CRYSTALLINE FORMS OF AN ANTIBIOTIC SUBSTANCE

FIELD OF THE INVENTION

The present invention relates to crystalline forms of 24-bromofusidic acid, to their preparation, pharmaceutical compositions containing them, and to the use of said crystalline 24-bromofusidic acid forms as medicaments in the treatment of infectious diseases.

BACKGROUND OF THE INVENTION

24-Bromofusidic acid (Br-FA) (WO 2005/007669) represents a new promising antibiotic for the treatment of bacterial infections with a broad range of antimicrobial activity. In vitro and in vivo tests of Br-FA have for example demonstrated excellent efficacy against gram positive bacteria (Staphylococcus Aureus, S. Pyogenes) including oxacillin and methicillin resistant strains of S. Aureus). Skin infections caused by Staphylococcus aureus species present a major problem for treating physicians today; greater than 80% of skin infections are complicated by S. aureus. S. aureus can cause various infections of the skin (impetigo, dermatitis, folliculitis, etc.) and other organs. S. aureus infections are common in people with frequent skin injury, particularly if the skin is dry. Staphylococcal skin infections are seen most commonly in pre-pubertal children and certain occupational groups such as healthcare workers. Several skin conditions, particularly atopic dermatitis, are exacerbated by Staphylococcus aureus, but most staphylococcal infections will be in normal individuals.

Antibiotic therapy remains the mainstay of treatment; however, staphylococci are becoming increasingly resistant to many commonly used antibiotics including penicillins, macrolides and recent reports also indicate mupirocin (Bactroban ^® ). Br-FA, having excellent skin-penetration properties, therefore represents a promising new chemical entity which is presently in clinical development for topical treatment of skin and mucosa/soft tissue infections, such as for the topical treatment of impetigo and secondarily infected traumatic lesions (SITL). More particularly, Br-FA may also be useful for the treatment of secondary infected dermatoses (SID).

The solid form, such as the crystal form, of a drug substance or active pharmaceutical ingredient used in a pharmaceutical formulation or medicament is important based on solubility, dissolution rate, hygroscopicity, bioavailability, e.g. skin-penetration properties, and stability differences between the different solid forms. Thus the existence of various solid forms, such as polymorphism or pseudo polymorphism can affect the properties of the quality of the drug product. Hence, a specific crystal form, including solvates and hydrates, might be preferable over another one. Furthermore certain forms may be preferable depending on the specific formulation and/or application. For example, the properties of a drug, such as the dissolution rate of the active ingredient, may be tuned by the proper choice of a certain crystal form, or mixtures thereof.

A crystalline form of an active pharmaceutical ingredient is usually preferred over a non-crystalline form, e.g. an amorphous form, in a drug formulation or during processing. Crystalline forms have inter alia the advantage of greater chemical stability (heat and light), easier processability and handling. In particular the provision of a crystalline form is an important advantage during drug synthesis, especially on an industrial scale, since crystals are generally easier isolated from a reaction mixture. Furthermore it is known that the crystallisation of a specific crystalline form of a compound in a particular solvent may result in an advantageous purification of the compound which would not be achieved by crystallisation of another form in a different solvent (partly due to differences in solubility properties of impurities in different solvents).

Various crystalline forms also differ in melting point, density, hardness, grinding properties, etc. and as a consequence a particular polymorphic form is preferred over another one depending on the specific application. Different crystalline forms have different stabilities in pharmaceutical formulations which depend on the excipients, vehicles, and other additives present in the dosage form. The instability of amorphous compounds represents in particular a problem when the drug substance is in suspension.

Accordingly while crystalline forms are generally preferred over non-crystalline forms of a drug substance, a specific crystalline form of a compound will be preferred depending on the various circumstances, such as its application or the process in

which it is being used. Sometimes a thermodynamically more stable form is preferred over a metastable form, sometime a metastable form which may have an increased dissolution rate is preferred.

WO 2005/007669 describes the synthesis of Br-FA and salts of Br-FA, but is silent about crystalline forms of the compound or the preparation of such forms.

WO 2007/087806 describes topical formulations of derivatives of fusidic acid including such formulations containing Br-FA as disclosed in WO 2005/007669.

SUMMARY OF THE INVENTION

The present invention surprisingly provides for the first time crystalline Br-FA, i.e. crystalline forms of Br-FA, i.e. polymorphs and pseudo-polymorphs, such as anhydrates, a hemihydrate and a hydrate of Br-FA, and processes for their preparation.

In one aspect the present invention relates to 24-bromofusidic acid (Br-FA) in crystalline form.

In one aspect, this invention relates to a crystalline form C (hydrate), D (hemihydrate), E (anhydrate), G (anhydrate), H (anhydrate), or I (anhydrate), of Br- FA, respectively; essentially exhibiting one or more of the features, or characteristic lines, shapes, or patterns depicted in Figures 1-32 respectively; or having one ore more of the values listed therein, e.g. wavenumbers in cm ^"1 (±3, ±4 or ±8 cm ^"1 depending on the method used), or angles of reflection in degrees 2θ (±0.1); or being represented by a spectrum/diffractogram substantially similar to that shown in said Figures.

In yet another aspect, this invention relates to an isolated crystalline form of Br-FA of the present invention as defined above which has a polymorphic purity of at least 80%, such as 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%.

In yet another aspect, this invention relates to an isolated crystalline form of Br-FA of the present invention as defined above which has a degree of crystallinity of at least 80%, such as %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%.

In yet another aspect, this invention relates to a mixture or composition of crystalline forms Br-FA, including pseudopolymorphs of Br-FA, comprising a crystalline form of Br-FA of the present invention as defined herein, e.g. a mixture of Br-FA anhydrates form E and G.

In yet another aspect, this invention relates to the use of a crystalline form of Br-FA of the present invention as defined herein, or mixtures thereof, for the manufacture of Br-FA form H (anhydrate).

In yet another aspect, this invention relates to a method for the preparation of a crystalline form of Br-FA of the present invention as defined herein, or mixtures thereof, said method comprising the step of crystallising a crystalline form of Br-FA of the present invention as defined herein in a suitable solvent or mixture of solvents.

In yet another aspect, this invention relates to a crystalline form of Br-FA of the present invention, or mixtures thereof, as defined herein for use in therapy.

In yet another aspect, this invention relates to a pharmaceutical composition comprising a crystalline form of Br-FA of the present invention as defined herein, or mixtures thereof, together with a pharmaceutically acceptable excipient or vehicle.

In yet another aspect, this invention relates to a method of treating, preventing or ameliorating infections in a patient, the method comprising administering to said patient an effective amount of a crystalline form of Br-FA of the present invention as defined herein, or mixtures thereof, and optionally further comprising concomitant or sequential administration of one or more other therapeutically active compounds.

In yet another aspect, this invention relates to the use of a crystalline form of Br-FA of the present invention as defined herein, or mixtures thereof, for the manufacture of a medicament for the treatment, amelioration or prophylaxis of infections.

In yet another aspect, this invention relates to the use of a crystalline form of Br-FA of the present invention as defined herein, or mixtures thereof, for the manufacture of a medicament for the treatment, amelioration or prophylaxis of bacterial infections.

In yet another aspect, this invention relates to the use of a crystalline form of Br-FA of the present invention as defined herein, or mixtures thereof, for controlling microbial growth.

In yet another aspect, this invention relates to the use of a crystalline form of Br-FA of the present invention as defined herein, or mixtures thereof, for the prevention or prophylaxis of bacterial infections during animal breeding.

In yet another aspect, this invention relates to a method for the preparation of Br-FA form E (anhydrate) or G (anhydrate), as described above, such as a mixture of the two forms, said method comprising the steps of a) dissolving Br-FA in a mixture of ethanol and/or methanol, and water, optionally with heating; b) optionally cooling and/or concentrating of the solution obtained in step a); c) allowing crystalline Br-FA form E (anhydrate) or G (anhydrate) of the present invention, such as a mixture of the two forms, to crystallise; d) isolating the crystalline Br-FA form E (anhydrate) or G (anhydrate), or a mixture thereof, of the present invention.

In yet another aspect, this invention relates to a method for the preparation of Br-FA form H (anhydrate), as described above, said method comprising the steps of a) suspending crystalline Br-FA form E (anhydrate) or G (anhydrate) of the present invention, such as a mixture of the two forms, in ethyl formate, optionally with heating; b) optionally cooling and/or concentrating of the suspension obtained in step a);

c) allowing crystalline Br-FA form H (anhydrate) of the present invention to crystallise; d) isolating the crystalline Br-FA form H (anhydrate) of the present invention.

In yet another aspect, this invention relates to a method for the preparation of Br-FA form H (anhydrate), as described above, said method comprising the steps of a) dissolving crystalline Br-FA form E (anhydrate) or G (anhydrate) of the present invention, such as a mixture of the two forms, in acetonitrile, optionally with heating; b) optionally cooling and/or concentrating of the solution obtained in step a); c) allowing crystalline Br-FA form H (anhydrate) of the present invention to crystallise; d) isolating the crystalline Br-FA form H (anhydrate) of the present invention.

In yet another aspect, this invention relates to a method for the preparation of Br-FA form C (hydrate), as described above, said method comprising the steps of a) dissolving Br-FA in a mixture of ethyl acetate and water, optionally with heating; b) optionally cooling and/or concentrating of the solution obtained in step a); c) allowing crystalline Br-FA form C (hydrate) of the present invention to crystallise; d) isolating the crystalline Br-FA form C (hydrate) of the present invention.

In yet another aspect, this invention relates to a method for the preparation of Br-FA form D (hemihydrate), as described above, said method comprising the steps of a) dissolving Br-FA in toluene saturated with water, optionally with heating; b) optionally cooling and/or concentrating of the solution obtained in step a), such as cooling to 0-10 ⁰ C for 1-2 days; c) allowing crystalline Br-FA form D (hemihydrate) of the present invention to crystallise; d) isolating the crystalline Br-FA form D (hemihydrate) of the present invention.

In yet another aspect, this invention relates to a method for the preparation of Br-FA form I (anhydrate), as described above, said method comprising the steps of a) suspending Br-FA of the present invention, in hexane, optionally with heating; b) optionally cooling and/or concentrating of the suspension obtained in step a); c) allowing crystalline Br-FA form I (anhydrate) of the present invention to crystallise;

d) isolating the crystalline Br-FA form I (anhydrate) of the present invention.

In yet another aspect, this invention relates to method of preparing a pharmaceutical formulation, said method comprising the step of mixing a crystalline Br-FA as anywhere defined herein with a pharmaceutically acceptable excipient or carrier.

In yet another aspect this invention relates to a mixture or composition of crystalline forms of 24-bromofusidic acid (Br-FA), including pseudopolymorphs of 24- bromofusidic acid, comprising crystalline form E of 24-bromo-fusidic acid (Br-FA) according to the invention and crystalline form G of 24-bromo-fusidic acid (Br-FA) according to the invention.

In yet another aspect this invention relates to the use of a mixture or composition of crystalline forms of 24-bromofusidic acid (Br-FA), including pseudopolymorphs of 24- bromofusidic acid, comprising crystalline form E of 24-bromo-fusidic acid (Br-FA) according to the invention and crystalline form G of 24-bromo-fusidic acid (Br-FA) according to the invention as an intermediate for the preparation of crystalline form H of 24-bromofusidic acid (Br-FA).

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a graph showing the infrared spectrum (FTIR-MIKRO-ATR) of the crystalline Br-FA form C (hydrate) of the present invention. The Y-axis shows absorbance units and the X-axis the wavenumber (cm ^'1 ).

Figure 2 is a graph showing the infrared spectrum (0.3% in KBr) of the crystalline Br-FA form C (hydrate) of the present invention. The Y-axis shows absorbance units and the X-axis the wavenumber (cm ¹ ).

Figure 3 is a graph showing the near infrared spectrum (FT-NIR) of the crystalline Br-FA form C (hydrate) of the present invention. The Y-axis shows the absorbance and the X-axis the wavenumber (cm ¹ ).

Figure 4 is a graph showing the Raman spectrum (FT-NIR-Raman) (neat) of the crystalline Br-FA form C (hydrate) of the present invention. The Y-axis shows the Raman intensity and the X-axis the wavenumber (cm ^"1 ).

Figure 5 is a graph showing the infrared spectrum (FTIR-MIKRO-ATR) of the crystalline Br-FA form D (hemihydrate) of the present invention. The Y-axis shows absorbance units and the X-axis the wavenumber (cm ¹ ).

Figure 6 is a graph showing the infrared spectrum (0.3% in KBr) of the crystalline Br-FA form D (hemihydrate) of the present invention. The Y-axis shows absorbance units and the X-axis the wavenumber (cm ¹ ).

Figure 7 is a graph showing the near infrared spectrum (FT-NIR) of the crystalline Br-FA form D (hemihydrate) of the present invention. The Y-axis shows the absorbance and the X-axis the wavenumber (cm ¹ ).

Figure 8 is a graph showing the Raman spectrum (FT-NIR-Raman) (neat) of the crystalline Br-FA form D (hemihydrate) of the present invention. The Y-axis shows the Raman intensity and the X-axis the wavenumber (cm ¹ ).

Figure 9 is a graph showing the infrared spectrum (FTIR-MIKRO-ATR) of the crystalline Br-FA form E (anhydrate) of the present invention. The Y-axis shows absorbance units and the X-axis the wavenumber (cm ¹ ).

Figure 10 is a graph showing the near infrared spectrum (FT-NIR) (fiber neat) of the crystalline Br-FA form E (anhydrate) of the present invention. The Y-axis shows the absorbance and the X-axis the wavenumber (cm ^"1 ).

Figure 11 is a graph showing the Raman spectrum (FT-NIR-Raman) (neat) of the crystalline Br-FA form E (anhydrate) of the present invention. The Y-axis shows the Raman intensity and the X-axis the wavenumber (cm ¹ ).

Figure 12 is a graph showing the infrared spectrum (0.3% in KBr) of the crystalline Br-FA form G (anhydrate) of the present invention. The Y-axis shows absorbance units and the X-axis the wavenumber (cm ^"1 ).

Figure 13 is a graph showing the near infrared spectrum (FT-NIR) (fiber neat) of the crystalline Br-FA form G (anhydrate) of the present invention. The Y-axis shows the absorbance and the X-axis the wavenumber (cm ¹ ).

Figure 14 is a graph showing the Raman spectrum (FT-NIR-Raman) (neat) of the crystalline Br-FA form G (anhydrate) of the present invention. The Y-axis shows the Raman intensity and the X-axis the wavenumber (cm ¹ ).

Figure 15 is a graph showing the infrared spectrum (0.3% in KBr) of the crystalline Br-FA form H (anhydrate) of the present invention. The Y-axis shows absorbance units and the X-axis the wavenumber (cm ¹ ).

Figure 16 is a graph showing the near infrared spectrum (FT-NIR) (fiber neat) of the crystalline Br-FA form H (anhydrate) of the present invention. The Y-axis shows the absorbance and the X-axis the wavenumber (cm ¹ ).

Figure 17 is a graph showing the Raman spectrum (FT-NIR-Raman) (neat) of the crystalline Br-FA form H (anhydrate) of the present invention. The Y-axis shows the Raman intensity and the X-axis the wavenumber (cm ¹ ).

Figure 18 is a graph showing the infrared spectrum (FTIR-MIKRO-ATR) of the crystalline Br-FA form I (anhydrate) of the present invention. The Y-axis shows absorbance units and the X-axis the wavenumber (cm ¹ ).

Figure 19 is a graph showing the near infrared spectrum (FT-NIR) (fiber neat) of the crystalline Br-FA form I (anhydrate) of the present invention. The Y-axis shows the absorbance and the X-axis the wavenumber (cm ¹ ).

Figure 20 is a graph showing the Raman spectrum (FT-NIR-Raman) (neat) of the crystalline Br-FA form I (anhydrate) of the present invention. The Y-axis shows the Raman intensity and the X-axis the wavenumber (cm ^"1 ).

Figure 21 shows the X-ray powder diffractogram (XRPD) of the crystalline Br-FA form C (hydrate) of the present invention. The Y-axis shows the absolute intensity and the X-axis the angle in degrees 2θ.

Figure 22 shows the X-ray powder diffractogram (XRPD) of the crystalline Br-FA form D (hemihydrate) of the present invention. The Y-axis shows the absolute intensity and the X-axis the angle in degrees 2θ.

Figure 23 shows the X-ray powder diffractogram (XRPD) of the crystalline Br-FA form E (anhydrate) of the present invention. The Y-axis shows the absolute intensity and the X-axis the angle in degrees 2θ.

Figure 24 shows the X-ray powder diffractogram (XRPD) of the crystalline Br-FA form G (anhydrate) of the present invention. The Y-axis shows the absolute intensity and the X-axis the angle in degrees 2θ.

Figure 25 shows the X-ray powder diffractogram (XRPD) of the crystalline Br-FA form H (anhydrate) of the present invention. The Y-axis shows the absolute intensity and the X-axis the angle in degrees 2θ.

Figure 26 shows the X-ray powder diffractogram (XRPD) of the crystalline Br-FA form I (anhydrate) of the present invention. The Y-axis shows the absolute intensity and the X-axis the angle in degrees 2θ.

Figure 27 is a graph showing the infrared spectrum (FTIR-MIKRO-ATR) of the crystalline Br-FA form H (anhydrate) of the present invention. The Y-axis shows absorbance units and the X-axis the wavenumber (cm ¹ ).

Figure 28 is a graph showing the infrared spectrum (FTIR-MIKRO-ATR) of the crystalline Br-FA form C (hydrate) of the present invention. The Y-axis shows absorbance units and the X-axis the wavenumber (cm ¹ ).

Figure 29 is a graph showing the infrared spectrum (FTIR-MIKRO-ATR) of the crystalline Br-FA form G (anhydrate) of the present invention. The Y-axis shows absorbance units and the X-axis the wavenumber (cm ¹ ).

Figure 30 shows the solid-state ¹³ C NMR spectrum of the crystalline Br-FA form H (anhydrate) of the present invention. The Y-axis shows the relative intensity and the X-axis the chemical shift (ppm).

Figure 31 shows the solid-state ¹³ C NMR spectrum of the crystalline Br-FA form C (hydrate) of the present invention. The Y-axis shows the relative intensity and the X- axis the chemical shift (ppm).

Figure 32 shows the solid-state ¹³ C NMR spectrum of the crystalline Br-FA form I

(anhydrate) of the present invention. The Y-axis shows the relative intensity and the X-axis the chemical shift (ppm).

DETAILED DESCRIPTION OF THE INVENTION

Crystallisation is a well known technique for the purification of chemical compounds and for obtaining a desired crystalline form of chemical compounds. However, it is known that the crystallisation of polymorphs is affected by a number of effects and the mechanism of these effects is not known and the quantitative relationship between the operational factors and the crystallisation characteristics of the polymorphs is not clearly understood.

The crystallisation process of polymorphous crystals is composed of competitive nucleation, growth, and the transformation from a metastable to a stable form. To selectively crystallise polymorphs, the mechanism of each elementary step in the crystallisation process needs to be in clear relation to the operational conditions and the key controlling factors [Crystal Growth & Design, 2004, Vol. 4, No.6, 1153- 1159].

An embodiment of the invention is crystalline form H of 24-bromofusidic acid (Br- FA), characterised by exhibiting one or more of the following features a)-e) :

a) an X-ray powder diffractogram (XRPD) exhibiting an angle of reflection, expressed in degrees 2θ (± 0.1), at approximately 16.5, 11.1 and/or 5.3; b) an attenuated total reflectance Fourier transform infrared (FTIR-ATR) spectrum exhibiting attenuated total reflectance peaks at approximately 3520 and/or 1183 cm ^{" 1} (± 3 cm ^"1 ); c) a near infrared (FT-NIR) spectrum exhibiting absorbance peaks at approximately 5820 cm ^"1 (± 8 cm ^"1 ); d) a Fourier transform (FT-NIR) Raman spectrum exhibiting intensity peaks at approximately 1654 and/or 1454 cm ^"1 (± 4 cm ^"1 ) or e) a ¹³ C CP/MAS solid-state NMR spectrum exhibiting one or more of the following resonances at approximately 151.5 and/or 151.0 ppm (±0.5 ppm), respectively.

Another embodiment of the invention is crystalline form H of 24-bromofusidic acid (Br-FA), characterised by exhibiting one or more of the following features a)-k) :

a) a Fourier transform (FT-NIR) Raman spectrum exhibiting the following intensity peaks at approximately 1720, 1676, 1654, 1454 and/or 591 cm ^"1 (± 4 cm ^"1 ), respectively; b) a Fourier transform (FT-NIR) Raman spectrum substantially similar to that shown in Figure 17; c) an attenuated total reflectance Fourier transform infrared (FTIR-ATR) spectrum exhibiting the following attenuated total reflectance peaks at approximately 3520, 1703, 1650, 1241, 1183 and/or 1017 cm ^"1 (± 3 cm ^"1 ), respectively; d) an attenuated total reflectance Fourier transform infrared (FTIR-ATR) spectrum spectrum substantially similar to that shown in Figure 27; e) a near infrared (FT-NIR) spectrum exhibiting the following absorbance peaks at approximately 5820, 5254 and/or 4433 cm ^"1 (± 8 cm ^"1 ), respectively; f) a near infrared (FT-NIR) spectrum substantially similar to that shown in Figure 16; g) an X-ray powder diffractogram (XRPD) exhibiting the following angles of reflection in degrees 2θ (±0.1) at approximately 16.5, 14.0, 13.7, 13.4, 11.1, 8.6 and/or 5.3, respectively; h) an X-ray powder diffractogram (XRPD) substantially similar to that shown in

Figure 25;

i) a ¹³ C CP/MAS solid-state NMR spectrum exhibiting the following resonances at approximately 175.8, 174.1, 173.8, 171.1, 151.5 and/or 151.0 ppm (±0.5 ppm), respectively; j) a ¹³ C CP/MAS solid-state NMR spectrum substantially similar to that shown in Figure 30; or k) the following single-crystal X-ray diffraction experimental data: crystal system = tetragonal and space group = P4χ2i2.

Another embodiment of the invention is crystalline form H of 24-bromofusidic acid (Br-FA), further characterised by exhibiting one or more of the following features a)- k):

a) a Fourier transform (FT-NIR) Raman spectrum exhibiting one or more of the following intensity peaks at approximately 2927 , 1720, 1676, 1654, 1454, 1338, 756, 688, 591, 535, 349 and/or 192 cm ^"1 (± 4 cm ^'1 ), respectively; b) a Fourier transform (FT-NIR) Raman spectrum substantially similar to that shown in Figure 17; c) an attenuated total reflectance Fourier transform infrared (FTIR-ATR) spectrum exhibiting one or more of the following attenuated total reflectance peaks at approximately 3520, 1719, 1703, 1650, 1377, 1256, 1241, 1183, 1017, 970, 757 and/or 699 cm ^"1 (± 3 cm ^"1 ), respectively; d) an attenuated total reflectance Fourier transform infrared (FTIR-ATR) spectrum spectrum substantially similar to that shown in Figure 27; e) a near infrared (FT-NIR) spectrum exhibiting one or more of the following absorbance peaks at approximately 8355, 6428, 5820, 5714, 5637, 5489, 5254, 4754, 4433 and/or 4361 cm ^"1 (± 8 cm ^"1 ), respectively; f) a near infrared (FT-NIR) spectrum substantially similar to that shown in Figure 16; g) an X-ray powder diffractogram (XRPD) exhibiting one or more of the following angles of reflection in degrees 2θ (±0.1) at approximately 20.6, 19.2, 18.3, 17.4, 16.5, 15.8, 14.0, 13.7, 13.4, 11.5, 11.1, 8.6 and/or 5.3, respectively; h) an X-ray powder diffractogram (XRPD) substantially similar to that shown in

Figure 25; i) a ¹³ C CP/MAS solid-state NMR spectrum exhibiting one or more of the following resonances at approximately 175.8, 174.1, 173.8, 171.1, 151.5,151.0, 76.9, 74.5, 72.8, 68.1 and/or 67.5 ppm (±0.5 ppm), respectively;

j) a ¹³ C CP/MAS solid-state NMR spectrum substantially similar to that shown in Figure 30; or k) one or more of the following single-crystal X-ray diffraction experimental data: crystal system = tetragonal, space group = ?4 _x 2{λ, a [A] = 20.5, b [A] = 20.5, c [A] = 27.9, α [°] = 90, β [°] = 90, γ [°] = 90, cell volume [A ³ ] = 11723, Z = 16, respectively.

Another embodiment of the invention is crystalline form C of 24-bromofusidic acid (Br-FA), characterised by exhibiting one or more of the following features a)-e):

a) an X-ray powder diffractogram (XRPD) exhibiting an angle of reflection, expressed in degrees 2θ (± 0.1), at approximately 19.3, 15.3 and/or 8.7; b) an attenuated total reflectance Fourier transform infrared (FTIR-ATR) spectrum exhibiting attenuated total reflectance peaks at approximately 1711 cm ^"1 (± 3 cm ^"1 ); c) a near infrared (FT-NIR) spectrum exhibiting absorbance peaks at approximately 5102 cm ^"1 (± 8 cm ^"1 ); d) a Fourier transform (FT-NIR) Raman spectrum exhibiting intensity peaks at approximately 1713 cm ^"1 (± 4 cm ^"1 ); or e) a ¹³ C CP/MAS solid-state NMR spectrum exhibiting one or more of the following resonances at approximately 155.8 ppm (±0.5 ppm), respectively.

Another embodiment of the invention is crystalline form C of 24-bromofusidic acid (Br-FA), characterised by exhibiting one or more of the following features a)-j):

a) a Fourier transform (FT-NIR) Raman spectrum exhibiting the following intensity peaks at approximately 1713, 1286, 1151, 1067, 1002 and/or 797 cm ^"1 (± 4 cm ^"1 ), respectively; b) a Fourier transform (FT-NIR) Raman spectrum substantially similar to that shown in Figure 4; c) an attenuated total reflectance Fourier transform infrared (FTIR-ATR) spectrum exhibiting the following attenuated total reflectance peaks at approximately 3457,

1711, 1672, 1383, 1265 and/or 1236 cm ^"1 (± 3 cm ^"1 ), respectively; d) an attenuated total reflectance Fourier transform infrared (FTIR-ATR) spectrum spectrum substantially similar to that shown in Figure 1;

e) a near infrared (FT-NIR) spectrum exhibiting the following absorbance peaks at approximately 7088 and/or 5102 cm ¹ (± 8 cm ^"11 ; f) a near infrared (FT-NIR) spectrum substantially similar to that shown in Figure 3; g) an X-ray powder diffractogram (XRPD) exhibiting the following angles of reflection in degrees 2θ (±0.1) at approximately 19.3, 15.3, 14.2, 8.7 and/or 8.1, respectively; h) an X-ray powder diffractogram (XRPD) substantially similar to that shown in Figure 21; i) a ¹³ C CP/MAS solid-state NMR spectrum exhibiting the following resonances at approximately 175.5, 173.6 and/or 155.8 ppm (±0.5 ppm); or j) a ¹³ C CP/MAS solid-state NMR spectrum substantially similar to that shown in Figure 31, respectively.

Another embodiment of the invention is crystalline form C of 24-bromofusidic acid (Br-FA), further characterised by exhibiting one or more of the following features a)- j):

a) a Fourier transform (FT-NIR) Raman spectrum exhibiting one or more of the following intensity peaks at approximately 2940, 1713, 1660, 1459, 1380, 1338, 1286, 1151, 1067, 1002, 797, 697, 537 and/or 188 cm ^" (± 4 cm ¹ ), respectively; b) a Fourier transform (FT-NIR) Raman spectrum substantially similar to that shown in Figure 4; c) an attenuated total reflectance Fourier transform infrared (FTIR-ATR) spectrum exhibiting one or more of the following attenuated total reflectance peaks at approximately 3457, 1711, 1672, 1444, 1383, 1375, 1265, 1236, 1030, 971, 818 and/or 755 cm ^"1 (± 3 cm ^"1 ), respectively; d) an attenuated total reflectance Fourier transform infrared (FTIR-ATR) spectrum spectrum substantially similar to that shown in Figure 1; e) a near infrared (FT-NIR) spectrum exhibiting one or more of the following absorbance peaks at approximately 10373, 10281, 7088, 5863, 5745, 5102, 4358 and/or 4285 cm ^"1 (± 8 cm ^"1 ), respectively; f) a near infrared (FT-NIR) spectrum substantially similar to that shown in Figure 3; g) an X-ray powder diffractogram (XRPD) exhibiting one or more of the following angles of reflection in degrees 2θ (±0.1) at approximately 19.3, 18.3, 17.5, 15.3, 14.2, 12.0, 8.7 and/or 8.1, respectively;

h) an X-ray powder diffractogram (XRPD) substantially similar to that shown in Figure 21; i) a ¹³ C CP/MAS solid-state NMR spectrum exhibiting one or more of the following resonances at approximately 175.5, 173.6, 155.8, 75.6, 73.1 and/or 67.0 ppm (±0.5 ppm), respectively; or j) a ¹³ C CP/MAS solid-state NMR spectrum substantially similar to that shown in Figure 31, respectively.

Another embodiment of the invention is crystalline form I of 24-bromofusidic acid (Br-FA), characterised by exhibiting one or more of the following features a)-e) :

a) an X-ray powder diffractogram (XRPD) exhibiting an angle of reflection, expressed in degrees 2θ (± 0.1), at approximately 19.7, 15.1 and/or 6.2; b) an attenuated total reflectance Fourier transform infrared (FTIR-ATR) spectrum exhibiting attenuated total reflectance peaks at approximately 3575 and/or 1695 cm ^{" x} (± 3 cm ^"1 ); c) a near infrared (FT-NIR) spectrum exhibiting absorbance peaks at approximately 6966 cm ^"1 (± 8 cm ^"1 ); d) a Fourier transform (FT-NIR) Raman spectrum exhibiting intensity peaks at approximately 1694 cm ^" '(± 4 cm ^"1 ); or e) a ¹³ C CP/MAS solid-state NMR spectrum exhibiting one or more of the following resonances at approximately 147.6 ppm (±0.5 ppm), respectively.

Another embodiment of the invention is crystalline form I of 24-bromofusidic acid (Br-FA), characterised by exhibiting one or more of the following features a)-j):

a) a Fourier transform (FT-NIR) Raman spectrum exhibiting the following intensity peaks at approximately 3015, 2943, 2910, 1694, 1329 and/or 990 cm ^"1 (± 4 cm ^"1 ), respectively; b) a Fourier transform (FT-NIR) Raman spectrum substantially similar to that shown in Figure 20; c) an attenuated total reflectance Fourier transform infrared (FTIR-ATR) spectrum exhibiting the following attenuated total reflectance peaks at approximately 3575, 3449, 1695, 1274, 760 and/or 696 cm ^"1 (± 3 cm ^"1 ), respectively;

d) an attenuated total reflectance Fourier transform infrared (FTIR-ATR) spectrum spectrum substantially similar to that shown in Figure 18; e) a near infrared (FT-NIR) spectrum exhibiting the following absorbance peaks at approximately 6966, 6596, 6526 and/or 6453 cm ^"1 (± 8 cm ^"1 ), respectively; f) a near infrared (FT-NIR) spectrum substantially similar to that shown in Figure 19; g) an X-ray powder diffractogram (XRPD) exhibiting the following angles of reflection in degrees 2θ (±0.1) at approximately 20.5, 19.7, 16.3, 15.1, 6.8 and/or 6.2, respectively; h) an X-ray powder diffractogram (XRPD) substantially similar to that shown in Figure 26; i) a ¹³ C CP/MAS solid-state NMR spectrum exhibiting the following resonances at approximately 176.0, 170.7 and/or 147.6 ppm (±0.5 ppm), respectively; or j) a ¹³ C CP/MAS solid-state NMR spectrum substantially similar to that shown in Figure 32, respectively.

Another embodiment of the invention is crystalline form I of 24-bromofusidic acid (Br-FA), further characterised by exhibiting one or more of the following features a)- j):

a) a Fourier transform (FT-NIR) Raman spectrum exhibiting one or more of the following intensity peaks at approximately 3015, 2943, 2910, 1694, 1459, 1329, 990, 757, 697, 687, 535, 190 and/or 105 cm ^'1 (± 4 cm ^"1 ), respectively; b) a Fourier transform (FT-NIR) Raman spectrum substantially similar to that shown in Figure 20; c) an attenuated total reflectance Fourier transform infrared (FTIR-ATR) spectrum exhibiting one or more of the following attenuated total reflectance peaks at approximately 3575, 3449, 1720, 1695, 1400, 1375, 1274, 1258, 1173, 1043, 977, 803, 760 and/or 696 cm ^"1 (± 3 cm ^"1 ), respectively; d) an attenuated total reflectance Fourier transform infrared (FTIR-ATR) spectrum spectrum substantially similar to that shown in Figure 18; e) a near infrared (FT-NIR) spectrum exhibiting one or more of the following absorbance peaks at approximately 8331, 6966, 6596, 6526, 6453, 5840, 5267, 4848 and/or 4726 cm ^"1 (± 8 cm ^"1 ), respectively; f) a near infrared (FT-NIR) spectrum substantially similar to that shown in Figure 19;

g) an X-ray powder diffractogram (XRPD) exhibiting one or more of the following angles of reflection in degrees 2θ (±0.1) at approximately 20.5, 19.7, 18.3, 16.3, 15.1, 14.7, 13.3, 12.1, 6.8 and/or 6.2, respectively; h) an X-ray powder diffractogram (XRPD) substantially similar to that shown in Figure 26; i) a ¹³ C CP/MAS solid-state NMR spectrum exhibiting one or more of the following resonances at approximately 176.0, 170.7,147.6, 74.3, 73.2 and/or 67.3 ppm (±0.5 ppm), respectively; or j) a ¹³ C CP/MAS solid-state NMR spectrum substantially similar to that shown in Figure 32, respectively.

Another embodiment of the invention is crystalline form E of 24-bromofusidic acid (Br-FA), characterised by exhibiting one or more of the following features a)-d):

a) an X-ray powder diffractogram (XRPD) exhibiting an angle of reflection, expressed in degrees 2θ (± 0.1), at approximately 16.3, 14.3 and/or 12.4; b) an attenuated total reflectance Fourier transform infrared (FTIR-ATR) spectrum exhibiting attenuated total reflectance peaks at approximately 3649 cm ^"1 (± 3 cm ^"1 ); c) a near infrared (FT-NIR) spectrum exhibiting absorbance peaks at approximately 7126 and/or 7042 cm ^"1 (± 8 cm ^'1 ); or d) a Fourier transform (FT-NIR) Raman spectrum exhibiting intensity peaks at approximately 181 cm ^" (± 4 cm ^"1 ), respectively.

Another embodiment of the invention is crystalline form E of 24-bromofusidic acid (Br-FA), characterised by exhibiting one or more of the following features a)-h):

a) a Fourier transform (FT-NIR) Raman spectrum exhibiting the following intensity peaks at approximately 1724, 1711, 1462, 941, 926, 751 and/or 181 cm ^"1 (± 4 cm ^{" 1} ), respectively; b) a Fourier transform (FT-NIR) Raman spectrum substantially similar to that shown in Figure 11; c) an attenuated total reflectance Fourier transform infrared (FTIR-ATR) spectrum exhibiting the following attenuated total reflectance peaks at approximately 3649, 3608, 3558 and/or 1443 cm ^"1 (± 3 cm ^"1 ), respectively;

d) an attenuated total reflectance Fourier transform infrared (FTIR-ATR) spectrum spectrum substantially similar to that shown in Figure 9; e) a near infrared (FT-NIR) spectrum exhibiting the following absorbance peaks at approximately 10433, 10300, 7126, 7042 and/or 4946 cm ^"1 (± 8 cm ^"1 ), respectively; f) a near infrared (FT-NIR) spectrum substantially similar to that shown in Figure 10; g) an X-ray powder diffractogram (XRPD) exhibiting the following angles of reflection in degrees 2θ (±0.1) at approximately 23.2, 19.0, 16.3, 15.0, 14.3, 12.4, 10.8, 9.9 and/or 9.2, respectively; or h) an X-ray powder diffractogram (XRPD) substantially similar to that shown in Figure 23, respectively.

Another embodiment of the invention is crystalline form E of 24-bromofusidic acid (Br-FA), characterised by exhibiting one or more of the following features a)-h), respectively:

a) a Fourier transform (FT-NIR) Raman spectrum exhibiting one or more of the following intensity peaks at approximately 2978, 2938, 1724, 1711, 1658, 1462, 1442, 1339, 941, 926, 751, 692, 643, 548, 532, 336 and/or 181 cm ^" (± 4 cm ^"1 ), respectively; b) a Fourier transform (FT-NIR) Raman spectrum substantially similar to that shown in Figure 11; c) an attenuated total reflectance Fourier transform infrared (FTIR-ATR) spectrum exhibiting one or more of the following attenuated total reflectance peaks at approximately 3649, 3608, 3558, 1721, 1443, 1374, 1174, 1014, 974, 848, 804 and/or 748 cm ^"1 (± 3 cm ^"1 ), respectively; d) an attenuated total reflectance Fourier transform infrared (FTIR-ATR) spectrum spectrum substantially similar to that shown in Figure 9; e) a near infrared (FT-NIR) spectrum exhibiting one or more of the following absorbance peaks at approximately 10433, 10300, 8393, 7126, 7042, 6522, 5875, 5803, 4946, 4755 and/or 4352 cm ^"1 (± 8 cm ^"1 ), respectively; f) a near infrared (FT-NIR) spectrum substantially similar to that shown in Figure 10; g) an X-ray powder diffractogram (XRPD) exhibiting one or more of the following angles of reflection in degrees 2θ (±0.1) at approximately 23.2, 22.5, 20.7, 19.0, 16.3, 15.0, 14.3, 12.4, 10.8, 9.9 and/or 9.2, respectively; or

h) an X-ray powder diffractogram (XRPD) substantially similar to that shown in Figure 23.

Another embodiment of the invention is crystalline form G of 24-bromofusidic acid (Br-FA), characterised by exhibiting one or more of the following features a)-d) :

a) an X-ray powder diffractogram (XRPD) exhibiting an angle of reflection, expressed in degrees 2θ (± 0.1), at approximately 15.2, 13.0 and/or 12.3; b) an attenuated total reflectance Fourier transform infrared (FTIR-ATR) spectrum exhibiting attenuated total reflectance peaks at approximately 3649 cm ^"1 (± 3 cm ^"1 ); c) a near infrared (FT-NIR) spectrum exhibiting absorbance peaks at approximately 7100 cm ^"1 (± 8 cm ^"1 ); or d) a Fourier transform (FT-NIR) Raman spectrum exhibiting intensity peaks at approximately 186 cm ^"1 (± 4 cm ^"1 ), respectively.

Another embodiment of the invention is crystalline form G of 24-bromofusidic acid (Br-FA), characterised by exhibiting one or more of the following features a)-h) :

a) a Fourier transform (FT-NIR) Raman spectrum exhibiting the following intensity peaks at approximately 1723, 1704, 1460, 944, 928, 754 and/or 186 cm ^"1 (± 4 cm ^{" x} ), respectively; b) a Fourier transform (FT-NIR) Raman spectrum substantially similar to that shown in Figure 14; c) an attenuated total reflectance Fourier transform infrared (FTIR-ATR) spectrum exhibiting the following attenuated total reflectance peaks at approximately 3649,

3608, 3558 and/or 1443 cm ^'1 (± 3 cm ^"1 ), respectively; d) an attenuated total reflectance Fourier transform infrared (FTIR-ATR) spectrum spectrum substantially similar to that shown in Figure 29; e) a near infrared (FT-NIR) spectrum exhibiting the following absorbance peaks at approximately 10393, 7100 and/or 6591 cm ^"1 (± 8 cm ^'1 ), respectively; f) a near infrared (FT-NIR) spectrum substantially similar to that shown in Figure 13; g) an X-ray powder diffractogram (XRPD) exhibiting the following angles of reflection in degrees 2θ (±0.1) at approximately 15.2, 13.0, 12.3, 10.2 and/or 9.4, respectively; or

h) an X-ray powder diffractogram (XRPD) substantially similar to that shown in Figure 24, respectively.

Another embodiment of the invention is crystalline form G of 24-bromofusidic acid (Br-FA), characterised by exhibiting one or more of the following features a)-h), respectively:

a) a Fourier transform (FT-NIR) Raman spectrum exhibiting one or more of the following intensity peaks at approximately 2980, 2938, 1723, 1704, 1660, 1460, 1442, 1337, 944, 928, 754, 698, 687, 641, 546, 537, 337 and/or 186 cm ^'1 ] (± 4 cm ^{" 1} J, respectively; b) a Fourier transform (FT-NIR) Raman spectrum substantially similar to that shown in Figure 14; c) an attenuated total reflectance Fourier transform infrared (FTIR-ATR) spectrum exhibiting one or more of the following attenuated total reflectance peaks at approximately 3649, 3608, 3558, 1721, 1443, 1374, 1174, 1014, 974, 848, 804 and/or 748 cm ^"1 (± 3 cm ^"1 ), respectively; d) an attenuated total reflectance Fourier transform infrared (FTIR-ATR) spectrum spectrum substantially similar to that shown in Figure 29; e) a near infrared (FT-NIR) spectrum exhibiting one or more of the following absorbance peaks at approximately 10393, 8447, 7100, 6591, 6520, 5867, 5796, 4822 and/or 4354 cm ^"1 (± 8 cm ^"1 ), respectively; f) a near infrared (FT-NIR) spectrum substantially similar to that shown in Figure 13; g) an X-ray powder diffractogram (XRPD) exhibiting one or more of the following angles of reflection in degrees 2θ (±0.1) at approximately 25.8, 24.8, 20.6, 19.5,

15.9, 15.2, 13.0, 12.3, 10.2 and/or 9.4, respectively; or h) an X-ray powder diffractogram (XRPD) substantially similar to that shown in

Figure 24.

Another embodiment of the invention is crystalline form D of 24-bromofusidic acid (Br-FA), characterised by exhibiting one or more of the following features a)-d) :

a) an X-ray powder diffractogram (XRPD) exhibiting an angle of reflection, expressed in degrees 2θ (± 0.1), at approximately 15.9, 13.7 and/or 7.1;

b) an attenuated total reflectance Fourier transform infrared (FTIR-ATR) spectrum exhibiting attenuated total reflectance peaks at approximately 1745 and/or 1687 cm ^{" 1} (± 3 cm ^"1 ); c) a near infrared (FT-NIR) spectrum exhibiting absorbance peaks at approximately 7076 cm ^"1 (± 8 cm ^"1 ); or d) a Fourier transform (FT-NIR) Raman spectrum exhibiting intensity peaks at approximately 1741 and/or 203 cm ^"1 (± 4 cm ^"1 ), respectively.

Another embodiment of the invention is crystalline form D of 24-bromofusidic acid (Br-FA), characterised by exhibiting one or more of the following features a)-h):

a) a Fourier transform (FT-NIR) Raman spectrum exhibiting the following intensity peaks at approximately 1741, 879, 702, 689, 625, 251 and/or 203 cm ^"1 (± 4 cm ^"1 ), respectively; b) a Fourier transform (FT-NIR) Raman spectrum substantially similar to that shown in Figure 8; c) an attenuated total reflectance Fourier transform infrared (FTIR-ATR) spectrum exhibiting the following attenuated total reflectance peaks at approximately 3436, 1745, 1687, 1188, 950 and/or 917 cm ^"1 (± 3 cm ^"1 ), respectively; d) an attenuated total reflectance Fourier transform infrared (FTIR-ATR) spectrum spectrum substantially similar to that shown in Figure 5; e) a near infrared (FT-NIR) spectrum exhibiting the following absorbance peaks at approximately 10351, 7076 and/or 5094 cm ^"1 (± 8 cm ^"1 ), respectively; f) a near infrared (FT-NIR) spectrum substantially similar to that shown in Figure 7; g) an X-ray powder diffractogram (XRPD) exhibiting the following angles of reflection in degrees 2θ (±0.1) at approximately 16.3, 15.9, 15.4, 14.3, 13.7, 12.6 and/or 7.1, respectively; or h) an X-ray powder diffractogram (XRPD) substantially similar to that shown in Figure 22, respectively.

Another embodiment of the invention is crystalline form D of 24-bromofusidic acid (Br-FA), characterised by exhibiting one or more of the following features a)-h), respectively:

a) a Fourier transform (FT-NIR) Raman spectrum exhibiting one or more of the following intensity peaks at approximately 2937, 1741, 1659, 1460, 1441, 994, 879, 755, 702, 689, 625, 534, 251 and/or 203 cm ^"1 (± 4 cm ^"1 ), respectively; b) a Fourier transform (FT-NIR) Raman spectrum substantially similar to that shown in Figure 8; c) an attenuated total reflectance Fourier transform infrared (FTIR-ATR) spectrum exhibiting one or more of the following attenuated total reflectance peaks at approximately 3436, 1745, 1687, 1443, 1379, 1230, 1188, 1052, 1031, 974, 950, 934, 917 and/or 755 cm ^"1 (± 3 cm ^"1 ), respectively; d) an attenuated total reflectance Fourier transform infrared (FTIR-ATR) spectrum spectrum substantially similar to that shown in Figure 5; e) a near infrared (FT-NIR) spectrum exhibiting one or more of the following absorbance peaks at approximately 10351, 8357, 7076, 5796, 5711, 5636, 5094 and/or 4348 cm ^"1 (± 8 cm ¹ ), respectively; f) a near infrared (FT-NIR) spectrum substantially similar to that shown in Figure 7; g) an X-ray powder diffractogram (XRPD) exhibiting one or more of the following angles of reflection in degrees 2θ (±0.1) at approximately 16.3, 15.9, 15.4, 14.3,

13.7, 12.6, 7.9, 7.1 and/or 5.9, respectively; or h) an X-ray powder diffractogram (XRPD) substantially similar to that shown in Figure 22.

An embodiment of the invention is a mixture or composition of crystalline forms of 24-bromofusidic acid (Br-FA), including pseudopolymorphs of 24-bromofusidic acid, comprising crystalline form H, form C, form I, form E, Form G and/or form D of 24- bromofusidic acid (Br-FA) according to the invention.

In an embodiment of the invention the mixture of crystalline forms of 24- bromofusidic acid essentially consists of form H, form C, form I, form E, Form G, or form D of 24-bromofusidic acid (Br-FA) anhydrate.

In an embodiment of the invention the mixture of crystalline forms of 24- bromofusidic acid consists of 90-99.9 (mol) % of form H, form C, form I, form E, Form G, or form D of 24-bromofusidic acid (Br-FA) anhydrate.

An embodiment of the invention is a method for the preparation of crystalline form H of 24-bromofusidic acid (Br-FA), said method comprising:

a) suspending or dissolving optionally with heating 24-bromofusidic acid (Br-FA) in a suitable solvent or mixture of solvents; b) optionally cooling and/or concentrating the solution/suspension in step a) allowing crystallisation of form H of 24-bromofusidic acid (Br-FA) according to the invention; and c) isolating the crystalline Br-FA form H anhydrate.

In an embodiment of the invention said solvent is selected from the group consisting of a ketone, a Ci-C ₄ alkyl ester of formic acid, an ether, a nitrile, water and mixtures thereof.

In an embodiment of the invention said solvent is selected from the group consisting of ethyl formate, acetonitrile, water, tert-butyl methyl ether, diisopropyl ether, acetone and mixtures thereof.

In an embodiment of the invention said solvent is ethyl formate.

In an embodiment of the invention said solvent is acetonitrile.

In an embodiment of the invention said solvent is acetone.

In an embodiment of the invention said solvent is a mixture of acetone and water.

In an embodiment of the invention said solvent is tert-butyl methyl ether.

In an embodiment of the invention said solvent is diisopropyl ether.

An embodiment of the invention is a method for the preparation of crystalline form C of 24-bromofusidic acid (Br-FA), said method comprising:

a) suspending or dissolving optionally with heating 24-bromofusidic acid (Br-FA) in a suitable solvent or mixture of solvents;

b) optionally cooling and/or concentrating the solution/suspension in step a) allowing crystallisation of form C of 24-bromofusidic acid (Br-FA) according to the invention; and c) isolating the crystalline Br-FA form C.

In an embodiment of the invention said solvent is selected from the group consisting of Ci-C ₄ alkyl esters of C ₂ -C ₃ carboxylic acids, water and mixtures thereof.

In an embodiment of the invention said solvent is selected from the group consisting of ethyl acetate, water and mixtures thereof.

In an embodiment of the invention said solvent is water.

In an embodiment of the invention said solvent is a mixture of ethyl acetate and water.

An embodiment of the invention is a method for the preparation of crystalline form E, form G or mixtures thereof of 24-bromofusidic acid (Br-FA), said method comprising :

a) suspending or dissolving optionally with heating 24-bromofusidic acid (Br-FA) in a suitable solvent or mixture of solvents; b) optionally cooling and/or concentrating the solution/suspension in step a) allowing crystallisation of form E, form G or mixtures thereof of 24-bromofusidic acid (Br-FA) according to the invention, and c) isolating the crystalline Br-FA form E, form G or mixtures thereof.

In an embodiment of the invention said solvent is selected from the group consisting of an alcohol, water and mixtures thereof.

In an embodiment of the invention said solvent is selected from the group consisting of methanol, ethanol, water and mixtures thereof.

In an embodiment of the invention said solvent is methanol.

In an embodiment of the invention said solvent is a mixture of methanol and water.

In an embodiment of the invention said solvent is a mixture of ethanol and water.

In an embodiment of the invention said solvent is a mixture of propan-2-ol and water.

An embodiment of the invention is a method for the preparation of crystalline form I of 24-bromofusidic acid (Br-FA), said method comprising:

a) suspending or dissolving optionally with heating 24-bromofusidic acid (Br-FA) in a suitable solvent or mixture of solvents; b) optionally cooling and/or concentrating the solution/suspension in step a) allowing crystallisation of form I of 24-bromofusidic acid (Br-FA) according to the invention; and c) isolating the crystalline Br-FA form I.

In an embodiment of the invention said solvent is selected from the group consisting of aliphatic hydrocarbons and mixtures thereof.

In an embodiment of the invention said solvent is hexane.

An embodiment of the invention is a method for the preparation of crystalline form D of 24-bromofusidic acid (Br-FA), said method comprising:

a) suspending or dissolving optionally with heating 24-bromofusidic acid (Br-FA) in a suitable solvent or mixture of solvents; b) optionally cooling and/or concentrating the solution/suspension in step a) allowing crystallisation of form D of 24-bromofusidic acid (Br-FA) according to the invention; and c) isolating the crystalline Br-FA form D.

In an embodiment of the invention said solvent is selected from the group consisting of aromatic hydrocarbons, water and mixtures thereof.

In an embodiment of the invention said solvent is selected from the group consisting of toluene, water and mixtures thereof.

In an embodiment of the invention said solvent is a mixture of toluene and water.

The crystalline Br-FA forms of the present invention may be useful for treating, preventing or ameliorating infections in a patient, including a mammalian, and in particular, a human patient. Animals that may be treated with a compound of the invention include, more specifically, domestic animals such as horses, cows, pigs, sheep, poultry, fish, cats, dogs and zoo animals.

The crystalline Br-FA forms of the present invention may be particularly useful in the treatment of bacterial infections, such as skin infections or secondary skin infections, or eye infections. The crystalline Br-FA forms of the present invention may be furthermore useful in the treatment of simple abscesses, impetiginous lesions, furuncles, or cellulites. The crystalline Br-FA forms of the present invention may be particularly useful for the treatment, e.g. the topical treatment, of contagious superficial infections of the skin, such as non-bullous impetigo (or impetigo contagiosa) or bullous impetigo.

Consequently, the present invention provides a method of treating, preventing or ameliorating bacterial infections, the method comprising administering to a patient an effective amount of the crystalline Br-FA forms, optionally together with another therapeutically active compound.

Examples of said other therapeutically active compounds include antibiotics, such as β-lactams, such as penicillins (phenoxymethyl penicillin, benzyl penicillin, dicloxacillin, ampicillin, amoxicillin, pivampicillin, flucloxacillin, piperacillin and mecellinam), cefalosporins (cefalexin, cefalotin, cefepim, cefotaxim, ceftazidim, ceftriazon and cefuroxim), monobactams (aztreonam) and carbapenems (meropenem); macrolides (azithromycin, clarithromycin, erythromycin and roxithromycin); polymyxins (colistin); tetracyclins (tetracycline, doxycyclin, oxytetracyclin and lymecyclin); aminoglycosides (streptomycin, gentamicin, tobramycin and netilmicin); fluoroquinolones (norfloxacin, ofloxacin, ciprofloxacin

and moxifloxacin); clindamycin, lincomycin, teicoplanin, vancomycin, oxazolidones (linezolid), rifamycin, metronidazol and fusidic acid.

Other compounds which may advantageously be combined with a compound of the invention, especially for topical treatment, include for instance corticosteroids, such as hydrocortisone, betamethasone- 17-valerate and triamcinolone acetonid. The crystalline Br-FA forms and the other compounds may either be administered concomitantly or sequentially.

The crystalline Br-FA forms of the present invention are further useful for the prevention or prophylaxis of bacterial infections in animals and are therefore useful during the breeding of domestic animals, such as mammals, such as horses, cows, pigs, sheep, poultry, fish, cats, dogs and zoo animals.

For use in therapy, the crystalline Br-FA forms of the present invention are typically in the form of a pharmaceutical composition. The invention therefore relates to a pharmaceutical composition comprising crystalline Br-FA described herein, optionally together with other therapeutically active compounds, together with a pharmaceutically acceptable excipient or vehicle. The excipient must be "acceptable" in the sense of being compatible with the other ingredients of the composition and not deleterious to the recipient thereof. Conveniently, the active ingredient comprises from 0.05-99.9% by weight of the formulation. The formulations include e.g. those in a form suitable for oral (including sustained or timed release), rectal, parenteral (including subcutaneous, intraperitoneal, intramuscular, intraarticular and intravenous), transdermal, ophthalmic, topical, nasal or buccal administration. The formulations may conveniently be presented in dosage unit form and may be prepared by any of the methods well known in the art of pharmacy, e.g. as disclosed in Remington, The Science and Practice of Pharmacy, 20 ^th ed., 2000. All methods include the step of bringing the active ingredient into association with the carrier, which constitutes one or more accessory ingredients. In general, the formulations are prepared by uniformly and intimately bringing the active ingredient into association with a liquid carrier or a finely divided solid carrier or both, and then, if necessary, shaping the product into the desired formulation. Formulations of the present invention suitable for oral administration may be in the form of discrete units as capsules, sachets, tablets or lozenges, each containing a predetermined amount

of the active ingredient; in the form of a powder or granules; in the form of a solution or a suspension in an aqueous liquid or non-aqueous liquid, such as ethanol or glycerol; or in the form of an oil-in-water emulsion or a water-in-oil emulsion. Such oils may be edible oils, such as e.g. cottonseed oil, sesame oil, coconut oil or peanut oil. Suitable dispersing or suspending agents for aqueous suspensions include synthetic or natural gums such as tragacanth, alginate, acacia, dextran, sodium carboxymethylcellulose, gelatin, methylcellulose, hydroxypropylmethylcellulose, hydroxypropylcellulose, carbomers and polyvinylpyrrolidone. The active ingredients may also be administered in the form of a bolus, electuary or paste. A tablet may be made by compressing or moulding the active ingredient optionally with one or more accessory ingredients. Compressed tablets may be prepared by compressing, in a suitable machine, the active ingredient(s) in a free-flowing form such as a powder or granules, optionally mixed by a binder, such as e.g. lactose, glucose, starch, gelatine, acacia gum, tragacanth gum, sodium alginate, carboxymethylcellulose, methylcellulose, hydroxypropylmethylcellulose, polyethylene glycol, waxes or the like; a lubricant such as e.g. sodium oleate, sodium stearate, magnesium stearate, sodium benzoate, sodium acetate, sodium chloride or the like; a disintegrating agent such as e.g. starch, methylcellulose, agar, bentonite, croscarmellose sodium, sodium starch glycollate, crospovidone or the like or a dispersing agent, such as polysorbate 80. Moulded tablets may be made by moulding, in a suitable machine, a mixture of the powdered active ingredient and suitable carrier moistened with an inert liquid diluent. Formulations for rectal administration may be in the form of suppositories in which the compound of the present invention is admixed with low melting water soluble or insoluble solids such as cocoa butter, hydrogenated vegetable oils, polyethylene glycol or fatty acids esters of polyethylene glycols, while elixirs may be prepared using myristyl palmitate. Formulations suitable for parenteral administration conveniently comprise a sterile oily or aqueous preparation of the active ingredients, which is preferably isotonic with the blood of the recipient, e.g. isotonic saline, isotonic glucose solution or buffer solution. The formulation may be conveniently sterilised by for instance filtration through a bacteria retaining filter, addition of sterilising agent to the formulation, irradiation of the formulation or heating of the formulation. Liposomal formulations as disclosed in e.g. Encyclopedia of Pharmaceutical Technology, vol.9, 1994, are also suitable for parenteral administration. Alternatively, the crystalline 24-bromofusidic acid may be presented as a sterile, solid preparation, e.g. a freeze-dried powder, which is readily dissolved

in a sterile solvent immediately prior to use. Transdermal formulations may be in the form of a plaster or a patch. Formulations suitable ophthalmic administration may be in the form of a sterile aqueous preparation of the active ingredients, which may be in microcrystalline form, for example, in the form of an aqueous microcrystalline suspension. Liposomal formulations or biodegradable polymer systems e.g. as disclosed in Encyclopedia of Pharmaceutical Technology, vol.2, 1989, may also be used to present the active ingredient for ophthalmic administration. Formulations suitable for topical or ophthalmic administration include liquid or semi-liquid preparations such as liniments, lotions, gels, applicants, oil-in-water or water-in-oil emulsions such as creams, ointments or pastes; or solutions or suspensions such as drops. Formulations suitable for nasal or buccal administration include powder, self- propelling and spray formulations, such as aerosols and atomisers. Such formulations are disclosed in greater detail in e.g. Modern Pharmaceutics. 2 ^nd ed., G. S. Banker and CT. Rhodes (Eds.), page 427-432, Marcel Dekker, New York; Modern Pharmaceutics. 3 ^th ed., G. S. Banker and CT. Rhodes (Eds.), page 618-619 and 718- 721, Marcel Dekker, New York and Encyclopedia of Pharmaceutical Technology vol. 10, J Swarbrick and J. C. Boylan (Eds), page 191-221, Marcel Dekker, New York. In addition to the aforementioned ingredients, the formulations of a compound of crystalline 24-bromofusidic acid may include one or more additional ingredients such as diluents, buffers, flavouring agents, colourant, surface active agents, thickeners, preservatives, e.g. methyl hydroxybenzoate (including anti-oxidants), emulsifying agents and the like.

The parenteral formulations are in particular useful in the treatment of conditions in which a quick response to the treatment is desirable. In the continuous therapy of patients suffering from infectious diseases, the tablets or capsules may be the appropriate form of pharmaceutical preparation owing to the prolonged effect obtained when the drug is given orally, in particular in the form of sustained-release tablets.

As suggested above, the composition may contain other therapeutically active components, which can appropriately be administered together with the compounds of the invention in the treatment of infectious diseases, such as other suitable antibiotics, in particular such antibiotics which may enhance the activity and/or prevent development of resistance. Corticosteroids may also beneficially be included in the compositions of the present invention. In particular, said other active

component may include β-lactams, such as penicillins (phenoxymethyl penicillin, benzyl penicillin, dicloxacillin, ampicillin, amoxicillin, pivampicillin, flucloxacillin, piperacillin and mecellinam), cefalosporins (cefalexin, cefalotin, cefepim, cefotaxim, ceftazidim,«ceftriazon and cefuroxim), monobactams (aztreonam) and carbapenems (meropenem); macrolides (azithromycin, clarithromycin, erythromycin and roxithromycin); polymyxins (colistin); tetracyclins (tetracycline, doxycyclin, oxytetracyclin and lymecyclin); aminoglycosides (streptomycin, gentamicin, tobramycin and netilmicin); fluoroquinolones (norfloxacin, ofloxacin, ciprofloxacin and moxifloxacin); clindamycin, lincomycin, teicoplanin, vancomycin, oxazolidones (linezolid), rifamycin, metronidazol and fusidic acid. Other compounds which advantageously may be combined with the compounds of the invention, especially for topical treatments, include e.g. corticosteroids, such as hydrocortisone, betamethason-17-valerate and triamcinolone acetonid.

The other therapeutically active compound may be in the same or separate containers adapted for concomitant or sequential administration of said therapeutically active compounds.

The treatment of infectious diseases often involves determining whether said disease is resistant or refractory to the treatment, before the treatment is, in fact, initiated. By way of example, samples containing the infectious microbe may be taken from the patient, e.g. blood or urine, after which the sample is cultured and exposed to the treatment to determine whether said infectious organism responds to the treatment. Accordingly, the present invention also provides a method for identifying compounds effective against a micro organism, the method comprising administering crystalline Br-FA of the present invention as described above, optionally together with other therapeutically active agents, to a micro organism, and determining whether said compound or mixture of compounds has a toxic or static effect on the micro organism in question.

The compositions of the present invention are not limited to pharmaceuticals, but may also be used in a non-therapeutic context to control microbial growth. For example may compositions or compounds of the present invention be useful as additives which inhibit microbial growth, such as during fermentation processes. By way of example, the selectivity of antimicrobial agents renders them useful to

enhance growth of particular micro organisms at the expense of others in a multi- species culture.

In yet another more specific aspect, this invention relates to a pharmaceutical composition comprising a crystalline Br-FA form of the present invention as described above together with a pharmaceutically acceptable excipient or vehicle further comprising another therapeutically active compound is selected from the group consisting of antibiotics and corticosteroids.

In yet another more specific aspect, this invention relates to a pharmaceutical composition comprising crystalline Br-FA of the present invention as described above together with a pharmaceutically acceptable excipient or vehicle further comprising another therapeutically active compound selected from the group consisting of penicillins (phenoxymethyl penicillin, benzyl penicillin, dicloxacillin, ampicillin, amoxicillin, pivampicillin, flucloxacillin, piperacillin and mecellinam), cefalosporins (cefalexin, cefalotin, cefepim, cefotaxim, ceftazidim, ceftriazon and cefuroxim), monobactams (aztreonam) and carbapenems (meropenem); macrolides (azithromycin, clarithromycin, erythromycin and roxithromycin); polymyxins (colistin); tetracyclins (tetracycline, doxycyclin, oxytetracyclin and lymecyclin); aminoglycosides (streptomycin, gentamicin, tobramycin and netilmicin); fluoroquinolones (norfloxacin, ofloxacin, ciprofloxacin and moxifloxacin) ; clindamycin, lincomycin, teicoplanin, vancomycin, oxazolidones (linezolid), rifamycin, metronidazol, fusidic acid, hydrocortisone, betamethason-17-valerate and triamcinolone acetonid.

In yet another more specific aspect, this invention relates to a method of treating, preventing or ameliorating infections in a patient, the method comprising administering to said patient an effective amount of crystalline Br-FA of the present invention as described above, and optionally further comprising concomitant or sequential administration of one or more other therapeutically active compounds, wherein said other therapeutically active compound is selected from the group consisting of antibiotics and corticosteroids.

In yet another more specific aspect, this invention relates to a method of treating, preventing or ameliorating infections in a patient, such as a bacterial infection the

method comprising administering to said patient an effective amount of crystalline Br-FA of the present invention as described above, and optionally further comprising concomitant or sequential administration of one or more other therapeutically active compounds, wherein said other therapeutically active compound is selected from the group consisting of penicillins (phenoxymethyl penicillin, benzyl penicillin, dicloxacillin, ampicillin, amoxicillin, pivampicillin, flucloxacillin, piperacillin and mecellinam), cefalosporins (cefalexin, cefalotin, cefepim, cefotaxim, ceftazidim, ceftriazon and cefuroxim), monobactams (aztreonam) and carbapenems (meropenem); macrolides (azithromycin, clarithromycin, erythromycin and roxithromycin); polymyxins (colistin); tetracyclins (tetracycline, doxycyclin, oxytetracyclin and lymecyclin); aminoglycosides (streptomycin, gentamicin, tobramycin and netilmicin); fluoroquinolones (norfloxacin, ofloxacin, ciprofloxacin and moxifloxacin); clindamycin, lincomycin, teicoplanin, vancomycin, oxazolidones (linezolid), rifamycin, metronidazol, fusidic acid, hydrocortisone, betamethason-17- valerate and triamcinolone acetonid.

In yet another more specific aspect, this invention relates to the use of crystalline Br- FA of the present invention as described above for the manufacture of a medicament for the treatment, amelioration or prophylaxis of infections, such as a bacterial infection, wherein said medicament further comprises another therapeutically active compound in the same or separate containers adapted for concomitant or sequential administration of said therapeutically active compounds.

In yet another more specific aspect, this invention relates to the use of crystalline Br- FA of the present invention as described above for the manufacture of a medicament for the treatment, amelioration or prophylaxis of infections, such as a bacterial infection, wherein said medicament further comprises another therapeutically active compound in the same or separate containers adapted for concomitant or sequential administration of said therapeutically active compounds, wherein said other therapeutically active compound is selected from the group consisting of penicillins (phenoxymethyl penicillin, benzyl penicillin, dicloxacillin, ampicillin, amoxicillin, pivampicillin, flucloxacillin, piperacillin and mecellinam), cefalosporins (cefalexin, cefalotin, cefepim, cefotaxim, ceftazidim, ceftriazon and cefuroxim), monobactams (aztreonam) and carbapenems (meropenem); macrolides (azithromycin, clarithromycin, erythromycin and roxithromycin); polymyxins (colistin); tetracyclins

(tetracycline, doxycyclin, oxytetracyclin and lymecyclin); aminoglycosides (streptomycin, gentamicin, tobramycin and netilmicin); fluoroquinolones (norfloxacin, ofloxacin, ciprofloxacin and moxifloxacin); clindamycin, lincomycin, teicoplanin, vancomycin, oxazolidones (linezolid), rifamycin, metronidazol, fusidic acid, hydrocortisone, betamethason-17-valerate and triamcinolone acetonid.

Definitions

The term "polymorphic purity" includes the purity relative to other polymorphic and pseudopolymorphic crystal forms.

The term "ketone" relates to compounds of the general formula R ₂ C(=O). Non- limiting examples thereof include acetone, methyl ethyl ketone etc.

The term "CrC ₄ alkyl esters of C ₂ -C ₃ carboxylic acids" relates to esters formed from C ₁ -C ₄ alcohols and C ₂ -C ₃ carboxylic acids. The term includes, but is not limited to, methyl acetate, ethyl acetate, propyl acetate, butyl acetate etc.

The term "ether" relates to compounds of the general formula ROR ' . Non-limiting examples thereof include dimethyl ether, diethyl ether, tert-butyl methyl ether, diisopropyl ether etc.

The term "nitrile" relates to compounds of the general formula RCN. Non-limiting examples thereof include acetonitrile, propionitrile etc.

The term "alcohol" relates to compounds of the general formula ROH. Non-limiting examples thereof include methanol, ethanol, n-propanol (propan-1-ol), isopropanol (propan-2-ol), butanol etc.

The term "aliphatic hydrocarbon" refers to compounds of the formula C _x H _y . Non- limiting examples thereof include pentane, hexane, heptane etc.

The term "aromatic hydrocarbon" refers to compounds having at least one aromatic ring. Non-limiting examples thereof include benzene, toluene, xylene (ortho, meta, para) etc.

The term "ethanol" in the context of the present invention includes but is not limited to all commercially available grades of ethanol, such as anhydrous ethanol or ethanol from obtained from azeotropic distillation containing water, typically containing 4-5% water, commonly named alcohol.

The term "polymorph" encompasses all solid forms, e.g. amorphous solids or solid crystal forms, including solvates with stoichiometric or non-stoichiometric amounts of solvent and hydrates with stoichiometric or non stoichiometric amounts of water.

The term "hexane" includes but is not limited to all commercially available grades of hexane such as pure hexane isomers, e.g. n-hexane, or mixtures of hexane isomers, optionally in mixture with other aliphatic hydrocarbons.

The term "crystalline forms" encompasses crystalline polymorphs in all degrees of crystallinity.

The term "crystalline types" encompasses crystalline polymorphs in all degrees of crystallinity. The term is used interchangeably in this context with the term "crystalline forms".

EXPERIMENTAL Analytical methods

X-ray powder diffraction (XRPD): The diffractogram was obtained in the range 3-30 degrees 2θ on a STADI-P instrument from STOE&CIE GmbH. [Diffractometer: transmission; monochromator: curved germanium (111); wavelength: 1.540598 Cu; detector: linear PSD; scan mode: transmission/moving PSD/fixed omega; scan type: 2theta: omega].

Single-crystal X-ray diffraction data were collected using a Bruker SMART Apex diffractometer with a CCD area detector (Temperature: 120(2) K; Mo /Ca Radiation λ = 0.7107 A; data collection method: ω/2q scans).

The ¹³ C solid-state NMR spectrum was acquired on a Varian Unity-INOVA NMR spectrometer with a magnetic field strength of 7.04 T. A 5 mm homebuilt CP/MAS

TLT probe using a spinning frequency of 5.0 kHz was used. The spectrum was acquired with a standard cross-polarization pulse sequence and referenced to an external of TMS.

FTIR-ATR spectroscopy (attenuated total reflectance fourier transform infrared spectroscopy): The spectrum was recorded on a FTIR instrument, Equinox 55 or Tensor 27 from Bruker equipped with a GoldenGate ATR unit from SPECAC. A spectral resolution of 3 cm ^"1 was used.

Raman spectroscopy: The spectrum was recorded on a FT-NIR-Raman instrument, RFS 100/S from Bruker. A spectral resolution of 4 cm ^"1 was used.

FT-NIR reflection spectroscopy (diffuse reflection mode): The spectrum was recorded using a fiber optic probe coupled to a FTIR instrument, Equinox 55 from Bruker. Measurements were conducted either directly on the sample or through a glass container. A spectral resolution of 8 cm ^"1 was used.

IR spectroscopy (KBr disc): The spectra were recorded on a FTIR instrument, Equinox 55 from Bruker. A spectral resolution of 3 cm ^"1 was used.

The given error ranges in this application for the X-ray diffractographic and spectroscopic characteristics, including those in the claims, may be more or less depending on factors well known to a person skilled in the art of spectroscopy and diffractography and may for example depend on sample preparation, such as particle size distribution, or if the crystal form is part of a formulation, on the composition of the formulation, as well as instrumental fluctuations, and other factors.

An error range of ±5 includes, but is not limited to variations of ±5, ±4, ±3, ±2, ±1, ±0.5, ±0.4, ±0.3, ±0.2, and ±0.1; an error range of ±3 includes, but is not limited to variations of ±3, ±2, ±1, ±0.5, ±0.4, ±0.3, ±0.2, and ±0.1; an error range of ±1 includes, but is not limited to variations of ±0.9, ±0.8, ±0.7, ±0.6, ±0.5, ±0.4, ±0.3, ±0.2, and ±0.1; and an error range of ±0.2 includes, but is not limited to variations of ±0.2, ±0.15, ±0.1, ±0.09, ±0.08, ±0.07, ±0.06, ±0.05, ±0.04, ±0.03, ±0.02, and ±0.01.

The present invention includes embodiments, where one or more steps in a procedure are omitted, one or more additional steps are added, and/or where the

order of steps is modified or reversed. All examples described herein shall be considered to be non-limiting.

It is to be understood that this invention is not limited to particular embodiments described, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting. Within the context of the present invention, each disclosed value may represent the upper or lower limit of a range that includes any other value. Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included in the smaller ranges and are encompassed within the invention, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the invention. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention belongs. Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present invention, the preferred methods and materials are described. All publications mentioned herein are incorporated herein by reference to disclose and describe the methods and/or materials in the appended claims, the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. The patents and publications discussed herein are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as and admission that the present invention is not entitled to antedate such patent or publication by virtue of prior invention. Further, the dates of publication provided may be different from the actual publication dated which may need to be independently confirmed. As will be apparent to those skilled in the art upon reading this disclosure, each of the individual embodiments described and illustrated herein has discrete components and features which may be readily separated from or combined with the features of any of the other several embodiments without departing from the scope or spirit of the present invention. The figures shown herein are not necessarily drawn to scale, with some components and features being exaggerated for clarity.

EXAMPLES

Example 1 : Br-FA form E (anhydrate) and/or G (anhydrate) : 10 g Br-FA, e.g. form H (anhydrate) or crude Br-FA, is suspended in a mixture of ethanol (80 ml_) and purified water (20 ml_). The resulting suspension is heated to 50 ⁰ C and stirred for 1 h. The resulting solution is cooled on an ice bath to 0-10 ⁰ C, filtered and dried using vacuum to yield Br-FA form E (anhydrate) and/or G (anhydrate).

Example 2:

Br-FA form E (anhydrate) and/or G (anhydrate) : 10 g Br-FA, e.g. form H (anhydrate) or crude Br-FA, is suspended in a mixture of methanol (80 ml_) and purified water (20 ml_). The resulting suspension is heated to 50 ⁰ C and stirred for 1 h. The resulting solution is cooled on an ice bath to 0-10 ⁰ C, filtered and dried using vacuum to yield Br-FA form E (anhydrate) and/or G (anhydrate).

Example 3:

Br-FA form H (anhydrate) : 10 g mixture of Br-FA forms E (anhydrate) and G (anhydrate) was suspended in ethyl formate (50 ml_). The resulting suspension is heated to reflux temperature and stirred for 3-4 h. The suspension is cooled on an ice bath to 0-10 ⁰ C, filtered and dried using vacuum to give Br-FA form H (anhydrate).

Example 4:

Br-FA form H (anhydrate): 0.3 g Br-FA as a mixture of Br-FA forms E (anhydrate) and G (anhydrate) was suspended in acetonitrile (6 ml_). The suspension is heated until a clear solution was obtained. The Br-FA form H (anhydrate) crystallised by cooling to 0-10 ⁰ C and was collected by filtration and dried using vacuum.

Example 5:

Br-FA form C (hydrate) : 1.0 g Br-FA, such as anhydrous Br-FA, was suspended in a mixture of ethyl acetate (10 mL) and purified water (1.0 ml_). The suspension was heated until a clear solution was obtained. The Br-FA form C (hydrate) was crystallised by cooling to 0-10 ⁰ C, collection by filtration and drying using vacuum.

Example 6:

Br-FA form D (hemihydrate): Br-FA (0.3 g) was added to toluene (20 mL) saturated with water. The resulting suspension was heated until a clear solution is obtained. The Br-FA form D (hemihydrate) was crystallised by cooling to 0-10 ⁰ C, optionally stirring for 1-2 day(s), collected by filtration and dried using vacuum.

Example 7:

Br-FA form I (anhydrate): 1 g Br-FA was suspended in hexane (10 mL). The resulting suspension was heated to reflux temperature and stirred for 3-4 h. The suspension was cooled on an ice bath to 0-10 ⁰ C, filtrated and dried using vacuum to yield Br-FA form I (anhydrate).

Example 8: Br-FA form H (anhydrate): The same procedure was used as in example 3, except that the starting Br-FA was from example 45 of WO 2005/007669.

Example 9:

Br-FA form H (anhydrate) : The same procedure was used as in example 4, except that the starting Br-FA was from example 45 of WO 2005/007669.

Example 10

Br-FA form H (anhydrate): 0.2985 g Br-FA was suspended in 6 ml acetonitrile and heated to 70 ⁰ C for 3 hours. The suspension was filtered through a 0.2 μm poly(tetrafluoroethylene) (PTFE) filter and the filtrate was stored at 6°C for 1 day. The precipitate was isolated by centrifugal filtration as a slightly humid sample to yield Br-FA form H (anhydrate).

Example 11 Br-FA form H (anhydrate): 0.1039 g Br-FA was suspended in 0.2 ml acetone at room temperature for 7 days. An aliquot of the solid was isolated as Br-FA form H (anhydrate).

Example 12

Br-FA form H (anhydrate): 0.0970 g Br-FA was suspended in 0.2 ml acetonitrile at room temperature for 7 days. An aliquot of the solid was isolated as Br-FA form H (anhydrate).

Example 13

Br-FA form H (anhydrate): 0.1049 g Br-FA was suspended in 0.2 ml tert-butyl methyl ether at room temperature for 7 days. An aliquot of the solid was isolated as Br-FA form H (anhydrate).

Example 14

Br-FA form H (anhydrate): 0.1063 g Br-FA was suspended in 0.2 ml diiso- propylether at room temperature for 7 days. An aliquot of the solid was isolated as Br-FA form H (anhydrate).

Example 15

Br-FA form H (anhydrate): 0.0718 mg Br-FA was suspended for 5 days in 0.6 ml of acetone/H ₂ O (1/1) at 25°C. After further 11 days an aliquot was isolated and dried for 1 hour under rotary oil pump vacuum to yield Br-FA form H (anhydrate).

Example 16

Br-FA form C (hydrate): 0.9969 g Br-FA was suspended in 10 ml ethyl acetate/H ₂ O (20/1) and heated to 70 ⁰ C for 2 hours. The solution was put in the fridge. No solid had formed after 15 days of storage. The solution was brought to room temperature and evaporated under a slight N ₂ flow. White crystals were obtained as a residue (slightly humid) to yield Br-FA form C (hydrate).

Example 17

Br-FA form C (hydrate): An aliquot of Example 16 was stored for 72 hours over 75% relative humidity (NaCI suspension) to yield Br-FA form C (hydrate).

Example 18

Br-FA form C (hydrate): 0.0341 g from Example 25 was suspended in 0.2 ml H ₂ O at room temperature for 24 hours. The solid was isolated by centrifugal filtration to yield Br-FA form C (hydrate).

Example 19

Br-FA form C (hydrate): 0.0374 g from Example 16 was stored open at 85% relative humidity and room temperature for 33 days and isolated as Br-FA form C (hydrate).

Example 20

Br-FA form C (hydrate): 0.1107 g Br-FA was suspended for 7 days in 0.2 ml ethyl acetate (saturated with H ₂ O) at 25°C. A sample was isolated and dried for 15 minutes under rotary pump vacuum. The remaining solid was dried for 5 days under rotary oil pump vacuum to yield Br-FA form C (hydrate).

Example 21

Br-FA form C (hydrate) : 0.1211 g Br-FA was suspended for 7 days in 0.2 ml ethyl acetate/H ₂ O (9/1) at 5°C. A sample was isolated as a humid and dried for 15 minutes under a rotary pump vacuum to yield Br-FA form C (hydrate).

Example 22 Br-FA form C (hydrate) : 0.4 g Br-FA was suspended in 10 ml ethyl acetate/H ₂ O (9/1) and stirred for 1 hour at 70 ⁰ C and the solution was brought to room temperature. After 10 minutes a slight turbidity was visible and the sample was stored at 6°C for 15 days. The solid was isolated and dried for 5 minutes under a rotary oil pump vacuum to yield Br-FA form C (hydrate).

Example 23

Br-FA as a mixture of forms E and G (anhydrates): 1.0 g Br-FA was dissolved in 10 ml methanol and filtered through a 0.22 μm filter. The solution was frozen with liquid nitrogen and the sample was lyophilized (0.0070 mbar, -82°C, 18 hours) to yield a mixture of Br-FA forms E and G (anhydrates).

Example 24 Br-FA as a mixture of forms E and G (anhydrates): 1.1034 g Br-FA was dissolved in

10 ml methanol and filtered through a 0.22 μm filter. The solution was frozen with liquid nitrogen and the sample was lyophilized (0.0030 mbar, -90 ⁰ C, 12 hours) to yield a mixture of Br-FA forms E and G (anhydrates).

Example 25

Br-FA as a mixture of forms E and G (anhydrates): 0.9918 g Br-FA was suspended in 5 ml ethanol/H ₂ O (4/1) and heated to 50 ⁰ C for 3 hours. The suspension was filtered through a 0.2 μm PTFE filter and the filtrate was stored at 6°C for 1 day. The precipitate was isolated by centrifugal filtration and dried for 24 hours under a rotary oil pump vacuum to yield a mixture of Br-FA forms E and G (anhydrates).

Example 26

Br-FA as a mixture of forms E and G (anhydrates) : 0.0110 g from Example 24 was stored open as a powder at 80 ⁰ C for 1 day to yield a mixture of Br-FA forms E and G (anhydrates).

Example 27

Br-FA as a mixture of forms E and G (anhydrates): 0.0204 g from Example 23 was stored open at 85% relative humidity and room temperature for 33 days to yield a mixture of Br-FA forms E and G (anhydrates).

Example 28 Br-FA form D (hemihydrate): 0.0992 g from Example 24 was dissolved in 7 ml toluene (saturated with H ₂ O) at 80 ⁰ C (10 minutes) and stored for 15 days at 6°C. An aliquot was isolated to yield Br-FA form D (hemihydrate).

Example 29 Br-FA form H (anhydrate): The same procedure was used as in example 3, except that the starting Br-FA was Br-FA form I such as that obtainable from example 7.

Example 30

Br-FA form H (anhydrate): The same procedure was used as in example 4, except that the starting Br-FA was Br-FA form C such as that obtainable from any of the examples 5 or 16-22. <_

Example 31

Br-FA form H (anhydrate): 10 g Br-FA were suspended in 100 ml acetone and 5 ml purified water and stirred to obtain a clear solution. The suspension was filtered and the filtrate was heated to 50 ⁰ C. To the solution was added 150 ml purified water.

Crystallisation took place, and the crystal suspension was kept at a constant

temperature at 50 ⁰ C. After 1 hour an aliquot of the crystal suspension was filtered to yield Br-FA form H (anhydrate).

Example 32 Br-FA as a mixture of forms E and G (anhydrates) : 10 g Br-FA were suspended in 100 ml isopropanol and 5 ml purified water and stirred to obtain a clear solution. The suspension was filtered and the filtrate was heated to 50 ⁰ C. To the solution was added 150 ml purified water. Crystallisation took place, and the crystal suspension was kept at a constant temperature at 50 ⁰ C. After 1 hour an aliquot of the crystal suspension was filtered to yield a mixture of Br-FA forms E and G (anhydrates).

Example 33

Br-FA as a mixture of forms E and G (anhydrates) : 10 g Br-FA were suspended in 100 ml methanol and 5 ml purified water and stirred to obtain a clear solution. The suspension was filtered. To the solution was added 150 ml purified water. Crystallisation took place

, and the crystal suspension was kept at a constant temperature at 25°C. After 1 hour an aliquot of the crystal suspension was filtered to yield a mixture of Br-FA forms E and G (anhydrates).

Example 34

Formulation containing Br-FA form C

The following composition was prepared :

24-bromo-fusidic acid, hydrate C 20 mg

Glyceryl myristate 210 mg

Glyceryl laurate 70 mg Glycerol 85% 60 mg

Diazolidinyl urea 5 mg

Sodium citrate 2.1 mg

Citric acid monohydrate 0.9 mg

HCI q.s. Water, purified up to Ig

Part of the aqueous phase was heated to about 70 ⁰ C and mixed with the melted oil phase (glyceryl myristate and glyceryl laurate) with homogenization. Part of the aqueous phase was mixed with citric acid monohydrate, sodium citrate, glycerol 85% and diazolidinyl urea and added to the cream blend with homogenization. The cream blend was cooled to room temperature with stirring. The 24-bromo-fusidic acid, hydrate C was added to the cream vehicle by means of a mortar and pestle. A stable cream formulation was obtained.

Example 35

Formulation containing Br-FA form H

24-bromo-fusidic acid, anhydrate H 20 mg

Glyceryl myristate 210 mg Glyceryl laurate 70 mg

Glycerol 85% 60 mg

Diazolidinyl urea 5 mg

Sodium citrate 2.1 mg

Citric acid monohydrate 0.9 mg HCI q.s.

Water, purified up to Ig

A formulation containing 24-bromo-fusidic acid, anhydrate H was prepared analogously to the procedure disclosed in Example 34. A stable cream formulation was obtained.

Example 36 Formulation containing Br-FA form I

24-bromo-fusidic acid, anhydrate I 20 mg Glyceryl myristate 210 mg

Glyceryl laurate 70 mg Glycerol 85% 60 mg

Diazolidinyl urea 5 mg

Sodium citrate 2.1 mg

Citric acid monohydrate 0.9 mg

HCI q.s. Water, purified up to Ig

A formulation containing 24-bromo-fusidic acid, anhydrate I was prepared analogously to the procedure disclosed in Example 34. A stable cream formulation was obtained.