5-methyl-(6s)-tetrahydrofolic acid and crystalline salts of l-valine ethyl ester

Abstract

The present invention relates to crystalline salts comprising 5-methyl-(6S)-tetrahydrofolic acid and L-valine ethyl ester and / or hydrates and / or solvates thereof and processes for obtaining the same, wherein the molar ratio of 5-methyl-(6S)-tetrahydrofolic acid to L-valine ethyl ester is from 1:0.3 to 1:3.0 (in mol / mol).

Description

[0001] The present invention relates to crystalline salts and / or hydrates and / or solvates of 5-methyl-(6S)-tetrahydrofolate and L-valine ethyl ester, wherein the molar ratio of 5-methyl-(6S)-tetrahydrofolate to L-valine ethyl ester is from 1:0.3 to 1:3.0 (mol / mol).

[0002] Tetrahydrofolate is mainly used as the calcium salt of 5-formyltetrahydrofolate (leucovorin and levoleucovorin) and 5-methyltetrahydrofolate. Or 5,10-methylenetetrahydrofolate sulfate The most prominent applications are in the treatment of megaloblastic folate anemia, as an antidote to increase the compatibility of folate antagonists (especially aminopterin and methotrexate) in cancer treatment (“antifolate rescue”), to enhance the therapeutic efficacy of fluorinated pyrimidines, and in the treatment of autoimmune diseases such as psoriasis and rheumatoid arthritis, to improve the mutagenic compatibility of certain antiparasitic drugs (such as trimethoprim-sulfamethoxazole), and to reduce the toxicity of bis(deazophosphatidylcholine) in chemotherapy.

[0003] The calcium salt of 5-methyl-(6S)-tetrahydrofolate is used in pharmaceuticals and food additives, as a vitamin preparation, for the prevention of neural tube defects, for the treatment of depression, and for influencing homocysteine ​​levels.

[0004] 5-Methyl-(6S)-tetrahydrofolate and its salts are known to be very unstable. In particular, they are highly susceptible to oxidation (see also A.L. Fitzhugh, Pteridines 4(4), 187-191(1993)), making them difficult to produce at a purity level acceptable for pharmaceutical active ingredients or food additives.

[0005] To overcome the instability of 5-methyltetrahydrofolate and its salts, various methods have been employed, such as removing oxygen as completely as possible or adding antioxidants such as ascorbic acid or reduced L-glutathione.

[0006] US 6,441,168 B1 discloses alkaline earth metal salts of 5-methyltetrahydrofolate, particularly calcium salts, their crystallization, and their uses. A disadvantage of such crystalline calcium salts of 5-methyl-(6S)-tetrahydrofolate is that they exhibit up to four polymorphic variants in their crystal form. Therefore, the preparation process of crystalline calcium salts of 5-methyl-(6S)-tetrahydrofolate must be controlled very precisely. Furthermore, the crystalline calcium salts of 5-methyl-(6S)-tetrahydrofolate of US 6,441,168 B1 typically contain at least one, but at most four, equivalents of water in each lattice of 5-methyl-(-6S)-tetrahydrofolate in all its polymorphic forms.

[0007] US 2016207925 A1 claims protection for lyophilized, spray-dried, or boiled-down compositions comprising L-asparagine or L-arginine and 5-methyl-(6S)-tetrahydrofolate. However, the disclosed compositions are simple non-stoichiometric mixtures and exist in an amorphous state.

[0008] New crystalline forms of pharmaceutically useful compounds offer opportunities to improve the performance characteristics of drugs and / or vitamins / medicinal foods. This expands the library of materials that formulation scientists can use to design new dosage forms with improved properties.

[0009] The technical problem of this invention is to provide a crystal form containing 5-methyl-(6S)-tetrahydrofolate, which overcomes the disadvantages of crystalline calcium salts of 5-methyl-(6S)-tetrahydrofolate known in the art.

[0010] In addition, new crystal forms often exhibit different physical and / or biological properties that can help in the manufacture or formulation of active compounds to achieve the purity levels and homogeneity required for regulatory approval.

[0011] To ensure the stability of tetrahydrofolate, the long-standing goal has been to provide compounds with low water absorption during storage and that can be thoroughly dried during manufacturing. Furthermore, there is a strong need for drugs that do not absorb large amounts of water under environmental conditions. In particular, substances whose water content does not change with variations in relative humidity are required, as large fluctuations in water content due to changes in relative humidity make it difficult to achieve high precision in dosage forms.

[0012] This technical problem was solved by a crystalline salt and / or hydrate and / or solvate of 5-methyl-(6S)-tetrahydrofolate and L-valine ethyl ester, wherein the molar ratio of 5-methyl-(6S)-tetrahydrofolate to L-valine ethyl ester is 1:0.3 to 1:3.0 (mol / mol).

[0013] The solid form of the present invention possesses improved pharmacological properties, thus providing the possibility of enhancing and designing improved pharmaceutical products. Compared to the polymorphic crystalline forms of the calcium salt of 5-methyl-(6S)-tetrahydrofolate known in the art, the crystalline salts of 5-methyl-(6S)-tetrahydrofolate and L-valine ethyl ester exhibit significantly lower water absorption, resulting in significantly improved control over the target dosage form level in pharmaceutical products, as changes in the amount of adsorbed water under varying relative humidity conditions are significantly less pronounced. Another advantageous aspect of the crystalline salts of 5-methyl-(6S)-tetrahydrofolate and L-valine ethyl ester is that high chemical and optical purity of 5-methyl-(6S)-tetrahydrofolate can be obtained in a single crystallization step.

[0014] Advantageously, the drug exhibits high kinetic solubility when administered orally, leading to improved and faster bioavailability. Consequently, the drug can act more readily.

[0015] 5-Methyl-(6S)-tetrahydrofolate is poorly soluble in water. The thermodynamically stable form of its calcium salt (crystal form III) is known to exhibit a water solubility of approximately 2.5 mg / ml at room temperature, while the metastable crystal form I has a solubility of approximately 10 mg / ml. Under certain pH conditions, particularly when the ambient pH is below the equilibrium pH of a given salt, the salt may potentially disproportionate into a free acid, resulting in a significant decrease in solubility. Therefore, the thermodynamic solubility of the claimed salt at approximately neutral to lower pH values ​​is unattainable due to the slow disproportionation of the salt (formation of a poorly soluble free acid). However, bioavailability is governed by kinetics. Drug products in solid form undergo dissolution after administration, and after the first dissolution step, the drug is diluted and distributed via body fluids. Therefore, kinetic solubility is a key parameter affecting bioavailability, as the initially dissolved drug substance is readily diluted and transported. Surprisingly, for salts of 5-methyl-(6S)-tetrahydrofolate and L-valine, the kinetic solubility was found to be approximately 50% higher than that of the known calcium salts (metastable form I). It is speculated that the difference in kinetic solubility of the salts of this invention relative to the thermodynamically stable form of the calcium salts (form III) is even greater. Therefore, much higher drug concentrations can be temporarily achieved.

[0016] Preferably, the molar ratio of 5-methyl-(6S)-tetrahydrofolate to L-valine ethyl ester is 1:0.5 to 1:2.5 (in mol / mol).

[0017] Even more preferably, the molar ratio of 5-methyl-(6S)-tetrahydrofolate to L-valine ethyl ester is 1:0.75 to 1:1.25 (in mol / mol).

[0018] Most preferably, the ratio of 5-methyl-(6S)-tetrahydrofolate to L-valine ethyl ester is about 1:1 (in mol / mol) and / or its hydrate and / or solvate.

[0019] Preferably, the salt of the present invention is a crystalline salt of 5-methyl-(6S)-tetrahydrofolate and L-valine ethyl ester, and has a PXRD pattern (crystal form A) containing at least one characteristic peak (expressed as 2θ±0.2°2θ (CuKα radiation)) selected from the following peaks located at 5.8, 6.9, 14.0, 19.0, 19.3, 22.2 and 25.9.

[0020] Most preferably, the salt of the present invention is a crystalline salt of 5-methyl-(6S)-tetrahydrofolate and L-valine ethyl ester, and has a PXRD pattern (crystal form A) containing at least three characteristic peaks (expressed as 2θ±0.2°2θ (CuKα radiation)) selected from the following at 5.8, 6.9, 14.0, 19.0, 19.3, 22.2 and 25.9. Even more preferably, the salt of the present invention is a crystalline salt of 5-methyl-(6S)-tetrahydrofolate and L-valine ethyl ester and has a PXRD pattern (crystal form A) containing characteristic peaks at 5.8, 6.9, 14.0, 19.0, 19.3, 22.2 and 25.9 (expressed as 2θ±0.2°2θ (CuKα radiation)).

[0021] Even more preferably, the salt of the present invention is a crystalline salt of 5-methyl-(6S)-tetrahydrofolate and L-valine ethyl ester, and has a PXRD pattern (crystal form A) containing at least one characteristic peak (expressed as 2θ±0.2°2θ (CuKα radiation)) selected from the following peaks located at 5.8, 6.9, 12.6, 14.0, 14.9, 17.5, 18.0, 19.0, 19.3, 20.0, 22.2 and 25.9.

[0022] Most preferably, the salt of the present invention is a crystalline salt of 5-methyl-(6S)-tetrahydrofolate and L-valine ethyl ester, and has a PXRD pattern (crystal form A) substantially as shown in FIG1.

[0023] Preferably, the salt of the present invention is a crystalline salt of 5-methyl-(6S)-tetrahydrofolate and L-valine ethyl ester, and has a PXRD pattern (crystal form B) containing at least one characteristic peak (expressed as 2θ±0.2°2θ (CuKα radiation)) selected from the following peaks located at 4.9, 7.4, 8.5, 14.1, 15.8, 16.3, 17.2, 18.6, 22.2 and 24.5.

[0024] More preferably, the salt of the present invention is a crystalline salt of 5-methyl-(6S)-tetrahydrofolate and L-valine ethyl ester, and has a PXRD pattern (crystal form B) containing at least three characteristic peaks (expressed as 2θ±0.2°2θ (CuKα radiation)) selected from the following at 4.9, 7.4, 8.5, 14.1, 15.8, 16.3, 17.2, 18.6, 22.2 and 24.5. More preferably, the salt of the present invention is a crystalline salt of 5-methyl-(6S)-tetrahydrofolate and L-valine ethyl ester, and has a PXRD pattern (crystal form B) containing peaks at 4.9, 7.4, 8.5, 14.1, 15.8, 16.3, 17.2, 18.6, 22.2 and 24.5.

[0025] Even more preferably, the salt of the present invention is a crystalline salt of 5-methyl-(6S)-tetrahydrofolate and L-valine ethyl ester, and has a PXRD pattern (crystal form B) containing at least one characteristic peak (expressed as 2θ±0.2°2θ (CuKα radiation)) selected from the following at 4.9, 7.4, 8.5, 14.1, 15.8, 17.2, 18.4, 18.6, 20.3, 20.9, 21.1, 22.2, 24.5 and 25.7. Most preferably, the salt of the present invention is a crystalline salt of 5-methyl-(6S)-tetrahydrofolate and L-valine ethyl ester, and has a PXRD pattern (crystal form B) substantially as shown in FIG2.

[0026] Even more preferably, the crystalline salt described above has a chemical and / or stereoisomeric purity of at least 99 wt% or higher.

[0027] Another aspect of the present invention is a method for obtaining a crystalline salt comprising 5-methyl-(6S)-tetrahydrofolate and L-valine ethyl ester, the method comprising the following steps:

[0028] i) Optionally, a mixture of 5-methyl-(6S)-tetrahydrofolate and L-valine ethyl ester is provided in a suitable solvent or solvent mixture.

[0029] ii) Add a base, optionally in a suitable solvent or solvent mixture, to dissolve the compound;

[0030] iii) Heat the composition to at least 60°C, and optionally perform clarification filtration;

[0031] iv) Crystallize the mixture and cool it to a temperature of 1°C to 30°C, optionally adding more solvent or a mixture of solvents; and

[0032] v) Separate the obtained solid material and optionally dry the product.

[0033] Preferably, the molar ratio of 5-methyl-(6S)-tetrahydrofolate to L-valine ethyl ester hydrochloride in step i) is 1:1 to 1:3.

[0034] More preferably, the solvent is water.

[0035] In steps iii) and / or iv), seed crystals may be added.

[0036] Preferably, L-valine ethyl ester is used as L-valine ethyl ester hydrochloride.

[0037] Furthermore, pharmaceutical compositions, food additives, and / or formulations comprising crystalline salts containing 5-methyl-(6S)-tetrahydrofolate and L-valine ethyl ester, and optionally one or more acceptable excipients, are part of this invention.

[0038] The pharmaceutical composition may be in the form of tablets, capsules, oral liquid preparations, powders, lyophilized preparations, granules, lozenges, reconfigurable powders, injectable or infusionable solutions or suspensions or suppositories.

[0039] The pharmaceutical composition may further comprise at least one additional therapeutic agent, and is preferably a pharmaceutical composition for oral, parenteral, intramuscular, intraspinal, intrathecal, periodontal, topical or rectal administration.

[0040] The present invention also covers the use of crystalline salts comprising 5-methyl-(6S)-tetrahydrofolate and L-valine ethyl ester as ingredients for the production of pharmaceuticals and / or as food additives.

[0041] Crystalline salts containing 5-methyl-(6S)-tetrahydrofolate and L-valine ethyl ester can be used to treat low homocysteine, anemia, neural tube defects, cardiovascular disease, depression, cognitive impairment, Alzheimer's disease and osteoporosis and / or for dietary management of low plasma and / or low red blood cell and / or low cerebrospinal fluid and / or low peripheral or central nervous system folate.

[0042] In summary, the performance characteristics provided by the crystalline salts of 5-methyl-(6S)-tetrahydrofolate and L-valine ethyl ester of the present invention are advantageous for use in pharmaceuticals or as food additives. In particular, the low variation in water content in environments with relative humidity between 20% and 75% is unpredictable to those skilled in the art.

[0043] Furthermore, its kinetic solubility is greater, which was something that those skilled in the art could not have foreseen. Example

[0044] Powder X-ray diffraction

[0045] Stoe Stadi P equipped with a Mythen 1K detector; Cu-Kα1 radiation; standard measurement conditions: transmission; 40 kV and 40 mA tube power; bent germanium monochromator; 0.02°2θ step size, 48 s step time, 1.5–50.5°2θ scan range; detector mode: step scan; 1°2θ detector step; standard sample preparation: 10–20 mg sample placed between two acetate / salt foils; sample holder: Stoe transmission sample holder; sample rotation during measurement. All sample preparation and measurements were performed in ambient air.

[0046] TG-FTIR

[0047] Thermogravimetric measurements were performed using a Netzsch Thermo-Microbalance TG 209 (sample disk with pinholes, N2 atmosphere, heating rate 10 K / min) coupled to a Bruker FTIR Spectrometer Vector 22.

[0048] DVS

[0049] DVS measurements are typically performed using the SPS11-100n “Sorptions Prüfsystem” from ProUmid (formerly known as “Projekt Messtechnik”), August-Nagel-Str. 23, 89079Ulm (Germany).

[0050] DVS measurements are performed as follows: The sample is placed on the aluminum support at the top of the microbalance and allowed to equilibrate at 50% RH, then a predefined humidity program is initiated:

[0051] (1) Keep at a constant relative humidity (RH) of 50% for two hours, then

[0052] (2) Increase RH to 95% at a rate of 5% per hour.

[0053] (3) Maintain RH at 95% for five hours.

[0054] (4) Reduce to 0% RH at a rate of 5% per hour.

[0055] (5) Keep RH at 0% for five hours.

[0056] (6) Increase RH to 95% at a rate of 5% per hour.

[0057] (7) Maintain RH at 95% for five hours.

[0058] (8) Reduce to 0% RH at a rate of 5% per hour.

[0059] (9) Keep RH at 0% for five hours.

[0060] (10) Increase to 50% RH at a rate of 5% per hour.

[0061] (11) Keep the RH at 50% for about one hour.

[0062] Example 1: Preparation of salts of 5-methyl-(6S)-tetrahydrofolate and L-valine ethyl ester without seed crystals.

[0063] 478 mg of 5-methyl-(6S)-tetrahydrofolate monohydrate was dissolved in 2.00 mL of 1.00 mol sodium hydroxide aqueous solution at room temperature, and 546 mg of L-valine ethyl ester hydrochloride was added. The solution was stirred at room temperature for about 20 minutes, and 0.300 mL of 1.00 mol hydrochloric acid aqueous solution was added. While stirring, the solution gradually became a concentrated suspension. 1.00 mL of water was added, and the suspension was sonicated. Another 0.300 mL of 1 mol hydrochloric acid aqueous solution was added, and the suspension was sonicated again. The suspension was stirred at room temperature for about 70 minutes, and the solid material was separated by centrifugation under ambient conditions. 0.5 mL of water was added to the wet solid material in the filter centrifuge, and centrifugation was repeated. This washing step was repeated twice more using 0.50 mL and 1.00 mL of water, respectively. The wet filter cake was transferred to a porous glass filter and air-dried by aspirating ambient air (about 22°C / about 34% RH) through the glass filter for about 20 minutes. 1 H-NMR examination of the dried material identified it as a 1:1 salt of 5-methyl-(6S)-tetrahydrofolate L-valine ethyl ester. TG-FTIR analysis of the sample showed a water content of approximately 0.5%. Powder X-ray diffraction was performed, yielding a PXRD pattern for crystal form A of the L-valine ethyl ester salt, essentially as shown in Figure 1.

[0064] Example 2: Vacuum drying of the salt of 5-methyl-(6S)-tetrahydrofolate and L-valine ethyl ester

[0065] Approximately 112 mg of the crystalline material according to Example 1 was vacuum dried at room temperature and approximately 10 mbar for about 1 hour, followed by ventilation with ambient air (approximately 22°C / approximately 23% RH). Analysis of the sample by TG-FTIR showed a water content of approximately 0.3%.

[0066] Equal portions of the sample for PXRD were prepared between two acetate foils at room temperature and approximately 25% relative humidity. Powder X-ray diffraction was performed, and the PXRD pattern of L-valine ethyl ester salt crystal form A was obtained as shown in Figure 1, exhibiting a peak at the 2θ angle as shown in Table 1.

[0067] Table 1: 2-θ angle, d-spacing, and qualitative strength of crystal form A of 5-methyl-(6S)-tetrahydrofolate L-valine ethyl ester salt according to Example 2. Vs = very strong strength, s = strong strength, m = moderate strength, w = weak strength, vw = very weak strength. It should be noted that the strength values ​​can vary significantly due to preferred orientation effects.

[0068]

[0069]

[0070] Example 3: Formation of a hydrate of the salt of 5-methyl-(6S)-tetrahydrofolate and L-valine ethyl ester

[0071] Approximately 100 mg of the crystalline material produced according to Example 1 was stored at room temperature and 75% relative humidity for 14 days. Aliquots for PXRD were prepared between two Kapton foils at room temperature and approximately 55% relative humidity. Powder X-ray diffraction was performed, and the PXRD pattern of L-valine ethyl ester salt crystal form B, as shown in Figure 2, was obtained, exhibiting a peak at the 2θ angle as shown in Table 2.

[0072] Table 2: 2-θ angle, d-spacing, and qualitative strength of 5-methyl-(6S)-tetrahydrofolate L-valine ethyl ester salt crystal form B according to Example 3. Vs = very strong strength, s = strong strength, m = moderate strength, w = weak strength, vw = very weak strength. It should be noted that the strength values ​​can vary significantly due to preferred orientation effects.

[0073]

[0074]

[0075] Example 4: Preparation of salts of 5-methyl-(6S)-tetrahydrofolate and L-valine ethyl ester

[0076] At room temperature, 4.78 g of 5-methyl-(6S)-tetrahydrofolate monohydrate (94.6% by determination, [6S]- content 97.6%) was dissolved in 20.0 mL of 1.0 mol sodium hydroxide aqueous solution. 5.47 g of L-valine ethyl ester hydrochloride was added. Then, 3.0 mL of 1.0 mol hydrochloric acid aqueous solution was added to the solution. While stirring, the solution gradually became a light suspension. Another 2.0 mL of 1.0 mol hydrochloric acid aqueous solution was added in 0.5 mL portions. The light suspension was seeded with crystals obtained as in Example 1. Another 1.0 mL of 1.0 mol hydrochloric acid aqueous solution was added. The solid material was separated by filtration and washed with 3.0 mL of water. The received solid was dried at 36 °C / 0–10 mbar. The dried material (2.61 g, corresponding to a determination-corrected yield of 43%) was examined by PXRD and HPLC. The content of 5-methyl-(6S)-tetrahydrofolate was determined to be 74.8% w / w. A powder X-ray diffraction pattern (crystal form A) was obtained, essentially as shown in Figure 1. HPLC showed a [6S]- content of 99.9%.

[0077] Example 5: Hygroscopicity and Water Content (DVS Experiment)

[0078] 21 mg of the salt of 5-methyl-(6S)-tetrahydrofolate and L-valine ethyl ester according to Example 2 was weighed into an aluminum sample dish for DVS measurement. DVS measurement was performed using an SPS11-100n “Sorptions Prüfsystem” from ProUmid, August-Nagel-Str. 23, 89079 Ulm (Germany). For relative humidity (RH) scans, a change rate of 5% per hour was used. The sample dish was placed in the instrument, and the defined relative humidity change program was started according to the following steps:

[0079] (1) Maintain RH at 50% for 2 hours, then

[0080] (2) Scan RH from 50% to 0% at a rate of 5% per hour, and keep RH at 0% for 5 hours, then

[0081] (3) Scan RH from 0 to 75% at a rate of 5% per hour, and maintain RH at 75% for 5 hours, then

[0082] (4) Scan RH from 75 to 0% at a rate of 5% per hour and keep RH at 0% for 5 hours.

[0083] (5) Scan RH from 0 to 75% at a rate of 5% per hour, and maintain RH at 75% for 5 hours, then

[0084] (6) Scan RH from 75% to 50% at a rate of 5% per hour and keep RH at 50% for 2 hours.

[0085] In parallel, the same experimental protocol was applied to the calcium salt samples used as a reference, and the results are shown in Figure 3. Within the relative humidity range of 0 to 55%, the relative sample mass change was less than 1% for the salts of 5-methyl-(6S)-tetrahydrofolate and L-valine ethyl ester (solid line), while for the calcium salts (dashed line), the relative sample mass change was approximately 6%.

[0086] Example 6: Kinetic solubility of crystalline salts of 5-methyl-(6S)-tetrahydrofolate and L-valine ethyl ester

[0087] 42.5 mg of anhydrous 5-methyl-(6S)-tetrahydrofolate L-valine ethyl ester salt (crystal form A) according to Example 2 was weighed into a 7 mL glass vial with a screw cap. 2.00 mL of purified / deionized water (e.g., water used for chromatography) was added to the solid using an adjustable-volume pipette. The mixture was vigorously stirred at room temperature for 1 minute. After one minute, a dilute suspension was observed, indicating that most of the sample had dissolved. The dilute suspension was filtered by centrifugation, and 1.50 mL of the aqueous solution was transferred to a tare glass vial (approximately 10 mL in volume). The water was dried in an air desiccator at 40°C for approximately 15 hours, then at 50°C for approximately 8 hours, followed by drying at 50°C under vacuum (10 to 20 mbar) for approximately 13 hours. Solubility was determined by gravimetric analysis of the solid residue. The solubility was 12.5 mg of 5-methyl-(6S)-tetrahydrofolate / mL.

[0088] Reference Example 1: Kinetic solubility of calcium 5-methyl-(6S)-tetrahydrofolate

[0089] 42.5 mg of anhydrous crystalline 5-methyl-(6S)-tetrahydrofolate calcium salt was weighed into a 7 mL glass vial with a screw cap. 2.00 mL of purified / deionized water (e.g., water used for chromatography) was added to the solid using an adjustable-volume pipette. The mixture was stirred vigorously at room temperature for 1 minute. After one minute, a suspension was observed. The suspension was filtered by centrifugation, and 1.50 mL of the aqueous solution was transferred to a tare glass vial (approximately 10 mL). The water was dried in an air desiccator at 40 °C for approximately 15 hours, then at 50 °C for approximately 8 hours, followed by drying at 50 °C under vacuum (10 to 20 mbar) for approximately 13 hours. Solubility was determined by gravimetric analysis of the solid residue. The solubility was 9.0 mg 5-methyl-(6S)-tetrahydrofolate / mL.

Claims

1. A crystalline salt comprising 5-methyl-(6S)-tetrahydrofolate and L-valine ethyl ester, wherein the molar ratio of 5-methyl-(6S)-tetrahydrofolate to L-valine ethyl ester is from 1 :0.75 to 1 :2.5, on a mol / mol basis, characterized in that said salt is a salt of 5-methyl-(6S)-tetrahydrofolate and L-valine ethyl ester and has a PXRD pattern with characteristic peaks at 5.8, 6.9, 14.0, 19.0, 19.3, 22.2 and 25.9, Form A, expressed in 2Θ ± 0.2° 2Θ, CuKa radiation, or characterized in that said salt is a salt of 5-methyl-(6S)-tetrahydrofolate and L-valine ethyl ester and has a PXRD pattern with characteristic peaks at 4.9, 7.4, 8.5, 14.1, 15.8, 16.3, 17.2, 18.6, 22.2 and 24.5, Form B, expressed in 2Θ ± 0.2° 2Θ, CuKa radiation.

2. The crystalline salt of claim 1, wherein the ratio of 5-methyl-(6S)-tetrahydrofolate to L-valine ethyl ester is 1 : 1, on a mol / mol basis.

3. The crystalline salt of claim 1 or 2, characterized by said salt is a salt of 5-methyl-(6S)-tetrahydrofolate and L-valine ethyl ester and has a PXRD pattern with at least one further characteristic peak selected from the group consisting of peaks at 12.6, 14.9, 17.5, 18.0 and 20.0, Form A, expressed in 2Θ ± 0.2° 2Θ, CuKa radiation.

4. The crystalline salt of claim 1 or 2, characterized by said salt is a salt of 5-methyl-(6S)-tetrahydrofolate and L-valine ethyl ester and has a PXRD pattern as shown in Figure 1, Form A.

5. The crystalline salt of claim 1 or 2, characterized by said salt is a salt of 5-methyl-(6S)-tetrahydrofolate and L-valine ethyl ester and has a PXRD pattern with at least one further characteristic peak at 18.4, 20.3, 20.9, 21.1 and 25.7, Form B, expressed in 2Θ ± 0.2° 2Θ, CuKa radiation.

6. The crystalline salt of claim 1 or 2, characterized by said salt is a salt of 5-methyl-(6S)-tetrahydrofolate and L-valine ethyl ester and has a PXRD pattern as shown in Figure 2, Form B.

7. The crystalline salt of claim 1 or 2, having a chemical purity of at least 99 wt%.

8. The crystalline salt of claim 7, having a stereochemical purity of at least 99 wt%.

9. A process for obtaining a crystalline salt comprising 5-methyl-(6S)-tetrahydrofolate and L-valine ethyl ester according to any one of claims 1 to 8, said process comprising the steps of: i) providing a mixture of 5-methyl-(6S)-tetrahydrofolate and L-valine ethyl ester, optionally in a suitable solvent or solvent mixture ii) adding a base, optionally in a suitable solvent or solvent mixture, to dissolve the compounds; iii) heating the composition to at least 60°C and optionally performing a clear filtration; iv) crystallizing the mixture and cooling to a temperature of 1 °C to 30°C, optionally adding more solvent or solvent mixture; and v) isolating the obtained solid material and optionally drying the product.

10. The method of claim 9, characterized by The molar ratio of 5-methyl-(6S)-tetrahydrofolate to L-valine ethyl ester in step i) is 1 : 1 to 1 :

3.

11. The method of claim 9 or 10, characterized in that The solvent is water.

12. The method of claim 9 or 10, characterized in that Seed crystals are added in step iii) and / or iv).

13. The method of claim 9 or 10, characterized in that L-valine ethyl ester is used as L-valine ethyl ester hydrochloride.

14. A pharmaceutical composition, food additive and / or a preparation comprising the crystalline salt comprising 5-methyl-(6S)-tetrahydrofolate and L-valine ethyl ester according to any one of claims 1 to 8 and optionally one or more acceptable excipients.

15. The pharmaceutical composition of claim 14, which is in the form of a tablet, a capsule, an oral liquid preparation, a powder, a lyophilizate, a granulate, a lozenge, a reconstitutable powder, a solution or suspension for injection or infusion or a suppository.

16. The pharmaceutical composition of claim 14 or 15, further comprising at least one additional therapeutic agent.

17. The pharmaceutical composition of claim 14 or 15, which is a pharmaceutical composition for oral, parenteral, intramuscular, intraspinal, intrathecal, periodontal or rectal administration.

18. The pharmaceutical composition of claim 14 or 15, which is a pharmaceutical composition for topical administration.

19. Use of the crystalline salt comprising 5-methyl-(6S)-tetrahydrofolate and L-valine ethyl ester according to any one of claims 1 to 8 as an ingredient for the manufacture of a medicament and / or as a food additive.

20. Use of the crystalline salt comprising 5-methyl-(6S)-tetrahydrofolate and L-valine ethyl ester according to any one of claims 1 to 8 for the manufacture of a medicament for the treatment of homocysteine reduction, anemia, neural tube defects, cardiovascular diseases, depression, cognitive impairment, Alzheimer's disease and osteoporosis and / or for the dietary management of low plasma and / or low red blood cell and / or low cerebrospinal fluid and / or low peripheral or central nervous system folate.

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