Patent Description:
Polymorphism is the ability of a chemical to exist in more than one distinct crystalline form having different arrangements of molecules in the crystal lattice. Although polymorphs of the same species are chemically identical, each polymorph has its own unique combinations of chemical, mechanical, thermal and physical properties. The variation in the physicochemical properties of different crystal forms makes polymorphism a potentially important issue for pharmaceutical companies (<NPL>). Difficulties and inconsistencies encountered in product performance and development can be attributed to polymorphism, and it is a common agreement within the pharmaceutical industry that polymorphism is a crucial aspect to consider when developing new drug candidates. Active pharmaceutical ingredients (API) are frequently delivered to patients in the solid state as solid forms offer convenience, physical and chemical stability, ease of product handling and low manufacturing costs. Because each solid form displays unique physicochemical properties, understanding and controlling the solid-state properties of an API is extremely important in the drug development process. Unintentional production of the wrong polymorph at the crystallization stage can result in pharmaceutical dosage forms that are either ineffective at a designated dose at the given application form or have the potential to become toxic. For these reasons regulatory agencies require pharmaceutical companies to control the crystallization process so that the desired polymorph is produced continually and has encouraged the application of process analytical technologies to crystallization process development.

Recrystallization from solution can be envisioned as a self-assembly process in which randomly organized molecules dissolved in an oversaturated solvent or solvent mixture come together to form an ordered three-dimensional molecular array with a periodic repeating pattern. Crystallization is vital to many processes occurring in nature and in the manufacturing of a wide range of materials. The quality of a crystalline product is usually judged by four main criteria: crystal size, - purity, -morphology, and crystal structure. Control of crystal morphology is essential in many applications because the particle habit can have a huge impact on post-crystallization processes. For the development of an API, it is vital to produce a specific polymorph to assure the bioavailability and stability of a drug substance in the final dosage form.

The German patent application (<CIT>) discloses <NUM>-alkyl-β-carbolines that due to their neuroprotective effect can be used for therapy and/or prophylaxis of movement disorders and/or neurologic diseases like for instance Alzheimer or Parkinson.

The US patent application <CIT> discloses the use of <NUM>-substituted <NUM>,<NUM>,<NUM>,<NUM>-tetrahydro-<NUM>-β-carbolines as active agents in the treatment of a variety of medical indications, including tinnitus. However, the substitution pattern of this group of β-carbolines differ structurally considerably from the substitution pattern of <NUM>-fluoro-<NUM>-methyl-β-carboline.

The international patent application (<CIT>) discloses β-carbolines, preferably <NUM>-alkyl-β-carbolines, preparation method thereof, and pharmaceutical composition containing said β-carbolines. Furthermore, this PCT application relates to the use of said β-carbolines for the prophylaxis and treatment of hearing loss, tinnitus, acoustic shocks, vertigo and equilibrium disorders.

The international patent application (<CIT>) discloses fluoro-<NUM>-methyl-β-carbolines including <NUM>-fluoro-<NUM>-methyl-<NUM>H-β-carboline, preparation method thereof, and pharmaceutical compositions containing fluoro-<NUM>-methyl-β-carbolines. In addition, this PCT application discloses medical use of fluoro-<NUM>-methyl-β-carbolines for treatment of acute and chronic ear diseases and hearing damages, dizziness and balance disturbances.

However, the international patent application (<CIT>) discloses <NUM>-fluoro-<NUM>-methyl-β-carboline and does not describe any crystalline or polymorphic form thereof.

It is the objective of the present invention to provide a stable crystalline polymorphic form of <NUM>-fluoro-<NUM>-methyl-β-carboline especially as active ingredient for the preparation of pharmaceutical compositions, and to provide such stable pharmaceutical compositions comprising said stable crystalline polymorphic form of <NUM>-fluoro-<NUM>-methyl-β-carboline as well as uses thereof and a method for preparation of that stable polymorphic form.

This objective of the present invention is solved by the teachings of the independent claims. Further advantageous features, aspects and details of the invention are evident from the dependent claims, the description, the figures, and the examples of the present application.

In the present invention several specific crystalline polymorphic forms of <NUM>-fluoro-<NUM>-methyl-β-carboline, also named herein <NUM>-FMC, are firstly provided and the technical features thereof are also disclosed. However, surprisingly only one of these specific crystalline polymorphic forms is sufficiently stable and thus suitable for the preparation of pharmaceutical compositions. All other polymorphic forms cannot be used for pharmaceutical formulations due to their instability.

The compound <NUM>-fluoro-<NUM>-methyl-β-carboline (<NUM>-FMC) exists in at least four polymorphic forms denominated polymorph A, B, C, and T. In practice, <NUM>-FMC is applied as a suspension to reach therapeutic concentrations in the target tissue. It is vital to produce a specific polymorph to assure the bioavailability and stability of the drug substance in the finished dosage form. Therefore, the chemical, mechanical, thermal and physical properties of each polymorph both in powder form and as part of the formulation are characterized. Conspicuous differences between the polymorphs were found. The melting points differed and recrystallisation yielded orthorhombic forms for polymorph A and monoclinic forms in the case of polymorph B. The spectra of x-ray powder diffractometry were clearly different as well as the spectra of ssNMR and infrared spectroscopy. The polymorphs C and T were hard to isolate in pure form due to their rapid decomposition so that clean spectra of these polymorphs were challenging to obtain. Investigations of the stability of the polymorphs revealed that polymorphic forms A, C and T are not suitable for the manufacturing of a pharmaceutical formulation, while polymorph A is not stable, but can be converted into polymorph B under the conditions disclosed herein. Surprisingly, the polymorphic form B was the only polymorph which is sufficiently stable and suitable for the preparation of a pharmaceutical formulation containing particles of crystalline <NUM>-fluoro-<NUM>-methyl-β-carboline of polymorphic form B. The polymorphic forms A, C, and T are not even sufficiently stable under normal storage conditions for pharmaceutical formulations at room temperature so that polymorphic forms A, C, and T of <NUM>-fluoro-<NUM>-methyl-β-carboline cannot be used as crystalline active ingredient in pharmaceutical formulations for the treatment of the inner ear. Such pharmaceutical formulations are preferably liposomal formulations, ointments, suspensions, gels and emulsions, wherein the polymorphic form B of the <NUM>-fluoro-<NUM>-methyl-β-carboline is present in crystalline form or micronized form, preferably as microparticles or nanoparticles.

Thus, several stability tests were performed with the polymorphic form B of the <NUM>-fluoro-<NUM>-methyl-β-carboline and it is proven herein that polymorph B is very stable and the perfect form for the intended pharmaceutical formulations. Only under drastic conditions as disclosed herein, polymorph B could be converted into polymorph A. A conversion of polymorph B into polymorph A could be achieved by extraction with supercritical carbon dioxide as well as by vacuum sublimation, while a spontaneous conversion of polymorph A into B happens in the formulation immediately after mixing. The reverse process has never been observed. Furthermore, the third polymorph C and the fourth polymorph T decompose even during the manufacture of a pharmaceutical formulation. Any conversion of polymorph B into polymorph C or into polymorph T could not be detected, not even under such drastic conditions like the exposure to supercritical carbon dioxide or vacuum sublimation or extreme heating.

Therefore, the present application is directed to the polymorphic form B of <NUM>-fluoro-<NUM>-methyl-β-carboline as the only stable polymorphic form of <NUM>-fluoro-<NUM>-methyl-β-carboline which is suitable for the preparation of the pharmaceutical formulations as disclosed herein.

Accordingly, the present invention relates to the crystalline polymorphic form of <NUM>-fluoro-<NUM>-methyl-<NUM>H-β-carboline of the formula (I)
<CHM>
wherein the crystalline polymorphic form of <NUM>-fluoro-<NUM>-methyl-<NUM>H-β-carboline (referred herein as polymorph B or polymorphic form B) has the X-ray powder diffraction pattern comprising <NUM>-theta angle values of <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> degrees with a deviation ± <NUM> degree.

Preferred, this crystalline polymorphic form B of <NUM>-fluoro-<NUM>-methyl-<NUM>H-β-carboline has the X-ray powder diffraction pattern comprising <NUM>-theta angle values of <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> degrees with a deviation ± <NUM> degree. More precisely, each indicated value has the deviation ± <NUM> degree and can be written as follows: <NUM> ± <NUM> degree, <NUM> ± <NUM> degree, <NUM> ± <NUM> degree, <NUM> ± <NUM> degree, <NUM> ± <NUM> degree, <NUM> ± <NUM> degree, <NUM> ± <NUM> degree, <NUM> ± <NUM> degree, <NUM> ± <NUM> degree, <NUM> ± <NUM> degree, <NUM> ± <NUM> degree, <NUM> ± <NUM> degree, and <NUM> ± <NUM> degree. Preferably the deviation is only ± <NUM> degree and more preferably only ± <NUM> degree.

In one embodiment, the crystalline polymorphic form of <NUM>-fluoro-<NUM>-methyl-<NUM>H-β-carboline (polymorph B) is in a monoclinic form having a space group of p2<NUM>/c, wherein one molecule of <NUM>-fluoro-<NUM>-methyl-<NUM>H-β-carboline is in an asymmetric unit cell having unit cell dimension of a = <NUM> ± <NUM>Å, b = <NUM> ± <NUM>Å, c = <NUM> ± <NUM>Å, α = <NUM> ± <NUM>°, β = <NUM> ± <NUM>° and γ = <NUM> ± <NUM>°.

In one embodiment, solid state <NUM>C-NMR spectrum of said crystalline polymorphic form (polymorph B) of <NUM>-fluoro-<NUM>-methyl-<NUM>H-β-carboline comprises peaks at <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> ppm with a deviation ± <NUM> ppm as shown in <FIG>. Thus, comprises peaks at <NUM> ± <NUM> ppm, <NUM> ± <NUM> ppm, <NUM> ± <NUM> ppm, <NUM> ± <NUM> ppm, <NUM> ± <NUM> ppm, <NUM> ± <NUM> ppm, <NUM> ± <NUM> ppm, <NUM> ± <NUM> ppm, <NUM> ± <NUM> ppm, <NUM> ± <NUM> ppm, <NUM> ± <NUM> ppm, <NUM> ± <NUM> ppm, <NUM> ± <NUM> ppm, <NUM> ± <NUM> ppm, <NUM> ± <NUM> ppm, <NUM> ± <NUM> ppm, and <NUM> ± <NUM> ppm. Preferably the deviation is only ± <NUM> ppm and more preferably only ± <NUM> ppm.

In one embodiment, the crystalline polymorphic form B of <NUM>-fluoro-<NUM>-methyl-<NUM>H-β-carboline according to the invention has a melting point of <NUM> ± <NUM>.

More preferred, IR-spectrum of said crystalline polymorphic form B of <NUM>-fluoro-<NUM>-methyl-<NUM>H-β-carboline comprises peaks at <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>-<NUM> with a deviation ±<NUM>-<NUM>. Preferably the deviation is only ± <NUM>-<NUM> and more preferably only ± <NUM>-<NUM>.

Most preferred, the IR-spectrum of said crystalline polymorphic form comprises peaks at <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>-<NUM> with a deviation ±<NUM>-<NUM>.

In the present application, another crystalline polymorphic form of <NUM>-fluoro-<NUM>-methyl-<NUM>H-β-carboline (hereafter, polymorph A, not forming part of the invention) has been identified as shown in <FIG>. However, this polymorphic form is not sufficiently stable and is disclosed herein as a reference example but is not part of the present invention. The crystalline polymorphic form of <NUM>-fluoro-<NUM>-methyl-<NUM>H-β-carboline (polymorph A) was fully characterized, while the polymorphic forms C and T (not forming part of the invention) are so instable that even full characterization was hardly possible. This crystalline polymorphic form A is in an orthorhombic form and has a space group of p2<NUM><NUM><NUM><NUM><NUM>, one molecule of <NUM>-fluoro-<NUM>-methyl-<NUM>H-β-carboline in an unit cell and unit cell dimension of a = <NUM> ± <NUM>Å, b = <NUM> ± <NUM>Å, c = <NUM> ± <NUM>Å, α = <NUM> ± <NUM>°, β = <NUM> ± <NUM>° and γ = <NUM> ± <NUM>°.

The crystal structure of polymorph A (not forming part of the invention)) (<FIG>) was characterized in some detail by X-ray crystallography. This polymorph crystallizes in an orthorhombic form within a space group p2<NUM><NUM><NUM><NUM><NUM>. Unit cell dimensions are a = <NUM> (<NUM>) Å, alpha = <NUM>°; b = <NUM> (<NUM>) Å, beta = <NUM>°; c = <NUM> (<NUM>) Å, gamma = <NUM>°. As shown in <FIG>), the <NUM>-FMC molecules are in multidimensional layers of pi-stacked molecules and orthogonal T-stacked molecules. It also shows clearly that there are no hydrates, solvates or salt-based counter ions present in the structure.

The picture of the formula confirmed the identity of the compound as disclosed.

Said polymorphic form A (not forming part of the invention) has the X-ray powder diffraction pattern comprising <NUM>-theta angle values of <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> degrees with a deviation ± <NUM> degree. Especially distinctive are the signals comprising <NUM>-theta angle values of <NUM>, <NUM>, <NUM> and <NUM>.

The melting points were measured in an open capillary Buechi M565 melting point apparatus. Heating rate was slowed down at <NUM> to 1centigrade per minute to determine the melting point more accurately. The uncorrected melting point turned out to be ~<NUM> +/-<NUM>. The melting point was confirmed by differential scanning calorimetry (DSC). The heating and cooling curves were recorded by differential scanning calorimetry (DSC; Netzsch DSC <NUM> F1) (<FIG>). The melting point was confirmed by DSC heating. The cooling curve demonstrated a broad range between <NUM> and <NUM> (<FIG>).

Solid state <NUM>C-NMR spectrum of said crystalline polymorphic form comprises peaks at <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM>-<NUM> (many C-F peaks) ppm with a deviation ± <NUM> ppm. (<FIG> shows ssNMR of polymorph A, and <FIG> shows ssNMR of the polymorph B (polymorphic form of the invention) of <NUM>-fluoro-<NUM>-methyl-<NUM>H-β-carboline. These spectra demonstrate clear differences between the two polymorphs A and B.

The extent of conversion generally depends on the relative stability of the polymorphs, kinetic barriers to phase conversion, and applied stress. Nonetheless, phase conversion generally is not of serious concern, provided that the conversion occurs consistently, as a part of a validated manufacturing process where critical manufacturing process variables are well understood and controlled.

The most thermodynamically stable polymorphic form of a drug substance is often chosen during development based on the minimal potential for conversion to another polymorphic form and on its greater chemical stability.

In the present application, the stability of the inventive and claimed polymorph of <NUM>-fluoro-<NUM>-methyl-<NUM>H-β-carboline (polymorph B) is tested and compared to other polymorphs of <NUM>-fluoro-<NUM>-methyl-<NUM>H-β-carboline (polymorphs A, C and T) as a reference.

It was tried to convert the inventive polymorph of <NUM>-fluoro-<NUM>-methyl-<NUM>H-β-carboline (polymorph B) into another polymorphic form (such as polymorph A) under various thermal conditions as described in Example <NUM>.

The crystalline polymorphic form of <NUM>-fluoro-<NUM>-methyl-<NUM>H-β-carboline (polymorph B) was dissolved in an organic solvent and said mixture was heated. As described in Example <NUM>, it failed to fully convert the crystalline polymorphic form (polymorph B) to another form (here polymorph A).

The thermal stability of the inventive polymorphic form compared to another polymorphic form is unexpected and technically advantageous, in particular, for the pharmaceutical process and regulation. The search results indicate that at room temperature and even below room temperature the polymorphic form A converts partially or fully into a thermally more stable form which is the polymorphic form B. This conversion can be accelerated by elevating the temperature. This thermal instability of polymorphic form A is a disadvantage which renders this polymorph unsuitable for pharmaceutical purposes.

The full conversion of the inventive polymorphic form (polymorph B) into polymorph A could be achieved only under drastic conditions, e.g. in supercritical CO<NUM> as described in Example <NUM>. The cylinder of the apparatus in which supercritical CO<NUM> had been introduced was loaded with polymorph B (<FIG> and heated to <NUM> and a pressure of <NUM> kPa. The time amounted to <NUM> hrs during which the API dissolved completely in the supercritical CO<NUM>. The spectrum of the final product is shown in <FIG>. It is quite obvious that a conversion happened of polymorph B in polymorph A. The powder was white (<FIG>). However, it is clear that such conditions are not applied during the preparation of the pharmaceutical formulations of interest. Moreover, the fact that polymorph B can only under extreme conditions be converted into another polymorphic form demonstrates that polymorph B is absolutely stable under the conditions the pharmaceutical formulations of interest are manufactured, stored and applied.

Various dissolution / crystallization conditions have been applied to try to convert polymorph B into polymorph A. As mentioned above, only with sophisticated procedures polymorph B could be fully converted into polymorph A (Example <NUM>). Polymorphic forms of a drug substance can undergo phase conversion when exposed to a range of manufacturing processes, such as drying, milling, micronization, wet granulation, spray-drying, and compaction. Exposure to environmental conditions such as humidity and temperature can also induce polymorph conversion. Therefore, polymorph A is unstable and thus not suited for pharmaceutical processes, while polymorph B was stable under all these conditions including drying, milling, micronization, wet granulation, spray-drying, and compaction.

In contrary to the polymorph A, the inventive crystalline (polymorph B) is very stable and thus no conversion occurs when exposed to a range of manufacturing and formulation processes. This is an unexpected technical advantage.

Third polymorphic form of <NUM>-fluoro-<NUM>-methyl-<NUM>H-β-carboline, polymorph C, was obtained after recrystallization of polymorph B in a ternary solvent mixture of heptane, ethanol and water as described in Example <NUM> and shown in <FIG>. The obtained polymorph C was very unstable under standard conditions and within a couple of weeks at room temperature, relative humidity of <NUM>% to <NUM>%, and atmospheric pressure polymorph C was completely converted into polymorph B.

By dissolving the <NUM>-fluoro-<NUM>-methyl-β-carboline in acidic water and titrating the solution to pH <NUM> a fourth polymorphic form of <NUM>-fluoro-<NUM>-methyl-<NUM>H-β-carboline, polymorph B appeared as the less stable polymorphic form of the <NUM>-fluoro-<NUM>-methyl-β-carboline. Already after a couple of days at standard conditions (room temperature, relative humidity of <NUM>% to <NUM>%, and atmospheric pressure) no polymorph T could be detected. This rapid disappearance of polymorph T made the full characterization quite challenging. However, it can be stated that none of the polymorphs C and T is a hydrate or a salt form. The isolation of said polymorph T failed. Upon storing polymorph A in aqueous media, conversion to polymorph B and signals of polymorph T are observed. At least the characteristic <NUM>-theta values of the polymorph T could be determined by subtraction of the signals belonging to polymorph B from a mixed diffractogram. Characteristic pattern of the X-ray powder diffraction is shown in <FIG>. All these findings clearly emphasize that polymorph B represents the most stable polymorph of <NUM>-FMC and is actually the only polymorph suitable for manufacturing the desired pharmaceutical formulations.

In a series of experiments, the polymorph stability has been analyzed. Micronized (≤ <NUM>) polymorphs A and B were added to phosphate buffer containing a non-ionic tenside as vehicle formulation. After <NUM> hours, aliquots were drawn, washed, dried and prepared for the polymorph identity measurement by x-ray powder diffractometry (XRPD). The XRPD analysis demonstrated that in sample initially made from polymorph A, a polymorph conversion of <NUM>% to polymorph B occurred during these <NUM> hours (<FIG>). <NUM> hours after preparation XRPD analysis resulted in a <NUM>% conversion of polymorphic form A to B. This data demonstrates that the inventive polymorph B is the stable crystal state in the formulation. Consistency analysis performed on a sample initially made from the inventive polymorph B in regular intervals over several months demonstrated no polymorph conversion (<FIG>).

In one embodiment, the crystalline polymorphic form of <NUM>-fluoro-<NUM>-methyl-<NUM>H-β-carboline has a particle size of the crystalline of ≤ <NUM>, preferred ≤ <NUM>, more preferred ≤ <NUM>, still more preferred ≤ <NUM>, still more preferred ≤ <NUM>, still more preferred ≤ <NUM>, and still more preferred ≤ <NUM>. Most preferred, said crystalline polymorphic form has a particle size of the crystal of ≤ <NUM>.

The present application demonstrates that the polymorphic form B of <NUM>-fluoro-<NUM>-methyl-β-carboline (<NUM>-FMC) impacts efficacy in vivo as outlined in Example <NUM>. The results are shown in <FIG> and <FIG>.

The effect of an intratympanic administration of polymorph A of <NUM>-FMC (<NUM>) prepared freshly (less than <NUM> before use) on the Permanent Threshold Shift has been investigated in guinea pigs (<FIG>). The Permanent Threshold Shift (PTS) is defined as the difference between the post-traumatic hearing threshold measured on day <NUM> and the baseline hearing threshold measured on day -<NUM>.

Furthermore, the effect of an intratympanic administration of polymorph B of <NUM>-FMC (<NUM>) prepared at least <NUM> before use, on the PTS in guinea pigs is presented in <FIG>.

Using a noise induced hearing loss model (NIHL) in guinea pigs, the applicant investigated the efficacy of a single intratympanic <NUM>-FMC application in the treatment of hearing loss. It was observed that animals treated with polymorph A of <NUM>-FMC have a moderate improvement on the recovery of the PTS. When compared to vehicle treated animals, polymorph A treatment demonstrated <NUM>-<NUM> dBs recovery of the PTS at <NUM> (<FIG>). However, for clinical use a stronger effect would be needed.

Surprisingly, during further development a clear improvement in efficacy of the <NUM>-FMC treated animals was observed, compared to previous experiments (<FIG>). Unexpectedly, a much stronger improvement of the PTS occurred across all investigated frequencies. The level of improvement increased from about <NUM>-<NUM> dBs as seen in <FIG> to <NUM>-<NUM> dBs as seen in <FIG>. This improvement of <NUM> dB and more as seen with polymorphic form B is clinically most meaningful as hearing is expressed in a logarithmic manner (decibel). In humans a hearing loss of <NUM> dB can hardly be noticed by the individual while a hearing loss of <NUM> dB makes communication difficult in particular if a background noise occurs simultaneously. Surprisingly some frequencies (for example <NUM> and <NUM>, <FIG>) of animals treated with polymorphic form B of <NUM>-FMC demonstrated a PTS close to zero.

This strong recovery is very important, because it elucidates the possibility that a treatment with polymorph B of <NUM>-FMC can lead to a complete recovery of hearing following a noise induced hearing loss.

In order to investigate what was the underlying cause for the improved efficacy data, the applicant performed a thorough analysis of the experimental procedures and demonstrated that improvement in the efficacy depended on the preparation of drug formulation. Initially, always freshly prepared formulation was used immediately after preparation containing polymorph A. However, in the experiments which demonstrated increased efficacy, the formulation was prepared in advance and stored for at least <NUM> before use. Subsequent analysis of the formulation demonstrated that formulation which initially was prepared with polymorphic form A, was fully converted into polymorphic form B, partially to <NUM>% within <NUM> (<FIG>) and fully already after <NUM> as shown in <FIG>. Taken together these data show that identity of the polymorphic form of <NUM>-FMC present in the formulation plays a very significant role. Additionally, the applicant demonstrated that formulation with polymorphic form B leads to a significant improvement of the in vivo efficacy data in the NIHL model in guinea pigs, when compared to formulation with polymorphic form A.

A further aspect of the present invention relates to a method for preparation of the inventive crystalline polymorphic form of <NUM>-fluoro-<NUM>H-methyl-β-carboline, comprising the following steps:.

It has to be stressed that all initial attempts to prepare a crystalline form of <NUM>-FMC resulted in the polymorphic form A. The polymorphic form A was obtained by crystallization from non-polar or slightly polar aprotic organic solvents like toluene cyclohexane or heptane. Therefore, the polymorphic form A was initially regarded as the stable polymorphic form by the Inventors, because always this polymorphic form A was obtained after recrystallization from n-heptane. Identifying the polymorphic form B as the much more stable and much more active form was a surprising result.

After realizing the polymorphic form B as pharmacologically highly potent and chemically highly stable, the above synthesis procedure was developed which selectively results in polymorphic form B.

The separated crystalline polymorphic form B of <NUM>-fluoro-<NUM>-methyl-<NUM>H-β-carboline has the X-ray powder diffraction pattern comprising <NUM>-theta angle values of <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> degrees with a deviation ± <NUM> degree as disclosed above.

Preferably, the crystalline polymorphic form B of <NUM>-fluoro-<NUM>-methyl-<NUM>H-β-carboline has the X-ray powder diffraction pattern comprising <NUM>-theta angle values of <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> degrees with a deviation ± <NUM> degree as disclosed above.

Also preferably, the inventive crystalline polymorphic form of <NUM>-fluoro-<NUM>-methyl-<NUM>-β-carboline (polymorph B) is in a monoclinic form having a space group of p2<NUM>c, wherein one molecule of <NUM>-fluoro-<NUM>-methyl-<NUM>H-β-carboline is in an asymmetric unit cell having unit cell dimension of a = <NUM> ± <NUM>Å, b = <NUM> ± <NUM>Å, c = <NUM> ± <NUM>Å, α = <NUM> ± <NUM>°, β = <NUM> ± <NUM>° and γ = <NUM> ± <NUM>° as disclosed above.

More preferred, solid state <NUM>C-NMR spectrum of said crystalline polymorphic form (polymorph B) of <NUM>-fluoro-<NUM>-methyl-<NUM>H-β-carboline comprises peak at <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> ppm with a deviation ± <NUM> ppm as shown in <FIG>.

More preferred, the crystalline polymorphic form B of <NUM>-fluoro-<NUM>-methyl-<NUM>H-β-carboline has a melting point of <NUM> ± <NUM> as disclosed above.

Still more preferred, IR-spectrum of said crystalline polymorphic form B of <NUM>-fluoro-<NUM>-methyl-<NUM>H-β-carboline comprises peaks at <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>-<NUM> with a deviation ±<NUM>-<NUM>. Most preferred, the IR-spectrum of said crystalline polymorphic form B comprises peaks at <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>-<NUM> with a deviation ±<NUM>-<NUM> as disclosed above.

Preferably, in step B1) the concentration of <NUM>-fluoro-<NUM>-methyl-<NUM>H-β-carboline in the mixture of organic solvents is in the range of <NUM> to <NUM>, preferably <NUM> to <NUM>, more preferably <NUM> to <NUM>.

After performing step C1), the suspension of <NUM>-fluoro-<NUM>-methyl-<NUM>H-β-carboline is also converted into the resulting solution as mentioned in step D1).

Preferably, in step C1) the solution or the suspension of <NUM>-fluoro-<NUM>-methyl-<NUM>H-β-carboline is heated at a temperature in the range between <NUM> to <NUM>.

Preferably, during step D1) or after step D1) of the above-mentioned methods, the following step D2) is performed:
D2) concentrating the mixture of the resulting solution or suspension by evaporating the solvents, preferably under vacuum.

Optionally, in step E1) after cooling down the resulting solution, the following step can be performed:
E2) seeding the crystalline polymorphic form B of <NUM>-fluoro-<NUM>-methyl-<NUM>H-β-carboline.

The various preparation methods are described in Examples <NUM> and <NUM> in details.

In some embodiments, in step A) of the above-described methods, <NUM>-fluoro-<NUM>-methyl-<NUM>H-β-carboline of the formula (I) is in a crystalline polymorphic form A, wherein, said polymorphic form has the X-ray powder diffraction pattern comprising <NUM>-theta angle values of <NUM>, <NUM>, <NUM>, and <NUM> degrees with a deviation ± <NUM> degree or alternatively <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> degrees with a deviation ± <NUM> degree.

A further aspect of the present invention relates to a medical use of the crystalline polymorphic form of <NUM>-fluoro-<NUM>-methyl-β-carboline (polymorphic form B) according to the invention, wherein the inventive crystalline polymorphic form of <NUM>-fluoro-<NUM>-methyl-<NUM>H-β-carboline has the X-ray powder diffraction pattern comprising <NUM>-theta angle values of <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> degrees with a deviation ± <NUM> degree.

Preferred, said crystalline polymorphic form B of <NUM>-fluoro-<NUM>-methyl-<NUM>H-β-carboline has the X-ray powder diffraction pattern comprising <NUM>-theta angle values of <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> degrees with a deviation ± <NUM> degree as disclosed above.

Also preferred, said crystalline polymorphic form is in a monoclinic form having a space group of p2<NUM>/c, wherein one molecule of <NUM>-fluoro-<NUM>-methyl-<NUM>H-β-carboline is in an asymmetric unit cell having unit cell dimension of a = <NUM> ± <NUM>Å, b = <NUM> ± <NUM>Å, c = <NUM> ± <NUM>Å, α = <NUM> ± <NUM>°, β = <NUM> ± <NUM>° and γ = <NUM> ± <NUM>° as disclosed above.

More preferred, solid state <NUM>C-NMR spectrum of said crystalline polymorphic form of <NUM>-fluoro-<NUM>-methyl-<NUM>H-β-carboline comprises peak at <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> ppm with a deviation ± <NUM> ppm as shown in <FIG> as mentioned above.

Still more preferred, said crystalline polymorphic form B of the pharmaceutical formulation has a melting point of <NUM> ± <NUM>.

Still more preferred, the IR-spectrum of said crystalline polymorphic form B of the pharmaceutical formulation comprises peaks at <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>-<NUM> with a deviation ±<NUM>-<NUM>.

In one embodiment, said above-mentioned crystalline polymorphic form of <NUM>-fluoro-<NUM>-methyl-β-carboline (polymorphic form B) according to the invention is useful for the treatment and/or prophylaxis of hearing damage, vertigo or vestibular disorder.

Preferably, said above-mentioned crystalline polymorphic form B of <NUM>-fluoro-<NUM>-methyl-β-carboline is useful for the treatment and/or prophylaxis of hearing damage, vertigo or vestibular disorder, wherein the hearing damage, vertigo or vestibular disorders is selected from the group consisting of Menière's disease, sudden sensorineural hearing loss, noise induced hearing loss, age related hearing loss, autoimmune ear disease, tinnitus, acoustic trauma, explosion trauma, labyrinthine deafness, presbycusis, trauma during implantation of inner ear prosthesis (insertion trauma), vertigo due to diseases of the inner ear, and hearing damages due to antibiotics and cytostatics.

A further aspect of the present invention relates to the pharmaceutical composition comprising the above-mentioned crystalline polymorphic form of <NUM>-fluoro-<NUM>-methyl-<NUM>H-β-carboline (polymorphic form B) together with at least one pharmaceutically acceptable carrier, excipient, solvent and/or diluent.

In one embodiment, said pharmaceutical composition is useful for the treatment and/or prophylaxis of hearing damage, vertigo or vestibular disorder.

Preferably, said pharmaceutical composition is useful for the treatment and/or prophylaxis of hearing damage, vertigo or vestibular disorder, wherein the hearing damage, vertigo or vestibular disorders is selected from the group consisting of Menière's disease, sudden sensorineural hearing loss, noise induced hearing loss, age related hearing loss, autoimmune ear disease, tinnitus, acoustic trauma, explosion trauma, labyrinthine deafness, presbycusis, trauma during implantation of inner ear prosthesis (insertion trauma), vertigo due to diseases of the inner ear, and hearing damages due to antibiotics and cytostatics.

The above-mentioned polymorphic form B of <NUM>-fluoro-<NUM>-methyl-β-carboline or the above-mentioned pharmaceutical compositions comprising the polymorphic form B of <NUM>-fluoro-<NUM>-methyl-β-carboline may be prepared and administered in form of transdermal application systems (plaster, film), droplets, pills, dragées, gels, hydrogels, ointments, sirups, granulates, suppositories (uvulas), emulsions, dispersions, microformulations, nanoformulations, liposomes, solutions, juices, suspensions, infusion solutions or injection solutions. Preferred are pharmaceutical compositions in form of liposomes, ointments, suspensions, gels and emulsions. Especially preferred are hydrogel formulations.

Such compositions are among others suitable for intravenous, intraperitoneal, intramuscular, subcutaneous, mucocutaneous, rectal, transdermal, topical, buccal, intradermal, intragastral, intracutaneous, intranasal, intrabuccal, percutaneous, intratympanic or sublingual administration. Especially preferred is the administration or injection into the middle ear as well as the topical administration through the ear drum.

As pharmaceutically acceptable carrier may be used for example lactose, starch, sorbitol, sucrose, cellulose, magnesium stearate, dicalcium phosphate, calcium sulfate, talc, mannitol, ethyl alcohol and the like. Powders as well as tablets can consists of <NUM> to <NUM> wt% of such a carrier.

Liquid formulations comprise solutions, suspensions, sprays and emulsions. For example, injection solutions based on water or based on water-propylene glycol for parenteral injections. For preparation of suppositories preferably low-melting waxes, fatty acid esters and glycerides are used.

The pharmaceutical compositions further comprise gels and other viscous drug carriers that are biodegradable or non-biologically degradable, aqueous or nonaqueous or based on microspheres.

Preferred, the pharmaceutical composition according to the invention is formulated for a topical and/or local administration. Suitable carrier for an otogenic administration, i.e. for an administration into the (middle) ear, are organic and inorganic substances that are pharmaceutically acceptable and do not react with the crystalline compound according to the invention and/or its further active agents, for instance cooking salt, alcohols, vegetable oils, benzyl alcohols, alkyl glycols, polyethylene glycols, glycerine triacetate, gelatine, carbohydrates like lactose or starch, magnesium carbonate (magnesia, chalk), stearate (waxes), talc and petrolatum (vaseline). The described compositions can be sterilized and/or can contain adjuvants like lubricants, preservatives like thiomersal (i.e. <NUM> wt%), stabilizers and/or humectants, emulsifiers, salts for affecting the osmotic pressure, buffer substances, dyes and/or flavors. These compositions may also contain one or multiple additional active agents, if necessary. The otogenic and/or audiological compositions according to the invention may comprise different compounds and/or substances, for instance other bioactive substances like antibiotics, anti-inflammatory active agents like steroids, corticoids, analgesics, antipyrines, benzocaines, procaines.

Compositions according to the present invention for topical administration can contain other pharmaceutically acceptable compounds and/or substances. In a preferred embodiment of the present invention a topical excipient is selected, which does not amplify the release of the crystalline <NUM>-fluoro-<NUM>-methyl-β-carboline, and of the possibly additional active agent or active agents to the blood circular system or to the central nervous system, when it is administered to the ear, in the middle ear or in the auditory canal. Possible carrier substances contain hydrocarbonic acids, water-free adsorbents like hydrophile petrolatum (vaseline) and water-free lanolin (i.e. Aquaphor®) and means based on water -oil emulsions like lanolin and Cold Cream. More preferred are carrier substances that essentially are non-excluding and that contain usually carrier substances, which are water soluble as well as substances based on oil-in-water emulsions (creams or hydrophilic ointments) and substances with a water-soluble basis like carrier substances based on polyethylene glycol and aqueous solutions that were gelled with several substances like methylcellulose, hydroxyethylcellulose and hydroxypropylmethylcellulose.

The following examples are included to demonstrate preferred embodiments of the invention. It should be appreciated by those of skilled in the art that the techniques disclosed in the examples which follow represent techniques discovered by the inventor to function well in the practice of the invention, and thus can be considered to constitute preferred modes for its practice. However, those skilled in the art should, in light of the present disclosure, appreciate that many changes can be made in the specific embodiments which are disclosed and still obtain a like or similar result without departing from the spirit and scope of the invention.

Further modifications and alternative embodiments of various aspects of the invention will be apparent to those skilled in the art in view of this description. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the general manner of carrying out the invention. It has to be understood that the forms of the invention shown and described herein are to be taken as examples of embodiments. Elements and materials may be substituted for those illustrated and described herein, parts and processes may be reversed, and certain features of the invention may be utilized independently, all as would be apparent to one skilled in the art after having the benefit of this description of the invention.

The ss-NMR was measured at RT with a Bruker Advance III HD, <NUM> ssMAS (solid state Magic Angle Spinning) with a <NUM> rotor and a spinning rate of <NUM> and a transmitter frequency of <NUM>. The sample was filled dry in the <NUM> rotor and measured at room temperature.

XRPD was measured in an open capillary with a STOE Modell Stadi, Detector:.

Data collection: XRPD was measured at room temperature with a STOE Modell StudyP, Detector: Mythen Dectris <NUM> using CuKα1-radiation (<NUM>Å) in transmission geometry, a Cu-long-fine focus X-Ray generator and a curved Germanium monochromator. Samples were measured from <NUM> to <NUM><NUM>-theta with the Debye-Scherrer Scan mode. The accuracy of the peak positions is defined as +/- <NUM> degrees two theta due to experimental differences like sample preparation and packing density of the capillary.

The IR was measured under standard conditions with a Jasco ATR Diamond unit (Golden Gate). First, the background is measured without a sample. Then, a visible amount of the sample is placed on the diamond ATR unit and screwed together. Samples were measured with <NUM> scans in a range from <NUM> -<NUM>-<NUM>. The background is subtracted from the actual scan to obtain the IR spectrum of the sample.

<NUM>-fluoro-<NUM>-methyl-β-carboline (<NUM>-FMC) is suspended in n-heptane (<NUM> per g) and the suspension is heated under reflux. The resulting solution is allowed to slowly cool to rt and stand overnight. The precipitated solid is filtered, washed with n-heptane and dried. Polymorphic form A of <NUM>-FMC is obtained as pale yellow-brown needles in <NUM>% yield.

<CIT> discloses a synthetic method of <NUM>-fluoro-<NUM>-methyl-β-carboline (<NUM>-FMC) and the <NUM>-FMC is obtained as raw product in forms of mustard-yellow crystals. Said crystals are in the polymorphic form A of the present invention. Elemental analysis of said crystals shows small amounts of impurities, such as water and solvent and such impurities may cause a depressed melting point compared to the highly purified pholymorphic form A obtained in this application which appeared as white crystals.

After <NUM> crystallization at room temperature, the crystals were removed by vacuum filtration, sucked as dry as possible (moving of the lose filter cake with a plastic spatula). The semi-dry product was transferred into a flask and dried for <NUM> at <NUM>. 5Pa at room temperature. The dry-yield was <NUM> (<NUM>%).

This sample was analyzed with X-ray diffraction and compared to the starting material, which was also re-analyzed to confirm the delivered spectra.

The XRPD of the recrystallization product shows that the crystals are mainly the "polymorph A", but also -<NUM>% of the polymorph B are present; probably because a smaller amount of heptane was used for the recrystallization. The XRPDs before and after the recrystallization are shown in an overlay. To eliminate the remaining polymorph B, the batch was subjected to a further recrystallization process (see part <NUM>).

Recrystallization under harsh conditions (too high temperature, too big flask and heating source <NUM> above the solvent level). The equipment was used as in the first experiment. <NUM> were refluxed in <NUM> of n-heptane in a <NUM> flask: The solution appeared clear, but above the solvent level, continuously crystals formed during the heating process and occasionally were rinsed back into the mixture by the dripping boiling heptane.

This mixture (with some preformed crystals was cooled down and quickly formed crystals in the solution (due to already present crystals). After crystallization was complete, the formed crystals in the flasks looked as if black dots were present and brown smear.

Second recrystallization: In a <NUM> flask, a suspension of <NUM> in <NUM> of heptane was refluxed (metal heating block) and the resulting clear solution was maintained at reflux for <NUM>, before the heating source was removed. The reaction was allowed to cool down and as the first crystals appeared, the solution was stirred occasionally to avoid the formation of big crystals. After standing for <NUM>, the fluffy crystals were removed by filtration, washed with <NUM> of n-heptane, sucked dry, collected in a smaller flask and dried overnight in a freeze dryer at r. with 100Pa. The resulting crystals appear fluffier and more voluminous than from the first recrystallization. The XRPD shows exclusively the polymorph A.

In a separate experiment we recorded the XRPD of the polymorph B as dry powder and in a capillary soaked with n- heptane to evaluate the influence of free heptane present during the measurement. This is important to make sure that none of the signals detected from the "heptane polymorph" are artifacts due to included residual heptane. It was confirmed that additional heptane has no influence on the recorded XRPDs.

X-ray powder diffractometry is currently regarded as the definitely method to detect polymorphism. In addition, demonstration of a nonequivalent structure by single crystal X-ray diffraction would corroborate polymorphic structures.

The crystal structure of polymorph A (<FIG>) was characterized in some detail by X-ray crystallography. This polymorph crystallizes in an orthorhombic form within a space group p2<NUM><NUM><NUM><NUM><NUM>. Unit cell dimensions are a = <NUM> (<NUM>) Å, alpha = <NUM>°; b = <NUM> (<NUM>) Å, beta = <NUM>°; c = <NUM> (<NUM>) Å, gamma = <NUM>°. As shown in <FIG>, the <NUM>-FMC molecules are in multidimensional layers of pi-stacked molecules and orthogonal T-stacked molecules. It also shows clearly that there are no hydrates, solvates or salt-based counter ions present in the structure.

X-ray powder diffraction of polymorph A has characteristic signals in <NUM>-theta.

<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> ppm.

<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>-<NUM>.

<NUM> of <NUM>-fluoro-<NUM>-methyl-β-carboline (<NUM>-FMC) is suspended in a mixture of isopropanol and n-heptane and the suspension is heated under reflux. The resulting solution is cooled and precipitated solids are filtered, washed with n-heptane and dried. Polymorphic form B of <NUM>-FMC is obtained as pale yellow-brown powder in <NUM>% yield.

<NUM> of <NUM>-fluoro-<NUM>-methyl-β-carboline (<NUM>-FMC) is dissolved in <NUM> of DCM and <NUM> of n-heptane is added into the solution. Precipitated solids are filtered, washed with n-heptane and dried. Polymorphic form B of <NUM>-FMC is obtained as pale yellow-brown powder in <NUM>% yield.

<NUM> of <NUM>-fluoro-<NUM>-methyl-β-carboline (<NUM>-FMC) is dissolved in <NUM> of DCM and <NUM> of MTBE is added into the solution. The resulting suspension is concentrated by rotary evaporator at <NUM> under 65kPa until a clear solution is obtained. After <NUM>, the evaporation is stopped, the solution is cooled, and the resulting suspension is filtered. The rough crystalline polymorphic form B of <NUM>-FMC is obtained as pale brown solid and dried. Yield = <NUM>%.

<NUM> of <NUM>-fluoro-<NUM>-methyl-β-carboline (<NUM>-FMC) is dissolved in <NUM> of acetone and <NUM> of MTBE is added into the solution. The resulting solution is concentrated by rotary evaporator at <NUM> under 45kPa until a clear solution is obtained. After <NUM>, the resulting suspension is cooled and filtered. The rough crystalline polymorphic form B of <NUM>-FMC is obtained as pale brown solid and dried. Yield =<NUM>%.

<NUM> of <NUM>-fluoro-<NUM>-methyl-β-carboline (<NUM>-FMC) is dissolved in <NUM> of DMSO. The clear solution is precipitated in <NUM> of distilled water and the formed precipitation is centrifuged down. The supernatant is discarded and the precipitation is washed 3x with distilled water to remove residual DMSO. (Vortex - centrifuge-process). After the last washing step, the bright white solids are frozen in liquid nitrogen, lyophilized and represent pure polymorph B.

An aqueous suspension of <NUM> of <NUM>-fluoro-<NUM>-methyl-β-carboline (<NUM>-FMC) is stirred and HCl is added to pH <NUM>. During the salt formation, a clear, yellow solution is obtained. To assure the absence of any solids, it is filtered through a <NUM> syringe filter. The solution is stirred again and basified with NaOH ad pH <NUM>. During the addition, a thick white precipitation of the free base is observed and centrifuged down. The supernatant is decanted off and the solid washed thoroughly by repeated treatment with distilled water, vortexing and centrifuging processes (4x). After the final wash, the solid is frozen in liquid nitrogen and lyophilized. Yield: <NUM>% of pure polymorph B.

The crystal structure of polymorph B (<FIG>) was characterized in some detail by X-ray crystallography as well. This polymorph crystallizes in a monoclinic form within a space group p2<NUM>c. Unit cell dimensions are a = <NUM> (<NUM>) Å, alpha = <NUM>°; b = <NUM> (<NUM>) Å, beta = <NUM> (<NUM>)°; c = <NUM> (<NUM>) Å, gamma = <NUM>°. As shown in <FIG>), the <NUM>-FMC molecules are in ordered layers of zig-zag bands. It also shows clearly that there are no hydrates, solvates or salt-based counter ions present in the structure. The analysis revealed absence of any solvent. The picture of the formula confirmed the identity of the compound as claimed.

The calculated XRPD pattern from polymorph B and the measured XRPD pattern of polymorph B are shown in <FIG> and as an overlay in <FIG>. Despite a slight variation in the absolute <NUM>-theta values, the patterns are relative to each other nearly identical.

<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>. <NUM>, and <NUM> ppm.

<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>-<NUM>.

Powders of the polymorphs of <NUM>-FMC were heated up under stirring whereby the heating was slowed at temperatures higher than <NUM> (<NUM> centigrade per minute). Polymorph A sample melted at ~<NUM>. The heating and cooling curves were recorded by differential scanning calorimetry (DSC; Netzsch DSC <NUM> F1) (<FIG>). The melting point was confirmed by DSC heating. The cooling curve demonstrated a broad range between <NUM> and <NUM> (<FIG>).

The polymorph B sample melted at ~<NUM>. Analysis of the DSC heating curve demonstrated a transition phase, characterized by a small slowdown of the melting process (<FIG>). During the cooling process of polymorph B, the curve showed a biphasic transition in a temperature range of <NUM>-<NUM> (<FIG>). This reflects down-grading of polymorph B. Diffractometry analysis revealed that the conversion of polymorph B into polymorph A correlated with the duration of the melting status up to a complete conversion. Vacuum sublimation yielded a complete conversion into polymorph A.

<NUM>-<NUM>: Polymorph B of <NUM>-FMC was dissolved in n-heptane, the suspension was heated (<NUM>) for <NUM>:<NUM> under stirring. Then the suspension was cooled and stirred at room temperature for <NUM> hrs. The precipitate was filtered, washed with n-heptane and dried by air. The resulting XRPD spectrum did not reveal conversion into form A.

<NUM>-<NUM>: Polymorph B of <NUM>-FMC was diluted in toluene and heated up to <NUM> and cooled down to room temperature. The precipitate was filtered, washed with toluene and dried in an air stream. The XRPD spectrum indicated some presence of polymorph A, but this experiment was not reproducible so that it is assumed that also under these conditions no conversion of polymorph B to polymorph A takes place.

<NUM>-<NUM>: A suspension of polymorph B of <NUM>-FMC was diluted in n-heptane and heated up to <NUM>. It was kept for <NUM> hrs <NUM> in a flask under reflux conditions, followed by gentle cooling down to room temperature, stirred for <NUM> hrs. The precipitate was filtered, washed with heptane and dried by air. The XRPD proved unchanged polymorph B.

<NUM>-<NUM>: A suspension of polymorph B of <NUM>-FMC was diluted in n-heptane and heated up to <NUM> until the substance was completely diluted. Seed crystals of polymorph A were added to the solution which was gentle cooled down to room temperature. The precipitate was filtered, washed with n-heptane and dried by air. The XRPD proved unchanged polymorph B.

Extraction / polymorph conversion with supercritical CO<NUM> was performed with <NUM> of crude, off-white polymorph B in an ExtrateX Rapid Expansion of a Supercritical Solution (REES) system. The extraction vessel was heated to <NUM> with a pressure of <NUM> bar. The nozzle was a stainless-steel capillary <NUM> length, inner diameter <NUM> at <NUM>. The expansion vessel was heated to <NUM> at <NUM>-5Mpa. Equilibration time: <NUM>; spraying-time: <NUM>. After the process, polymorph A is obtained as a bright white powder.

The cylinder of the apparatus in which the supercritical CO<NUM> had been introduced was loaded with polymorph B (<FIG>) and heated to <NUM> and a pressure of 35MPa. The time amounted to <NUM> hrs during which the API dissolved completely in the supercritical CO<NUM>. The spectrum of the final product is shown in <FIG>. It is quite obvious that a transformation happened of polymorph B into polymorph A. The powder was white (<FIG>).

The polymorph B sample melted at ~<NUM>. Analysis of the DSC heating curve demonstrated a transition phase, characterized by a small slowdown of the melting process (<FIG>). During the cooling process polymorph B, the curve showed a biphasic transition in a temperature range of <NUM>-<NUM> (<FIG>). This reflects down-grading of polymorph B. Diffractometry analysis revealed that the conversion of polymorph B into polymorph A correlated with the duration of the melting status up to a complete conversion. Vacuum sublimation at <NUM>-<NUM> kPa yielded a complete conversion into white crystals of polymorph A.

<NUM> of poloxamer based formulation with <NUM>/ml <NUM>-FMC were cooled to <NUM>, vortexed and transferred into a <NUM> Eppendorf vial. The cooled vial was centrifuged for <NUM> with a table-centrifuge, the supernatant polymer solution was removed with a pipette and discarded. The remaining <NUM>-FMC was resuspended and vortexed with <NUM> of ice cold milli-Q water and centrifuged down as described before. The supernatant water was again removed with a pipette and the washing procedure is repeated <NUM> times (in total <NUM> washings). Note: Keep the solution cool to facilitate the centrifugation process. After the last washing, the remaining white <NUM>-FMC is cooled with liquid nitrogen and freeze dried overnight at 100Pa at room temperature.

After <NUM> hours in formulation <NUM>% of polymorphic form A is converted into polymorphic form B (see <FIG>). Keeping the formulation for <NUM> hours or longer results in <NUM>% conversion of polymorphic form A into polymorphic form B as shown in <FIG>.

<NUM> <NUM>-FMC (polymorph B) were dissolved in <NUM> ethanol and 500µL water. Then <NUM> of heptane were added, resulting in phase separation. Despite the phase separation, the rotary evaporator was used at <NUM> and 14kPa. An oil film on the piston wall separated, which suddenly became firm. This crystalline solid substance was analyzed demonstrating polymorph B only.

A further <NUM> of heptane was added to the reaction product and heated under reflux conditions (temperature about <NUM>) for <NUM> at normal pressure until the solution looked clear. The solution was cooled overnight, while stirring, to room temperature. Darker lumps were formed on the piston wall while a homogeneous crystal pulp formed on the bottom of the piston. The homogeneous crystal pulp consisted of polymorph C.

The X-RPD of the polymorphic form C is measured as shown in <FIG> and characteristic peaks are summarized in Table <NUM>.

<NUM> <NUM>-FMC of polymorph B, micronized, were acidified with HCl followed by sonication at <NUM>. The cloudy solution was basified with sodium hydroxide to pH <NUM> which caused a fine, powdery precipitation. The powder was streaked out on a weighing paper for air drying. The resulting XRPD revealed a mixture of a new polymorph and polymorph B. The percentage was ~<NUM> to <NUM>%. The new polymorph was clearly different from polymorphs A, B, and C and denominated polymorph T.

An NMR analysis of polymorph BIT mixture, extra-dry polymorphs BIT mixture and pure polymorph B was conducted to check for the presence of water. None of the samples showed more water than present in the deuterated chloroform. Therefore, the analyses did not reveal any evidence for hydrates.

The X-RPD of the polymorphic form T is measured as shown in <FIG> and characteristic peaks are summarized in Table <NUM>.

General procedures: All in vivo proof of principle studies were performed in the well-established guinea pig model of NIHL. The guinea pig was chosen because the anatomy is comparable in both structure and size to that of humans. Hearing function was assessed by brain evoked response audiometry (BERA).

Methods: Adult guinea pigs received an intratympanic (i. ) injection of either <NUM>-FMC formulated in a thermosensitive hydrogel or hydrogel alone. All procedures were performed under anesthesia. BERA was used to measure auditory brainstem responses (ABRs) on day -<NUM> and day <NUM>. The auditory stimuli were sinus tones (<NUM> duration at <NUM>, <NUM>, <NUM>) at 5dB steps from <NUM>-90dB. These measurements were used to calculatethe PTS. The acoustic trauma was performed on day <NUM> and consisted of a single continuous band (quarter-octave centered at <NUM>) at 118dB SPL for <NUM>. Animals were treated <NUM> after the end of the acoustic exposure. The round window was visualized under a surgical microscope via a small hole drilled in the bone of the bulla of the left ear. 10µL of gel containing either <NUM>-FMC or vehicle was injected using a Hamilton syringe and a motorized pump onto the round window membrane (RWM) before the hole was closed with dental cement.

Formulation preparation: a non-ionic tenside based solution is prepared in advance, by dissolving an appropriate amount of the non-ionic tenside in water or in PBS buffer and allowing for an overnight mixing under refrigerated conditions. Once the non-ionic tenside is completely dissolved, osmolality and pH are adjusted if desired. Next the solution is filtered through a <NUM> sieve to remove undissolved gel particles. This concludes compounding of the vehicle. API (Active Pharmaceutical Ingredient) containing formulation is prepared by addition of micronized <NUM>-FMC (≤<NUM>) at a concentration of <NUM>/mL. For experiments presented in <FIG>, <NUM>-FMC formulation was applied directly after being prepared. For experiments in <FIG>, <NUM>-FMC formulation was prepared at least <NUM> prior to animal experiments.

An intratympanic treatment with <NUM>-FMC in either polymorphic form A or B resulted in a substantial reduction in NIHL (<FIG> and <FIG>).

For polymorphic form A a moderate effect could be achieved, where the PTS was reduced by an average of <NUM> dB (<FIG>). Overall, the noise exposure led to an average PTS of <NUM> dB in the vehicle-treated controls and this was reduced by about <NUM> dB to a <NUM> dB threshold shift in animals treated with polymorphic form A of the <NUM>-FMC.

For polymorphic form B this effect was considerably stronger and significant across all investigated frequencies and resulted in a therapeutically useful reduction of PTS by at least <NUM> dB up to a remarkable <NUM> dB (<FIG>). Importantly, at some frequencies the PTS was reduced to <NUM>, which demonstrates that treatment with polymorph B of <NUM>-FMC has the potential of complete recovery from noise induced hearing loss. Overall the noise exposure led to an average PTS of <NUM>. 7dB in the vehicle treated controls and this was significantly reduced by an average of <NUM> dB to a <NUM> dB threshold shift in animals treated with polymorphic form B of the <NUM>-FMC.

Claim 1:
A crystalline polymorphic form of <NUM>-fluoro-<NUM>-methyl-<NUM>H-β-carboline of the formula (I)
<CHM>
wherein the crystalline polymorphic form has the X-ray powder diffraction pattern measured by using CuKα1-radiation, comprising <NUM>-theta angle values of <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> degrees with a deviation ± <NUM> degree.