Process for preparing (15 [alpha], 16 [alpha], 17 [beta])-estra-1, 3, 5 (10)-triene-3, 15, 16, 17-tetraol (estetrol) monohydrate

Abstract

The present invention relates to a process for the preparation of (15 [alpha], 16 [alpha], 17 [beta])-estra-1, 3, 5 (10)-triene-3, 15, 16, 17-tetrol monohydrate, also known as estetrol monohydrate, having the following formula (I).

Description

Technical Field

[0001] This invention relates to the field of methods for synthesizing pharmaceutically active ingredients (APIs), and particularly to a method for preparing (15α,16α,17β)-estra-1,3,5(10)-triene-3,15,16,17-tetrol monohydrate, also known as estradiol monohydrate, on an industrial scale. Background Technology

[0002] Estradiol is a pharmacologically active ingredient used in hormone replacement therapy (HRT), female contraception, and the treatment of autoimmune disorders associated with hormonal imbalances. This compound, a natural product isolated from human urine, has been known for many years; it was first described in the article "Synthesis of epimeric 15-hydroxyestriols, new and potential metabolites of estradiol", J. Fishman et al., JOC Vol.33, No.8, August 1968, pp.3133-3135 (compound Ia in the figure on page 3133).

[0003] The structural formula of estradiol is as follows:

[0004]

[0005] The steroid skeleton has a hydroxyl group at positions 15, 16, and 17 (highlighted in the above-reported structural formula), and as shown in the above structural formula, it has a defined spatial arrangement, that is, the hydroxyl groups at positions 15 and 16 have an α configuration, while the hydroxyl group at position 17 has a β configuration.

[0006] The presence of impurities in the active ingredient below set limits is a mandatory requirement for its use in pharmaceutical formulations; international guidelines accept a limit of 0.1% for unknown drugs and 0.15% for known drugs. Therefore, the ability to meet these limits is a fundamental characteristic defining an industrial application method. Any method, regardless of yield, that provides an API with impurity levels that do not meet these limits is industrially useless because the resulting API cannot be granted market access by the relevant authorities (EMA, FDA, etc.).

[0007] Regarding estradiol, scientific and patent literature to date has focused on methods for producing this compound in high yields, suitable for industrial applications, and possessing the high purity required for pharmaceutical products; in particular, one objective of this industrial method is to avoid the presence of the compound's isomers 15β, 16β, and 17β, which have the following structural formula, from which estradiol must be purified for use in pharmaceutical formulations:

[0008]

[0009] Patent application WO 2004 / 041839 A2 (page 6, lines 5-10) describes a method for obtaining estradiol with a purity of up to 99%, wherein the sum of individual impurities does not exceed 1%.

[0010] Subsequent applications related to the production of estradiol include, for example, WO 2012 / 164096 A1, WO 2013 / 034780 A1, WO2013 / 050553A1, WO 2015 / 040051 A1, WO 2015-086643 A1 and WO 2021 / 044302 A1; for example, WO 2015 / 040051A1 shows in its examples an estradiol / isomeric 15β, 16β, 17β ratio of up to 99:1.

[0011] Other requirements of the pharmaceutical industry relate to the stability and processability of the target compound.

[0012] When provided in the form of salts, complexes, or solvates, active molecules may be more stable, and under metabolic conditions, the molecules can be readily released from the salts, complexes, or solvates. In addition, active molecules are almost always formulated with excipients to produce an administerable composition, in which the excipients perform various functions, such as controlling the release rate of the active ingredient, masking unpleasant tastes, and making the dosage unit reach a manageable weight and volume.

[0013] One useful form of estradiol is a monohydrate, which is a solvate formed by the compound and water in a 1:1 stoichiometric ratio; estradiol monohydrate can be represented as follows:

[0014]

[0015] The aforementioned patent publications mention methods for synthesizing estradiol and incidentally mention salts or solvates of the compound, for example in WO 2015-086643 A1, or not at all; none of the publications report a reproducible method for preparing estradiol monohydrate with the required purity level on an industrial scale.

[0016] Patent application WO 2021 / 058716 A1, filed in the name of the applicant, describes a method for producing estradiol monohydrate, comprising dissolving anhydrous estradiol in a water-miscible organic solvent, mixing the resulting solution with water, removing the organic solvent by distillation to obtain a suspension, maintaining the suspension in agitation, then filtering, washing, and finally drying the solid under reduced pressure. The method of WO2021 / 058716A1 is reliable and consistently provides estradiol monohydrate of suitable quality and purity for the intended application; however, it involves the use of an organic solvent that needs to be distilled off and then recovered, increasing the time and cost of the entire process; furthermore, very careful care must be taken to ensure that the solvent is completely removed and not included in the final dosage unit.

[0017] The object of this invention is to provide a method for preparing estradiol monohydrate suitable for industrial applications, providing a pharmaceutically acceptable compound while avoiding the use of organic solvents. Summary of the Invention

[0018] The purpose of this invention is to provide an industrially applicable method for preparing estradiol monohydrate without the need for purification techniques.

[0019] This invention relates to a method for converting estradiol to estradiol monohydrate:

[0020]

[0021] This is achieved by contacting anhydrous estradiol with pure water in liquid or vapor form. Attached Figure Description

[0022] Figure 1 and Figure 2 The DRX diffraction patterns of estradiol monohydrate obtained by the first embodiment of the method of the present invention under different conditions are shown.

[0023] Figure 3 The DRX diffraction pattern of estradiol monohydrate obtained by a second embodiment of the method of the present invention is shown. Detailed Implementation

[0024] This invention relates to a method for preparing estradiol monohydrate from anhydrous estradiol.

[0025] Anhydrous estradiol can be produced by any method known in the art; a preferred method is the method comprising steps A) to D) of WO2021 / 058716A1. Anhydrous estradiol can be used in crystalline and amorphous forms.

[0026] In this specification and claims, "pure water" refers to distilled water.

[0027] In a first embodiment, the invention relates to a method comprising contacting anhydrous estradiol with pure water according to the following steps:

[0028] a) Prepare a suspension of anhydrous estradiol in water and stir for at least 5 minutes to obtain a suspension of estradiol monohydrate;

[0029] b) Filter the suspension of estradiol monohydrate obtained in step a) to produce wet estradiol monohydrate.

[0030] c) Dry the wet estradiol monohydrate from step b) to obtain estradiol monohydrate.

[0031] The stirring in step a) is carried out at a temperature of 5°C to 90°C, preferably 15°C to 35°C.

[0032] The inventors prepared a slurry of anhydrous estradiol in water, sampled the slurry at different times, dried the samples, and analyzed them using XRPD to study the evolution of the transformation from anhydrous estradiol to estradiol monohydrate over time; one example of the results obtained is... Figure 1 Different diffraction patterns are shown. Analysis indicates that after stirring in water for several minutes, the signal corresponding to anhydrous estradiol disappears, rapidly converting to estradiol monohydrate.

[0033] The drying in step c) is carried out at a pressure of less than 800 mbar, preferably less than 500 mbar, more preferably less than 250 mbar, and at a temperature of 15°C to 50°C, preferably 15°C to 35°C.

[0034] In a second embodiment, the invention relates to a method for converting anhydrous estradiol into estradiol monohydrate via a simple conditioning procedure, the method comprising a first step d) exposing anhydrous estradiol powder to an atmosphere with a relative humidity (RH) of at least 75% for at least 24 hours at a temperature of 20°C to 25°C, and a second step e) recovering the estradiol monohydrate powder.

[0035] At the end of step d), the conversion is complete, and the estradiol monohydrate powder can be simply recovered in step e) for use in pharmaceutical formulations without further processing.

[0036] Step d) is preferably carried out in an atmosphere with a RH of at least 90%, and independently of the RH, preferably for at least 36 hours.

[0037] The present invention will be further illustrated by the following embodiments.

[0038] Experimental instruments, methods and conditions

[0039] HPLC:

[0040] Agilent Infinity 1260 chromatography system; UV detector model G1315C DAD VL+

[0041] Method: HPLC

[0042] Chromatographic conditions:

[0043] - Column: Supelco discovery C18 150x4.6mm, 5μm

[0044] - Flow rate: 1 mL / min

[0045] - Detector: UV 280nm

[0046] - Injection volume: 25μL

[0047] Temperature: 22℃

[0048] -Mobile phase A: 4.29 g / L CH3COONH4 solution in a water / methanol / acetonitrile ratio of 90 / 6 / 4.

[0049] -Mobile phase B: 38.6 g / L CH3COONH4 solution in water / methanol / acetonitrile ratio of 10 / 54 / 36.

[0050] Time (min) Mobile phase A (v / v) Mobile phase B (v / v) 0 70 30 0-5 70 30 5-15 10 90 15-30 10 90 30-31 70 30 31-40 70 30

[0051] XPRD:

[0052] XRPD analysis was performed using a Bruker D2 Phaser (2nd edition) powder diffractometer operating in Bragg-Brentano geometry, equipped with a rotating multiplexer and a linear SSD detector (Lynxeye). The X-ray source was an X-ray tube with a copper anode, operating at 30 kV and 10 mA. For analysis, the wavelength corresponding to the average Kα of copper was used. X-rays. Kβ rays are filtered through a nickel filter.

[0053] A "zero-background" silicon sample holder with a flat surface is used, on which the sample is spread to form a thin layer. During the analysis, the sample holder rotates at a speed of 60 rpm.

[0054] The scan was performed in the range of 4-40°2θ, with an increment of 0.016°2θ, and the acquisition time for each increment was 1.0s.

[0055] The diffraction pattern was processed using Bruker DIFFRAC.EVA software.

[0056] Note:

[0057] Unless otherwise stated, the water used in the experimental description should be understood as pure water.

[0058] Example 1

[0059] This embodiment relates to a first implementation of the method of the present invention, which involves hydrating anhydrous estradiol in a slurry in water.

[0060] Place 3.0 g of pure crystalline anhydrous estradiol in a 100 mL flask.

[0061] Add pure water (30 mL, 10 V / w) and stir the mixture using a mechanical stirrer at 20-25 °C.

[0062] Slurry samples were taken after 5 min, 1 h and 4.5 h.

[0063] The sample was filtered under vacuum, dried on the filter for 10 min, and analyzed by XRPD.

[0064] The results of the XRPD experiment are shown below. Figure 1 and Figure 2 .

[0065] exist Figure 1 In the diagram, the lower diffraction pattern, representing the time zero point (t = 0h), refers to the initial anhydrous estradiol, the three intermediate diffraction patterns refer to the samples collected at the indicated times, and the upper diffraction pattern was obtained from a pure estradiol monohydrate sample prepared according to the method described in WO 2021 / 058716 A1 and is included as a reference.

[0066] Figure 2 yes Figure 1 The magnified view of the two diffraction patterns at t=0h and t=4.5h on the vertical axis allows for easier examination of the disappearance of the anhydrous estradiol peak and the appearance of the estradiol monohydrate peak.

[0067] After 4.5 hours of pulping, the final sample was estradiol monohydrate (white crystals, HPLC purity = 100%).

[0068] The XRPD peak list is shown in Table 1 below:

[0069] Table 1

[0070] 2θ angle (°) relative strength 7.0 8.1％ 12.2 15.4％ 12.6 100.0％ 13.4 11.7％ 13.6 88.3％ 15.0 8.4％ 17.6 10.3％ 18.7 11.8％ 21.0 85.9％ 21.8 9.1％ 23.2 17.9％ 25.3 6.9％ 30.8 6.5％ 34.6 4.4％ 38.4 6.2％

[0071] The peak list in Table 1 corresponds to the data for estradiol monohydrate reported in WO 2021 / 058716 A1, with typical approximations of ±0.2°.

[0072] Example 2

[0073] This example relates to the second embodiment of the method of the present invention, and hydrates anhydrous estetrol in a 100% RH chamber.

[0074] Place 3.0 g of pure anhydrous estetrol as a thin layer in a crystallizer.

[0075] Place the crystallizer in a glass desiccator with water at 20 °C < T < 25 °C at the bottom.

[0076] Collect small samples of the powder after 3.5 h, 7 h, 24 h, and 48 h and analyze by XRPD. The obtained diffraction patterns are reproduced in Figure 3 where the diffraction pattern at time zero (t = 0 h) refers to anhydrous estetrol, and the upper diffraction pattern (added as a reference) was obtained from a sample of pure estetrol monohydrate prepared by the method described in WO 2021 / 058716 A1. Four intermediate diffraction patterns were recorded on the samples obtained after the indicated processing times.

[0077] After 48 h of exposure to humid air, the final sample is estetrol monohydrate (white crystals, HPLC purity = 100%). The list of XRPD peaks is shown in Table 2 below:

[0078] Table 2

[0079]

[0080]

[0081] The list of peaks in Table 2 corresponds to the data of estetrol monohydrate reported in WO 2021 / 058716 A1, with a typical approximation of ±0.2°.

Claims

1. Method for converting estradiol to estradiol monohydrate: The method involves contacting anhydrous estradiol with pure water in liquid or vapor form.

2. The method of claim 1, wherein anhydrous estradiol is contacted with pure water in liquid form, the method comprising the following steps: a) Prepare a suspension of anhydrous estradiol in water and stir for at least 5 minutes to obtain a suspension of estradiol monohydrate; b) Filter the suspension of estradiol monohydrate obtained in step a) to produce wet estradiol monohydrate. c) Dry the wet estradiol monohydrate from step b) to obtain estradiol monohydrate.

3. The method according to claim 2, wherein step a) is performed at a temperature of 5°C to 90°C.

4. The method according to claim 3, wherein step a) is carried out at a temperature preferably between 15°C and 35°C.

5. The method according to any one of claims 2 to 4, wherein step c) is performed at a pressure below 800 mbar.

6. The method of claim 5, wherein step c) is performed at a pressure below 500 mbar.

7. The method of claim 6, wherein step c) is performed at a pressure below 250 mbar.

8. The method according to any one of claims 2 to 7, wherein step c) is carried out at a temperature of 15°C to 50°C.

9. The method according to claim 8, wherein step c) is performed at a temperature of 15°C to 35°C.

10. The method of claim 1, wherein anhydrous estradiol is contacted with pure water in vapor form, the method comprising the steps of: d) Expose anhydrous estradiol powder to an atmosphere with a relative humidity (RH) of at least 75% for at least 24 hours at a temperature of 20°C to 25°C; e) Recover the estradiol monohydrate obtained in step d).

11. The method of claim 10, wherein step d) is carried out in an atmosphere with a RH of at least 90%.

12. The method according to claim 10 or 11, wherein step d) is performed for at least 36 hours.

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