PHARMACEUTICAL COMPOSITIONS COMPRISING CEFQUINOME

The present invention is concerned with a pharmaceutical composition for intrauterine administration of cefquinome and its use for the treatment of metritis in mammalian animals.

Acute postpartum metritis ranks among the top health problems of fresh cows in dairy farming. At least one-fourth of all fresh cows experience acute metritis, an inflammation of the entire uterine wall caused by bacterial infection. Acute puerperal metritis occurs within two weeks postpartum. It results from contamination of the reproductive tract at parturition and often, but not invariably, follows complicated parturition.

The causative organisms in cattle are most frequently Escherichia coli, Arcanobacterium (Actinomyces) pyogenes in association with gram-negative anaerobic bacteria such as Fusobacterium necrophorum and Prevotella spp. Metritis can cause reduced fertility and can lead to higher culling rates of female animals, especially cows. The severity of uterine inflammation varies from an acute septic metritis involving the entire thickness of the uterine wall to a mild superficial endometritis. (Bretzlaff K, "Rationale for Treatment of Endometritis in the Dairy Cow", Veterinary Clinics of North America: Food Animal Practice - VoI 3, No. 3, 593-607, 1987).

For decades, metritis in cows has been treated with the intrauterine infusion of antimicrobials. However, many preparations routinely administered into the bovine uterus are detrimental to uterine tissue. Very often, they do not restore fertility, they are not active against all major pathogens, and they do not persist for enough time to treat the infection. Therefore specific formulations for intra-uterine administration are required.

Although antibiotic compositions for intrauterine application for the treatment of metritis have been described in prior art, such a composition for cefquinome has not yet been allied in practice in the veterinary market. Cefquinome is the first fourth-generation cephalosporin developed for use in veterinary medicine. It is a semi-synthetic aminothiazolyl cephalosporin resembling cefotaxime, but with a bicyclic pyridinium group at the C-3 position.

Cefquinome proved highly effective against the most commonly isolated metritis pathogens (Sheldon, I et al "Minimum inhibitory concentrations of some antimicrobial drugs against bacteria causing uterine infections in cattle" The Veterinary Record, 155, 383-387, 2004).

Injectable formulations of cefquinome and intramammary preparations of cefquinome (Cobactan® LC and Cobactan® DC) for the use during the lactation and dry period of cows are available on the veterinary market (sold under the trademark Cobactan® by Intervet International b.v., Boxmeer, The Netherlands).

International patent application WO 2004/037265 discloses a prolonged release injectable formulation of cefquinome comprising an oil and aluminium distearate.

International patent application WO 2003/063877 discloses a composition for intramammary administration for the treatment and prevention of mammary disorders during the dry period, comprising cefquinome in an oil / colloidal silicon dioxide base.

These formulations are however not optimal for intrauterine administration.

Thus, a need exists for a pharmaceutical composition for cefquinome that overcomes one or more of the limitations of the prior art and is suited for intrauterine administration. Such an advantageous pharmaceutical composition needs to be active against the major pathogens present, non- irritant to the uterine tissue, and should have an activity persisting for enough time to treat the infection successfully. The present invention provides a composition for cefquinome with such advantageous properties that causes effective levels of the antibiotic in the uterus of the mammal that are suitable for the control of important pathogens over a sufficient time.

The present invention provides a topical pharmaceutical composition for intrauterine administration, characterised in that it comprises cefquinome in a base, said base comprising at least one medium chain triglyceride, at least one thickener and at least one macrogol cetostearyl ether.

The term "cefquinome" when used herein includes pharmaceutically acceptable salts and esters thereof. A typical pharmaceutical composition according to the invention comprises 1 to 20 % by weight of cefquinome. Preferably the pharmaceutical composition comprises 2 to 10 % by weight of cefquinome, especially 2.5 to 6.0 %, most preferred 3.0 to 4.2 % by weight of cefquinome.

By "by weight" in this patent application it is meant a percentage by weight of the total composition.

In general all pharmaceutically acceptable cephalosporin salts can be incorporated in the current pharmaceutical composition. Various crystalline cephalosporin salts have been disclosed e.g. in European Patent No. EP 280157 and European Patent No. EP 71 1774. In a preferred embodiment the current invention provides a pharmaceutical composition characterised in that the cefquinome is cefquinome sulphate.

The base is selected so as to be non-irritant to the uterine tissue, veterinary acceptable, compatible with the antibacterial agent, and of a viscosity to permit administration, using a syringe at ambient temperature, including low winter temperatures.

The base comprises a pharmaceutical acceptable low viscosity oily medium, such as medium chain triglyceride or a mixture of medium chain triglycerides.

Medium chain triglycerides (MCT oil) have fatty acid chains of 6 - 12 carbon atoms and for the medically refined grades of MCT oil each chain has 8 - 10 carbon atoms. The MCT oil may comprise either triglycerides of the C8-C10 fatty acids, or propylene glycoldiesters of these fatty acids or a mixture of both triglycerides and propylene glycol diesters. Preferably these C8 -C10 fatty acids are fully saturated, such as n-caprylic and n-capric acids. These are conveniently prepared by the commercial fractionating of naturally occurring vegetable (e.g. coconut) oil to give mainly C8-10 fatty acids followed by esterification of these acids with a chosen alcohol. Fractionated vegetable oil having the desired composition is commercially available. Proprietary examples of such oils are Miglyol® 812 as capric/caprylic triglycerides and Miglyol® 840 as propylene glycol dicaprylate/caprate.

Equivalents of these oils are for example: Aldo® MCT KFG, Aldo® TC, Calgene CC-33, Calgene CC-33-F, Calgene CC-33-L, Calgene CC-33-S, Captex® 300, Captex® 355, Crodamol GTCC, Estasan GT 8-40 3578, Estasan GT 8-60 3575, Estasan GT 8-60 3580, Estasan GT 8-65 3577, Estasan GT 8-65 3581 , Estasan GT 8-70 3579, Labrafac® LIPO, Labrafac® lipophile WL 1349, Lexol® GT-855, Lexol® GT-865, Miglyol® 810, Miglyol® 812, Myritol® 312, Myritol® 318, Neobee® 1053, Neobee® M-5, Neobee® O, Pelemol® CCT, Standamul® 318, Standamul® 7105 and Calgene CC-22, Calgene CC-22-S, Captex® 200, Lexol® PG-865, Miglyol® 840, Myritol® PC, Neobee® 1054, Neobee® M-20, Pelemol® PDD, Standamul® 302.

Most preferred is Miglyol® grade 812. The composition according to the invention comprises a thickener. A thickener in a pharmaceutical formulation in general is useful to provide good suspending properties and increases the viscosity of the composition without negatively affecting the syringeability.

In one embodiment the thickener is hydrogenated castor oil. In another embodiment the thickener is glycerol dibehenate. Alternatively combination thereof or mixtures with other thickening agents known in the art are employed.

It is preferred that the composition has a viscosity that is not very temperature dependent to have a good syringeability also under cooler temperature conditions as during winter time.

Typically the composition according to the present invention comprises 0.2 to 2.0% of the thickener.

The base further comprises one or more macrogol cetostearyl ether.

Macrogol cetostearyl ethers (Polyoxyethylated cetylstearyl alcohols) are non- ionic emulsifiers. In general they are used to stabilize oil in water emulsions. Macrogol cetostearyl ethers are manufactured by reacting higher saturated fatty alcohols with ethylene oxide. In the current composition they promote the dispersion of the oily suspension in the aqueous content of the uterus. They are e.g. available under the trademark Cremophor ® A grades from

BASF, Ludwigshafen; Eumulgin B1 PH and Eumulgin B2 PH from Cognis Deutschland GmbH & Co KG, Dϋsseldorf; Simulsol 58 PHA and Simulsol 68 PHA from Selectchemie AG, Zurich.

In one embodiment a combination of Macrogol cetostearyl ether 12 (degree of ethoxylation 12, e.g. Eumulgin B1 PH, US DMF No. 17079) and Macrogol cetostearyl ether 20 (degree of ethoxylation 20, e.g. Eumulgin B2 PH, US dMF 17198, or SIMULSOL 58 PHA, Fa. SEPPIC, Polyoxyl 20 cetostearyl ether, 20 EO units) is employed. In the current composition they promote the dispersion of the oily suspension in the aqueous content of the uterus. The ratio of Macrogol cetostearyl ether 12 and Macrogol cetostearyl ether 20 is from 1 : 10 to 10:1 , preferably 1 :5 to 5:1 , more preferably 1 :2 to 2:1.

Alternatively mixtures with other emulsifiers known in the art are employed.

Typically the composition according to the present invention comprises 0.5 to 5.0% of the macrogol cetostearyl ether The pharmaceutical composition according to the current invention may further comprise additional pharmaceutical excipients known in the art. Such pharmaceutical excipients are e.g. described in "Gennaro, Remington: The Science and Practice of Pharmacy" (20. Edition, 2000) incorporated by reference herein. A more specific composition according to the present invention typically contains 1 to 10 % of cefquinome sulphate, 0.5 to 3 % of macrogol cetostearyl ether, 0.1 to 3 % hydrogenated castor oil and up to 100 % of Miglyol® grade 812.

The pharmaceutical composition contemplated herein can, if desired, include more than one pharmacologically active ingredient.

The current invention furthermore provides a process for preparing a veterinary composition as claimed in any of the preceding claims comprising the steps of mixing the medium chain triglyceride, thickener and macrogol cetostearyl ether to create the base and suspending the cefquinome in said base.

More specifically the current invention provides a process according to the invention characterised in that the hydrogenated castor oil and macrogol cetostearyl ether are added to the medium chain triglyceride under gentle stirring and heating to form the base and the mixture is allowed to cool before adding the cefquinome.

A detailed description of the manufacturing process for a composition according to the invention is provided in examples 1 to 5.

Furthermore the current invention provides the use of the pharmaceutical composition according to the current invention for the manufacture of a medicament for the treatment or prevention of metritis, especially acute metritis in mammalian animals, especially in cows after parturition.

Example 6 shows a pharmacokinetic study after intrauterine administration of the composition according to the invention.

The composition according to the invention proved highly effective against the most commonly isolated metritis pathogens, (£. coli, A. pyogenes, Prevotella spp., Fu so bacterium spp.).

To be efficacious in the control of a pathogen, an antibiotic should be present at a minimum concentration level in tissues or biological fluids, which is characterized by its MIC (Minimum Inhibitory Concentration) against a pathogen. The minimum concentration level, in the lochia and endometrium of postpartum cows that is considered to be efficacious, is determined by the MICs of cefquinome against the different pathogens. As shown in example 6, after intrauterine administration of the pharmaceutical composition according to the invention during the effective period a therapeutic efficient level in the lochia and endometrium above the MIC for the different pathogens was reached.

Example 7 shows another pharmacokinetic study after intrauterine administration of the composition according to the invention compared with a known cefquinome sulphate formulation for intramammary administration in lactating cows. This Cobactan LC formulation contains 75 mg Cefquinome sulphate in a paraffinum liquidum base.

These experiments show that the intra-uterine formulation according to the invention provides higher plasma concentrations and prolonged concentrations in lochia that are helpful in achieving the therapeutic effect of the composition. Hence, example 7 shows that a topical formulation developed for other body cavities (udder) is less suitable for intrauterine administration. The veterinary composition according to the invention can be applied in general to all mammalian species that need treatment or prevention of metritis and bacterial infections of the uterus such as e.g. pigs, cattle, camel, buffalo, horses, goats, sheep, and companion animals such as cats, dogs, but especially to cows. The chosen formulation may be filled into the tube or syringe packs of the conventional type for intrauterine administration, i.e. connected to a catheter for insertion to allow extrusion directly into the uterus via the cervical canal.

A single dose of the composition will normally contain 1 to 50 gram, preferably 15 to 35 gram of the composition. The particular amount of composition required for a particular treatment will vary, depending upon the species, age and weight of the host animal being treated, the particular disease to be guarded against, or treated, as well as the specific antimicrobial agent selected for the treatment, the route and the frequency of administration. For example the dose of cefquinome sulphate for the treatment of acute metritis in post partum cows is 900 mg of cefquinome for intrauterine administration.

Examples

Example 1 : Preparation of a cefquinome sulphate composition (100 kg)

3.60 kg Cefquinome as sulphate

1.1 1 kg Macrogol cetostearyl ether -12 0.47 kg Macrogol cetostearyl ether- 20

0.79 kg Hydrogenated castor oil up to 100 kg Medium chain triglycerides

The manufacturing process encompasses the following steps:

1. The base of macrogol cetostearyl ether - 12 , macrogol cetostearyl ether - 20, hydrogenated castor oil is weighted and mixed in medium chain triglycerides, and homogenized under heating

2. the cefquinome sulphate is suspended under homogenisation

3. the product is filled in syringes.

Example 2: Preparation of cefquinome sulphate composition (100 kg) 3.60 kg Cefquinome as sulphate

2.22 kg Macrogol cetostearyl ether -12

0.94 kg Macrogol cetostearyl ether- 20

0.79 kg Hydrogenated castor oil up to 100 kg Medium chain triglycerides The composition is manufactured as disclosed in Example 1

Example 3: Preparation of cefquinome sulphate composition (100 kg)

3.60 kg Cefquinome as sulphate

1.66 kg Macrogol cetostearyl ether -12

0.70 kg Macrogol cetostearyl ether- 20 0.79 kg Hydrogenated castor oil up to 100 kg Medium chain triglycerides

The composition is manufactured as disclosed in Example 1

Example 4: Preparation of a cefquinome sulphate composition (100 kg) 3.60 kg Cefquinome as sulphate

1.57 kg Macrogol cetostearyl ether -12

0.79 kg Hydrogenated castor oil up to 100 kg Medium chain triglycerides

The manufacturing process encompasses the following steps:

4. The base of macrogol cetostearyl ether and hydrogenated castor oil is weighted and mixed in medium chain triglycerides, and homogenized under heating 5. the cefquinome sulphate is suspended under homogenisation 6. the product is filled in syringes. Example 5: Preparation of a cefquinome sulphate composition (100 kg)

3.60 kg Cefquinome as sulphate

1.57 kg Macrogol cetostearyl ether -20 0.79 kg Hydrogenated castor oil up to 100 kg Medium chain triglycerides

The composition is manufactured as disclosed in Example 4

Example 6: In vivo pharmacokinetic study

Two pharmacokinetic studies were performed, during which plasma, lochia, and endometrium cefquinome concentrations after administration of a composition according to the invention (Examplei ) were measured.

In parallel, bacteria isolated from field cases of acute metritis were tested against cefquinome to determine MICs.

Cefquinome concentrations from the pharmacokinetic studies were compared to MICs of cefquinome against acute metritis pathogens.

Material and methods:

One to six days after calving, fourteen healthy cows received an intra-uterine administration of 900mg cefquinome in a composition of example 1.

Lochia samples and endometrium biopsies were collected at 7, 24, 48, and 72 hours after treatment. Blood samples were collected just before treatment, and then for up to 48 hours after treatment.

Cefquinome concentrations in lochia and endometrium were determined with validated microbiological assays. Cefquinome concentrations in plasma were determined with a validated HPLC assay.

The strains used to determine the MICs were isolated between 2000 to 2005, from cows with acute metritis from different European countries (France, Germany, Hungary and Netherlands). Strains were collected by intra-uterine swabbing, before any treatment.

The pathogens identified were used to determine cefquinome MICs, using standard broth micro-dilution or agar dilution techniques.

Results:

One hour after treatment the median maximum plasmatic concentration was 1.28μg/ml_. Plasmatic concentrations then steadily decreased to values below 0.03μg/ml_ (limit of quantification) over 48 hours (Figure 1 ). Cefquinome was detected in lochia and endometrium samples (Figure 1 ) for up to 72 hours after treatment.

From the 194 field cases of acute metritis sampled for bacteriology, 504 microbial strains were identified. MICs of cefquinome against the most frequent pathogens (£. coli, A. pyogenes, Prevotella spp., Fusobacterium spp.) are presented in Table 1.

Table 1 : MIC ₅ O snd MIC ₉₀ (μg/mL of cefquinome) against key acute metritis pathogens.

Discussion: After intra-uterine administration there is a moderate diffusion of cefquinome to the plasma. Antibacterial concentrations of cefquinome in lochia and endometrium are reached after a single intra-uterine administration.

In lochia the median cefquinome concentration was above or equal to the MIC ₅₀ of 3 of the main acute metritis pathogens for up to 72 hours after treatment, and above the MIC ₉₀ for at least 48 hours after treatment.

In endometrium, the median concentration of cefquinome was above the MIC ₉₀ of the main acute metritis pathogens for more than 24 hours after treatment. Prolonged presence of cefquinome at antibacterial concentrations in endometrium and lochia can prevent dissemination of the bacteria beyond the uterus cavity and can decrease the intra-uterine bacterial load, allowing the cow to recover from the infection.

Conclusion:lntra-uterine administration of 900 mg of cefquinome in the composition provides prolonged local antibacterial concentrations of cefquinome.

Example 7: In vivo pharmacokinetic (PK) study

Two pharmacokinetic studies were performed, during which plasma and lochia cefquinome concentrations after administration of a composition according to the invention (Examplei ) in comparison with a commercially available intramammary formulation of Cefquinome sulphate for lactating cows (Cobactan LC) were measured.

The results are illustrated in Figure 2 and Figure 3.

.After intra uterine administration the cefquinome plasma concentrations measured can be considered as a marker for the endometrial tissue cefquinome concentration. The availability of cequinome within endometrial tissue is important for the successful treatment of metritis.

The PK studies show that Cobactan IU formulation according to the invention (with 600 mg cefquinome) gives more plasmatic diffusion than the Cobactan LC formulation (also 600 mg), and therefore, leads to higher endometrial tissue concentrations.

The same formulations were compared by analysing samples of lochia (intra uterine fluid).

Compared to Cobactan LC (with 600 mg cefquinome), Cobactan IU, provides a lower concentration (sufficient for antimicrobial activity), and with a prolonged release, which makes the Cobactan IU formulation more suitable for the control of metritis than the Cobactan LC formulation.