Preparation process of high-purity crystal form calcium folinate

Abstract

The invention belongs to the technical field of chemical raw material medicine synthesis, and particularly relates to a preparation process of high-purity crystal form calcium folinate. According to the method, the high-purity crystal form calcium folinate (compound I) is prepared from folic acid (compound II) through key process steps of reduction reaction, formylation reaction, hydrolysis ring-opening reaction, salt forming reaction, recrystallization refining and the like. The amide solvent is added in the recrystallization refining process, the crystal form of the calcium folinate is optimized, the formation of hydrophilic groups of the calcium folinate on the crystal surface is blocked, and the problems that the finished product calcium folinate is high in moisture content in the pure water crystallization process and high in hygroscopicity in the storage and stability period are solved. The preparation process disclosed by the invention has the advantages of simple process, short production period, stable product quality, low hygroscopicity, high purity and the like, and can be suitable for industrial large-scale production.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of chemical bulk drug synthesis, and particularly relates to a preparation process of high-purity crystalline calcium folinate. BACKGROUND

[0002] Calcium folinate, chemically named as N-[4-[[(2-amino-5-formyl-1,4,5,6,7,8-hexahydro-4-oxo-6-pteridinyl) methyl] amino] benzoyl]-L-glutamic acid calcium salt, is a calcium salt of the activated form of folic acid in vivo. It is a white or white-like crystalline powder at room temperature, and can replace folic acid as a carrier of one-carbon units in physiological processes, and is involved in the metabolic process of nucleic acids and amino acids. Its core clinical value lies in that it can be used as a detoxifying agent of folic acid antagonists (such as methotrexate, aminopterin or trimethoprim, etc.), and by bypassing the inhibited dihydrofolate reductase (DHFR), it directly provides biologically active tetrahydrofolic acid, thereby protecting normal cells from toxicity. In addition, calcium folinate is also used to prevent or reduce the severe toxic side effects caused by high-dose methotrexate therapy, and to treat megaloblastic anemia caused by folic acid deficiency.

[0003] At present, calcium folinate on the market mainly includes four dosage forms of injection, lyophilized powder injection, tablets and capsules. Among them, injection, lyophilized powder injection and capsule usually use amorphous calcium folinate for preparation, while tablets mainly use crystalline calcium folinate. The most significant difference between the two is that the solubility of amorphous calcium folinate is significantly higher than that of crystalline calcium folinate, while crystalline calcium folinate shows better compressibility. The preparation of amorphous calcium folinate is mostly by ethanol crystallization method, such as the method described in US4500711A and Chinese patent CN101863889, that is, excessive ethanol is added to the aqueous solution of calcium folinate, and crystallization is obtained by stirring; the traditional preparation process of crystalline calcium folinate is usually realized by cooling crystallization in purified water, such as described in Indian patent IN202041003386. Due to the hydrogen bond effect, the hydrophilic groups (such as carboxyl, hydroxyl, etc.) of the crystalline calcium folinate obtained by this method are easily exposed on the surface of the crystal, resulting in that the sample has strong water binding capacity in the process of recrystallization purification, the water content of the finished product is high, and it shows strong hygroscopicity during storage and stability. Studies have shown that even under double aluminum foil bag packaging, the water content during storage and stability can exceed the standards of Chinese Pharmacopoeia (CP) and European Pharmacopoeia (EP) within only 10 days.

[0004] Therefore, it is of great industrial significance and industrial value to develop a new process that can stably prepare high-purity crystalline calcium folinate and meet the standards of various pharmacopoeias, in order to ensure the quality of drugs. SUMMARY

[0005] TECHNICAL PROBLEM

[0006] The crystal form of calcium folinate product prepared by the traditional aqueous phase crystallization method has a rapid increase in moisture content within a short time (e.g., within 10 days) during storage and stability, which exceeds the standard defined in the pharmacopoeia, because the crystal surface exposes hydrophilic groups. The purpose of the present application is to develop a new preparation process to change the crystallization habit through technical means, so as to obtain a crystal form of calcium folinate with high purity, low hygroscopicity and high stability, so as to meet the requirements of industrial production and global pharmacopoeia quality.

[0007] Technical scheme

[0008] The first aspect of the present application provides a preparation process of a high-purity crystal form of calcium folinate, which is shown as follows:

[0009] The step of preparing compound I from compound V specifically includes: suspending compound V in a water-amide mixed solvent, heating to 35-45 DEG C, adding anhydrous calcium chloride to adjust the pH of the reaction solution to 7.0-7.5, adding activated carbon for decolorization, and then performing recrystallization purification after suction filtration to obtain compound I.

[0010] In some embodiments, the mass ratio of compound V to the water-amide mixed solvent is 1:7-12; the mass ratio of water to amide solvent in the water-amide mixed solvent is 1:0.05-0.6; and the mass ratio of compound V to anhydrous calcium chloride is 1:0.2-0.4; wherein the amide solvent includes N,N-dimethylformamide, N,N-dimethylacetamide or N-methylformamide.

[0011] In some embodiments, the mass ratio of folic acid to activated carbon is 1:0.05-0.10.

[0012] In some embodiments, the cooling rate in the recrystallization purification process is 0.3-0.5 DEG C / min, the crystallization temperature is 14-16 DEG C, and the stirring speed is 32-48 rpm.

[0013] In some embodiments, the step of preparing compound III from compound II specifically includes: dissolving compound II in an alkaline solvent, slowly adding a reducing agent, and then reacting at 30-40 DEG C for 1-5 h, followed by cooling, adjusting the pH of the reaction solution to 3.0-4.0 with dilute hydrochloric acid solution, and then suction filtration to obtain compound III.

[0014] In some embodiments, the alkaline solvent is sodium hydroxide or potassium hydroxide; and the mass ratio of compound II to the reducing agent is 1:0.4-0.6; wherein the reducing agent is KBH4.

[0015] In some embodiments, the step of preparing compound IV from compound III specifically comprises: dissolving compound III in a formylating agent, adding a catalyst, and reacting at 5-30℃ in the dark, and then performing a salting reaction after the reaction is completed to obtain compound IV solid.

[0016] In some embodiments, the reaction is performed at 15-20℃ in the dark.

[0017] In some embodiments, the mass ratio of compound III to the formylating agent is 1:1.8-2.0, and the mass ratio of compound III to the catalyst is 1:0.06-0.10; wherein the formylating agent is formic acid, and the catalyst is trifluoroacetic acid.

[0018] In some embodiments, the salting reaction specifically comprises: adding a dilute hydrochloric acid solution to the reaction solution, stirring to crystallize at 20-30℃, and obtaining compound IV solid; wherein the mass concentration of the dilute hydrochloric acid solution is 5.5%-7.0%.

[0019] In some embodiments, the mass ratio of folic acid to the dilute hydrochloric acid solution is 1:10-13.

[0020] In some embodiments, the step of preparing compound V from compound IV specifically comprises: dispersing compound IV in water, adjusting the pH of the reaction solution to 6.0-7.0 with an alkaline solvent, and then reacting at 70-100℃, and then performing a salting reaction after the reaction is completed to obtain compound V solid.

[0021] In some embodiments, the salting reaction specifically comprises: adding activated carbon to decolorize the reaction solution, filtering, cooling to 0-5℃, adding a hydrochloric acid solution to adjust the pH of the reaction solution to 3.0-3.5, and filtering to obtain compound V solid.

[0022] In some embodiments, the mass ratio of folic acid to activated carbon is 1:0.5-0.8.

[0023] The second aspect of the present application provides high-purity crystalline calcium folinate prepared by any of the above preparation processes, and the X-ray powder diffraction pattern of the crystalline calcium folinate has diffraction peaks at 7.71°, 8.25°, 9.73°, 10.96°, 11.82°, 13.89°, 14.34°, 15.44°, 16.25°, 21.97°, 24.15°, and 27.42°, wherein 11.82° is the main diffraction peak, and the error range of the 2θ value is ±0.2°.

[0024] In some embodiments, the X-ray powder diffraction pattern of the crystalline calcium folinate is as shown in Figure 1 .

[0025] Technical effects

[0026] (1) The present application refines by recrystallization in a "water-amide" mixed solvent system, adjusts the molecular arrangement of calcium folinate in the crystallization process by using the molecular polarity characteristics of the amide solvent, and blocks the formation of hydrophilic groups on the crystal surface, thereby reducing the initial moisture content of the product and the hygroscopicity during storage. The moisture content of the obtained product can also stably meet the strict standards of the Chinese Pharmacopoeia (CP moisture standard is not more than 16%) and the European Pharmacopoeia (EP moisture standard is 10% to 17%) during stability test and accelerated test under double-layer aluminum foil bag packaging, solving the problems of easy moisture absorption and poor stability of the crystal form of calcium folinate prepared by traditional water phase crystallization.

[0027] (2) The "water-amide" mixed solvent system used in the present application has good solubility for calcium folinate, and by controlling the cooling rate, crystallization temperature and stirring conditions, a slow and controllable crystallization process is realized, the crystal growth rate is moderate, and the impurities have sufficient time to diffuse back to the mother liquor, so as not to be wrapped into the crystal lattice, and finally high-purity crystal form of calcium folinate is obtained.

[0028] (3) The preparation process of high-purity crystal form of calcium folinate provided by the present application has the advantages of simple process, short production cycle, stable product quality and high purity, and can be applied to the industrialized large-scale production of related raw materials for pharmaceutical production enterprises. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 The X-ray powder diffraction pattern of the crystal form of calcium folinate prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0030] In order to facilitate the implementation of the technical solutions of the application, the following first generally explains and defines the terms and phrases involved in the present application.

[0031] The term "comprising" or "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or equipment. Without more limitation, the element defined by the sentence "including a…" does not exclude the presence of other identical elements in the process, method, article or equipment including the element.

[0032] In each group of comparative experiments provided by the present application, unless otherwise specified, the experimental conditions, materials, etc. remain the same except for the differences indicated by each group, in order to have comparability.

[0033] The reagents and instruments and equipment used in the examples of the present application, if not specifically explained, can be purchased from the market.

[0034] The preparation process of the high-purity crystalline calcium folinate provided in the present application is further described below.

[0035] Preparation of high-purity crystalline calcium folinate

[0036] (1) Preparation of tetrahydrofolic acid (compound III) by reduction reaction: A four-necked flask equipped with a stirrer, a thermometer and a dropping funnel was charged with folic acid (compound II) 100 g, water 1000 g, and stirred until uniformly suspended. The pH of the solution was adjusted to dissolve the folic acid completely. The temperature of the reaction solution was maintained at 40°C, and potassium borohydride powder 60 g was slowly added. After the addition was completed, the reaction was stirred for 3 h. The temperature was lowered, and the pH of the reaction solution was adjusted to 3.0 using a dilute hydrochloric acid solution. White solid was precipitated, and was filtered under suction. The filter cake was washed with anhydrous ethanol to obtain a tetrahydrofolic acid wet filter cake. The reaction step is shown below:

[0037]

[0038] (2) Preparation of (6R,S)-5,10-methylene-5,6,7,8-tetrahydrofolic acid chlorohydrochloride (compound IV) by formylation reaction and salt formation: The tetrahydrofolic acid wet filter cake obtained in step (1) was transferred to a four-necked flask equipped with a stirrer, a thermometer and a dropping funnel. Formic acid 180 g and trifluoroacetic acid 6 g were added, and the filter cake was stirred to dissolve. The reaction temperature was maintained at 20°C, and the solution was left to stand to react for 16 h in the dark. Then, 5.5% hydrochloric acid solution 1000 g was added to the obtained reaction solution, and the solution was stirred at 20°C to crystallize for 24 h. Yellow solid was precipitated, and was filtered under suction to obtain a (6R,S)-5,10-methylene-5,6,7,8-tetrahydrofolic acid chlorohydrochloride wet filter cake. The reaction step is shown below:

[0039]

[0040] (3) Preparation of 5-formyltetrahydrofolic acid hydrochloride (compound V) by hydrolysis and ring-opening reaction and salt formation: The (6R,S)-5,10-methylene-5,6,7,8-tetrahydrofolic acid chlorohydrochloride wet filter cake obtained in step (2) was dispersed in water, and the pH of the reaction solution was adjusted to 6.0 using a sodium hydroxide solution. The solution was reacted at 80°C for 5 h, and then activated carbon 80 g was added to the obtained reaction solution. The solution was stirred for 30 min to decolorize, and was filtered while hot. The temperature was lowered to 5°C, and the pH of the reaction solution was adjusted to 3.0 using a hydrochloric acid solution. White solid was precipitated, and was filtered to obtain a 5-formyltetrahydrofolic acid hydrochloride wet filter cake. The reaction step is shown below:

[0041]

[0042] (4) Preparation of crystalline calcium leucovorin (Compound I) by recrystallization: The wet filter cake of 5-formyltetrahydrofolic acid hydrochloride obtained in step (3) was suspended in 700 g of 20% N,N-dimethylformamide aqueous solution, and heated to 40°C. Then, 40 g of anhydrous calcium chloride was added, and the pH of the reaction solution was adjusted to 7.5. Then, 5 g of activated carbon was added, and the solution was stirred for 30 min to decolorize. The solution was filtered while hot, and the filtrate was placed in a crystallizer. The filtrate was cooled to 16°C at a cooling rate of 0.5°C / min, and the stirring speed was 48 rpm during the crystallization. After the crystallization was completed, the filter cake was washed with 1 L of anhydrous ethanol and 2 L of anhydrous ether, and dried under vacuum at 43°C to obtain crystalline calcium leucovorin with high purity. The purity was 99.88% based on the European Pharmacopoeia (EP) test method. The reaction step is shown below:

[0043]

[0044] The X-ray powder diffraction pattern of the crystalline calcium leucovorin is shown in Figure 1 The characteristic XRPD diffraction peaks are shown in Table 1.

[0045] Table 1 XRPD parameters of crystalline calcium leucovorin

[0046]

[0047] Example 2 Preparation of crystalline calcium leucovorin with high purity

[0048] The preparation process was the same as in Example 1, except that the recrystallization solvent in step (4) was 700 g of 20% N,N-dimethylacetamide aqueous solution. The purity was 99.79% based on the European Pharmacopoeia (EP) test method.

[0049] Example 3 Preparation of crystalline calcium leucovorin with high purity

[0050] The preparation process was the same as in Example 1, except that the recrystallization conditions in step (4) were that the filtrate was cooled to 14°C at a cooling rate of 0.5°C / min, and the stirring speed was 32 rpm during the crystallization. The purity was 99.80% based on the European Pharmacopoeia (EP) test method.

[0051] The products obtained in Examples 1-3 were packaged in double-layer aluminum foil bags, and subjected to an accelerated test at 40°C and a relative humidity of 75% for 6 months. The test results are shown in Table 2.

[0052] Table 2 Accelerated test results

[0053]

[0054] Comparative Example 1

[0055] The preparation process is the same as Example 1. The difference is that the recrystallization solvent in step (4) is 700 g purified water. Its purity is 99.70% based on the European Pharmacopoeia (EP) test method; the moisture content is 16.3% by the Fiesher-Karl method, and 23.3% on the 9th day.

[0056] Comparative Example Two

[0057] The preparation process is the same as Example 1. The difference is that the recrystallization solvent in step (4) is 700 g 10% ethanol-water solution. Its purity is 99.75% based on the European Pharmacopoeia (EP) test method; the moisture content is 15.6% by the Fiesher-Karl method, and 23.1% on the 9th day.

[0058] Comparative Example Three

[0059] The preparation process is the same as Example 1. The difference is that the recrystallization solvent in step (4) is 700 g ethanol solution. Its purity is 99.61% based on the European Pharmacopoeia (EP) test method; the leucovorin calcium prepared using this method is an amorphous powder.

[0060] The above detailed description further explains the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above is only a specific embodiment of the present application and is not intended to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made on the basis of the technical solutions of the present application should be included in the protection scope of the present application.

Claims

1. A process for the preparation of high purity crystalline calcium folinate characterized in that, The preparation process is shown as follows: The step of preparing compound I from compound V specifically comprises: suspending compound V in a water-amide mixed solvent, heating to 35-45 DEG C, adding anhydrous calcium chloride to adjust the pH of the reaction solution to 7.0-7.5, adding activated carbon for decolorization, and performing recrystallization purification after suction filtration to obtain compound I.

2. The manufacturing process according to claim 1, characterized in that, The mass ratio of compound V to the water-amide mixed solvent is 1:7-12; the mass ratio of water to the amide solvent in the water-amide mixed solvent is 1:0.05-0.6; and the mass ratio of compound V to anhydrous calcium chloride is 1:0.2-0.4; wherein the amide solvent comprises N,N-dimethylformamide, N,N-dimethylacetamide or N-methylformamide.

3. The manufacturing process of claim 1, wherein, The cooling rate in the recrystallization purification process is 0.3-0.5 DEG C / min, the crystallization temperature is 14-16 DEG C, and the stirring speed is 32-48 rpm.

4. The manufacturing process of claim 1, wherein, The step of preparing compound III from compound II specifically comprises: dissolving compound II in an alkaline solvent, slowly adding a reducing agent, reacting at 30-40 DEG C for 1-5 h, cooling, adjusting the pH of the reaction solution to 3.0-4.0 with dilute hydrochloric acid solution, and then performing suction filtration to obtain compound III.

5. The manufacturing process of claim 4, wherein, The alkaline solvent is sodium hydroxide or potassium hydroxide; the mass ratio of compound II to the reducing agent is 1:0.4-0.6; wherein the reducing agent is KBH4.

6. The manufacturing process of claim 1, wherein, The step of preparing compound IV from compound III specifically comprises: dissolving compound III in a formylating agent, adding a catalyst, reacting in the dark at 5-30 DEG C, and then performing a salt formation reaction to obtain compound IV solid.

7. The manufacturing process of claim 6, wherein, The mass ratio of compound III to the formylating agent is 1:1.8-2.0; the mass ratio of compound III to the catalyst is 1:0.06-0.10; wherein the formylating agent is formic acid, and the catalyst is trifluoroacetic acid.

8. The manufacturing process of claim 6, wherein, The salt formation reaction specifically comprises: adding dilute hydrochloric acid solution to the reaction solution, stirring to crystallize at 20-30 DEG C to obtain compound IV solid; wherein the mass concentration of the dilute hydrochloric acid solution is 5.5%-7.0%.

9. The manufacturing process of claim 1, wherein, The step of preparing compound V from compound IV specifically comprises: dispersing compound IV in water, adjusting the pH of the reaction solution to 6.0-7.0 with an alkaline solvent, reacting at 70-100 DEG C, and then performing a salt formation reaction to obtain compound V solid.

10. The manufacturing process of claim 9, wherein, The salt formation reaction specifically comprises: adding activated carbon for decolorization to the reaction solution, filtering, cooling to 0-5 DEG C, adding hydrochloric acid solution to adjust the pH of the reaction solution to 3.0-3.5, and then filtering to obtain compound V solid.

11. High purity crystalline calcium folinate prepared by the manufacturing process of any one of claims 1-10, characterized by, The X-ray powder diffraction pattern of the crystal form calcium folinate has diffraction peaks mainly at 7.71°, 8.25°, 9.73°, 10.96°, 11.82°, 13.89°, 14.34°, 15.44°, 16.25°, 21.97°, 24.15°, 27.42°, wherein 11.82° is the main diffraction peak, and the error range of the 2θ value is ±0.2°.

12. The high purity crystalline calcium folinate of claim 11, characterized by, The X-ray powder diffraction pattern of the crystal form calcium folinate is shown in Fig. 1.

Images