissolved in the organic solvent.

Preferably, each animal is provided with an injection delivering at least 200mcg/kg of eprinomectin: per kg of body weight of the animal.

Preferably, each animal is injected whilst being held head first in bail of a milking installation such as a rotary milking shed, or a herringbone-milking shed.

Preferably, anthelmintic injectable formulation is a nil milk withholding injection containing both eprinomectin and vitamin E.

In another aspect, the invention can be said to be the use of an anthelmintic injectable formulation containing eprinomectin as an injection applied at an injection site at or near the rear of the animal.

In another aspect, the invention involves the use of eprinomectin in the manufacture of an anthelmintic injectable formulation to be applied at an injection site at or near the rear of the animal.

In another aspect, the invention provides an injectable anthelmintic formulation suitable for treatment of cattle, the formulation comprising:

More than 1% w/v Eprinomectin;

benzyl alcohol;

sorbitan monooleate; a Vegetable oil or derivative; and

one or more co-solvents.

This allows a lower dose/higher concentration of eprinomectin thereby reducing the injection time per animal.

Preferably, the formulation contains at least 1.5% eprinomectin w/v.

Preferably the co-solvent(s) is selected from glycerol formal, dimethyl acetamide and dimethyl isosorbide.

Preferably the formulation further includes Vitamin E acetate. Preferably the formulation further includes water and a water-soluble vitamin such as Vitamin B12.

In another aspect the invention provides a method of treating a herd of cattle with an anthelmintic injectable formulation containing eprinomectin dissolved in an organic solvent and in which the dosage recommendations provide for a dose rate of no less than 200mcg/kg and the injection site to be at or near the rear of each animal. Preferably the injection site is at the base of the tail, the tail fold or the depression on either side of the tail head of the cow.

Preferably the formulation contains greater than 1.5% w/v eprinomectin.

Preferably the method involves treating cattle with a nil milk withholding injection containing both eprinomectin and vitamin E. In another aspect the invention provides an injectable anthelmintic formulation suitable for treatment of cattle containing:

- At least 1.5% Eprinomectin

Vitamin E acetate or other oil soluble trace element

Benzyl alcohol

- Sorbitan monooleate

- A Vegetable oil or derivative (e.g. Miglyol)

One or more co-solvents

Optional antioxidant Preferably the co-solvent is selected from glycerol formal, dimethyl acetamide and dimethyl isosorbide.

Preferably the injectable anthelmintic formulation also contains a water-soluble vitamin such as Vitamin B12 as well as water and other optional elements, including surfactants, water, antioxidants, buffers and preservatives.

In the present invention two factors have been addressed to develop the improved method of treatment:

Development of a nil-milk residue injectable formulation that also allows for the coadministration of other beneficial agents

- Development of a method of injectable treatment that can reduce the time taken to administer an injectable treatment to cattle without reducing the quality of the treatment.

The method of treatment subject to this invention is such that it enables the farmer to treat animals by injection in a period of time substantially similar to that needed to administer pour-on treatments.

These and other aspects of this invention which should be considered in all its novel aspects will be apparent from the following description which is given by way of example only with reference to the accompanying drawings and examples.

DRAWINGS:

Figure 1 is a schematic drawing of a conventional rotary cowshed.

Figure 2 is a graph showing the mean concentration of Eprinomectin (over time) in bovine plasma after treatment with Eprinomectin injection or Pour-on.

Figure 3 is a front on view of the posterior end of a cow showing the preferred application site.

Figure 4 is a top view of a conventional herringbone milking shed. Figure 5 is a further schematic drawing of a conventional rotary cowshed. DETAILED DESCRIPTION OF THE INVENTION

Figure 3 shows the preferred injection site (20) on the cattle. This site has the advantage of being easily accessiable, contains sufficiently "loose" skin to enable the area to be 'tented' to permit subcutaneous administration. In a traditional herringbone milking configuration as shown in figure 4, cattle enter (32) the shed from the yard (36), wherein the milker/farmer (30) is located in a central race located below the level of the cattle, which is accessed by the steps (31). Typically the milker/farmers eye level is in line with the prosterior end of the cattle. The suction cups are then placed on the cattle by the farmer in preparation for for milking. Once milking is completed, the suction cups are removed and the the exit gate (33) is opened allowing the cattle to exit out to pasture (34).

As it can been seen in figure 4, cows are presented in an inline position on either side of a central race. In such a situation it is very difficult for a farmer/milker (30) to access the back of the cow to permit treatment with a topical/pour-on formulation. The inventive formulation permits treatment at a larger number of admnistration points (marked with an X). The advantages of a nil-milk injectable of low volume that can be adminstered in the rear of the cow are quite obvious in this situation.

In the rotary milking parlour situation, as shown in figures 1 and 5, the cows are on a raised central platform while the Milker ( 43) is on a lower level. The cattle enter the rotary platfrom from the yard (40) by means of a backing gate (41), forcing the cattle towards the entry point (42). Once on the central rotary platform, suction cups are then placed on the cattle by machine or manually by the milker. Milking continues for one rotation (44). Once completed, the suction cups are then removed and the cow exits out the exit gate(45).

When treating with a typical nil-milk topical formulation the only practical position in which the cow can be treated is at the entry (42)or exit (45) points. The inventive formulation permits treatment at a larger number of admnistration points (such as those marked with an X) even while the platform is turning.

EXAMPLE 1:

Formulation

Various injectable formulations of eprinomectin were trialled in which eprinomectin and Vitamin E oil were dissolved in a blend of Benzyl alcohol, sorbitan monooleate and caprylic capric triglyceride (Miglyol). While the active ingredients remained within their proposed shelf-life specifications there was an undesirable tendency for the formulation to crystallise upon refrigeration. w/v% AL16-37

Eprinomectin 2

Vit E acetate 5

Benzyl Alcohol 10 Sorbitan monooleate

(Span 80) 4

Caprylic capric triglyceride

(Miglyol 840) Qs

Various means were tried to eliminate this tendency. Included in these trials was the testing of a range of co-solvents.

Alternative manufacturing methods were also attempted. Results demonstrated that the addition of a small quantity of a co-solvent such as glycerol formal is a preferred means of eliminating this problem without significantly changing the base formulation:-

Method 1:

1. In a mixing vessel, add Caprylic capric triglyceride (Miglyol 840).

2. Add and dissolve eprinomectin.

3. Add Benzyl alcohol, Glycerol formal and Sorbitan monooleate (Span 80).

4. Add and dissolve vitamin E.

5. Make up volume with Caprylic capric triglyceride (Miglyol 840).

Method 2:

1. In a mixing vessel, add Caprylic capric triglyceride (Miglyol 840).

2. Add BA, GF and Sorbitan monooleate (Span 80), and mix.

3. Add and dissolve eprinomectin.

4. Add and dissolve vitamin E.

5. Make up volume with Caprylic capric triglyceride (Miglyol 840). w/v% AL16-40 AL16-41 AL16-42

Eprinomectin 2 2 2

Vit E acetate 5 5 5

Benzyl Alcohol 10 10 10

Sorbitan monooleate

(Span 80) 4 4 4

Co-solvent 3% GF 4% GF 5% GF

Caprylic capric

triglyceride (Miglyol

840) qs qs qs

Method 2 2 2

The results of these studies demonstrated that a level of around 3% or more would required to prevent crystallisation of the 5% Vitamin Acetate present in the formulation.

Observations:

Tests were then conducted to determine the suitability of the formulation in the treatment of cattle.

The first study conducted was to determine blood levels of eprinomectin obtained by administration of the injectable product when compared to a topical formulation of eprinomectin. Results are presented in Table 1:

Table 1: Geometric mean AUC and Cmax values for animals treated with an Eprinomectin injection or an Eprinomectin pour-on

a ^,b = means within a column with different superscript are significantly different from each other. Figure 2 is a graph that shows the mean concentration of Eprinomectin in bovine plasma after treatment with Eprinomectin injection or Pour-on.

Such blood levels would mean that the endoparasite protection delivered by the tested eprinomectin vitamin E injection would be likely be superior to that of the marketed eprinomectin pour-on formulation.

Injection Efficiency

Injection efficiency is a function of the following factors:

- Time taken to access and locate the injection needle at the injection site on the animal;

Time taken to inject the dose;

Effectiveness of the dose (absence of injection site leakage, absence of injection site abscesses, clinical outcome).

To treat large animals in a production herd situation it is simply not possible to access the neck/shoulder of the animal in a milking shed or large herd situation.

In New Zealand the average herd size is approx. 350 cows. In some cases 1,000 or more cows are present. Even if it were to take one minute for the farmer to move to a position in which the neck/shoulder area could be accessed this would be almost 6 hours of time taken to treat an average herd size. In actual fact Dairy NZ statistics indicate that cow throughput at peak lactation ranges from an average of 149 cows/hour for small 40 bail rotary sheds, to 447 cows/hour for 80 bail rotaries. That is one cow milked for every 8-24 seconds. This is an indication of the speed at which a dairy rotary platform can move.

A second aspect to treatment of large animals by injection is that the practice can be inherently dangerous as the cow may react violently to attempts to move its head or to lift its neck into a position where the injection can be given. There are also practical difficulties involved with "tenting" the skin so that the injection can be given subcutaneously. The time taken to inject the anthelmintic solution also means that the head/neck must be held relatively stationery for a period of time.

Treatment of a cow by injection at other sites at or near the rear of the animal is preferred. However there are a limited number of sites on the body of the animal which allow for easy access, easy "tenting" of the skin and are not likely to cause tissue damage/residue concerns at the injection site if the cow is slaughtered. Of the potential sites the base of the tail, the tail fold, or the depression on either side of the tail head would offer the best combination of these factors. When coupled with a formulation that reduces the dose size the administration of an anthelmintic in the desired timeframe would become easy to accomplish.

In reality the times when cows are likely to be treated are:

In a race, with the cows stationary;

- In a race, with cows moving through;

On a dairy platform while being milked;

On a dairy platform while not being milked;

The inventive concept of a high concentration eprinomectin-based injection combined with a low administration dose, convenient injection site and nil milk-withholding periods offers an effective and desirable alternative to pour-on formulations in all of these situations.

Where the treatment occurs while the cow is being milked on a rotary platform the method ensures that the milker was not unnecessarily inconvenienced by the need to administer the treatment.

Where the animals are treated in a race situation the method of treatment also ensures greater safety to the farmer and less stress to the animal.

The general instructions given to users on packs of the formulation would be:

This product is to be given by subcutaneous injection only. The recommended dose is ImL per 100kg bodyweight (200mcg eprinomectin per kg). Inject under loose skin in one of the two sites indicated in the illustration: A. Anterior portion of the neck

B. In the depression on either side of the tail head (this injection site is recommended for treatment of cattle in dairy shed situations or in situations where unintended animal movement could pose a risk to the user). Milk Residue Study

A study was undertaken in which a group of lactating dairy cows were treated with the test product at study hour 0 at a dose volume of over lmL/100 kg (slightly in excess of 200mcg/kg eprinomectin). Cows were milked twice daily and milk specimens were collected from study hour 0 to study hour 96. Milk yields and milk fat percentage were not significantly affected by the treatment. Statistical analysis of milk eprinomectin concentrations indicated that even at the highest observed level of eprinomectin (24 hours post treatment) the UCL (upper confidence level) remained below the MRL of 0.02 mg/kg. This demonstrated that the formulation achieved the objective of providing for a high sustained peak of eprinomectin in the blood without leading to residues which would restrict its use in lactating dairy cows.

Injection Site Tolerance Comparative injection site tolerance studies were undertaken to determine the suitability of the tail depression as a site for injection with the invention. The study demonstrated that the invention was well tolerated and caused no adverse reactions.

Stability Longer term stability testing has also demonstrated that the formulation provides for very good stability of the active ingredients over at least 12 months at room temperature.

ADVANTAGES OF THE PREFERRED EMBODIMENT

Treatment with an injectable formulation is better than a topical delivery (pour on) as injectable formulations are capable of delivering much higher blood levels of drug.

The method allows rapid treatment by injection the preferred formulation at an injection site on the rear of the animal typically while it is trapped in the bail of a (rotary) milking shed.

The injectable formulation provides a nil-milk withholding injectable anthelmintic formulation. This means that it is possible to treat cows with this injectable formation all the year round whether they are lactating or not.

The method provides a specific method of injectable anthelmintic treatment suitable for large herds and particularly lactating dairy cows, which can be administered in a dairy shed situation. The preferred formulation also provides for the supplemental delivery of other trace elements important to the health of cattle, in particular Vitamin E and/or Vitamin B12

Having thus described in detail, preferred embodiments of the present invention, it is to be understood that the invention described above is not to be limited to particular details set forth in the above description as many apparent variations thereof are possible without departing from the scope of the claims of the present invention.