AU2002320806B2

AU2002320806B2 - Compositions

Info

Publication number: AU2002320806B2
Application number: AU2002320806A
Authority: AU
Inventors: William Keen; John LeBreton
Original assignee: Anagen Tech Pty Ltd
Current assignee: HEINIGER AUSTRALIA Pty Ltd
Priority date: 2001-12-21
Filing date: 2002-12-20
Publication date: 2009-03-26
Anticipated expiration: 2022-12-20
Also published as: NZ523376A; AUPR971001A0

Description

P/00/011 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Invention Title: COMPOSITIONS Applicant: BIOCLIPPTY LTD The following statement is a full description of this invention, including the best method of performing it known to me: 1 Document1 1A Compositions Field of the Invention The present invention relates to an improved method for the biological defleecing of animals and to improved compositions for the biological defleecing of animals. The improved compositions may be used to carry out the improved method. In particular, the present invention relates to an improved method for the biological defleecing of sheep and to improved compositions for use in the defleecing of sheep. The methods and compositions find particular application with the Merino breed of sheep as with Australian Merino sheep the fleece of the sheep is sufficiently valuable that removal of the fleece such as prior to slaughter is commercially desirable. In addition, given the rising cost of shearing of sheep alternative methods of fleece removal are being considered in all areas of the sheep industry.

Background of the Invention Biological defleecing agents, such as epidermal growth factor (EGF), when administered to animals such as mammals, cause disruption to one or more of the processes involved in the formation of hair fibres. As a result of this disruption, the biological defleecing agent causes a weakness to occur in the hair fibre as it grows out of the hair follicle. In the case of wool producing animals the weakness occurs in the wool fibre and is observed in the wool growing out of the wool follicle. At some period after administration of the biological defleecing agent, the point of weakness in the wool emerges from the skin of the mammal. If the wool fibre has been sufficiently weakened, the fleece can then be easily removed from the animal without requiring the use of shears or other cutting apparatus. The use of biological defleecing agents can, at least in theory, provide an alternative to the traditional methods of fleece removal which have involved shearing of the animal.

The shearing process, whilst practiced widely, has a number of disadvantages that may be deemed commercially unacceptable depending on the type of sheep being shorn and the purpose of the shearing. One of the primary reasons for shearing is fleece retrieval. With the rising cost of shearing due to rising labour costs it is found that the higher costs are unattractive with C:4ellompositions2.doc 2 sheep breeds that do not produce high quality wool. In these cases the cost of the shearing operation is rapidly approaching the value of the wool retrieved and so the attractiveness of the shearing process for these breeds is diminishing as a means of fleece retrieval. It is envisaged that this trend will continue as labour costs continue to increase the cost of the shearing process.

Another reason for fleece removal occurs prior to slaughter as a means of both recovering the valuable fleece prior to slaughter of the animal and to ensure that the fleece does not contaminate the meat during the processing of the animal during the slaughter process. Unfortunately the shearing process is a very physical process and in certain instances can lead to bruising of the meat of the animal. This therefore makes shearing commercially unappealing as a process of fleece removal of sheep destined for slaughter. Alternatives to the shearing process would therefore be desirable for use with animals prior to slaughter.

In current methods used for the biological defleecing of sheep, a liquid form of EGF or an analogue of EGF is injected into the sheep and a woolretaining net is typically placed on the sheep. It will be appreciated that the wool-retaining net is used to prevent the fleece from falling off the sheep in the field or paddock and to simplify removal and recovery of the fleece from the animal. The process of biological defleecing may be carried out without the use of a net; however the efficiency of recovery of the fleece is reduced. A period of time later, which is typically from 7 to 28 days later, the wool retention net is removed from the sheep. The fleece from the sheep is typically removed at the same time without requiring the use of shearing apparatus due to the weakness in the wool that has grown out through the skin of the sheep. In general the wool can be removed by hand by grasping the wool and applying sufficient pressure to break the wool at the point of weakness caused by the administration of the defleecing agent. This therefore enables the fleece to be removed from the sheep.

Biological defleecing of sheep using the injection of liquid EGF or an analogue of EGF is now used to defleece a substantial number of sheep in Australia. This process is effective to remove the fleece from about 80% of Australian Merino sheep so treated. This figure is unacceptable from a C:lellCOflompostiOlns2.doC commercial viewpoint as it means that a substantial number of sheep either have to be shorn or resubjected to the process, both of which are clearly undesirable. In addition, the effectiveness of the process in defleecing lambs and young sheep is much lower. It is also much less effective in defleecing adult sheep who have an effected metabolism, eg those enduring drought conditions or the like. The effectiveness of the process in treating breeds of sheep other than Australian Merino sheep is also lower than desirable and is therefore commercially unacceptable. There is therefore a need to develop improved methods for the biological defleecing of animals, particularly sheep, and to develop improved compositions for the biological defleecing of animals.

With the known biological defleecing of sheep it was thought that what was required was the administration of EGF or an analogue of EGF sufficient to provide a blood plasma concentration of 100Ong/ml for a period of 10 hours. As discussed above when treatments are used that provide these plasma concentrations the efficacy of the process is too low to be considered commercially acceptable. The present applicants have studied the process in detail and have discovered that the threshold level of the defleecing agent is not the critical variable as previously thought. In contrast the present applicants have found that it is a combination of both the threshold level and the time period over which the blood plasma concentration is above this level that is critical in terms of controlling the effectiveness of the process of fleece removal.

The applicants have found that control of these two variables within certain parameters leads to process efficiencies approaching 98% for the biological defleecing of animals. Whilst this is a significant improvement for adult sheep it is even more so with young sheep where existing biological treatments could not be sue due to the low efficiency. The present methods allow for the process to be extended into young sheep.

In particular the applicants have found that methods that extend the length of time of the active agents in the blood plasma above certain concentration levels for a sufficient period of time leads to remarkable improvements in process efficiency. The present process therefore provides an improved method for the biological defleecing of sheep that is, for the first time, C: eUIonposition2.doc commercially acceptable for most applications. The present invention also provides compositions having these types of efficacy levels.

Summary of the Invention In one aspect the present invention provides a composition for biological defleecing of an animal, the composition including a biological defleecing agent and one or more excipients, diluents or carriers wherein a single administration of said composition to an animal is able to provide a blood plasma concentration of the defleecing agent in the animal above a threshold level (X ng/ml) for at least a period of time (Y hours), the period of time (Y hours) being at least 10 hours and being dependent on the threshold level (X ng/ml), the combination of threshold level and period of time being effective to defleece at last 80% of animals treated with said composition.

The composition may be a sustained release composition or a multistage release composition. Alternatively the composition may be in the form of a viscous liquid that is only slowly absorbed by the body following subcutaneous administration of the composition to the body.

One preferred composition is a solid sustained release composition.

The composition preferably includes from 30% to 70 of the defleecing agent, from 5% to 45% of an excipient such as surface active agent, and from 5% to of a dissolution modifier. More preferably the composition includes from to 60% of the defleecing agent, from 15% to 35% of an excipient such as a surface active agent and from 15% to 35 of a dissolution modifier. The defleecing agent is preferably EGF or an analogue of EGF. Where the excipient is a surface active agent it is preferably polyethylene glycol. The dissolution modifier is preferably selected from the group consisting of bioabsorbable polymers and disintegrants. Particularly preferred disintegrants may be selected from the group consisting of starch, vinyl pyrrolidone analogues, clays, cellulosics, algins and gums. A particularly preferred composition includes about 49% EGF, about 24% PEG and about 27% R104.

Another preferred composition is a solid composition including a core C:\Nellcompositions2.doc containing a defleecing agent such as EGF or an EGF analogue. The core is preferably at least partially encased in a coating. A particularly preferred composition is a solid composition in the form of a tubular pellet, the pellet including a core containing the defleecing agent and an outer coating substantially in the shape of a tube at least partially encasing the core. It is particularly preferred that either the outer tubular coating has open ends to allow egress of the defleecing agent from the pellet or (ii) the coating at the ends of the tubular pellet has a property so that the coating at the ends 'of the tube is degraded in the biological environment faster than the coating of the remainder of the tube. In those embodiments where the composition is in the form of a tubular pellet it is preferred that the tubular pellet has a diameter of from 2.0 to 2.6mm, more preferably from 2.2 to 2.4 mm, most preferably about 2.3 mm.

It is preferred that the core is a solid and contains from 30% to EGF or an analogue of EGF, 5% to 45% polyethylene glycol and 5% to polylactide. In a more preferred embodiment of the invention the core contains from 40% to 60% EGF or an analogue of EGF, from 15% to 35% polyethylene glycol and from 15% to 35 polylactide. In a most preferred embodiment the core contains about 50.9 EGF or an analogue of EGF, about 24.8%% polyethylene glycol and about 24.3 polylactide.

In an alternative embodiment the core may be a viscous liquid that includes EGF, a carrier, and a thickening agent. The thickening agent is preferably cellulose or a cellulose derivative with Methylcellulose A15 being particularly preferred.

In another embodiment the composition is a slowly absorbable liquid composition. If a composition of this type is administered in a subcutaneous fashion it provides a slow release of the defleecing agent as the composition is only slowly absorbed into the body. There are a number of ways well known in the art to formulate active agents to produce slowly absorbable liquid compositions for subcutaneous injection. For example it is known that increasing the viscosity of the composition or lowering its pH both lead to a C:AleIIcompositionS2.doc 6 more prolonged release of the active agent into the bloodstream of the animal treated. Without wishing to be bound by theory it is though that most of these methods rely on modification of a physical property to reduce the speed that the agent diffuses under the skin (i.e increasing viscosity) or decrease the compatibility between the composition and the biological environment (decreasing pH). A preferred liquid composition is a viscous liquid composition.

A particularly preferred viscous liquid composition includes EGF or an analogue of EGF, a carrier, and a thickening agent. The thickening agent is preferably cellulose or a cellulose derivative with Methylcellulose A15 being particularly preferred It is preferred that the compositions are such that upon administration to an animal they produce a blood plasma concentration of the defleecing agent (X ng/ml) for a period of time (Y hours) such that X and Y satisfy the criteria: Y 10 hours and X*Y 1500 ng hours/mi. It is particularly preferred that X*Y 1800 ng hours/mi, more preferably greater than 2000 ng hours/mi yet even more preferably greater than 2400: ng hours/mi, most preferably greater than 3000 ng hours/mi. In one preferred embodiment the composition upon administration provides a blood plasma concentration in the animal of above about 100 ng/ml for a period of at least 16 hours, more preferably it provides a blood plasma concentration of above about 100 ng/ml for at least 20 hours, most preferably it provides a blood plasma concentration of above about 100 ng/ml for at least 24 hours. In another preferred embodiment the composition provides a blood plasma concentration in the animal of above 50 ng/ml for aperiod of at least 30 hours, preferably for a period of at least 36 hours.

In a further aspectthe present invention provides -a method of biological defleecing of an animal including treatment of the animal with a biological defleecing agent in a manner so as to provide a blood plasma concentration of the defleecing agent in the animal above a threshold level (X ng/ml) for at least a period of time (Y hours), the period of time (Y hours) being greater than hours and being dependent on the threshold level (X ng/ml), wherein the combination of threshold level and period of time are effective to defleece at least 80% of animals subjected to the treatment.

C:Neir'compOSitiOns2.dOc In a preferred embodiment the method is such that X and Y satisfy the criteria X*Y 1500 ng hours/mi. It is particularly preferred that X*Y 1800 ng hours/mi, more preferably greater than 2000 ng hours/mi, yet even more preferably greater than 2400 ng hours/mi, most preferably greater than 3000 ng hours/mi. These results can be achieved in a number of ways although in one preferred embodiment the method provides a blood plasma concentration in the animal of above about 100 ng/ml for a period of at least hours, even more preferably for a period of at least 16 hours, more preferably for a period of at least 20 hours, most preferably for a period of at least 24 hours. In another preferred embodiment the method provides a blood plasma concentration in the animal of above 50 ng/ml for a period of at least 30 hours, more preferably at least 36 hours.

In a further aspect the present invention provides a method of biological defleecing of an animal including treatment of the animal with a biological defleecing agent, wherein the treatment is such that when a group of at least of the animals is subjected to the treatment the averageblood plasma concentration of the defleecing agent in the blood of the animals in the group is above a threshold level (X1 ng/ml) for at least a period of time (Y hours), the period of time (Y hours) being greater than 10 hours and being dependent. on the threshold level (X1 ng/ml), wherein the combination of threshold level and period of time are effective to defleece at least 80% of animals subjected to the treatment.

In yet an even further aspect the invention provides method of biological defleecing of a group of animals including treatment of the animals in the group with a biological defleecing agent in a manner to provide an average blood plasma concentration of the defleecing agent in the blood of the animals in the group above a threshold level (X1 ng/ml) for at least a period of time (Y hours), the period of time (Y hours) being greater than 10 hours and being dependent on the threshold level (X1 ng/ml), wherein the combination of threshold level and period of time are effective to defleece at least 80% of animals subjected to the treatment.

C:leiftoposolnS2.doC In these latter two methods it is preferred that X1 and Y satisfy the criteria X1*Y 1500 ng hours/ml. It is particularly preferred that X1*Y 1800 ng hours/ml, more preferably greater than 2000 ng hours/ml, yet even more preferably greater than 2400 ng hours/ml, most preferably greater than 3000 ng hours /ml. These results can be achieved in a number of ways although in one preferred embodiment the method provides a blood plasma concentration in the animal of above about 100 ng/ml for a period of at least 15, hours, even more preferably for a period of at least 16 hours, more preferably for a period of at least 20 hours, most preferably for a period of at least 24 hours. In another preferred embodiment the method provides a blood plasma concentration in the animal of above 50 ng/ml for a period of at least 30 hours, more preferably at least 36 hours.

The methods of the invention are preferably effective to defleece at least of animals treated, more preferably at least 95% of the animals thus treated, even more preferably at least 98% of the animals.

The methods of the invention are preferably carried out with sheep or goats, most preferably with a sheep of a breed selected from the group consisting of Bond, Border Leicester, Cheviot, Coopworth, Corriedale, Dorper, Dohne, Damara, Dorset, Lincoln, Merino, Perendale, Polwarth, Rambouillet, Romney, Southdown, South African Mutton Merino, 'Suffolk, Texel, White Suffolk, Xinjiang Finewool and crossbreeds thereof.

The methods of the invention may be carried out with sheep of any age or condition although it is preferably carried out with young sheep such as sheep under the age of 12 months, preferably a sheep under the age of 8 months, most preferably a sheep under the age of 6 months. The methods of the invention may be carried out with a number of biological defleecing agents although it is preferred that the defleecing agent is EGF or an EGF analogue. It is most preferred that the defleecing agent is URO-EGF.

The methods of the invention may be carried out by multiple C:\Neil\compostions2.doc 9 administrations of a composition containing a defleecing agent, by administration of a sustained release composition containing a defleecing agent, or by administration of a multi-stage release composition containing a defleecing agent.

In one preferred form of the methods of the invention the treatment includes administration to the animal (or group of animals) of a first dose of a composition including a defleecing agent, and at a period of time after administering the first dose, administering at least one further dose of a composition including a biological defleecing agent. In a particularly preferred form of the invention two doses of a composition containing a defleecing agent are administered to the animal (or group of animals). It is preferred that the further dose is administered to the animal from 10-14 hours after the first dose.

It is particularly preferred that each of the doses contains from 4.0 mg to 11 mg of defleecing agent, the total amount of defleecing agent administered to the animal being from 8 mg to 22 mg.

A number of sustained release compositions are suitable for use in the methods of the invention with a preferred sustained release composition being in the form of a tubular pellet, the pellet including an inner core containing the defleecing agent and an outer coating substantially in the shape of a tube. It is preferred that either the outer tubular coating has open ends to allow egress of the defleecing agent from the pellet or (ii) the coating at the ends of the tubular pellet has a property so that the coating at the ends of the tube is degraded in the biological environment faster than the coating of the remainder of the tube. If a sustained release composition of this type is used the inner core preferably contains from 30% to 70% EGF or an analogue of EGF, 5% to polyethylene glycol and 5% to 45% polylactide. In a more preferred embodiment the inner core contains from 40% to 60% EGF or an analogue of EGF, from 15% to 35% polyethylene glycol and from 15% to 35 polylactide.

In a most preferred embodiment the inner core contains about 50.9 EGF or an EGF analogue, about 24.8%% polyethylene glycol and about 24.3 polylactide. It is preferred that the tubular pellet has a diameter of from 2.0 to 2.6 mm more preferably from 2.2 mm to 2.4 mm, most preferably about 2.3 mm.

C:\Nelcomposilions2.doc In a further preferred embodiment of the invention the method includes administration of a composition that includes from 30% to 70 of the defleecing agent, from 5% to 45% of an excipient such as a surface active agent, and from 5% to 45% of a dissolution modifier. In this embodiment the composition preferably includes from 40% to 60% of the defleecing agent, from to 35% excipient such as a surface active agent and from 15% to 35 dissolution modifier. The defleecing agent is preferably EGF or an analogue of EGF and the excipient (surface active agent) is preferably polyethylene glycol.

The dissolution modifier is preferably selected from the group consisting of bioabsorbable polymers and disintegrants. A preferred disintegrant is selected from the group consisting of starch, vinyl pyrrolidone analogues, clays, cellulosics, algins and gums.

Brief Description of the Figures Figure la shows the average blood plasma concentration of EGF in sheep using the prior art single dose liquid formulation.

Figure lb shows the average blood plasma concentration for sheep administered with EGF in a split dose of liquid formulation in accordance with one preferred embodiment of the present invention.

Figure 1c shows a preferred average blood plasma concentration for sheep administered with a slow release liquid formulation in accordance with the present invention.

Figure ld shows a preferred average blood plasma concentration for sheep administered with a slow release solid composition made in accordance with one preferred form of the present invention Figure le shows a preferred average blood plasma concentration for sheep administered with a single administration of a multi-stage release solid composition made in accordance with one preferred form of the invention.

C:%Neilcompositions2.doc Detailed Description of the Invention.

The Compositions of the Invention The compositions of the present invention are suitable for the biological defleecing of animals. As noted previously prior art compositions did not provide acceptable performance especially in young sheep as they were unable to provide sustained blood plasma profiles of the active agents required for effective defleecing. Whilst theoretically the compositions could be used for the defleecing of any animal that has a hair or wool forming a fleece, it is preferred that the compositions are used for the biological defleecing of sheep or goats. It is particularly preferred that the animal is a sheep, with a sheep of a breed selected from the group consisting of Bond, Border Leicester, Cheviot, Coopworth, Corriedale, Dorper, Dohne, Damara, Dorset, Lincoln, Merino, Perendale, Polwarth, Rambouillet, Romney, Southdown, South African Mutton Merino, Suffolk, Texel, White Suffolk, Xinjiang Finewool and crossbreeds thereof being particularly preferred.

The compositions may be administered or used in the biological defleecing of sheep of any age and condition although it is found .that the compositions have particular application in respect of young sheep such as sheep under 12 months of age, more preferably sheep under 8 months of age, particularly sheep under 6 months of age. It is found that the prior art compositions are particularly ineffective when used on sheep of this age. This therefore limits the application of the prior art compositions as a majority of sheep sent to slaughter are under 8 months of age.

The compositions of the present invention include a biological defleecing agent and one or more excipients, diluents or carriers and are formulated in such a manner that a single administration of the composition to an animal is able to provide a blood plasma concentration of the defleecing agent in the animal above a threshold level for at least a period of time the period of time being dependent on the threshold level the combination of threshold level and period of time being effective to defleece at last 90% of animals treated with the composition.

C:Neillcompositions2.doc 12 The compositions may include any known defleecing agent or a combination of defleecing agents. The composition typically contains an effective amount of a defleecing agent to defleece an animal upon administration of the composition to the animal. In the case of liquid compositions the composition typically contains from 5 to 10 mg/ml of the defleecing agent, more typically about 7.5 mg/ml. In the case of a solid dosage forms the composition contains an effective amount of the defleecing agent to defleece an animal upon administration of the solid dose. Once again this means that the solid dosage form typically contains from 5 to 25 mg of the defleecing agent, more typically from 7 to 18 mg, yet even more typically 10 to 17 mg, most typically about 15 mg of the defleecing agent.

It is preferred that the biological defleecing agent includes EGF or an analogue of EGF. EGF is a polypeptide of 53 amino acids (EGF 1-53).

Although the present invention will be described with particular reference to EGF, a number of substances that could be classed as 'EGF analogues' exhibit similar properties, and may be used instead of EGF as defleecing agents. In addition to human EGF, the term 'EGF analogue' as used in this specification embraces the following substances from human, sheep and other species; urogastrone (URO) and fragments thereof, typically URO 1-47, URO 1-52, EGF 1-47, EGF 1-48 and EGF 1-51. In effect the term includes all synthetic and natural derivatives of the EGF polypeptide family which contain a sequence of amino acids (or amino acid substitutes) effective in regulating hair growth. The EGF or EGF analogue may be in any suitable form although it is preferred that it is in the form of a lyophilised powder. A particularly preferred EGF analogue is URO EGF.

The compositions of the invention may be sustained (slow) release solid or liquid compositions or multi-stage release solid or liquid compositions.

Alternatively the composition may be in the form of a viscous liquid composition that is only slowly absorbed by the body following subcutaneous administration of the composition to the body.

In one preferred embodiment, the composition is a solid composition C:\Neicompositions2.doc 13 such as in the form of a pellet or a tablet. In addition to the defleecing agent the composition typically contains one or more pharmaceutically or veterinary acceptable excipients, diluents or carriers. The one or more excipients may be any suitable excipients, diluents or carriers that may be used in the manufacture of pharmaceutical or veterinary substances. The types of materials that can be used in this manner would be well known to a skilled worker in the art as are the methods for formulating them.

It will be appreciated that in these embodiments the biological defleecing agent and the one or more excipients, diluents or carriers are chosen such that a solid composition is obtained. For example, a solid form of the biological defleecing agent may be mixed with one or more excipients that are in liquid form or include liquids, provided that the mixture can form a solid.

Alternatively, the biological defleecing agent may be in the form of a liquid that can be mixed with one or more solid excipients, provided that the resulting mixture can form a solid. More preferably, the biological defleecing agent is in the form of a solid and it is mixed with excipients that include a liquid excipient and a solid excipient. A particularly preferred combination of excipients is polyethylene glycol and polylactide. The polyethylene preferably has a molecular weight of from 4000 to 20000, more preferably 20000.

The compositions preferably contain one or more surface active agents selected from chelating agents such as polyethylene glycol, absorbance enhancing agents such as fatty acids and their analogues and amino acid derivatives.

The compositions also preferably contain a dissolution modifier. The dissolution modifier is preferably selected from the group consisting of bioabsorbable polymers and disintegrants. Any of the known bioabsorbable polymers may be used and the exact choice of bioabsorbable polymer to use will depend on the desired solubility profile of the other ingredients in the composition. A particularly preferred bioabsorbable polymer is a polylactide polymer. In those embodiments in which a disintegrant is used the disintegrant is preferably selected from the group consisting of starch, vinyl pyrrolidone C:\Neilconmpositions2.doc 14 analogues, clays, cellulosics, algins and gums. A particularly preferred disintegrant is R104.

The composition may also contain additional pharmaceutically or veterinary acceptable components that may be present to provide further functionality to the composition. For example, the composition may contain binders such as gum tragacanth, acaci, cornstarch, gelatine and the like. The composition may also contain additional disintegrating agents such as cornstarch, potato starch, alginic acid and the like. The composition may also contain lubricants-such as magnesium stearate. There may also be solubility enhancers present such as sodium citrate, sodium bicarbonate, magnesium carbonate and the like. A number of various additional surface-active agents (surfactants) may also be present. Examples of such surface active agents include proteins such as albumins, biological detergents, the salts of long chain fatty acids and tweens. In addition to these components the composition may also contain plasticisers, anti-static agents, anti-sticking agents, flow promoters, absorbance enhancers, buffers and the like. The types of materials that could be added to the composition in this way will be clear to a skilled formulation chemist who will include the additional components as required to produce a formulation having the required properties. In general the compositions of the invention are produced using standard formulation techniques as would be clear to a skilled worker in the art.

In one particularly preferred embodiment the composition preferably includes from 30% to 70 of the defleecing agent, from 5% to 45% of an excipient such as a surface active agent, and from 5% to 45% of a dissolution modifier. More preferably the composition includes from 40% to 60% of the defleecing agent, from 15% to 35% of an excipient such as a surface active agent and from 15% to 35 of a dissolution modifier. The defleecing agent is preferably EGF or an analogue of EGF. The excipient (surface active agent) is preferably polyethylene glycol, particularly polyethylene glycol having a molecular weight of 20000. The dissolution modifier is preferably selected from the group consisting of bioabsorbable polymers and disintegrants. Particularly preferred disintegrants may be selected from the group consisting of starch, C:%NeilcomposlionS2.dOC vinyl pyrrolidone analogues, clays, cellulosics, algins and gums. A particularly preferred composition includes about 49% EGF, about 24% PEG and about 27% R104.

In a further preferred embodiment, the solid composition includes EGF or an analogue of EGF, polyethylene glycol and polylactide. In this embodiment, the EGF or analogue of EGF may be present in an amount of from to 70% by weight, the polyethylene glycol may be present in an amount of from 5% to 45% by weight and the polylactide may be present in an amount of from 5% to 45% by weight, with all weight percentages being calculated on the basis of the total weight of EGF or EGF analogue plus polyethylene glycol plus polylactide. More preferably, the solid composition of this embodiment comprises from 40% to 60% by weight EGF or EGF analogue, from 15% to by weight polyethylene glycol and from 15% to 35% polylactide.

In embodiments of the invention where the composition is in the form of a solid it is further preferred that the solid composition is in the form of a pellet or tablet. It is even more preferable that the pellet or tablet is at least partially encased in a coating. When the pellet or tablet is coated standard coating techniques may be used. A skilled worker would be well aware of the methodologies that may be used to form a coated tablet or pellet. Indeed any method that may be used to form a coating on a tablet or pellet may be advantageously utilised in the production of the compositions of the invention.

The choice of method will depend on the coating to be used and the amount of coating to be applied. In a similar way the pellet or tablet to be coated is typically produced using standard pelleting techniques The types of coatings that may be used include those that are well known in the art in the coating of tablets or pellets. The coating may include any veterinary or pharmaceutically acceptable polymeric material. Particularly preferred substances for the coating material include polylactide co-glycolide polymers, polyesters, polysaccharides, polyamides, poly (amino acids), poly (ortho esthers), polyanhydrides, polyphosphoesters and polymers formed through combinations of chemical bonds (such as pseudo-peptides, poly C:Neil\composilions2.doc 16 (phosphoester-urethanes) and polydepsipeptides). The coating may also contain a combination of these materials. The coating is typically applied at standard coating levels and thicknesses as would be appreciated by a skilled formulator.

A particularly preferred solid composition is in the form of a tubular pellet, the pellet including a core containing the defleecing agent and an outer coating substantially in the shape of a tube at least partially encasing the core.

Formulations of this type may be produced in any of a number of ways as described, for example, in W098/27927. Of course, in producing an openended pellet, the process described in this prior art technique needs to be modified somewhat as would be clear to a skilled worker in the art.

In this embodiment it is preferred that the composition is formulated in such a way to facilitate sustained release of the active defleecing agent from the core of the tubular pellet. This can be done in a number of different ways such as by piercing the coating in a number of places to facilitate egress of the defleecing agent, by arranging the tubular coating such that it has open ends (such that the tubular coating is in the form of a pipe) to allow egress of the defleecing agent or by ensuring that the coating at the ends of the tubular pellet is such that, it degrades in a biological environment at a faster rate than the remainder of the coating. This latter property can be achieved, for example, by ensuring that the coating at the ends is thinner than the remainder of the coating or by coating the ends of the pellet with a more rapidly disintegrable coating material. A skilled worker in the art will readily perceive how this may be done.

It is particularly preferred that either the outer tubular coating has open ends to allow egress of the defleecing agent from the pellet or (ii) the coating at the ends of the tubular pellet has a property so that the coating at the ends of the tube is degraded in the biological environment faster than the coating of the remainder of the tube.

The dimensions of the solid dosage form may vary greatly with the C:%Neico mposftions2.doc 17 dimensions being chosen to deliver the appropriate amount of defleecing agent to the animal. In those embodiments where the composition is in the form of a tubular pellet it is preferred that the tubular pellet has a diameter of from 2.0 to 2.6 mm, more preferably from 2.2 to 2.4 mm, most preferably about 2.3 mm.

The diameter of the pellet is typically controlled by either controlling the diameter of the core of the pellet during manufacture or by control of the diameter of the tubular coating during manufacture of the tubular coating structure. The pellet may be of any suitable length that when combined with the pellet diameter delivers an appropriate amount of defleecing agent. It is typical, however, that the dimensions of the pellet are chosen such that the pellet contains from 5 to 25 mg of defleecing agent, more preferably from 7 to 18mg of defleecing agent, most preferably from 10 to 17 mg of defleecing agent per pellet. A typical pellet is from 5 to 10 mm in length, more typically from 6 to 8 mm in length. The preferred pellets of the invention are 2.3 mm in diameter and 7.6 mm in length.

It is preferred that the core of the pellet is a solid and contains from to 70% EGF or EGF analogue, 5% to 45% polyethylene glycol and 5% to polylactide. In a more preferred embodiment of the invention the core contains from 40% to 60% EGF or EGF analogue, from 15% to 35% polyethylene glycol and from 15% to 35% polylactide. In a most preferred embodiment the core contains about 50.9% EGF or EGF analogue, about 24.8% polyethylene glycol and about 24.3 polylactide.

In an alternative embodiment the core is a solid and includes from to 70 of the defleecing agent, from 5% to 45% of an excipient such as a surface active agent, and from 5% to 45% of a dissolution modifier. More preferably the composition includes from 40% to 60% of the defleecing agent, from 15% to 35% of an excipient such as a surface active agent and from to 35 dissolution modifier. The defleecing agent is preferably EGF or an analogue of EGF. The excipient (surface active agent) is preferably polyethylene glycol. The dissolution modifier is preferably selected from the group consisting of bioabsorbable polymers and disintegrants. Particularly preferred disintegrants disintegrant may be selected from the group consisting C:Neil\compositions2.doc 18 of Starch, Vinyl Pyrrolidone analogues, Clays, Cellulosics, Algins and Gums. A particularly preferred composition includes about 49% EGF, about 24% PEG and about 27% R104.

In an alternative embodiment the core of the pellet may be a liquid composition. It is preferred that the liquid composition is a viscous liquid composition that includes EGF or an EGF analogue, a carrier, and a thickening agent. The thickening agent is preferably cellulose or a cellulose derivative with Methylcellulose A15 being particularly preferred. In this embodiment it is the viscosity of the composition that is believed to lead to the sustained release of the defleecing agent core from the pellet.

In another embodiment the composition is a liquid composition such as a viscous liquid composition. The liquid composition preferably includes EGF or an analogue of EGF, a carrier, and a thickening agent. The thickening agent is preferably cellulose or a cellulose derivative with Methylcellulose A15 being particularly preferred In a further embodiment the composition is able to provide multi-stage release of the defleecing agent to the animal. As will be appreciated by a skilled addressee the multi-stage delivery of the active agent to the animal can be achieved in a number of ways.

One way in which a multi-stage delivery can be achieved is to produce a solid composition containing a plurality of EGF or EGF analogue containing layers and at least one layer that does not contain such an agent. These layers are then combined so that the layers alternate with an EGF containing layer being in contact with a layer that does not contain EGF. As the solid composition disintegrates in the body there will be a multi-stage administration of the active agent to the animal as the successive layers dissolve. The length of time between the delivery of each stage and the duration of delivery of each stage will be controlled by the thickness of the layers.

In embodiments where the composition is a multi-stage tablet it is C:ANeicomposilion2.doc 19 preferred that the total amount of defleecing agent in the tablet is from 5-25 mg, more preferably from, 7-18 mg, most preferably 10 to 17 mg mg. It is typical that this is evenly dispersed through the defleecing agent containing layers.

containing layers.

By way of example the simplest embodiment of a multi stage delivery composition of this type would consist of an EGF containing core, surrounded by a coating layer that did not contain EGF, followed by another EGF containing layer. Upon administration of the composition there would be a release of EGF as the outer EGF layer disintegrated and was absorbed by the animal. Upon complete dissolution of the outer EGF containing layer the delivery of EGF would stop whilst the layer that did not contain EGF was being dissolved. Once disintegration of this layer had reached a certain stage the structural integrity of the layer would be compromised and EGF would commence being delivered from the core. This would therefore lead to a multi-staged delivery of EGF to the animal where the EGF was delivered in a pulse like manner. In this way, at least in theory, any number of stages of addition of EGF could be achieved.

Another method of achieving multi-stage delivery would involve modification of the tubular pellet as discussed above. Rather than having a substantially uniform core that was situated in the centre of the tube it would be possible to produce a core in which the core was layered with a plurality of layers that contained EGF and a plurality of layers that did not contain EGF. If these layers were alternated with respect to the ends of the tube then the final tubular pellet would provide multi-stage delivery of the active substance.

It is preferred that the compositions are such that upon administration to an animal they produce a blood plasma concentration of the defleecing agent for a period of time such that X and Y satisfy the criteria: Y 10 hours and X*Y 1500 ng hours/mi. It is particularly preferred that X*Y 1800 ng hours/mi, more preferably greater than 2000 ng hours/mi yet even more preferably greater than 2400 ng hours/mi, most preferably greater than 3000 ng hours/mi. In one preferred embodiment the composition upon administration provides a blood plasma concentration in the animal of above about 100ng/ml C:~eIlleomposliOns2doC for a period of at least 15 hours, at least 16 hours, more preferably for a period of at least 20 hours, yet even more preferably for at least a period of 24 hours.

In another preferred embodiment the composition provides a blood plasma concentration in the animal of above 50 ng/ml for a period of at least 30 hours, more preferably at least 36 hours.

Methods of the invention As discussed previously the present invention provides improved methods for the biological defleecing of an animal. In a second aspect therefore the present invention provides a method for biologically defleecing an animal including the step of administering to the animal a composition as described with reference to the first aspect of the invention.

In the methods of the invention the composition is preferably administered to the animal by placing the composition under the skin of the animal (ie subcutaneously). Methodology for the administration of both solid or liquid compositions to an animal via the subcutaneous route are well known and any of the known methods may be utilised in the present invention. The choice of method will depend on the form of the composition that is being administered.

It is preferred that the method involves subcutaneous injection of the composition to the animal.

In a further aspect the present invention provides a method of biological defleecing of an animal including treatment of the animal with a biological defleecing agent in a manner so as to provide a blood plasma concentration of the defleecing agent in the animal above a threshold level (X ng/ml) for at least a period of time (Y hours), the period of time being greater than 10 hours and being dependent on the threshold level wherein the combination of threshold level and period of time are effective to defleece at least 80% of animals subjected to the treatment.

In a preferred embodiment the method is such that X and Y satisfy the criteria X*Y 1500 ng hours/ml. It is particularly preferred that X*Y 1800 ng hours/mi, more preferably greater than 2000 ng hours/mi, yet even C:\eio mpostions2.do c more preferably greater than 2400 ng hours/mi, most preferably greater than 3000 ng hours/mi. These results can be achieved in a number of ways although in one preferred embodiment the method provides a blood plasma concentration in the animal of above about 100 ng/ml for a period of at least hours, even more preferably for a period of at least 16 hours, more preferably for a period of at least 20 hours, most preferably for a period of at least 24 hours. In another preferred embodiment the method provides a blood plasma concentration in the animal of above 50 ng/ml for a period of at least 30 hours, more preferably at least 36 hours.

In a further aspect the present invention provides a method of biological defleecing of an animal including treatment of the animal with a biological defleecing agent, wherein the treatment is such that when a group of at least of the animals is subjected to the treatment the average blood plasma concentration of the defleecing agent in the blood of the animals in the group is above a threshold level (X1 ng/ml) for at least a period of time (Y hours), the period of time being greater than 10 hours and being dependent on the threshold level wherein the combination of threshold level and period of time are effective to defleece at least 80% of animals subjected to the treatment.

In yet an even further aspect the invention provides method of biological defleecing of a group of animals including treatment of the animals with a biological defleecing agent in a manner to provide an average blood plasma concentration of the defleecing agent in the blood of the animals in the group above a threshold level (Xl ng/ml) for at least a period of time (Y hours), the period of time being greater than 10 hours and being dependent on the threshold level wherein the combination of threshold level and period of time are effective to defleece at least 80% of animals subjected to the treatment.

In these latter two methods it is preferred that X1 and Y satisfy the criteria X1*Y 1500 ng hours/mi. It is particularly preferred that X1*Y 1800 ng hours/ml, more preferably greater than 2000 ng hours/mi, yet even more C:%Neilcomposlions2 doc 22 preferably greater than 2400 ng hours/mi, most preferably greater than 3000 ng hours /ml. These results can be achieved in a number of ways although in one preferred embodiment the method provides a blood plasma concentration in the animal of above about 100 ng/ml for a period of at least 15, hours, even more preferably for a period of at least 16 hours, more preferably for a period of at least 20 hours, most preferably for a period of at least 24 hours. In another preferred embodiment the method provides a blood plasma concentration in the animal of above 50 ng/ml for a period of at least 30 hours, more preferably at least 36 hours.

As with the earlier aspects of the invention these methods preferably include the subcutaneous administration of the composition containing the biological defleecing agent.

Although the methods of the invention can be used to treat any animal that has a hair or wool forming a fleece -it is preferred that the compositions are used for the biological defleecing of sheep or goats. It is particularly preferred that the animal is a sheep of a breed a breed selected from the group consisting of Bond, Border Leicester, Cheviot, Coopworth, Corriedale, Dorset, Dorper, Dohne, Damara, Lincoln, Merino, Perendale, Polwarth, Rambouillet, Romney, Southdown, South African Mutton Merino, Suffolk, Texel, White Suffolk, Xinjiang Finewool and crossbreeds thereof being particularly preferred.

The compositions may be administered or used in the biological defleecing of sheep of any age and condition although it is found that the compositions have particular application in respect of young sheep such as sheep under 12 months of age, preferably under 8 months of age, particularly sheep under 6 months of age. It has been found that the method is particularly effective with young sheep where the prior art methods have been found to have particularly low efficacy. Without wishing to be bound by theory it is thought that the prior art methods are ineffective for the treatment of young sheep due to the increased metabolism of sheep of this age. It is thought that as a result of their increased metabolism the active substance is not maintained at a sufficient plasma concentration in the body for a sufficient time to be C:Neil\compositionS2.doc effective.

The method of the invention may be carried out with a number of biological defleecing agents although it is preferred that the defleecing agent is EGF or an analogue of EGF as disclosed previously in relation to the first aspect of the invention. The preferred EGF is URO-EGF. The amount of EGF or analogue of EGF administered may vary although typically it is of the order of from 5 to 25 mg, more preferably from 10 to 18mg, more preferably from 10 to 17 mg, most preferably 15 mg.

As discussed previously the applicants have found that the critical variable in successfully carrying out the inventive method is maintaining the blood plasma concentration at a sufficiently high level for a sufficiently long time to achieve the desired results. In a preferred embodiment the method is such that X and Y satisfy the criteria X*Y 1500 ng hours/ml. It is particularly preferredthat X*Y 1800 ng hours/mi, more preferably greater than 2000 ng hours/mi, yet even more preferably greater than 2400 ng hours/mi, most preferably greater than 3000 ng hours/mi. As will be appreciated by a skilled worker these results may be achieved in a number of ways.

In one preferred embodiment the method is carried out so that it provides a blood plasma concentration in the animal of above about 100 ng/ml for a period of at least 15 hours, more preferably at least 16 hours, more preferably for a period of at least 20 hours, most preferably for a period of at least 24 hours. In another preferred embodiment the method is carried out so that it provides a blood plasma concentration in the animal of above 50 ng/ml for a period of at least 30 hours, more preferably for a period of at least 36 hours. It has been found that if these parameters are complied with the defleecing efficacy of the method is of the order of 98% for sheep of all ages and conditions.

As will be appreciated blood plasma concentrations of these orders may be achieved in a number of ways. The method may be carried out by administration of a sustained release composition, a multi-stage release C:1Nel\composlions2.doc 24 composition, or by multiple administrations of a composition containing a defleecing agent. The composition is preferably subcutaneously administered by one of the known methods such as by injection.

In one preferred embodiment the 'method involves multiple administrations of a defleecing agent. In this embodiment a first administration of a defleecing agent is administered to the animal followed by at least one further administration of a defleecing agent. In general there are only two separate administrations of the defleecing agent although as a skilled worker would appreciate there may be any number of administrations carried out to produce the desired result. The second administration is generally given to the animal between 8 to 14 hours, preferably 10.to 14 hours most preferably hours after the first administration. If the blood plasma concentrations of the animal are being monitored it is preferred that the second administration is given as soon as the blood plasma concentration falls to about 100 ng/ml. In embodiments where there are two does it is it is particularly preferred that each of the doses contains from 4 mg to 11 mg of defleecing agent, the total amount of defleecing agent administered to the animal being from 8 mg to 22 mg.

In circumstances where there are more than two doses the doses are typically spaced relatively evenly over the desired length of time for which the blood plasma is desired to be raised. As an example if it was desired to maintain an elevated blood plasma profile for 20 hours the first additional dose would be administered from 6-10 hours after the first dose with a further dose administered from 14-16 hours after the initial dose.

The form of the composition containing the defleecing agent given in each administration may be of any suitable type and may, for example be in an immediate release or a sustained release dosage form. For example -the method may involve the split administration of two liquid doses, a split administration of a liquid and a solid dose or a split administration of two solid doses. The solid dosages used may be immediate release formulations as discussed above or may be sustained release formulations.

C:ANel compositions2.doc The amount of EGF or EGF analogue administered in each administration is typically less than the amount that would be administered in a single dose treatment. In general the amount administered in each dose in a multi dose treatment is dependent on the number of doses. For example where there are two doses each dose is typically half the dosage that would be administered in a single dose. As stated previously a single dose treatment typically involves administration of from 5 to 25 mg of the defleecing agent. In the double dosage treatment regimes, each dose therefore typically contains from 2.5 to 12.5 mg per dose. If more than 2 doses are used in the multiple dose regimes then the amount administered in each dose is reduced accordingly. As such where there is three doses each dose contains approximately one third of the dose that would be administered in a single dose.

In the multiple dose regime it is typical that the amount of defleecing agent administered in each dose is the same although this is not required.

In a further preferred embodiment the method involves the single administration.of a sustained release composition. A number of sustained release compositions are suitable for use in the methods of the invention.

One particularly preferred embodiment of eth invention includes administration of a sustained release composition that from 30% to 70 of the defleecing agent, from 5% to 45% of an excipient such as a surface active agent, and from 5% to 45% of a dissolution modifier. In this embodiment the composition administered preferably includes from 40% to 60% of the defleecing agent, from 15% to 35% of an excipient such as a surface active agent and from 15% to 35 dissolution modifier. The defleecing agent is preferably EGF or an analogue of EGF and the excipient (surface active agent) is preferably polyethylene glycol. The dissolution modifier is preferably selected from the group consisting of bioabsorbable polymers and disintegrants. A preferred disintegrant is selected from the group consisting of Starch, Vinyl Pyrrolidone analogues, Clays, Cellulosics, Algins and Gums. A particularly preferred embodiment of the method includes administration of a composition that includes 49% EGF, about 24% PEG and about 27% R104.

C:0NeiICompOSilonS2 doc 26 In a further preferred embodiment of the invention the method includes administration of a solid composition in the form of a coated pellet or tablet wherein the coating at least partially encases the core containing the defleecing agent. A particularly preferred coated composition is a tubular pellet, the pellet including a core containing the defleecing agent and an outer coating substantially in the shape of a tube at least partially encasing the core.

In this embodiment it is preferred that the composition is formulated in such a way to facilitate sustained release of the active defleecing agent from the core of the tubular pellet. This can be done in a number of different ways such as by piercing the coating in a number of places to facilitate egress of the defleecing agent, by arranging the tubular coating such that it has open ends (such that the tubular coating is in the form of a pipe) to allow egress of the defleecing agent or by ensuring that the coating at the ends of the tubular pellet is such that it degrades in a biological environment at a faster rate than the remainder of the coating. This latter property can be achieved, for example, by ensuring that the coating at the ends is thinner than the remainder of the coating or by coating the ends of the pellet with a more rapidly disintegrable coating material.

It is particularly preferred that either the outer tubular coating has open ends to allow egress of the defleecing agent from the pellet or (ii) the coating at the ends of the tubular pellet has a property so that the coating at the ends of the tube is degraded in the biological environment faster than the coating of the remainder of the tube. In those embodiments where the composition used in the method of the invention is in the form of a tubular pellet it is preferred that the tubular pellet has a diameter of from 2.0 to 2.6mm, more preferably from 2.2 to 2.4 mm, most preferably about 2.3 mm. The pellet used in the method of the invention may be of any suitable length that when combined with the pellet diameter delivers an appropriate amount of defleecing agent. It is typical, however, that the dimensions of the pellet are chosen such that the pellet contains from 10 to 25 mg of defleecing agent, more preferably from 12 to 18mg of defleecing agent, most preferably from 15 to 17 mg of defleecing agent per pellet. A typical pellet is from 5 to 10 mm in length, more typically from 6 to C: NeIVhcompositionS2dOC 27 8 mm in length. The preferred pellets of the invention are 2.3 mm in diameter and 7.6 mm in length.

In an alternative embodiment the core of the pellet may be a viscous liquid composition that includes EGF or an EGF analogue, a carrier, and a thickening agent, The thickening agent is preferably cellulose or a cellulose derivative with Methylcellulose A15 being particularly preferred.

Discussion SThe present inventors have found that biological defleecing of sheep using the methods of the present invention results in superior efficacy to prior art administrations of liquid EGF. Experiments by the present inventors have found that sustaining an EGF blood plasma concentration of about 100 ng/ml for at least 15 hours provides near 100% efficacy in all sheep, regardless of age, breed and variations in the environmental factors experienced. It has been found that if this elevated blood plasma concentration is maintained for at least 20 hours, more preferably for at least 24 hours then the efficiency of the process is improved further.

In particular, in sheep under 6 months of age, the present invention has been adequate in raising efficacy rates from an unacceptable 60% to a superior 98%. It is believed that a threshold lower than about 100 ng/ml will be capable of providing the same results provided that the reduced threshold is sustained for a correspondingly longer period. It is believed that EGF blood plasma concentrations as low as 50 ng/ml can provide near 100% efficacy though this threshold would need to be sustained for at least approximately 30 hours, more C:Nellompoiionsl2.doc preferably approximately 36 hours.

The applicants of the present invention have performed trials on the use of the current liquid EGF formulations and have established over many thousands of data entry points that the average blood plasma concentration levels obtained using the present methods are as shown in Figure la. Figure la therefore provides the typical blood plasma concentration profile obtained using the prior art single dose liquid formulation. As can be seen from this Figure, the blood plasma concentration falls below about 100 ng/ml at 12-14 hours after administration. Further, the concentration falls below about 50 ng/ml after approximately 18 hours. Whilst this leads to reasonable efficacy in adult sheep of 80%, in young sheep the efficacy rate is an unacceptable 60%. The results of treatment of sheep with the existing prior art formulations can be seen from the sheep in example 1. As can be seen the harvest scores vary markedly however in general unacceptable harvest scores were obtained. This demonstrates the lack of certainty in harvest performance achieved using the present methods.

Example 2 demonstrates he results achieved by the use of a spit liquid administration regime. As can be seen from the table by using a split liquid dose the blood plasma concentration is maintained at a higher level for an improved length of time leading to improved harvest scores being obtained. In Figure lb there is shown a typical graph obtained of EGF blood plasma concentrations for sheep administered with EGF in a split dose of liquid formulation in accordance with one preferred embodiment of the present invention. As is evident in this figure, the concentration level is sustained above about 100 ng/ml until approx hours after administration of the first dose at which time the second dose is administered and the concentration remains above about 100 ng/ml for at least 18 hours. In all trials in which a split liquid dose was administered there was a 98% efficacy for all sheep. This is clearly an improvement over the methods that have been utilised previously.

Example 3 demonstrates the efficacy of a single sustained release dose of the invention. As can be seen from the table the inventive composition C:N ei1compoStions2 .doc 29 provides sustained blood plasma profiles and improved harvest results.

Example 4 details the procedure for the production of a liquid formulation for use in the multi dose strategies. Figure Ic shows a preferred blood plasma profile for a slow release liquid formulation in accordance with the present invention. As is evident in the graph of Figure Ic, the single administration of the formulation is capable of sustaining blood plasma concentrations above about 100 ng/ml for at least 18 hours. These results gave an efficacy of 98% for all sheep. The single administration has the obvious benefit of requiring only single handling of the animals when compared to the split dose method described above. It is therefore clearly preferable from a manual handling perspective.

Example 5 details the methodology for forming a preferred solid dosage form of the invention. In this case the example produces a tubular coated pellet wherein the active defleecing agent is contained in the core of the pellet with a tubular coating at least partially encasing the core.

Example 6 details the procedure to be followed in forming a preferred solid release composition of the invention.

Example 7 details a trial in which a solid dose was administered to sheep using one of the improved formulations of the invention.

In Figure le there is shown the preferred results for a single administration of a multi-stage release solid composition made in accordance with one preferred form of the invention. The composition includes two core regions having different coating types or thicknesses such that the first core region is released into the animal shortly after administration and The second core region is released approximately 10 hours later. As is evident from the results, the composition is able to sustain EGF blood plasma concentrations above about 100 ng/ml for 18 to 20 hours. This product gave an efficacy of 98% for all sheep.

Without wishing to be bound by theory, the present inventors believe C:ANellcomposlions2doc that administering a composition containing EGF of the type described herein to the sheep results in an extension of the release profile of EGF in the blood plasma of the sheep. This sustained release of EGF to the sheep is believed to result in increased efficacy of the defleecing process. By providing a composition having a sustained EGF release profile, which can translate to a sustained EGF blood plasma profile, animal safety is improved in comparison to prior art compositions because the maximum EGF concentration that the animal experiences can be reduced. Furthermore, for solid compositions or encapsulated liquid compositions, handler safety can be improved because accidental injection into the handler can be removed before the composition takes effect.

The present invention will now be illustrated in further detail with reference to the following examples.

Examples The following examples are provided to illustrate preferred aspects of the present invention. The present invention should not be considered to be limited solely to the features described in the following examples.

In many of the following examples a fleece harvest score is provided.

This is because the efficacy of the process is determined by the subsequent ability to harvest the wool from the animal. The following harvest score scale has been developed to assess the efficacy of the results.

Harvest Score: 1 Unable to Harvest 2 Difficult to Harvest 3 Able to be Harvested (Not commercially suitable) 4 Easily Harvested Complete Wool Separation C:leiconpostions2.doc 31 Example 1 (Blood Plasma results for prior art formulations) The currently available liquid EGF formulation was administered in a subcutaneous manner to 4 healthy sheep under the age of 6 months via subcutaneous injection of 2ml of the formulation. A fleece retention net was then applied to the sheep in the normal manner. The formulation was such that 2ml contains 15 mg EGF. After waiting the prescribed period the nets were removed from the sheep and an attempt was made to harvest the fleece from the sheep by hand. The harvest scores were recorded for each sheep. All data collected is shown in table 1.

Table 1 Harvest scores obtained for the prior art formulations Sheep No Harvest Score 1 2 2 3 3 1-2 4 3-4 Example 2 A Split dose methodology.

A trial was conducted in which ten sheep were subjected to a split dose of the prior art liquid formulation in which 1 ml of the formulation was administered at 0 and 14 hrs. Blood plasma tests were taken at 0, 1, 2, 4, 8, 12, 16 and 24 hours post the first dose. The sheep were then allowed to return to the paddock and, after waiting the required time period, the fleece retention nets were removed and fleece attempted to be harvested by hand. The results are given in table 2.

C:ANell\compositions2.doc

M

Table 2 Individual blood plasma results (ng/ml) in Example 2 Sheep Time (hours) Harvest No Score 0 1 2 4 8 12 16 24 1 0 90 129 147 123 94 177 86 4 2 0 80 136 167 193 138 344 95 4 3 1 83 92 151 172 149 316 66 4 4 0 130 145 183 183 118 378 69 4 1 138 142 162 191 101 426 164 6 0 152 163 140 128 95 289 134 7 0 161 241 296 255 163 552 94 3 8 2 173 193 141 83 102 447 116 9 4 186 188 238 232 170 381 150 4 0 291 292 274 281 132 445 196 Av 1 148 172 190 184 126 376 117 4.3 Example 3 A single sustained release dose A trial was conducted in which ten sheep were subjected to a single sustained release dose. This involved subcutaneous injection of the pellet under the skin of the sheep. The pellet utilised contained 15 mg of EGF and was dimensioned so that it was 6.8 mm x 2.3 mm. The formulation contained 49% EGF, 24% PEG and 27% R104.

Upon completion of the subjection of the sheep to the administration the sheep were monitored with blood plasma readings being taken at 0, 1, 2, 4, 8, 12, 16, 24, and 30 hours after initial treatment. The sheep were returned to the paddock and allowed to wait the required period. They were then returned to the holding area, the fleece retention nets removed and the fleece was attempted to be harvested by hand. The results of the experiment are listed in tables 3.

C:Neilocompositions2.doc Table 3 Individual blood plasma results (ng/ml) in Example 3 Sheep Time (hours) Harvest No Score 0 1 2 4 8 12 16 24 1 3 65 264 606 655 281 68 13 4 2 0 101 344 778 659 333 100 8 3 1 141 339 600 587 297 91 22 4 4 1 144 403 768 758 714 485 83 1 168 369 694 820 489 186 18 6 2 174 534 737 657 319 109 15 4 7 1 219 526 763 699 375 148 19 8 8 25 43 133 303 272 141 10 9 4 80 132 309 614 476 193 11 4 7 165 369 504 781 512 169 14 Av 3 128 332 589 653 407 169 21 4.7 Example 4 A Sample liquid formulation for multiple administration A liquid formulation for use in the multi-dose strategy of the invention was prepared containing the following components: URO-EGF, Methylcellulose Ethylene diamine tetra acetic acid (tetra sodium salt), sodium acetate (anhydrous) sodium methyl hydroxy benzoate, sodium propyl hydroxy benzoate, sterile pyrogen free water. The formulation was prepared as follows.

Seventy five litres of sterile water was added to a mixing tank followed by 3.68 kg of methylcellulose and the mixing tank stirred until the cellulose was well dispersed. A further 20 L of sterile water was added and 50 g of sodium methyl hydroxy benzoate added. The mixture was stirred until all the material had dissolved. 5 g of sodium propyl benzoate was then added and agitation continued until it had dissolved. The EDTA was then added with continued agitation until it too had dissolved. Upon dissolution of the EDTA the sodium acetate was added and stirring continued until it had dissolved. In general it was found that 15 minutes of agitation is required between additions. Following completion of addition the mixture was transferred to a cold room and incubated overnight at 40C to allow for complete hydration of the cellulose. 750g of URO- EGF was then added and the mixture agitated gently until complete dissolution C:NeiRcompositions2doc 34 was achieved. The mixture was then diluted with sterile water to produce a solution containing 8.35 mg/ml of the active agent (URO-EGF).

Example 5 Pellet or Solid dose A solid pellet was prepared by mixing together polyethylene glycol, polylactide and lyophilised EGF powder in the proportions of 24.8% polyethelene glycol, 24.3% polylactide and 50.9% EGF (all weight percentages calculated on the basis of the total weight of polyethelene glycol plus polylactide plus EUF). The thus formed mixture was compressed into an appropriate shape. A heated shell was then extruded over the compressed mixture of EGF, polyethylene glycol and polylactide. The heated shell was allowed to cool until it contracted around the active constituents to form a coating around the pellet.

The pellet was then cut into appropriate sections for administration.

A pellet was.subcutaneously placed into an Australian Merino sheep. A fleece-retaining net was then fitted to the sheep. The fleece-retaining net was removed 21 days later. Removal of the fleece-retaining net caused removal of the fleece from the sheep. Tests on a number of sheep using this process resulted in 100% efficacy of the defleecing process. Figure Id shows the preferred results for a single administration of a slow release solid composition made in accordance with one preferred form of the present invention. As is evident from the figure, the slow release composition is capable of sustaining a blood plasma concentration of EGF above about 1.00 ng/ml for 18 to 20 hours.

These results gave 98% efficacy in removing the fleece for all sheep.

Example 6 Improved sustained release composition.

A solid pellet was prepared by mixing together polyethylene glycol, R104 and lyophilised EGF powder in the proportions of 24% polyethylene glycol, 27% R104 and 49% EGF (all weight percentages calculated on the basis of the total weight of polyethylene glycol plus R104 plus EGF). The thus formed mixture was compressed into an appropriate shape and cut into pellets for administration. This was the pellet used in example 3 C:Nellcomposiions 2.doc Example 7 Controlled Release dosage Form A trial was performed on thirty sheep using the methodology outlined in Example 1 and using a tubular pellet of the invention.

The specifications for the pellet were as follows.

Average 16.7 mg EGF/tablet mg formulation/mm 7.6 mm x 2.3 mm tablet The pellet also contained polyethylene glycol and polylactide in accordance with the preferred embodiment of the invention, The results of the trial are shown in Table 4.

Table 4 Individual harvest results.

Sheep Number Harvest Score 1 4 2 3 Missing 4 4 6 3 7 3 8 3 9 3 Missing 11 4 12 4 13 4 14 4 4 16 4 17 4 18 4 C:1Neicompositions2.doc 19 4 21 4 22 23 24 26 27 4 28 29 3 Missing Average 4.1 Example 8 Lamb trial 100 lambs were injected with the pellet used in example 7 and a further 100 lambs were injected with a split liquid injection regime according to the procedure of example 2. The average harvest score for the lambs treated with the pellet was 4.0 whilst the average harvest score for the lambs treated with the split liquid was 4.5. This clearly demonstrates the improved results obtained using the methods and compositions of the present invention.

Example 9 Coated Sustained release product.

A trial was conducted in which a number of sheep were treated with a coated sustained release dosage form of the invention. The results are summarised in table Table 5 results achieved in example 9 Harvest Score Single Dose (Coated) 4 Single Dose (Coated) Single Dose (Coated) 4 Single Dose (Coated) Single Dose (Coated) 3 C:V4ei\omposltions2.doc Single Dose (Coated) 3 Single Dose (Coated) 3 Single Dose (Coated) 3 Single Dose (Coated) 4 Single Dose (Coated) 4 Single Dose (Coated) 4 Single Dose (Coated) 4 Single Dose (Coated) 4 Single Dose (Coated) 4 Single Dose (Coated) 4 Single Dose (Coated) 4 Single Dose (Coated) 4 Single Dose (Coated) Single Dose (Coated) 4 Single Dose (Coated) Single Dose (Coated) Single Dose (Coated) Single Dose (Coated) Single Dose (Coated) Single Dose (Coated) 4 Single Dose (Coated) Single Dose (Coated) 3 Those skilled in the art will appreciate that the present invention may be susceptible to variations and modifications other than those specifically described. It is to be understood that the present invention encompasses all such variations and modifications that fall within its spirit and scope.

C:~NeiIonmpoitions2.dOC

Claims

2. A method according to claim 1 wherein X*Y 2000 ng hours/ml.
3. A method according to claim 2 wherein X*Y 3000 ng hours/ml.
4. A method according to any one of claims 1 to 3 wherein Y is greater than hours. A method according to any one of the preceding claims wherein Y is greater than 30 hours.
6. A method according to claim 1 wherein the treatment provides a blood plasma concentration in the animal of above about 100ng/ml for a period of at least hours.
7. A method according to claim 1 wherein the treatment provides a blood plasma concentration in the animal of above about 50 ng/ml for a period of at least hours.
8. A method according to any one of the preceding claims wherein the animal is a sheep or a goat.
9. A method according to any one of the preceding claims wherein the defleecing agent is administered subcutaneously. W \NKI\NKIWORK\85O035\) S035 SPECI 100209doc
10. A method according to claim 1 wherein the treatment includes administration to the animal of a first dose of a composition including a defleecing agent and at a period of time after administering the first dose, administering at least one I further dose of a composition including a biological defleecing agent, each of (N the doses contains from 4.0 mg to 11 mg of defleecing agent, the total amount IN of defleecing agent administered to the animal being from 8 mg to 22 mg. 0
11. A method according to claim 9 wherein the method includes administration of a solid sustained release composition containing the defleecing agent. O(N c
12. A method according to claim 11 wherein the composition includes from 30% to of the defleecing agent, form 5% to 45% of a surface active agent, and from 5% to 45% of a dissolution modifier.
13. A method according to claim 12 wherein the defleecing agent is EGF or an analogue of EGF.
14. A method according to claim 12 or claim 13 wherein the surface active agent is polyethylene glycol. A method according to claim 12 wherein the composition contains about
50.9% EGF, about 24.8%% polyethylene glycol and about 24.3% polylactide. 16. A method according to claim 12 wherein the composition contains about 49% EGF, about 24% PEG and about 27% R104. 17. A method according to any one of claims 12 to 16 wherein the composition is at least partially encased in a coating. 18. A method according to claim 17 wherein the defleecing agent is administered in a multi-stage dosage form. 19. A method according to claim 18 wherein the multi stage dosage form is a solid tablet or pellet including a plurality of EGF or EGF analogue containing layers and at least one layer not containing EGF or an EGF analogue, the layers W .NKI\NKIWORKb85035'685035 SPECI 100209 doc alternating so as to provide multistage release of the EGF or EGF analogue to an animal upon administration of the pellet. I 20. A method according to claim 9 wherein the defleecing agent is administered in (N the form of a viscous liquid. O 00 21. A composition for defleecing an animal wherein the composition includes from 30% to 70% of a defleecing agent, from 5% to 45% of a surface active agent, and from 5% to 45% of a dissolution modifier. 22. A composition according to claim 21 wherein the composition includes from to 17 mg of the defleecing agent. W:'\NI'\NKIWORK68!0S35k68503-« SPECI 00209 do