Crystalline salt comprising 5-methyl-(6S)-tetrahydrofolate and 4-(2-hydroxyethyl)-morpholine

Abstract

The present invention relates to a crystalline salt comprising 5-methyl-(6S)-tetrahydrofolate and 4-(2-hydroxyethyl)-morpholine, wherein the molar ratio of 5-methyl-(6S)-tetrahydrofolate to 4-(2-hydroxyethyl)-morpholine is 1:0.3 to 2.0 (in mol / mol) and / or their hydrates and / or solvates and methods for obtaining them.

Description

[0001] The present invention relates to a crystalline salt containing 5-methyl-(6S)-tetrahydrofolate (N-[4-[[(2-amino-1,4,5,6,7,8-hexahydro-5-methyl-4-oxo-(6S)-pteridinyl)methyl]amino]benzoyl]-L-glutamate) and 4-(2-hydroxyethyl)-morpholine and a method for obtaining the same.

[0002] Tetrahydrofolate is mainly used as the calcium salt of 5-formyltetrahydrofolate (calcium folinate and L-phosphatidylcholine), the calcium salt of 5-methyltetrahydrofolate or 5,10-methylenetetrahydrofolate sulfate The most prominent areas of application are the treatment of megaloblastic folate, as an antidote for improving the compatibility of folate antagonists (especially aminopterin and methotrexate) in cancer therapy ("antifolate rescue"), for improving the therapeutic effect of fluorinated pyrimidines and for the treatment of autoimmune diseases such as psoriasis and rheumatoid arthritis, for improving the compatibility of certain antiparasitic drugs with mutations, such as trimethoprim-sulfamethoxazole. Azoles, and for reducing the toxicity of dideoxytetrahydrofolate (salt) in chemotherapy.

[0003] The calcium salt of 5-methyl-(6S)-tetrahydrofolate is used, inter alia, as a medicament and food additive, 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)-tetrahydrofolic acid and its salts are known to be very unstable. In particular, they are very susceptible to oxidation (see also AL Fitzhugh, Pteridines 4(4), 187-191 (1993) in this respect) and are therefore difficult to produce at a purity level acceptable for pharmaceutical active ingredients or food additives.

[0005] In order to overcome the instability of 5-methyltetrahydrofolate and its salts, various approaches have been used, such as excluding 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, in particular calcium salts, their crystals and uses. The disadvantage of such crystalline calcium salts of 5-methyl-(6S)-tetrahydrofolate is that it exists in up to four polymorphic modifications in its crystalline form. Therefore, the preparation process of the crystalline calcium salt of 5-methyl-(6S)-tetrahydrofolate must be controlled very accurately. In addition, the crystalline calcium salt of 5-methyl-(6S)-tetrahydrofolate of US 6,441,168 B1 generally contains at least 1 but up to 4 equivalents of water per equivalent of 5-methyl-(6S)-tetrahydrofolate in its crystal lattice in all polymorphic forms.

[0007] New crystalline forms of pharmaceutically useful compounds offer the opportunity to improve the performance profile of drugs and / or vitamins / medical foods. It expands the library of materials available to formulators for designing new dosage forms with improved properties.

[0008] The technical problem underlying the present invention is to provide a crystalline form comprising 5-methyl-(6S)-tetrahydrofolate which overcomes the disadvantages of the crystalline calcium salt of 5-methyl-(6S)-tetrahydrofolate known in the art.

[0009] Additionally, the new crystalline forms often exhibit desirable different physical and / or biological properties, which can aid in preparing or formulating the active compound to the purity levels and homogeneity required for regulatory approval.

[0010] For the stability of tetrahydrofolate (salt), the goal has always been to provide compounds that have low water absorption during storage and can be fully dried during the preparation process. In addition, drugs that do not absorb large amounts of water under ambient conditions are highly desirable. Particularly desirable are materials that do not change their water content when the relative humidity of the environment changes, because large changes in water content due to changes in the relative humidity of the environment make it more difficult to achieve high precision with respect to dosage forms.

[0011] The underlying technical problem of the present invention is solved by a crystalline salt comprising 5-methyl-(6S)-tetrahydrofolic acid and 4-(2-hydroxyethyl)-morpholine and / or a hydrate and / or a solvate thereof, wherein the molar ratio of 5-methyl-(6S)-tetrahydrofolic acid to 4-(2-hydroxyethyl)-morpholine is 1:0.3 to 1:2.0 (in mol / mol).

[0012] The solid forms of the present invention have improved pharmacological properties, thus providing increased possibilities for regulating and designing improved pharmaceutical products. The water absorption of the crystalline salt of 5-methyl-(6S)-tetrahydrofolate and 4-(2-hydroxyethyl)-morpholine is significantly lower than the polymorphs of the calcium salt of 5-methyl-(6S)-tetrahydrofolate known in the art, resulting in significantly improved control of the target dosage level in the drug product, since the variation of the water absorption under conditions of relative humidity variation is significantly less pronounced. Another advantageous aspect of the crystalline salt of 5-methyl-(6S)-tetrahydrofolate and 4-(2-hydroxyethyl)-morpholine is that high chemical and optical purity of 5-methyl-(6S)-tetrahydrofolate can be achieved in a single crystallization step. In addition, the crystalline form comprising the crystalline salt of 5-methyl-(6S)-tetrahydrofolate and 4-(2-hydroxyethyl)-morpholine exists in a well-defined polymorphic modification. Thus, the process for preparing a crystalline salt comprising 5-methyl-(6S)-tetrahydrofolate and 4-(2-hydroxyethyl)-morpholine does not require very precise control of the crystallization conditions.

[0013] Preferably, the molar ratio of 5-methyl-(6S)-tetrahydrofolate to 4-(2-hydroxyethyl)-morpholine of the crystalline salt is 1:0.5 to 1:1.5 (in mol / mol).

[0014] Even more preferably, the molar ratio of 5-methyl-(6S)-tetrahydrofolate to 4-(2-hydroxyethyl)-morpholine is from 1:0.75 to 1:1.25 (in mol / mol).

[0015] Most preferably, the ratio of 5-methyl-(6S)-tetrahydrofolate to 4-(2-hydroxyethyl)-morpholine is about 1:1 (mol / mol).

[0016] Preferably, the salt of the present invention is a crystalline salt of 5-methyl-(6S)-tetrahydrofolate and 4-(2-hydroxyethyl)-morpholine, and its PXRD pattern has at least one characteristic peak selected from the following peaks located at 14.2, 14.8, 19.7, 20.0 and 20.6 (expressed in 2θ±0.2°2θ (CuKα radiation)).

[0017] More preferably, the salt of the present invention is a crystalline salt of 5-methyl-(6S)-tetrahydrofolate and 4-(2-hydroxyethyl)-morpholine, and its PXRD pattern has at least three characteristic peaks selected from the following peaks located at 14.2, 14.8, 19.7, 20.0 and 20.6 (expressed in 2θ±0.2°2θ (CuKα radiation)).

[0018] Even more preferably, the salt of the present invention is a crystalline salt of 5-methyl-(6S)-tetrahydrofolate and 4-(2-hydroxyethyl)-morpholine and its PXRD pattern has characteristic peaks selected from the peaks located at 14.2, 14.8, 19.7, 20.0 and 20.6 (expressed in 2θ ± 0.2° 2θ (CuKα radiation)).

[0019] Even more preferably, the salt of the present invention is a crystalline salt of 5-methyl-(6S)-tetrahydrofolate and 4-(2-hydroxyethyl)-morpholine and has a PXRD pattern having at least one characteristic peak selected from the group consisting of peaks at 4.9, 12.2, 14.2, 14.8, 15.1, 15.3, 17.4, 19.7, 20.0, 20.6, 23.6, 24.9 and 28.1 (expressed in 2θ ± 0.2° 2θ (CuKα radiation)).

[0020] Most preferably, the salt of the present invention is a crystalline salt of 5-methyl-(6S)-tetrahydrofolate and 4-(2-hydroxyethyl)-morpholine and has a PXRD pattern substantially as shown in FIG. 1 .

[0021] The above-mentioned salt of 5-methyl-(6S)-tetrahydrofolate and 4-(2-hydroxyethyl)-morpholine may have a chemical and / or stereoisomeric purity of at least 99 wt% or more.

[0022] A comparison of the salt of 5-methyl-(6S)-tetrahydrofolate and 4-(2-hydroxyethyl)-morpholine with the calcium salt of 5-methyl-(6S)-tetrahydrofolate shows that the water content of the salt of 5-methyl-(6S)-tetrahydrofolate and 4-(2-hydroxyethyl)-morpholine varies by less than 2% in the most relevant range of 20% to 80% (Example 2, FIG. 2 ), while the water content of the calcium salt of 5-methyl-(6S)-tetrahydrofolate varies by more than 4% (Reference Example 2, FIG. 3 ). This result is very surprising to a person skilled in the art and is not expected in view of the teaching of US 6,441,168 B1. Moreover, the salt of 5-methyl-(6S)-tetrahydrofolate and 4-(2-hydroxyethyl)-morpholine according to the present invention clearly solves the underlying technical problem of the present invention.

[0023] Advantageously, salts of 5-methyl-(6S)-tetrahydrofolate are included which have very low water contents and in particular have a low tendency to absorb / desorb water, for example when handling the materials for complexing in a temperature / humidity controlled environment or in tropical countries where the relative humidity is often high.

[0024] Thus, even under these conditions, the salts of the present invention exhibit improved storage stability. These improved properties are not expected in view of the teachings of US Patent 6,441,168 Bl.

[0025] 5-methyl-(6S)-tetrahydrofolate is poorly soluble in water. It is known that the thermodynamically stable form of the calcium salt at room temperature (Form III) exhibits a water solubility of about 2.5 mg / ml, and the solubility of the metastable form I is about 10 mg / ml. Under certain pH conditions, particularly when the pH of the environment is lower than the equilibrium pH of a given salt, the salt may potentially disproportionate to a free acid, resulting in a significant reduction in solubility. Therefore, due to the slow disproportionation of the salt (formation of insoluble free acids), the thermodynamic solubility of the claimed salt at about neutral to low pH values ​​is unavailable. However, bioavailability is governed by kinetics. The drug in solid form dissolves after administration, and after the first dissolution step, the drug is diluted and distributed by body fluids. Therefore, kinetic solubility is a key parameter affecting bioavailability, because the initially dissolved drug is easy to dilute and deliver. Surprisingly, for the salts of 5-methyl-(6S)-tetrahydrofolate and 4-(2-hydroxyethyl)-morpholine, the kinetic solubility is improved by about three times relative to the known calcium salt (metastable form I). The difference in kinetic solubility between the salts of the invention and the thermodynamically stable form of the calcium salt (Form III) is presumably greater. Thus, higher drug substance concentrations can be temporarily achieved.

[0026] Another aspect of the present invention is a method for obtaining a crystalline salt comprising 5-methyl-(6S)-tetrahydrofolate and 4-(2-hydroxyethyl)-morpholine, comprising the following steps:

[0027] a) providing a mixture of 5-methyl-(6S)-tetrahydrofolate and 4-(2-hydroxyethyl)-morpholine, optionally in a suitable solvent or solvent mixture,

[0028] b) crystallization,

[0029] c) optionally adding more solvent or solvent mixture, and

[0030] d) isolating the obtained crystals.

[0031] Preferably, the molar ratio of 5-methyl-(6S)-tetrahydrofolate to 4-(2-hydroxyethyl)-morpholine in step a) is 1:1 to 1:3.

[0032] Further preferably, the solvent is water, an alcohol and / or a ketone.

[0033] In steps b) and / or c), seed crystals may be added.

[0034] Since the crystalline salt comprising 5-methyl-(6S)-tetrahydrofolate and 4-(2-hydroxyethyl)-morpholine exists in only one well-defined polymorphic modification, the process for the preparation of the crystalline salt does not require particularly precise control of the crystallization conditions.

[0035] Another aspect of the present invention is a pharmaceutical composition, a food additive and / or a preparation comprising a crystalline salt of 5-methyl-(6S)-tetrahydrofolate and 4-(2-hydroxyethyl)-morpholine and optionally one or more acceptable excipients, which is also a part of the present invention. The pharmaceutical composition can be in the form of a tablet, a capsule, an oral liquid preparation, a powder, a lyophilized agent, a granule, a lozenge, a reconstituted powder, an injectable or infusible solution or suspension or a suppository. Moreover, the pharmaceutical composition can further comprise at least one additional therapeutic agent. The pharmaceutical composition according to the present invention is suitable for all modes of administration, preferably for oral, parenteral, intramuscular, intraspinal, intrathecal, periodontal, topical or rectal administration.

[0036] Another aspect of the invention is the use of a crystalline salt comprising 5-methyl-(6S)-tetrahydrofolate and 4-(2-hydroxyethyl)-morpholine as an ingredient for the production of a medicament and / or as a food additive.

[0037] Preferably, the crystalline salt comprising 5-methyl-(6S)-tetrahydrofolate and 4-(2-hydroxyethyl)-morpholine is used for the homocysteine ​​lowering treatment of anemia, neural tube defects, cardiovascular disease, depression, Alzheimer's disease, cognitive impairment and osteoporosis and / or the dietary management of low plasma folate and / or low red blood cell folate and / or low cerebrospinal fluid folate and / or low peripheral or central nervous system folate.

[0038] In summary, the salts of 5-methyl-(6S)-tetrahydrofolate and 4-(2-hydroxyethyl)-morpholine of the present invention provide a profile of properties that are advantageous for use in medicines or as food additives. In particular, the low variation in water content and the higher kinetic solubility in an environment with a relative humidity of 20% to 80% were not foreseen by the skilled person. Example

[0039] Powder X-ray diffraction

[0040] Stoe Stadi P equipped with Mythen1K detector; Cu-Kα1 radiation; standard measurement conditions: transmission; tube power of 40 kV and 40 mA; bent germanium monochromator; step size of 0.02° 2θ, step time of 48 s, scan range of 1.5-50.5° 2θ; detection mode: step scan; 1° 2θ detector step; standard sample preparation: 10 to 20 mg sample was placed between two acetate foils; sample holder: Stoe transmission sample holder; sample was rotated during measurement. All sample preparation and measurements were performed in ambient air.

[0041] TG-FTIR

[0042] Thermogravimetric measurements were performed with a Netzsch Thermo-Microbalance TG209 connected to a Bruker FTIR spectrometer Vector 22 (sample pan with pinhole, N2 atmosphere, heating rate 10 K / min).

[0043] DVS

[0044] DVS measurements are usually carried out using an SPS11-100n “Sorptions Prüfsystem” from ProUmid (formerly “Projekt Messtechnik”), August-Nagel-Str. 23, 89079 Ulm (Germany).

[0045] DVS measurements were performed as follows: The sample was placed on an aluminum holder on top of a microbalance and allowed to equilibrate at 50% RH before starting a predetermined humidity program:

[0046] (1) Maintain at 50% constant relative humidity (RH) for two hours, then

[0047] (2) Increase RH to 95% at a rate of 5% per hour

[0048] (3) Maintain RH at 95% for five hours

[0049] (4) Reduce to 0% RH at a rate of 5% per hour

[0050] (5) Maintain RH at 0% for five hours

[0051] (6) Increase RH to 95% at a rate of 5% per hour

[0052] (7) Maintain RH at 95% for five hours

[0053] (8) Reduce to 0% RH at a rate of 5% per hour

[0054] (9) Maintain RH at 0% for five hours

[0055] (10) Increase to 50% RH at a rate of 5% per hour

[0056] (11) Maintain RH at 50% for about an hour

[0057] Example 1: Preparation of a crystalline salt of 5-methyl-(6S)-tetrahydrofolic acid and 4-(2-hydroxyethyl)-morpholine

[0058] 4.763 grams of 5-methyl-(6S)-tetrahydrofolate monohydrate (97.65% w / w of 5-methyltetrahydrofolate assay) were weighed into a glass flask equipped with a magnetic stirring bar. 9.5 mL of water and 4.76 mL of 4-(2-hydroxyethyl)-morpholine (Aldrich #H28203) were added. After stirring at room temperature for about 2 minutes, a brown clear solution was formed. While stirring the solution at room temperature, 95 mL of acetone was slowly added over about 2.5 hours. The formed suspension was stirred at room temperature for about 23 hours. The suspension was then filtered through a sintered glass filter (porosity P4) and the filter cake was air-dried at ambient temperature. 100 mL of ethanol was added to the filter cake and the washing solution was drawn through the filter by vacuum suction. The washing step was repeated with an additional 100 mL of ethanol. The filter cake was then air-dried for about 0.5 hours (air was drawn through the sintered glass filter). About 5.6 grams of solid product was obtained and characterized by HPLC, powder X-ray diffraction, H-NMR spectroscopy and TG-FTIR. Powder X-ray diffraction showed that the material was crystalline with a PXRD pattern as shown in Table 1 with peak positions as shown in FIG. 1 .

[0059] Table 1: 2-θ angles, d-spacing and qualitative intensity of the salt of 5-methyl-(6S)-tetrahydrofolate and 4-(2-hydroxyethyl)-morpholine according to Example 1. For intensity, Vs = very strong, s = strong, m = medium, w = weak, vw = very weak. It should be noted that the intensity values ​​can vary significantly due to preferred orientation effects.

[0060]

[0061]

[0062] Example 2: Preparation of a crystalline salt of 5-methyl-(6S)-tetrahydrofolic acid and 4-(2-hydroxyethyl)-morpholine

[0063] 47.63 g of 5-methyl-(6S)-tetrahydrofolate monohydrate (assay 5-methyl-(6S)-tetrahydrofolate 97.99% w / w, 6S-diastereomer: 98.0%) were suspended in 95 mL of water at room temperature. 47.6 mL of 4-(2-hydroxyethyl)-morpholine were added while the temperature was raised to about 50°C without cooling. The mixture was cooled to room temperature. 950 mL of acetone were slowly added to the dark brown transparent solution over about 2.5 hours. The resulting suspension was stirred at room temperature for about 23 hours. The suspension was then filtered through a sintered glass filter (porosity G3) and the filter cake was washed with 1000 mL of ethanol. The light beige solid thus obtained was dried overnight at 40°C / 10 mbar. About 52.4 g of solid product were obtained and analyzed by HPLC, powder X-ray diffraction and 1 H-NMR spectroscopy was used for characterization. HPLC analysis showed a purity of 98.7% in the region, 6S diastereomer: 98.7%. Powder X-ray diffraction showed that the material was crystalline, with a PXRD pattern as shown in Table 1 with peak positions as shown in Figure 1.

[0064] Example 3: Hygroscopicity and water content (DVS test)

[0065] TG-FTIR analysis of a sample of the salt of 5-methyl-(6S)-tetrahydrofolate and 4-(2-hydroxyethyl)-morpholine according to Example 1 showed that the sample contained about 8.9% w / w of water. This value was determined by TG-FTIR at a relative humidity of about 35%. The sample was examined by dynamic water vapor sorption analysis (DVS) in a relative humidity range of 0 to 95% rh. DVS measurements were performed as described above.

[0066] Comparison of the results for the salt of 5-methyl-(6S)-tetrahydrofolate and 4-(2-hydroxyethyl)-morpholine with the results for the calcium salt of 5-methyl-(6S)-tetrahydrofolate showed that the water content of the salt of 5-methyl-(6S)-tetrahydrofolate and 4-(2-hydroxyethyl)-morpholine varied by about 2% over a relative humidity range of 20% to 80%, whereas the variation for the calcium salt of 5-methyl-(6S)-tetrahydrofolate was about 4% (Reference Example 2). In addition, this example shows that the water content of the salt of 5-methyl-(6S)-tetrahydrofolate and 4-(2-hydroxyethyl)-morpholine at 50% relative humidity is about 10%, and that the compound absorbs about 2% additional water when the relative humidity increases from 50% to 95%. 50% rh is a typical ambient relative humidity condition in central Europe during the summer; however, when the drug is stored in a bathroom, the relative humidity can temporarily reach at least 95%.

[0067] Example 3: Kinetic Solubility of the Salt of 5-Methyl-(6S)-Tetrahydrofolate and 4-(2-Hydroxyethyl)-Morpholine

[0068] 27.1mg of the salt of 5-methyl-(6S)-tetrahydrofolate and 4-(2-hydroxyethyl)-morpholine prepared according to Example 1 was weighed into a 7mL glass vial with a screw cap, and 0.5mL of purified / deionized water was added to the solid with an adjustable volume pipette. The mixture was stirred vigorously at room temperature, and after a few seconds, all solids dissolved and a clear solution was obtained. This means that for the salt of 5-methyl-(6S)-tetrahydrofolate and 4-(2-hydroxyethyl)-morpholine, every milliliter of water can easily dissolve greater than 54mg. This corresponds to the instant kinetic solubility of 5-methyl-(6S)-tetrahydrofolate greater than 37mg per milliliter of water.

[0069] Reference Example 1: Kinetic Solubility of Calcium Salt of 5-Methyl-(6S)-Tetrahydrofolate

[0070] 42.5 mg of the crystallized 5-methyl-(6S)-tetrahydrofolate calcium salt in anhydrous form was weighed into a 7 mL glass vial with a screw cap. 2.00 mL of purified / deionized water was added to the solid using an adjustable volume pipette. The mixture was stirred vigorously at room temperature for 1 minute. One minute later, a suspension was observed. The suspension was filtered by centrifugal filtration, and 1.50 mL of the aqueous solution was transferred to a tared glass vial (volume of about 10 mL). Water was evaporated in an air dryer at 40 ° C for about 15 hours, and then evaporated at 50 ° C for about 8 hours. Drying was subsequently completed at 50 ° C under vacuum (10 to 20 mbar) for about 13 hours. Solubility was determined by weight assessment of the solid residue. The solubility was 9.0 mg 5-methyl-(6S)-tetrahydrofolate per milliliter of water.

[0071] Reference Example 2: Hygroscopicity and water content of calcium salt of 5-methyl-(6S)-tetrahydrofolate

[0072] TG-FTIR analysis of a sample of 5-methyl-(6S)-tetrahydrofolate calcium salt showed that the sample contained about 12.4% water. The sample was examined by dynamic vapor sorption analysis (DVS) over a relative humidity range of 0 to 95% rh. DVS measurements were performed as described above.

[0073] The results are shown in Figure 3 and indicate that within the most relevant range of 20% to 80%, the water content of 5-methyl-(6S)-tetrahydrofolate calcium salt varies by about 4%. In addition, the reference example indicates that the water content of 5-methyl-(6S)-tetrahydrofolate calcium salt at 50% relative humidity is about 12.4%, and that the compound absorbs more than 10% additional water when the relative humidity increases from 50% to 95%.

Claims

1. A crystalline salt comprising 5-methyl-(6S)-tetrahydrofolic acid and 4-(2-hydroxyethyl)-morpholine, wherein the molar ratio of 5-methyl-(6S)-tetrahydrofolic acid to 4-(2-hydroxyethyl)-morpholine is from 1:0.3 to 1:2.0, characterized in that The PXRD pattern of the salt has characteristic peaks selected from the group consisting of peaks at 4.9, 12.2, 14.2, 14.8, 15.1, 15.3, 16.5, 16.9, 17.4, 17.8, 18.7, 19.3, 19.7, 20.0, 20.6, 21.0, 21.2, 21.7, 22.0, 22.7, 23.6, 24.9, 25.1, 25.5, 25.8, 26.1, 26.6, 26.9, 28.1, 29.4 and 32.5, wherein the characteristic peaks are expressed as 2θ ± 0.2° 2θ, CuKα radiation.

2. The crystalline salt of claim 1, wherein the molar ratio of 5-methyl-(6S)-tetrahydrofolate to 4-(2-hydroxyethyl)-morpholine is 1:0.5 to 1:1.

5.

3. The crystalline salt of claim 1, wherein the molar ratio of 5-methyl-(6S)-tetrahydrofolate to 4-(2-hydroxyethyl)-morpholine is 1:0.75 to 1:1.

25.

4. The crystalline salt of claim 1, wherein the molar ratio of 5-methyl-(6S)-tetrahydrofolate to 4-(2-hydroxyethyl)-morpholine is 1:

1.

5. The crystalline salt according to any one of claims 1 to 4, characterized in that The salt is a salt of 5-methyl-(6S)-tetrahydrofolic acid and 4-(2-hydroxyethyl)-morpholine, and has a PXRD pattern as shown in FIG1 .

6. The crystalline salt of any one of claims 1 to 4, having a chemical and / or stereoisomeric purity of at least 99 wt% or more.

7. A method for obtaining a crystalline salt comprising 5-methyl-(6S)-tetrahydrofolate and 4-(2-hydroxyethyl)-morpholine according to any one of claims 1 to 6, comprising the following steps: a) providing a mixture of 5-methyl-(6S)-tetrahydrofolate and 4-(2-hydroxyethyl)-morpholine, optionally in a suitable solvent or solvent mixture, b) crystallization, c) optionally adding more solvent or solvent mixture, and d) The isolated crystals.

8. The method according to claim 7, characterized in that The molar ratio of 5-methyl-(6S)-tetrahydrofolic acid to 4-(2-hydroxyethyl)-morpholine in step a) is 1:1 to 1:

3.

9. The method according to claim 7 or 8, characterized in that The solvent is water, alcohol and / or ketone.

10. The method according to claim 7 or 8, characterized in that Seed crystals are added in step b) and / or c).

11. A pharmaceutical composition comprising a crystalline salt of 5-methyl-(6S)-tetrahydrofolate and 4-(2-hydroxyethyl)-morpholine according to any one of claims 1 to 6 and optionally one or more acceptable excipients.

12. A pharmaceutical composition according to claim 11, prepared by the crystalline salt of 5-methyl-(6S)-tetrahydrofolate and 4-(2-hydroxyethyl)-morpholine according to any one of claims 1 to 6, in the form of tablets, capsules, oral liquid preparations, powders, lyophilisates, granules, lozenges, reconstitutable powders, injectable or infusible solutions or suspensions or suppositories.

13. The pharmaceutical composition according to claim 11 or 12, further comprising at least one additional therapeutic agent.

14. The pharmaceutical composition according to claim 11 or 12, which is for oral, parenteral, intramuscular, intraspinal, intrathecal, periodontal, topical or rectal administration.

15. Use of a crystalline salt comprising 5-methyl-(6S)-tetrahydrofolate and 4-(2-hydroxyethyl)-morpholine according to any one of claims 1 to 6 as an ingredient for the production of a medicament.

16. Use of a crystalline salt comprising 5-methyl-(6S)-tetrahydrofolate and 4(2-hydroxyethyl)-morpholine according to any one of claims 1 to 6 for the preparation of a medicament for lowering homocysteine ​​and / or low plasma folate and / or low red blood cell folate and / or low cerebrospinal fluid folate and / or low peripheral or central nervous system folate for the treatment of anemia, neural tube defects, cardiovascular disease, depression, cognitive impairment, Alzheimer's disease and osteoporosis.

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