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Title:
ANTIBIOTIC FORMULATIONS
Document Type and Number:
WIPO Patent Application WO/2013/095166
Kind Code:
A1
Abstract:
A suspension formulation for administration to an animal, the suspension formulation including: at least one cephalosporin antibiotic or a pharmaceutically similar salt thereof; an oil; and a glycerol acetate solvent.

Inventors:
AL ALAWI, Fadil (c/- Level 12, KPMG Centre85 Alexandra Stree, Hamilton 3204, NZ)
NANJAN, Karthigeyan (c/- Level 12, KPMG Centre85 Alexandra Stree, Hamilton 3204, NZ)
Application Number:
NZ2012/000245
Publication Date:
June 27, 2013
Filing Date:
December 21, 2012
Export Citation:
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Assignee:
BAYER NEW ZEALAND LIMITED (c/-Level 12, KPMG Centre85 Alexandra Stree, Hamilton 3204, NZ)
AL ALAWI, Fadil (c/- Level 12, KPMG Centre85 Alexandra Stree, Hamilton 3204, NZ)
NANJAN, Karthigeyan (c/- Level 12, KPMG Centre85 Alexandra Stree, Hamilton 3204, NZ)
International Classes:
A61K31/545; A61K9/10; A61K47/14; A61P31/04
Domestic Patent References:
WO2009032843A22009-03-12
Foreign References:
CN101401787A2009-04-08
CN1517090A2004-08-04
EP0391369A21990-10-10
Attorney, Agent or Firm:
BROWN, Peter et al. (James & Wells Intellectual Property, Private Bag 3140Hamilton, 3240, NZ)
Download PDF:
Claims:
WHAT WE CLAIM IS:

1. A suspension formulation for administration to an animal, the suspension formulation including: a) at least one cephalosporin antibiotic or a pharmaceutically similar salt thereof; b) an oil; and c) a glycerol acetate solvent.

2. The suspension formulation as claimed in claim 1 wherein the

cephalosporin antibiotic is selected from the group consisting of third generation cephalosporin antibiotics.

3. The suspension formulation as claimed in claim 2 where the

cephalosporin antibiotic is ceftiofur.

4. The suspension formulation as claimed in any one of the above claims wherein the concentration of the cephalosporin antibiotic is between 1 - 30% w/v.

5. The suspension formulation as claimed in any one of the above claims wherein the concentration of the cephalosporin antibiotic is between 5 - 6 % w/v.

6. The suspension formulation as claimed in any one of the above claims wherein the oil is selected from the group consisting of canola oil, corn oil, cottonseed oil, olive oil, peanut oil, sesame oil, soybean oil, safflower oil, coconut oil, sunflower oil, palm oil, monoglyceride, diglyceride and triglyceride medium chain succinic acid triglyceride.

7. The suspension formulation as claimed in claim 6 wherein the oil is

cottonseed oil.

8. The suspension formulation as claimed in any of the above claims

wherein the glycerol acetate solvent is selected from the group consisting of acetin, diacetin and triacetin.

9. The suspension formulation as claimed in claim 8 wherein the glycerol acetate solvent is triacetin.

10. The suspension formulation as claimed in any of the above claims

wherein the glycerol acetate solvent is included in the formulation in the range of 0.05 - 5% w/v.

11. The suspension formulation as claimed in any of the above claims

wherein the glycerol acetate solvent is included in the formulation in the range of 0.5% w/v.

12. The suspension formulation as claimed in any of the above claims

wherein the formulation includes a surfactant.

13. The suspension formulation as claimed in claim 12, wherein the

surfactant is sorbitan monooleate.

14. The suspension formulation as claimed in any of the above claims,

wherein the formulation includes a dispersing agent.

15. The suspension formulation as claimed in claim 14, wherein the

dispersing agent is hydrogenated phosphatidylcholine.

16. A container including an amount of a suspension formulation as claimed in any one of the above claims characterised in that the container is made substantially of PET (polyethylene teraphthate). 7. A method of administering a suspension formulation as claimed in any one of the above claims, to an animal for the treatment or prevention of a bacterial infection or resulting condition.

18. The method of claim 17 wherein the suspension formulation is

administered at a rate of between 0.5 to 5 mg/kg animal/day.

19. The use in the manufacture of a medicament including a suspension formulation as claimed in any of claims 1 to 15 for the treatment or prevention of a bacterial infection or condition in an animal.

20. The use as claimed in the claim 9 wherein the bacterial infection or condition to be treated or prevented is bovine bacterial respiratory disease, swine bacterial respiratory disease, foot rot or metritis.

21. A method of preparing a suspension formulation as claimed in any one of claims 1 to 15 wherein the method includes the steps of a. adding an amount of an oil to a first container; b. adding an amount of an oil to a second container, and heating to a temperature between room temperature and 100°C; c. adding an amount of a dispersing agent to the second container; d. adding an amount of a surfactant to a third container; e. adding the glycerol acetate solvent to the third container; f. mixing the contents of the first, second and third containers together; g. adding the cephalosporin antibiotic to the mixed contents; and h. optionally, making the mixture up to a desired volume with an oil.

22. A method as claimed in claim 21 wherein the heating step in (b)

comprises heating the oil to between 15-90°C.

23. A method as claimed in either claim 21 or 22 wherein the mixture

resulting from step b) is incubated for between 5 minutes and 60 minutes.

24. A suspension formulation as herein described and with reference to

Example 1 in the Best Modes section.

25. A method of manufacture of the suspension formulation as herein

described and with reference to Example 2 in the Best Modes section.

Description:
ANTIBIOTIC FORMULATIONS TECHNICAL FIELD

The present invention relates to antibiotic formulations. In particular, the present invention relates to cephalosporin antibiotic suspension formulations, their methods of manufacture and use.

BACKGROUND ART

Cephalosporin antibiotics are a subset of the β-lactam family of antibiotics and are used to treat bacterial infections, typically in the veterinary industry. The core structure of cephalosporin antibiotic is shown below:

The cephalosporin antibiotics are classified into "generations" as outlined in Martindale: The Complete Drug Reference, 35th Edition, the content of which is incorporated by reference. It is generally understood cephalosporins act by blocking the production of the peptidoglycan layer of bacterial cell walls. Although first-generation cephalosporins are predominantly active against Gram-positive bacteria, successive generations have heightened activity against Gram-negative bacteria (albeit often with reduced activity against Gram-positive organisms). New types of cephalosporin antibiotics have been identified, which have yet to be assigned to a particular generation.

Cephalosporin antibiotics are characterised as being difficult to provide in a formulation due to their low solubility and poor stability. While cephalosporin antibiotics, such as Ceftiofur (a third generation antibiotic), can be administered orally or topically, it has been found that they are poorly absorbed upon oral administration, and are more rapidly absorbed after intramuscular administration. However, ceftiofur in aqueous solution degrades rapidly and must be stored as a sterile powder for reconstitution when required, such as the commercial product Excenel™. Following dissolution of ceftiofur in sterile water, storage stability is limited to 12 hours at room temperature, or up to 7 days in a refrigerator.

As such, a ready-to-use ( TU) Ceftiofur and other cephalosporin antibiotics are preferentially administered in an oily (typically vegetable oil) suspension for parenteral injection.

However, oily suspensions containing cephalosporin antibiotics can be problematic due to formulations being physically and/or chemically unstable. This is due to suspensions being present in more than one state, such as a liquid and a solid, and also the difficult insoluble nature of the active itself. Four major issues may arise in relation to such suspensions: a) dispersion of particles in a vehicle; b) settling of the dispersed particles; c) caking of such particles in the sediment so as to prevent dispersion when required (typically just prior to administration); and d) degradation of the cephalosporin antibiotic.

There has been much investigation into how these problems can be avoided in suspensions, the aim being to achieve controlled aggregation (termed flocculation). Many different types of vehicles are used to help with flocculation, including a preserved sodium chloride solution or a parenterally acceptable vegetable oil.

This flocculation effect should allow the particles to settle, but then separate when required. Several additives have been identified which specifically help

cephalosporin antibiotic suspensions flocculate, as set out below.

One particularly effective antibiotic is Ceftiofur. In cattle Ceftiofur hydrochloride is a broad spectrum cephalosporin antibiotic active against Fusobacterium necrophorum and Bacteroides melaninogenicus the two main pathogens associated with bovine foot rot. Ceftiofur hydrochloride also has excellent in vitro and in vivo activity against Pasteurella hemolytica and P.

multocida., two of the major pathogenic bacteria associated with bovine respiratory disease (BRD). It also has excellent in vitro and in vivo activity against

Haemophilus somnus and in vitro activity against Corynebacterium pyogenes, two other bacterial pathogens associated with bovine respiratory disease. In addition, Ceftiofur has excellent in vitro activity against other Gram-negative pathogens, such as E. coli, Salmonella choleraesuis, Salmonella typhimurium and

Haemophilus pleuropneumonia and agalactiae, Streptococcus dysgalactiae, Streptococcus uberis, Streptococcus bovis and Streptococcus suis.

In pigs, Ceftiofur has excellent in vitro and in vivo activity against Gram-negative pathogens such as Actinobacillus (Haemophilus) pleuropneumoniae, Salmonella choleraesuis, Pasteurella multocida and the Gram-positive pathogen

Streptococcus suis, all of which singly or in combination can be associated with swine bacterial respiratory disease (swine-bacterial pneumonia). Ceftiofur also has excellent in vitro activity against other Gram-negative pathogens, such as E. coli and Salmonella typhumurim and against Gram-positive pathogens such as Staphylococcus aureus, Streptococcus agalactiae, Streptococcus dysgalactiae, Streptococcus uberis and Streptococcus bovis. Ceftiofur was effective when tested in a variety of mouse disease models involving E. coli, Staphylococcus aureus, Streptococcus agalactiae, Pasteurella multocida or Salmonella typhimurium. However, the clinical significance of these findings in swine is not known.

US 5,736,151 discloses an oily suspension including Ceftiofur and water as a flocculating agent to provide better re-suspendability of the suspension.

US 4,902,683 discloses a host of excipients which are suggested as being appropriate to help prepare a suspension of Ceftiofur for systemic administration.

WO 2004/014390 discloses the use of a re-suspendability enhancer for an oily suspension of Ceftiofur, wherein the re-suspendability enhancer is selected from polyoxyl hydrogenated vegetable oil, polyoxyl vegetable oil, glycerol, propylene glycol or polyethylene glycol.

WO 2010-059747 discloses the use of benzyl alcohol as a re-suspendability enhancer when used for ceftiofur and ketoprofen.

Despite the discussion in these documents, there remains a need to identify suitable additives to achieve improved physical stability for cephalosporin antibiotic containing oily suspensions, particularly those designed for parenteral injection.

Likewise, the additives used to improve physical stability of the cephalosporin antibiotic containing oily suspensions can often lead to chemical instability of the antibiotic itself, obviously resulting in an undesirably short-shelf life of the formulation and/or a shortened effectiveness after administration. For example, US 5,736,151 merely uses water as a flocculating agent. The present inventors have found such a formulation can have a limited shelf-life and generally undesirable pharmacokinetic properties. Similar results were found for carriers such as glycols as disclosed in WO 2004/014390. Also, the use of additives such as glycols can increase the costs associated with the production of such formulations, cause site reaction on delivery, allergies and the like.

A commercially available ready-to-use Ceftiofur formulation is Excenel RTU , marketed by Pfizer. Excenel RTU is an oil based suspension that uses a small quantity of water as a flocculating agent. According to the directions that accompanies the Excenel RTU product, shaking for 20-30 seconds is required for re-suspension of the active.

Many suspension formulations are kept in glass vials. This has been found to help counter the major problems with suspensions as outlined above. However, there are subsequent concerns with glass storage including the greater likelihood of breakage and higher costs of production/storage. It would be preferable to store suspensions that have an improved flocculation and/or stability in PET

(polyethylene teraphthate) or other plastic vials which would overcome these issues with storage in glass. However, PET vials have been known to cause caking meaning that currently available formulations do not store particularly well in PET vials. As known to one skilled in the art, water and oxygen can diffuse through the PET packaging and be absorbed into the contents. This can accelerate degradation of the active, and interfere with the physical stability such as by enhancing sedimentation and caking. For example, the inventors found that the commercially available Ceftiofur formulation, Cefaguard™ (marketed by Stockguard) had 10% less active than the label requirement when the formulation was stored in PET vials. Testing revealed the Cefaguard™ formulation had a water content similar to Excenel™ RTU (ready- to-use). As previously discussed, suspensions containing water such as that described in US 5,736,151 can have poor storage stability. One object of the present invention is therefore to provide a cephalosporin antibiotic containing formulation which is more storage stable in a wider range of conditions and/or for longer durations with lesser or no decrease in the active agent concentration in the suspension, and/or may be effectively stored in PET vials without caking or other problems seen with currently available formulations. It can be appreciated there is a significant commercial advantage if a composition is able to retain an active concentration above the label requirement for a longer duration. This avoids the consumer or retailer having to frequently replenish supplies , making it a more attractive product to supply or purchase.

An alternative object of the present invention is to address the foregoing problems with cephalosporin antibiotic containing suspensions or at least to provide the public with a useful choice.

All references, including any patents or patent applications cited in this

specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert, and the applicants reserve the right to challenge the accuracy and pertinency of the cited documents. It will be clearly understood that, although a number of prior art publications are referred to herein, this reference does not constitute an admission that any of these documents form part of the common general knowledge in the art, in New Zealand or in any other country. Throughout this specification, the word "comprise", or variations thereof such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.

DISCLOSURE OF INVENTION

According to one aspect of the present invention there is provided a suspension formulation for administration to an animal, the suspension formulation including a) at least one cephalosporin antibiotic or a pharmaceutically similar salt

thereof, b) an oil, and c) a glycerol acetate solvent.

The use of a glycerol acetate solvent in present invention provides improved suspension of the cephalosporin antibiotic active agent. The glycerol acetate solvent was surprisingly found by the inventors to provide improved mixing and re- suspending of the oil and cephalosporin antibiotic and good anti-caking properties. This is very important not only during the manufacturing stage (to reduce time and resources required) but also for re-suspension prior to delivery by the administrator of the formulation.

Furthermore, the use of a glycerol acetate solvent in the suspension formulation was found to improve the shelf-life of the suspension compared to a commercially available Ceftiofur suspension. This is further discussed in the Best Modes section of this document. Surprisingly, the inventors found that suspensions formulated according to the present invention were particularly stable, and had good anti-caking characteristics, particularly when stored in plastic PET vials. As previously discussed, these results may help to overcome a number of problems associated with current industry practice of storing cephalosporin antibiotic suspensions in glass vials due to poor storage characteristics in other types of containers.

Throughout this specification, the term "PET vials" should be taken as meaning any container or vessel which includes polyethylene terephthalate (also known as poly (ethylene terephthalate). PET consists of polymerised units of ethylene

terephthalate, with repeating C 10 H 8 O 4 units.

Additionally, preliminary animal studies suggest that the use of a glycerol acetate solvent results in a cephalosporin antibiotic containing suspension that is longer- acting than other known cephalosporin antibiotic containing suspensions.

It was also found that the use of a glycerol acetate solvent led to a lower site reaction on delivery than was expected. When compared to aqueous-based compositions, the present composition (being non-aqueous based) would be expected to cause a significantly higher site reaction upon injection.

Further aspects and advantages of the present invention will be discussed below.

Throughout the specification, the term "cephalosporin antibiotic" should be taken as meaning a class of β-lactam antibiotics derived from Acremonium.

The cephalosporin antibiotics include a number of different members which are commonly classified into "generations". Currently there are five broad generations as outlined below:

• Generation 1 members include Cefacetrile (cephacetrile), Cefadroxil

(cefadroxyl; Duricef), Cephalexin (cephalexin; Keflex), Cefaloglycin (cephaloglycin), Cefalonium (cephalonium), Cefaloridine (cephaloradine), Cefalotin (cephalothin; Keflin), Cefapirin (cephapirin; Cefadryl), Cefatrizine, Cefazaflur, Cefazedone, Cefazolin (cephazolin; Ancef, Kefzol), Cefradine (cephradine; Velosef), Cefroxadine, Ceftezole.

Generation 2 members include Cefaclor (Ceclor, Distaclor, Keflor,

Raniclor), Cefonicid (Monocid), Cefprozil (cefproxil; Cefzil), Cefuroxime (Zefu, Zinnat, Zinacef, Ceftin, Biofuroksym, Xorimax), Cefuzonam. Second generation cephalosporins with antianaerobe activity: Cefmetazole, Cefotetan, Cefoxitin. The following cephems are also sometimes grouped with second-generation cephalosporins: Carbacephems: loracarbef (Lorabid); Cephamycins: cefbuperazone, cefmetazole (Zefazone), cefminox, cefotetan (Cefotan), cefoxitin (Mefoxin).

Generation 3 members include Cefcapene, Cefdaloxime, Cefdinir (Zinir, Omnicef, Kefnir), Cefditoren, Cefetamet, Cefixime (Zifi, Suprax),

Cefmenoxime, Cefodizime, Cefotaxime (Claforan), Cefovecin (Convenia), Cefpimizole, Cefpodoxime (Vantin, PECEF), Cefteram, Ceftibuten (Cedax), Ceftiofur, Ceftiolene, Ceftizoxime (Cefizox), Ceftriaxone (Rocephin). Third- generation cephalosporins with antipseudomonal activity: Cefoperazone (Cefobid), Ceftazidime (Fortum, Fortaz). The following cephems are also sometimes grouped with third-generation cephalosporins: Oxacephems: latamoxef (moxalactam).

Generation 4 members include Cefclidine, Cefepime (Maxipime),

Cefluprenam, Cefoselis, Cefozopran, Cefpirome (Cefrom), Cefquinome. The following cephems are also sometimes grouped with fourth-generation cephalosporins: Oxacephems: flomoxef.

Generation 5 members include Ceftobiprole, Ceftaroline. Other cephalosporin antibiotics have been identified, but have yet to be assigned to a particular generation. These include Cefaloram, Cefaparole, Cefcanel,

Cefedrolor, Cefempidone, Cefetrizole, Cefivitril, Cefmatilen, Cefmepidium,

Cefoxazole, Cefrotil, Cefsumide, Ceftaroline, Ceftioxide, Cefuracetime. The cephalosporin antibiotics share substantial structural features, similar stability and solubility characteristics, and a similar mode of action. Therefore, it would be reasonably expected by someone skilled in the art that using any one or combination of cephalosporin antibiotics other than Ceftiofur, either as currently known or as developed/identified in future, in combination with a glycerol acetate solvent and an oil in a suspension formulation according to the present invention will provide the same advantageous results as described herein.

Preferably, the cephalosporin antibiotic is selected from the group consisting of a third generation cephalosporin antibiotic as listed above.

Most preferably, the cephalosporin antibiotic is Ceftiofur. Preferably, the suspension formulation includes approximately between 1 - 30% w/v of the cephalosporin antibiotic.

More preferably, the suspension formulation includes 5 - 6% w/v of the

cephalosporin antibiotic. The inventors identified that a concentration of 5.35% w/v Ceftiofur HCI was required to give a 5% Ceftiofur base. The upper concentration of the cephalosporin is usually governed by the resulting viscosity of the

formulation since eventually the formulation will become too viscous to effectively syringe.

Throughout the specification the term "oil" should be taken as any substance that is liquid at ambient temperatures, is hydrophobic and is soluble in organic solvents. Preferably the oil is of a vegetable, animal or synthetic origin. More preferably, the oil is selected from the group consisting of canola oil, corn oil, cottonseed oil, olive oil, peanut oil, sesame oil, soybean oil, safflower oil, coconut oil, sunflower oil, palm oil, monoglyceride, diglyceride and triglyceride medium chain succinic acid triglyceride. Most preferably, the oil is cottonseed oil.

The suspension formulation may include approximately between 70-99% w/v of the oil. However it should be appreciated that the oil may be used at an amount sufficient to increase the suspension to a desired volume (qs), such as 1000 ml.

Throughout the specification the term "glycerol acetate solvent" (also known as glycerine acetate) should be taken as meaning the ester produced from the esterification of glycerol with acetic acid.

Multiple products can be produced from this reaction including mono- acetyglycerols, diacetylglycerols and triacetalglycerols (more commonly known as triacetin). Preferably, the glycerol acetate solvent is selected from the group consisting of acetin, diacetin and triacetin.

Most preferably, the glycerol acetate solvent is triacetin.

It is expected that triacetin would work particularly well compared to acetin or diacetin, however any of these solvents from this group can preferably be used. Triacetin is also known as triglyceride 1 ,2,3-tricetoxypropane and glycerine triacetate. Triacetin is the triester of glycerol and acidic acid.

Triacetin compounds (and related acetin and diacetin compounds) have been described as having transdermal and solvent properties and have the general structure: Various patent disclosures describe the use of triacetin as a solvent for veterinary formulations containing different active agents and different modes of delivery (See for example NZ 234802, NZ 520707 and NZ 306249).

Despite the known use of triacetin as a solvent, it is well understood in the art that different active agents can react very differently to solvents, often affecting both physical stability of the formulation and chemical stability of the active itself. For this reason it may be impossible to accurately predict from the use of one solvent type in an anthelmintic formulation that the same solvent type would also be an appropriate solvent for a cephalosporin antibiotic.

Also, the specific type of formulation (e.g. drench, pour-on, parenteral injectable solution, suspension, bolus, and so forth) has a significant impact on the type and applicability of solvent used.

Furthermore, the present invention is complicated by the insoluble nature of the cephalosporin antibiotic active, requiring the formulation to be provided as an oily suspension. The difficulty in formulating cephalosporin antibiotics such as Ceftiofur is clearly exemplified in US 5,736, 151 , US 4,902,683 and WO

2004/014390 discussed above.

Despite much work in this field, until now it has not been identified that a glycerol acetate solvent such as triacetin may improve the storage characteristics, shelf-life and persistency of a cephalosporin antibiotic active containing oily suspension. Also, the inventors have determined that the formulations herein described have a site reaction on injection similar or better than currently available references.

Without being limited to the possible mode of action, the inventors consider this beneficial yet unexpected effect may possibly be due to the use of the glycerol acetate solvent. Further studies are underway to confirm these results.

Preferably, the suspension formulation includes approximately between 0.05 to 5% w/v of a glycerol acetate solvent.

More, preferably, the suspension formulation includes approximately 0.5 % w/v of a glycerol acetate solvent. Other Ceftiofur formulations, such as described in WO 2004/014390, disclose the use of 0.5% w/v of a glycol. The inventors have found that using the same amount of a glycerol acetate solvent (such as triacetin) as a substitute for a glycol (as disclosed in WO 2004/014390) surprisingly leads to substantially improved mixing and resuspendibility characteristics, shelf-life and duration of action of the suspension.

Preferably the suspension formulation includes a surfactant. Almost any surfactant may be used with the present invention and it should be appreciated that someone skilled in the art would be able to identify an appropriate surfactant to use with the formulation. Most preferably, the surfactant is sorbitan monooleate (e.g. Span80).

Preferably, the formulation includes a dispersing agent. Almost any dispersing agent may be used with the present invention and it should be appreciated that someone skilled in the art would be able to identify an appropriate dispersing agent to use with the formulation. Most preferably, the dispersing agent is phosphatidylcholine, hydrogenated (e.g. Phospolipon H90).

Method of treatment

According to a further aspect of the present invention there is provided a method of administering a suspension formulation as substantially described herein to an animal for the treatment or prevention of a bacterial infection or resulting condition.

Preferably, the bacterial infection or condition to be treated or prevented is bovine bacterial respiratory disease or wine bacterial respiratory disease.

Alternatively the bacterial infection or condition to be treated or prevented is bovine foot rot.

In a further alternative embodiment, the bacterial infection or condition to be treated or prevented is bovine metritis.

However, it should be appreciated that the present invention may be used to treat any infection or condition for which a cephalosporin antibiotic is known to be useful, now or in the future.

Preferably, the method of treatment includes administering to the animal in need thereof the formulation substantially as described herein at a rate of between approximately 0.5 - 5 mg of the cephalosporin antibiotic per kilogram body weight of the animal to be treated per day. Preferably, the method of treatment is by injection. However, the inventors also acknowledge that the formulation may be configured to be administered orally or topically. For example the inventors foresee the present invention may have particular advantage in oral administration, where cephalosporin antibiotics have typically shown poor absorption. The use of a glycerol acceptable solvent may have a particular effect in the absorption characteristics of the active.

The particular dosage used may depend on the animal and condition/infection to be treated. For example, the inventors have found that the following dosages were particularly suitable for the animal and disease/condition outlined in the table below:

A significant advantage of the present invention is the improved storage stability and re-suspendability characteristics in PET vials. Based on the preferred dosages below, it will become apparent that a single 125 ml PET vial may be sufficient to use in the treatment of an animal for a full dosage regime, or potentially even several animals, depending on the requirements. The ability to effectively use PET vials for the present formulation provides a significant advantage over previous formulations which must typically be stored in more fragile and expensive glass vials. Method of manufacture

According to another aspect of the present invention there is provided a method of preparing a formulation substantially as described above wherein the method includes the steps of: (a) adding an amount of an oil to a first container,

(b) adding an amount of an oil to a second container and heating to a

temperature between room temperature and 100°C;

(c) adding an amount of a dispersing agent to the second container;

(d) adding an amount of a surfactant to a third container; (e) adding the glycerol acetate solvent to the third container;

(f) mixing the contents of the first, second and third containers together;

(g) adding the cephalosporin antibiotic to the mixed contents; and

(h) optionally, making the mixture up to a desired volume with an oil.

A method of manufacturing Ceftiofur formulations is disclosed in WO 2004/014390. However, the process is quite time consuming and requires high temperatures, for example up to 160°C for 2 hours.

The present manufacturing method is more production friendly as there is no extensive heating required, nor the long incubation times described for example in WO 2004/014390. It is believed by the inventors that the use of triacetin surprisingly leads to better mixing with the oil, making the overall manufacturing process easier and less time consuming.

Preferably, the heating step in (b) comprises heating the oil to between 15-90°C. Preferably, the mixture resulting from step (b) is incubated for between 5 minutes and 60 minutes.

According to a further aspect of the present invention there is provided a use in the manufacture of a medicament including a suspension formulation as substantially described above for the treatment or prevention of a bacterial infection or condition in an animal in need thereof.

Preferably, the use is for the treatment or prevention of bovine and/or swine bacterial respiratory disease, bovine foot rot or bovine metritis.

BRIEF DESCRIPTION OF DRAWINGS Further aspects of the present invention will become apparent from the ensuing description which is given by way of example only and with reference to the accompanying examples.

BEST MODES FOR CARRYING OUT THE INVENTION

Example 1 : Formulation 1

5.35% of Ceftiofur HCI provides 5% (50mg/ml_) of ceftiofur base Example 2: Preferred manufacturing procedure

Step 1

• In a clean and dry manufacturing vessel load 65% of sterile Cotton Seed Oil Step 2

• In a separate, clean and dry manufacturing vessel load 25% of sterile

Cotton Seed Oil and heat to 60-65°C

• Add Phospolipon H90 (Phosphatidylcholine, hydrogenated) and disperse whilst stirring

Step 3

• In a separate, clean and dry manufacturing vessel load required quantity of sterile Sorbitan Mono Oleate (Span 80)

• Add and mix sterile Triacetin

Step 4

• Add step 2 and step 3 to step 1 and mix well

• Add and suspend sterile Ceftiofur Hydrochloride and mix well

• Make up to final volume with sterile Cotton Seed Oil, mix and homogenise well

Example 3: Assessment of composition and shelf life/stability characteristics

The study reported involves three pilot scale batches (3.5L - batch numbers T1707, T1708, T1709), which were produced using the manufacturing process described above. The batches produced were then packed in 125ml_ clear PET vials and the physical and chemical characteristics recorded at regular intervals as recommended by the ACVM.

The results following 9-12 months of storage at 25°C/60%RH, 30°C/65%RH and 40°C/75%RH are provided in detail. A comparison is provided to a reference Ceftiofur composition which was tested in PET vials under the same conditions (40°C / 75% RH). The stability programme is ongoing and as more data becomes available, the regulatory authorities will be provided with updates and appropriate recommendations for further perusal. The preliminary results show the formulation of Example 1 has beneficial storage and re-suspendability characteristics in PET vials and is storage stable in a wide variety of conditions. After three months (at 40°C / 75% RH) the composition of Example 1 showed a decrease of 0.9% w/v Ceftiofur (as HCI). The value of 0.9% w/v was calculated by the average % loss in active agent seen in batch T1707, T1708 and T1709 under these conditions. This is in comparison to the reference composition which showed a decrease of 2.3% w/v Ceftiofur over the same period.

Over a longer test period, this difference in stability between the composition of Example 1 and reference composition would be expected to be even greater.

This emphasizes the commercial important of the present invention, as the composition of Example 1 can be stored for longer periods whilst keeping above the label requirements. The time taken to re-suspend the active by shaking the vial, after long-term storage of the formulation of Example 1 , was less than 5 seconds. This indicates that there was no deleterious caking even after long periods of storage in PET vials. The batches were assessed according to the following test conditions:

No growth in Fluid Thioglycollate medium after 14 days incubation at 30-35°C

No growth in Soyabean Casein Digest medium after 14 days incubation at 20-25°C

Test Composition Analysis Batch Number: T1707 Storage Conditions: 25°C/60%RH

Batch Size: 3.5L Packaging: 125mL Clear PET Vials

Batch Number: T1707 Storage Conditions: 30°C/65%RH Batch Size: 3.5L Packaging: 125mL Clear PET Vials

Batch Number: T1707 Storage Conditions: 40°C/75%RH

Batch Size: 3.5L Packaging: 125mL Clear PET Vials

Batch Number: T1708 Storage Conditions: 25°C/60%RH

Batch Size: 3.5L Packaging: 125mL Clear PET Vials

Batch Number: T1708 Storage Conditions: 25°C/60%RH Batch Size: 3.5L Packaging: 125mL Clear PET Vials

Batch Number: T1708 Storage Conditions: 40°C/75%RH

Batch Size: 3.5L Packaging: 125mL Clear PET Vials

Batch Number: T1709 Storage Conditions: 25°C/60%RH

Batch Size: 3.5L Packaging: 125mL Clear PET Vials

Batch Number: T1709 Storage Conditions: 30°C/65%RH

Batch Size: 3.5L Packaging: 125mL Clear PET Vials

Batch Number: T1709 Storage Conditions: 40°C/75%RH

Batch Size: 3.5L Packaging: 125mL Clear PET Vials

Reference Composition

Example 4: Bioavailability studies

Animal studies were performed to determine the bioavailability of formulation 1 when used in pigs and cattle. The results proved that formulation 1 is bioequivalent with the reference product Excenel™.

Example 5: Site reaction on injection

Results in animal studies using formulation 1 in comparison to the commercial reference product Excenel™ show no site reaction swelling in pigs or cattle in either the test formulation or reference.

Example 6: Residue studies Animal studies have shown that formulation has remarkably low residues in cattle and pigs in all tissues. The expected withhold period (WHP) for milk when used in cattle is nil.

Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof as defined in the appended claims.