Ornidazole phosphate crystal, preparation method therefor and use thereof

Abstract

An ornidazole phosphate crystal, an X-ray powder diffraction pattern thereof having characteristic absorption at the following 2θ±0.2 locations: 12.5, 13.2, 14.1, 17.0, 20.3, 21.6, 23.5, 23.9, 28.5 and 28.8; crystal form characteristics thereof are a=12.680 Å, b=8.898 Å, c=21.107 Å, α=90°, β=99.653°, γ=90°, V=2347.7 Å3. The ornidazole phosphate crystal has high purity, good crystal stability and a simple preparation method, and is suitable for industrial production.

Description

Ornidazole phosphate crystal, preparation method and use thereof Technical Field

[0001] The present invention belongs to the technical field of pharmaceutical chemistry, and particularly relates to a novel ornidazole phosphate crystal and a preparation method thereof. Background Art

[0002] Ornidazole, a nitroimidazole antibacterial drug, has been widely used against anaerobic and antiprotozoal infections. Following metronidazole, ornidazole is a third-generation nitroimidazole derivative with higher efficacy, shorter treatment duration, improved tolerability, and wider distribution in the body. Ornidazole's antimicrobial activity is achieved through the reduction of the nitro group in its molecular formula to an amino group in an anaerobic environment or through free radical interaction with cellular components, leading to the death of microorganisms.

[0003] Ornidazole is mostly used clinically in the form of large-volume injections. It has extremely poor water solubility and requires strong acidity when made into an infusion preparation. Patients are prone to phlebitis when taking the drug. In addition, the toxic degradation product 2-methyl-5-nitroimidazole produced during high-temperature sterilization of the infusion is relatively high, which brings great safety risks to clinical use.

[0004] To address the poor water solubility of ornidazole products, domestic researchers have made various structural modifications. For example, patent CN200310100057.0 improves solubility by introducing a morpholine ring into the ornidazole structure to form a tertiary amine structure. Patent CN200610166893.2 proposes the structure of left-ornidazole phosphate and its salts, which further improve solubility by phosphorylating the hydroxyl group in the left-ornidazole structure and forming a salt. The process of precipitating left-ornidazole phosphate uses a large amount of organic solvent petroleum ether, which is not conducive to industrial production. Moreover, the stability of ornidazole phosphate after salt formation is poor and it is prone to degradation and discoloration.

[0005] Patent CN101177433 mentions the crystalline form and preparation method of levornidazole disodium phosphate pentahydrate, patent CN107151257 mentions levornidazole disodium phosphate hexahydrate and its preparation method, and patent CN109776609 mentions the formulation and use of levornidazole disodium phosphate heptahydrate. The inventors prepared these compounds according to the descriptions of these patents and conducted stability studies at room temperature and under accelerated conditions. They found that these crystalline compounds were unstable at room temperature. Patent CN1803811A proposes a method for preparing ornidazole phosphate, but only an amorphous solid was obtained, and its pH value was inconsistent with the pH of the ornidazole phosphate crystals described in this patent.

[0006] As a derivative of ornidazole phosphate, levonidazole disodium phosphate has excellent solubility in water. However, its insufficient stability severely limits its application scenarios. If there is a new, more stable ornidazole phosphate derivative, this deficiency will be well resolved. However, for a long time, due to its extremely strong solubility, the work of obtaining more stable compounds or crystal forms has been stagnant. The only goal that can be achieved is to obtain several compounds containing different crystal water. Although they have a certain degree of stability advantage compared to the original compound, they still cannot solve the problem of the application of this product in the field of solid dosage forms.

[0007] At present, no relevant crystal forms of ornidazole phosphate have been reported in the literature. It is well known that the crystal form of a drug has an impact on the quality of the preparation and the production process. The study of the crystal form of a drug can provide a reference for formulation workers in terms of prescription development, new dosage form design, optimization of production process, drug quality control and clinical efficacy. Different crystal forms of the same drug may have significant differences in appearance, solubility, melting point, dissolution, bioequivalence, etc., thereby affecting the stability, bioavailability and efficacy of the drug. Therefore, it is necessary to study the crystal form of ornidazole phosphate and develop one or more crystal forms with simple preparation methods, good solubility, high stability, high purity, low hygroscopicity and suitable for industrial production.

[0008] To solve the above problems, the present invention has conducted in-depth research on ornidazole phosphate and obtained ornidazole phosphate crystals with relatively stable physical and chemical properties, which provides a basis for safe application.

[0009] Summary of the Invention

[0010] The present invention provides an ornidazole phosphate crystal and a preparation method thereof, with the aim of providing a new ornidazole phosphate crystal with a stable spatial structure, thereby providing a new and more stable material basis for the clinical application of ornidazole phosphate derivatives.

[0011] The novel ornidazole phosphate crystal provided by the present invention has a stable spatial structure, and the specific structure is as follows:

[0012] The present invention also provides the X-ray powder diffraction pattern and characteristic peak data of the ornidazole phosphate crystal.

[0013] The crystal has characteristic absorption at the following 2θ angles ±0.2: 12.4, 13.2, 14.1, 16.9, 19.9, 20.2, 20.3, 21.6, 21.9, 23.2, 23.5, 23.7, 23.9, 24.4, 25.0, 25.2, 25.6, 26.5, 26.7, 28.3, 28.5, 31.3, 34.4, 36.9, 37.1, and 39.6.

[0014] The present invention also provides an X-ray powder diffraction pattern and characteristic peak data of the ornidazole phosphate crystals. The crystals have characteristic absorption at the following 2θ angles ±0.2: 12.4, 13.2, 14.1, 17.0, 18.4, 20.3, 21.6, 21.9, 23.2, 23.5, 23.7, 23.9, 25.0, 25.2, 25.6, 26.5, 26.7, 28.3, 28.5, 28.8, 31.3, 34.4, 35.8, 36.9, 37.1, and 38.4.

[0015] The present invention also provides the X-ray powder diffraction pattern and characteristic peak data of the ornidazole phosphate crystal.

[0016] The crystal has characteristic absorption at the following 2θ angles ±0.2: 12.5, 13.2, 14.1, 17.0, 19.9, 20.2, 20.3, 21.6, 21.9, 23.2, 23.5, 23.8, 23.9, 25.0, 25.6, 26.5, 26.7, 28.3, 28.5, 28.8, 31.1, 31.3, 34.4, 36.8, 37.1, and 38.5.

[0017] The present invention also provides an X-ray powder diffraction pattern and characteristic peak data of the ornidazole phosphate crystals. The crystals have characteristic absorption at the following 2θ angles ±0.2: 12.5, 13.2, 14.1, 17.0, 20.2, 20.3, 21.6, 21.9, 23.2, 23.5, 23.7, 23.9, 25.0, 25.3, 26.5, 26.7, 28.3, 28.5, 28.8, 31.2, 31.3, 35.4, 35.8, 36.9, 37.1, and 38.5.

[0018] The present invention also provides the X-ray powder diffraction pattern and characteristic peak data of the ornidazole phosphate crystal.

[0019] The crystal has characteristic absorption at the following 2θ angles ±0.2: 12.4, 13.2, 14.1, 16.9, 20.2, 20.3, 21.6, 21.9, 23.2, 23.5, 23.7, 23.9, 25.0, 26.5, 26.7, 26.9, 28.3, 28.5, 28.8, 31.0, 31.3, 34.8, 35.4, 36.9, 37.1, and 38.5.

[0020] The invention provides an ornidazole phosphate crystal X-ray powder diffraction spectrum, which mainly has characteristic absorption at 2θ±0.2: 12.5, 13.2, 14.1, 17.0, 20.3, 21.6, 23.5, 23.9, 28.5, 28.8.

[0021] The crystal characteristic peaks in this invention are expressed using methods commonly used in the art. Typically, the tolerance is ±0.2° when accurate to 0.1°. In actual measurements, larger deviations may occur due to particle size, sample height, preferred orientation, or sample transparency, but these deviations should still be understood to fall within the scope of this patent.

[0022] The characteristic unit cell parameters of the ornidazole phosphate crystal of the present invention are: monoclinic system, C2 / c space group, and the unit cell volume calculated by the unit cell parameters is α=90°, β=99.653°, γ=90°,

[0023] The single crystal crystallographic parameters and structure refinement parameters of the novel ornidazole phosphate crystal provided by the present invention are as follows:

[0024] This data is only the test data obtained under the test experimental conditions. The difference in test results caused by changes in the test experimental conditions should also be within the reasonable scope of protection of the present invention.

[0025] The ornidazole phosphate crystals of the present invention, as shown in the structural unit schematics and structural stacking schematics, show that in the unit cell microstructure, two molecules of the same chirality are tightly connected by hydrogen bonds through the two PO groups of the phospholipid group in the molecular structure; and two molecules of different chirality are connected by hydrogen bonds through the last remaining PO group of the phospholipid group in one molecular structure and the nitrogen atom at the 3-position of the imidazole group in the other molecule. This sequential stacking forms the unique stable crystal structure of the crystals of the present invention.

[0026] The X-ray powder diffraction patterns of ornidazole phosphate crystals are basically shown in Figures 8, 12, 13, 14, and 15.

[0027] The X-ray powder diffraction pattern obtained by calculation based on the single crystal diffraction measurement data of ornidazole phosphate crystals of the present invention is shown in Figure 9. The calculated X-ray powder diffraction pattern result is consistent with the actual measured X-ray powder diffraction pattern.

[0028] The differential scanning calorimetry (DSC) of the ornidazole phosphate crystals of the present invention is shown in FIG10 , from which it can be seen that the crystal form has an endothermic peak at a temperature of 210° C. to 230° C.

[0029] The thermogravimetric analysis (TGA) spectrum of the ornidazole phosphate crystals of the present invention is shown in FIG11 .

[0030] The ornidazole phosphate crystals described in the present invention can be obtained by the following method:

[0031] Ornidazole phosphate is dissolved in an organic solvent-water mixed solvent, activated carbon is added for decolorization, and the mixture is filtered. The filtrate is kept at -5°C to 40°C, and an organic solvent is added under stirring to precipitate crystals, which are filtered. The filter cake is dried with hot air at 20-50°C.

[0032] Preferably, the preparation method of ornidazole phosphate crystals described in this patent is prepared by the following method:

[0033] Take the crude product of ornidazole phosphate, add water, start stirring, heat until dissolved, add 0.05 g of activated carbon, continue stirring for 10 minutes, filter, add an organic solvent (methanol, ethanol, isopropanol, acetone) to the filtrate, slowly cool to -5°C ~ 40°C for crystallization for 5 hours, separate, and dry the solid at 20°C ~ 50°C to obtain crystals.

[0034] The preferred crystallization temperature here is -5°C to 40°C. This does not mean that crystallization cannot be achieved if the temperature is lower than -5°C or higher than 40°C. Similarly, the preferred drying temperature of 20°C to 50°C only means that the purpose of the operation can be achieved under normal drying conditions. In fact, this product has good stability, and temperature changes have little effect on product quality. Intentionally changing the drying temperature to speed up or slow down the drying speed should also be understood as falling within the scope of this patent.

[0035] The organic solvent used is one of methanol, ethanol, isopropanol, and acetone, or a mixture of two or more thereof.

[0036] The organic solvent-water mixed solvent mentioned in the preparation method of ornidazole phosphate described in this patent refers to the solvent system state of ornidazole phosphate before crystallization. This state can be formed by sequentially adding water and organic solvent or directly mixing and then dissolving ornidazole phosphate. In addition, the adjustment of the order of addition of ornidazole phosphate, to the extent that professionals in this field can understand, ultimately forms an organic solvent-water system containing ornidazole phosphate, which should be understood as within the scope of this patent.

[0037] During the preparation process, the solubility and crystallization rate of ornidazole phosphate are adjusted by adding an organic solvent. The organic solvent used is an alcohol solvent such as methanol, ethanol, and isopropanol; a ketone solvent such as acetone; and an ester solvent such as ethyl acetate. The amount of the organic solvent used is 0-100 times the amount of ornidazole phosphate.

[0038] During the preparation process, the amount of water added is typically 30 to 100 times that of ornidazole phosphate. As professionals in the field of crystallization will appreciate, similar crystals can be obtained by appropriately increasing or decreasing the amount of water added and adjusting the amount of organic solvent, and this should also be understood to fall within the scope of this patent.

[0039] In the preparation of ornidazole phosphate, an organic solvent-water mixture is a solvent system that is very effective in obtaining crystals. However, this does not mean that a pure water or organic solvent system cannot obtain the crystals described in this patent. In fact, the target crystals can also be obtained well when only water is added. The crystals can also be obtained in a pure organic solvent system, but this condition is not preferred.

[0040] The ornidazole phosphate (crude product) mentioned in the invention can be obtained by the following method:

[0041] In a 2L reaction flask, add 50g of ornidazole disodium phosphate and 700ml of methanol and start stirring. After 5 minutes, add approximately 115ml of 2M hydrochloric acid solution dropwise. When the solution reaches pH 2, stop adding the hydrochloric acid solution and add 700ml of water. Continue stirring for 4 hours, filter, and slurry the filter cake three times with 100ml of water. The resulting solid is dried under reduced pressure at 40°C to 60°C to obtain crude ornidazole phosphate.

[0042] The applicant has discovered that the crystals described in this patent can be obtained in an aqueous system at a pH of 2±0.5. Therefore, the aqueous system is also a characteristic of this crystallization process. Similarly, methods that intentionally adjust the organic solvent-water ratio, or increase stirring and shaking during the precipitation process, thereby interfering with the precipitation process to obtain results that differ from X-ray powder diffraction patterns should still be understood to fall within the scope of this patent.

[0043] After obtaining the ornidazole phosphate crystals described in this patent, in comparison with previous research results, we have a new understanding of the preparation process of ornidazole phosphate. Comparative data revealed that in the preparation process of ornidazole phosphate, the HCl generated after the hydrolysis of the ornidazole phosphoryl chloride intermediate will form a hydrochloride substance with the N on the imidazole in its structure. Therefore, in the absence of pH control, the hydrolysis step forms an intermediate state of a salt mixture, and it is difficult to obtain good crystals in this state. In other words, ornidazole phosphate crystals can only be effectively obtained under the condition of controlling the pH of the solution. At present, the preferred solution pH is 2±0.5.

[0044] As mentioned above, ornidazole phosphate crystals can be obtained when the solution pH is 2±0.5. The crude ornidazole phosphate provided in this patent is also obtained based on this pH control point. The specific embodiment of this patent is to obtain ornidazole phosphate through a series of operations using ornidazole phosphate disodium as the starting material. Similarly, we adjust the pH of the ornidazole phosphate hydrochloride intermediate state after the hydrolysis of ornidazole phosphoryl chloride described above to reach pH 2±0.5, which can also meet the conditions for obtaining ornidazole phosphate. Therefore, similar embodiments should also be understood as the scope of this patent.

[0045] The method for obtaining the crude ornidazole phosphate mentioned in the present invention is characterized by using a solution system with a pH of 2±0.5 as the pH range for precipitation. As generally understood by professionals in chemistry, changes in pH within a certain range without causing essential changes in the compound should also be understood as falling within the scope of this patent. The acquisition method mentioned therein is merely for the purpose of describing the main steps of its preparation process. In fact, during the pH adjustment process, precipitation of salt substances may occur. In order to obtain a higher purity product, the intentional addition of a desalting operation should also be understood as falling within the scope of this patent.

[0046] In the previous preparation of ornidazole disodium phosphate, the phosphate ester formed after hydrolysis of the phosphorus oxychloride intermediate was considered difficult to obtain stable crystals, and the ultimate reaction target was ornidazole disodium phosphate. However, the structure of ornidazole disodium phosphate suffers from poor stability due to the high activity of chlorine.

[0047] In the process for producing ornidazole disodium phosphate, ethanol is typically added in a fourfold amount to adjust the pH. During the entire desalination and formation process of ornidazole phosphate, no ornidazole phosphate derivatives are observed to precipitate. Only after the disodium salt is formed can a compound containing crystalline water precipitate. Because the entire reaction step is performed in low-volume ethanol-water solutions and no precipitation occurs, ornidazole phosphate was previously considered to be a substance with high solubility in both ethanol and water.

[0048] By chance, we treated the prepared levonidazole disodium with acid to remove the cations. The resulting product unexpectedly obtained a compound with unexpected solubility properties under appropriate water-isopropanol conditions. Furthermore, unexpectedly, we obtained crystals of a special compound in an aqueous system. After determining its structure, it was confirmed that the substance was levonidazole phosphate.

[0049] Subsequent investigations and studies of ornidazole phosphate crystals revealed that ornidazole phosphate can form a stable structure through hydrogen bonding between PO and PO groups on different molecules, resulting in a unique crystal form. Compared to ornidazole phosphate disodium, this substance exhibits superior stability. Therefore, in practice, ornidazole phosphate can effectively replace ornidazole phosphate disodium in its applications. Furthermore, it can address some of the limitations of ornidazole phosphate disodium due to its poor stability. For example, ornidazole phosphate disodium is generally difficult to use in solid dosage forms such as tablets and capsules due to its poor stability. Ornidazole phosphate crystals, however, possess excellent stability and can be well-suited for the preparation of such preparations. The availability of ornidazole phosphate crystals provides a new, more stable material foundation for the clinical application of ornidazole phosphate derivatives.

[0050] According to existing information, a preparation method of ornidazole phosphate is described in CN1803811A. A method for preparing left ornidazole phosphate is mentioned in CN101007823A. With reference to the technical solution, left ornidazole is changed to ornidazole. Ornidazole hydrochloride is prepared by a method for preparing left ornidazole phosphate hydrochloride in patent CN102516298A. Also with reference to the technical solution, left ornidazole is changed to ornidazole. According to the above method, a batch of compounds are prepared. By comparison, the solubility of the compound obtained according to CN1803811A and the pH value are basically the same as those of CN102516298A. The pH of the compound obtained according to CN101007823A is higher. Their pH values ​​are different from the pH values ​​of the compounds described in this patent. In combination with their physicochemical properties, it is known that the above three compounds are not the same as those described in this patent.

[0051] The inventors prepared levornidazole disodium phosphate pentahydrate according to patent CN101177433, prepared levornidazole disodium phosphate hexahydrate according to patent CN107151257, and prepared levornidazole disodium phosphate heptahydrate according to patent CN109776609, and compared their stability with the compounds provided by the present invention. It was found that the stability of the ornidazole phosphate compound obtained by the present invention was much higher than that of the comparative compound in the form of sodium salt.

[0052] When the ornidazole phosphate crystals of the present invention are used as an active ingredient in a pharmaceutical composition, they can be prepared into a variety of drug delivery preparations, including various solid drug delivery preparations, due to their good stability.

[0053] The medicine of the present invention can be used for preventing, improving and treating diseases caused by anaerobic bacteria infection and protozoan infection, and is particularly suitable for use as a medicine for human and veterinary medicine.

[0054] The dosage of ornidazole phosphate of the present invention is 1-100 mg per kg of body weight, preferably 1-20 mg per kg of body weight over a 24-hour period. The optimal treatment regimen is a once-daily dose of 1-50 mg / kg of body weight. To meet the ideal dosing regimen for human or veterinary use, this dosage can be adjusted upward or downward depending on the severity of the condition and the difficulty of treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1: Ornidazole phosphate crystal planar morphology

[0056] Figure 2: Schematic diagram of the crystal structure unit of ornidazole phosphate

[0057] Figure 3: Schematic diagram of the crystal structure unit of ornidazole phosphate - partial diagram (same configuration)

[0058] Figure 4: Schematic diagram of the crystal structure unit of ornidazole phosphate - partial diagram (different configurations)

[0059] Figure 5: Schematic diagram of the molecular stacking structure of the crystal structure of ornidazole phosphate (a-axis)

[0060] Figure 6: Schematic diagram of the molecular stacking structure of the crystal structure of ornidazole phosphate (b-axis)

[0061] Figure 7: Schematic diagram of the molecular stacking structure of the crystal structure of ornidazole phosphate (c-axis)

[0062] Figure 8: X-ray diffraction pattern of ornidazole phosphate crystalline powder

[0063] Figure 9: XRPD pattern calculated from single crystal structure data of ornidazole phosphate

[0064] Figure 10: DSC spectrum of ornidazole phosphate crystals

[0065] Figure 11: TGA spectrum of ornidazole phosphate crystals

[0066] Figure 12: XRPD pattern of ornidazole phosphate crystals prepared in Example 3 of the present invention

[0067] Figure 13: XRPD pattern of ornidazole phosphate crystals prepared in Example 5 of the present invention

[0068] Figure 14: XRPD pattern of ornidazole phosphate crystals prepared in Example 6 of the present invention

[0069] Figure 15: XRPD pattern of ornidazole phosphate crystals prepared in Example 7 of the present invention

[0070] Figure 16: X-ray diffraction pattern of ornidazole phosphate powder obtained in the prior art (CN101007823A)

[0071] Figure 17: X-ray diffraction pattern of ornidazole phosphate powder obtained in the prior art (CN1803811A) Specific embodiments

[0072] The following examples will illustrate the implementation of the present invention in more detail, but are not intended to limit the scope of the present invention.

[0073] Example 1: Preparation of crude ornidazole phosphate

[0074] In a 2L reaction flask, add 50g of ornidazole disodium phosphate and 700ml of methanol and start stirring. After 5 minutes, add approximately 115ml of 2M hydrochloric acid solution dropwise. When the solution reaches pH 2, stop adding the hydrochloric acid solution and add 700ml of water. Continue stirring for 4 hours, filter, and slurry the filter cake three times with 100ml of water. The resulting solid is dried under reduced pressure at 40°C to 60°C to obtain crude ornidazole phosphate.

[0075] Example 2: Preparation of Ornidazole Phosphate Crystals

[0076] In a 100 ml three-necked flask, 1 g of crude ornidazole phosphate was added, 40 g of water was added, stirring was started, and the mixture was heated to 90°C. 0.1 g of activated carbon was added and stirring was continued for 10 minutes. The mixture was filtered and the filtrate was slowly cooled to -5°C for crystallization for 5 hours. The solid was separated and dried at 30°C to obtain 0.4 g of crystals. The crystal structure, single crystal structure, X-ray powder diffraction pattern, DSC pattern, and TGA pattern are shown in Figures 1-11. The measured unit cell parameters are as follows:

[0077] Example 3: Preparation of Ornidazole Phosphate Crystals

[0078] In a 100 ml three-necked flask, 1 g of crude ornidazole phosphate was added, 60 g of water was added, stirring was started, and the mixture was heated to 60° C. 0.05 g of activated carbon was added, stirring was continued for 10 minutes, and the mixture was filtered. 90 g of anhydrous ethanol was added to the filtrate, and the mixture was slowly cooled to -5° C. for crystallization for 5 hours. The solid was separated and dried at 50° C. to obtain 0.5 g of crystals. The X-ray powder diffraction pattern is shown in FIG12 , and the measured unit cell parameters are as follows:

[0079] Example 4: Preparation of Ornidazole Phosphate Crystals

[0080] In a 100ml three-necked flask, add 1g of crude ornidazole phosphate, add 70g of 20% ethanol aqueous solution, stir, heat to micro-reflux, add 0.05g of activated carbon, continue stirring for 20 minutes, filter, add 10g of acetone dropwise to the filtrate, slowly cool to -5°C for crystallization for 5 hours, separate, and dry the solid at room temperature (20°C) to obtain 0.6g of crystals.

[0081] Example 5: Preparation of Ornidazole Phosphate Crystals

[0082] In a 100 ml three-necked flask, 1 g of crude ornidazole phosphate was added, 30 g of water was added, and the mixture was stirred. The mixture was heated to 50° C. and stirred for 30 minutes. The mixture was filtered, and 10 g of methanol was added dropwise to the filtrate. The mixture was slowly cooled to -5° C. for crystallization for 5 hours. The solid was separated and dried at 40° C. to obtain 0.3 g of crystals. The X-ray powder diffraction pattern is shown in FIG13 . The measured unit cell parameters are as follows:

[0083] Example 6: Preparation of Ornidazole Phosphate Crystals

[0084] In a 200ml three-necked flask, 1g of crude ornidazole phosphate was added, 60g of water was added, stirred, heated to 70°C, 0.05g of activated carbon was added, stirring was continued for 20 minutes, filtered, and the filtrate was cooled to 50°C, 60g of acetone was added dropwise, and the temperature was slowly lowered to 10°C for crystallization for 5 hours. After separation, the solid was dried at 40°C to obtain 0.6g of crystals. The X-ray powder diffraction pattern is shown in Figure 14. The measured unit cell parameters are as follows:

[0085] Example 7: Preparation of Ornidazole Phosphate Crystals

[0086] In a 200 ml three-necked flask, 1 g of crude ornidazole phosphate was added to 60 g of water, stirred, heated to 70°C, and continued to stir for 10 minutes. The mixture was filtered, and the filtrate was slowly cooled to 40°C. 40 g of isopropyl alcohol was slowly added dropwise. The mixture was crystallized for 5 hours, separated, and dried at 50°C to obtain 0.7 g of crystals. The X-ray powder diffraction pattern is shown in Figure 15. The unit cell parameters determined are as follows:

[0087] Example 8: Preparation of Ornidazole Phosphate Crystals

[0088] In a 200 ml three-necked flask, add 1 g of crude ornidazole phosphate and 120 g of a mixed solvent of ethanol and water (W / W = 1:1), heat to 60°C with stirring, filter, and slowly cool the filtrate to room temperature to precipitate crystals, filter, and dry the solid at 45°C to obtain 0.5 g of crystals.

[0089] Example 9: Preparation of Ornidazole Phosphate Capsules

[0090] Prescription: Ornidazole Phosphate 300g

[0091] 150g microcrystalline cellulose

[0092] Magnesium stearate 3.0g

[0093] Made into 1000 tablets

[0094] Preparation method: Take the prescribed amount of ornidazole phosphate, granulate it by dry method, add magnesium stearate, mix it, measure the content of the intermediate, and fill it into capsules to obtain it.

[0095] Comparative Example 1: Preparation of Levorotatory Ornidazole Disodium Phosphate Pentahydrate

[0096] Levoornidazole disodium phosphate pentahydrate was prepared according to the method provided in patent CN101177433. 300g of Levoornidazole disodium phosphate and 3500ml of 90% ethanol were placed in a reaction flask, heated to 45°C with stirring, and kept stirring for 10 minutes. The mixture was filtered while hot, and the filtrate was cooled to room temperature and then placed at 15°C for 8 hours to allow crystallization. The resulting solid was then filtered, washed with cold ethanol and acetone, and dried at 38°C for 8 hours to obtain Levoornidazole disodium phosphate pentahydrate.

[0097] Comparative Example 2: Preparation of Ornidazole Disodium Phosphate Hexahydrate

[0098] Levoornidazole disodium phosphate hexahydrate was prepared according to the method provided in patent CN107151257. 20g of levonidazole disodium phosphate was dissolved in 120ml of 95% methanol, followed by decolorization with 1.2g of activated carbon. The mixture was stirred for 30 minutes and filtered. The filtrate was incubated at 40°C and 500ml of ethanol was slowly added dropwise with stirring until a solid precipitated. The solid was filtered and dried at 40°C to obtain levonidazole disodium phosphate hexahydrate.

[0099] Comparative Example 3: Preparation of Ornidazole Disodium Phosphate Heptahydrate

[0100] According to the method provided in patent CN109776609, levonidazole disodium phosphate heptahydrate was prepared. 10 g of levonidazole disodium phosphate was added to 500 ml of a mixed solvent (water / ethanol = 1:15, V / V) to dissolve the mixture, equilibrate at 25° C. for half an hour, filter, and filtrate. A small amount of sample was added to the filtrate as seed crystals. The mixture was sealed at 25° C. and then slowly cooled to 10° C., kept at 10° C. for crystallization, and the resulting crystals were collected and dried at room temperature to obtain levonidazole disodium phosphate heptahydrate.

[0101] Comparative Example 4

[0102] Ornidazole phosphate was prepared by referring to the preparation method of ornidazole phosphate in patent CN101007823A.

[0103] Dissolve 110 g of ornidazole in 500 ml of dry ethyl acetate solution, add 100 ml of phosphorus oxychloride dropwise, control the reaction temperature at 10-20 ° C, control the reaction in the liquid phase until there is a peak with almost no ornidazole, recover the ethyl acetate under reduced pressure to obtain a chlorophosphate intermediate, cool, slowly add 600 ml of pure water, hydrolyze for 1 hour, slowly add 10% sodium carbonate solution to adjust the pH to 6.0, concentrate to dryness under reduced pressure, add 500 ml of methanol, filter, add 500 ml of petroleum ether to the filtrate, freeze crystallize, and filter to obtain ornidazole phosphate.

[0104] This preparation method is similar to the existing technology. The obtained product was subjected to X-ray powder diffraction, and the results are shown in Figure 16.

[0105] Comparative Example 5

[0106] Ornidazole phosphate was prepared according to the ornidazole phosphate method in patent CN1803811A.

[0107] Dissolve 44 g of ornidazole in 300 ml of acetonitrile, add 40 ml of phosphorus oxychloride dropwise while stirring, and control the reaction temperature to 10-15 ° C. After the addition is complete, continue to keep warm and react for 1 hour, cool and crystallize for 5 hours (0 ° C), filter, dissolve the filter cake in 200 ml of water, hydrolyze for 40 minutes, and distill under reduced pressure. Add 300 ml of anhydrous ethanol to the residual liquid, freeze and crystallize, filter to obtain a solid, and dry in vacuo at 30 ° C to 60 ° C to obtain ornidazole phosphate.

[0108] This preparation method is a prior art, and the obtained product was subjected to X-ray powder diffraction, and the results are shown in Figure 17.

[0109] Comparative Example 6

[0110] Ornidazole phosphate hydrochloride was prepared according to the method of ornidazole phosphate hydrochloride in patent CN102516298A.

[0111] Dissolve 100 g of ornidazole phosphate in 500 ml of acetone at 50°C, cool to room temperature, filter, and add concentrated hydrochloric acid dropwise to the filtrate while stirring until almost no solid is produced. Stir for 1 hour and then filter. Dry the solid in a vacuum at 40°C to dryness to obtain ornidazole phosphate hydrochloride.

[0112] Experimental Example 1:

[0113] The samples of Examples 2-8 and Comparative Examples 4-6 were taken for quality comparison, and their solubility in water, solid hygroscopicity, and pH value were examined respectively.

[0114] Solubility determination refers to the classification standards of solubility in the Chinese Pharmacopoeia:

[0115] Very soluble means that 1g (ml) of solute can be dissolved in less than 1ml of solvent;

[0116] Soluble means that 1g (ml) of solute can be dissolved in 1 to less than 10ml of solvent;

[0117] Solubility means that 1g (ml) of solute can be dissolved in 10 to less than 30ml of solvent;

[0118] Slightly soluble means that 1g (ml) of solute can be dissolved in 30 to less than 100ml of solvent;

[0119] Slightly soluble means that 1g (ml) of solute can be dissolved in 100 to less than 1000ml of solvent;

[0120] Very slightly soluble means that 1g (ml) of solute can be dissolved in 1000 to less than 10000ml of solvent;

[0121] Almost insoluble or insoluble means that 1g (ml) of solute cannot be completely dissolved in 10000ml of solvent.

[0122] Test method: Unless otherwise specified, weigh the test sample ground into fine powder or measure the liquid test sample, shake vigorously for 30 seconds every 5 minutes at 25℃±2℃; observe the dissolution within 30 minutes. If no solute particles or droplets are visible, it is completely dissolved.

[0123] The criteria for determining hygroscopicity refer to the provisions of the Guiding Principles for Drug Hygroscopicity Test in the Chinese Pharmacopoeia:

[0124] Deliquescent: Absorbs sufficient water to form a liquid.

[0125] Highly hygroscopic: weight gain upon moisture absorption is not less than 15%.

[0126] Hygroscopic: Weight gain due to moisture absorption is less than 15% but not less than 2%.

[0127] Slightly hygroscopic: weight gain due to moisture absorption is less than 2% but not less than 0.2%.

[0128] No or almost no hygroscopicity: weight gain due to moisture is less than 0.2%.

[0129] Test method:

[0130] 1. Take a dry stoppered glass weighing bottle (outer diameter 50mm, height 15mm) and place it in a suitable 25℃±1℃ constant temperature desiccator (with ammonium chloride or ammonium sulfate saturated solution placed at the bottom) or an artificial climate box (set temperature at 25℃±1℃, relative humidity at 80%±2%) the day before the test, and accurately weigh the weight (m1).

[0131] 2. Take an appropriate amount of the test sample and spread it evenly in the above-mentioned weighing bottle. The thickness of the test sample is generally about 1mm. Accurately weigh the weight (m2).

[0132] 3. Open the weighing bottle and place it with the bottle cap under the above constant temperature and humidity conditions for 24 hours.

[0133] 4. Close the weighing bottle lid and accurately weigh the weight (m3).

[0134] Weight gain percentage = (m2-m1) / (m3-m2) x 100%

[0135] The pH value was determined according to the conventional pH determination method, pH meter model: FE28 (Mettler Toledo)

[0136] The results are shown in the table below:

[0137] Table: Typical physical and chemical properties of ornidazole phosphate

[0138] The solubility, hygroscopicity and pH results of the ornidazole phosphate crystals of the present invention are stable and consistent, while the stability of comparative examples 4-6 is poor and difficult to store; the ornidazole phosphate crystals of the present invention are superior to comparative examples 4-6.

[0139] Experimental Example 2: Stability comparison with ornidazole disodium phosphate

[0140] Select levonidazole disodium phosphate pentahydrate (Comparative Example 1), levonidazole disodium phosphate hexahydrate (Comparative Example 2), levonidazole disodium phosphate heptahydrate (Comparative Example 3), ornidazole phosphate (patent CN1803811A, Comparative Example 5), ornidazole phosphate hydrochloride (Comparative Example 6), and the compounds of the present invention (Examples 2-8) and the crude product of the present compound (Example 1) for stability comparison test at a temperature of 60°C ± 2°C and a relative humidity of 75% ± 5%.

[0141] The structural formula of impurity A is as follows

[0142] X represents hydrogen or sodium

[0143] The appearance, related substances and content were measured at 0 days, 5 days, 10 days and 30 days respectively. The test results are shown in the table below:

[0144] Upon comparison, the ornidazole phosphate crystals of the present invention have great advantages in stability compared with the currently known ornidazole phosphate disodium levorotatory ester; and compared with the ornidazole phosphate and ornidazole phosphate hydrochloride mentioned in existing patents, the ornidazole phosphate crystals of the present invention have obvious advantages in stability.

[0145] Experimental Example 3: Comparison of Stability of Ornidazole Phosphate Crystals

[0146] Take an appropriate amount of ornidazole phosphate crystals prepared according to the method described in Example 2-8, place them in a 20 mL colorless transparent glass bottle, and place the sample bottle under the following conditions: high temperature: 60°C, high humidity: 92.5% RH, light: 4500 lux, accelerated: 40°C 75% RH;

[0147] After 2 weeks, the crystals were taken out, their appearance was observed, and XRPD was performed to characterize them in order to investigate the physical stability of the crystals.

[0148] The crystal stability results are shown in the table below.

[0149] The above results show that the ornidazole phosphate crystals of the present invention have good stability and the crystal form does not change under high temperature, high humidity and light conditions.

[0150] Experimental Example 4: In vivo efficacy study of ornidazole phosphate crystals

[0151] Experimental samples: samples prepared in the present invention. Experimental methods: clinical isolates were used to establish a systemic infection model in mice, and the tail vein was used for treatment to observe the therapeutic effect. 50 The test steps are as follows:

[0152] 1. Select clinical isolates of Bacteroides, Pulmonaria, Veillonella, Peptostreptococcus, and Clostridium perfringens.

[0153] 2. Each selected test bacteria was prepared into different concentration series with 5% gastrosin and injected into mice by intraperitoneal injection. The 100% minimum lethal dose (100% MLD) was measured. The 100% MLD of each test bacteria was as follows:

[0154] (1) Bacteroides fragilis about 1.9×10 8 CFU / mouse

[0155] (2) P. volucrata: approximately 4.75×10 7 CFU / mouse

[0156] (3) Veillonella about 1.15×10 8 CFU / mouse

[0157] (4) Peptostreptococci: about 7.5×10 7 CFU / mouse

[0158] (5) Clostridium perfringens about 1.65×10 7 CFU / mouse

[0159] 3. Preparation of test drugs: Use sterile physiological saline to prepare the test drugs into 5 doses at a dose ratio of 1:0.7. The dosages are shown in Tables 1 to 5.

[0160] 4. With 2x MLD 100 Each group of mice was intraperitoneally infected with bacterial concentration, with an infection volume of 0.5 ml / mouse. After infection, the drug was accurately prepared into each dose solution with sterile saline before use. The drug was injected twice via the tail vein, half an hour and 6 hours after infection. The sum of the two doses was the administered dose. The mice were observed for seven days, and the number of surviving mice was recorded. ED was analyzed by Bliss method. 50 calculate.

[0161] Table 1 The samples of the present invention have an effect on the ED of Peptostreptococcus 50 Measurement results

[0162] Table 2 The samples of the present invention have an effect on Bacteroides ED 50 Measurement results

[0163] Table 3: Effect of the samples of the present invention on the ED of P. 50 Measurement results

[0164] Table 4 The samples of the present invention have no effect on the ED of Veillonella 50 Measurement results

[0165] Table 5 The samples of the present invention have an effect on Clostridium perfringens ED 50 Measurement results

[0166] In vivo efficacy studies have shown that ornidazole phosphate crystals have a definite therapeutic effect on mouse infections caused by common pathogenic anaerobic bacteria such as Bacteroides, Pulmonaria, Veillonella, Streptococcus and Clostridium perfringens.

[0167] The above-described embodiments represent only a few implementations of the present invention and should not be construed as limiting the scope of the patent. It should be noted that those skilled in the art may make various modifications and improvements without departing from the spirit of the present invention, and these modifications and improvements fall within the scope of protection of the present invention. The scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. An ornidazole phosphate crystal having a stable spatial structure, the specific structure of which is as follows: The ornidazole phosphate crystal has characteristic absorption in its X-ray powder diffraction mainly at the following 2θ±0.2: 12.5, 13.2, 14.1, 17.0, 20.3, 21.6, 23.5, 23.9, 28.5 and 28.

8.

2. The ornidazole phosphate crystal according to claim 1, characterized in that X-ray powder diffraction has characteristic absorption at the following 2θ±0.2: 12.4, 13.2, 14.1, 16.9, 19.9, 20.2, 20.3, 21.6, 21.9, 23.2, 23.5, 23.7, 23.9, 24.4, 25.0, 25.2, 25.6, 26.5, 26.7, 28.3, 28.5, 31.3, 34.4, 36.9, 37.1, 39.

6.

3. The ornidazole phosphate crystal according to claim 2, characterized in that: The X-ray powder diffraction pattern of the ornidazole phosphate crystals is substantially as shown in FIG8 .

4. The ornidazole phosphate crystal according to claim 1, characterized in that The X-ray powder diffraction has characteristic absorption at the following 2θ±0.2: 12.4, 13.2, 14.1, 17.0, 18.4, 20.3, 21.6, 21.9, 23.2, 23.5, 23.7, 23.9, 25.0, 25.2, 25.6, 26.5, 26.7, 28.3, 28.5, 28.8, 31.3, 34.4, 35.8, 36.9, 37.1, and 38.

4.

5. The X-ray powder diffraction characteristic absorption of ornidazole phosphate according to claim 4, characterized in that: The X-ray powder diffraction pattern of the ornidazole phosphate crystals is substantially as shown in FIG12 .

6. The ornidazole phosphate crystal according to claim 1, characterized in that: X-ray powder diffraction has characteristic absorption at the following 2θ±0.2: 12.5, 13.2, 14.1, 17.0, 19.9, 20.2, 20.3, 21.6, 21.9, 23.2, 23.5, 23.8, 23.9, 25.0, 25.6, 26.5, 26.7, 28.3, 28.5, 28.8, 31.1, 31.3, 34.4, 36.8, 37.1, and 38.

5.

7. The ornidazole phosphate crystal according to claim 6, characterized in that: The X-ray powder diffraction pattern of the ornidazole phosphate crystals is substantially as shown in FIG13 .

8. The ornidazole phosphate crystal according to claim 1, characterized in that: X-ray powder diffraction has characteristic absorption at the following 2θ±0.2: 12.5, 13.2, 14.1, 17.0, 20.2, 20.3, 21.6, 21.9, 23.2, 23.5, 23.7, 23.9, 25.0, 25.3, 26.5, 26.7, 28.3, 28.5, 28.8, 31.2, 31.3, 35.4, 35.8, 36.9, 37.1, and 38.

5.

9. The ornidazole phosphate crystal according to claim 8, characterized in that: The X-ray powder diffraction pattern of the ornidazole phosphate crystals is substantially as shown in FIG14 .

10. The ornidazole phosphate crystal according to claim 1, characterized in that: The X-ray powder diffraction has characteristic absorption at the following 2θ±0.2: 12.4, 13.2, 14.1, 16.9, 20.2, 20.3, 21.6, 21.9, 23.2, 23.5, 23.7, 23.9, 25.0, 26.5, 26.7, 26.9, 28.3, 28.5, 28.8, 31.0, 31.3, 34.8, 35.4, 36.9, 37.1, 38.

5.

11. The ornidazole phosphate crystal according to claim 10, characterized in that: The X-ray powder diffraction pattern of the ornidazole phosphate crystals is substantially as shown in FIG15 .

12. The ornidazole phosphate crystal according to any one of claims 1 to 11, characterized in that: The unit cell parameters are: monoclinic system, C2 / c space group, and the unit cell parameters are used to calculate the unit cell volume: α=90°, β=99.653°, γ=90°, 13. The ornidazole phosphate crystal according to any one of claims 1 to 12, characterized in that: The unit cell structure is characterized by: two molecules with the same chirality are tightly connected by hydrogen bonds through two POs on the phosphoester group in the molecular structure; two molecules with different chirality are connected by hydrogen bonds through the last remaining PO of the phosphoester group in one molecular structure and the 3-position nitrogen atom of the imidazole group in the other molecule.

14. The ornidazole phosphate crystal according to claim 1, characterized in that: When measured using differential scanning calorimetry, the ornidazole phosphate crystals have an endothermic peak at a temperature of 210° C. to 230° C.

15. The method for preparing ornidazole phosphate crystals according to claim 1, characterized in that: The preparation method comprises the following steps: taking a crude product of ornidazole phosphate, adding water, starting stirring, heating at 40°C to 100°C until dissolved, adding activated carbon, continuing stirring for 10 minutes, filtering, adding an organic solvent to the filtrate, slowly cooling to -10°C to 40°C for crystallization, separating, and drying the solid at 20°C to 50°C to obtain crystals.

16. The method for preparing ornidazole phosphate crystals according to claim 15, characterized in that: The preparation process of crude ornidazole phosphate is as follows: in a reaction bottle, add disodium ornidazole phosphate and methanol, start stirring, after 5 minutes, dropwise add a hydrochloric acid solution twice the molar amount of disodium ornidazole phosphate, add water and continue stirring for 4 hours, filter, slurry the filter cake with water 3 times, and dry the obtained solid under reduced pressure at 40°C to 60°C to obtain crude ornidazole phosphate.

17. The preparation method according to claim 16, characterized in that: Crystallization was carried out under the condition of pH = 2 ± 0.

5.

18. The preparation method according to claim 15, characterized in that: The organic solvent used in the preparation method is one or more mixed solvents of methanol, ethanol, isopropanol, n-propanol and acetone, the amount of water used is 30 to 100 times the weight ratio of ornidazole phosphate, and the amount of the organic solvent used is 0 to 100 times the weight ratio of ornidazole phosphate.

19. Use of the ornidazole phosphate crystal according to claim 1 in the preparation of a medicament for treating infection caused by anaerobic bacteria.

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