CN109438370B

CN109438370B - Methylpyrazine derivative anhydrous crystal form

Info

Publication number: CN109438370B
Application number: CN201811644125.2A
Authority: CN
Inventors: 马庆文; 翟立海; 夏祥来; 刘忠
Original assignee: Lunan Pharmaceutical Group Corp
Current assignee: Lunan Pharmaceutical Group Corp
Priority date: 2018-12-30
Filing date: 2018-12-30
Publication date: 2022-02-22
Anticipated expiration: 2038-12-30
Also published as: CN109438370A

Abstract

The invention belongs to the technical field of medicines, and particularly provides a methylpyrazine derivative anhydrous crystal form, a preparation method thereof and application thereof in preparing a blood fat reducing medicine. The methylpyrazine derivative anhydrous crystal form prepared by the invention uses Cu-Kalpha radiation, and an X-ray diffraction spectrogram expressed by 2 theta has characteristic peaks at 5.4 +/-0.2 degrees, 6.2 +/-0.2 degrees, 9.3 +/-0.2 degrees and 27.3 +/-0.2 degrees. The methylpyrazine derivative prepared by the invention has good solubility of an anhydrous crystal form, which is 3 times of the solubility of the crystal form of the existing methylpyrazine derivative. The methylpyrazine derivative prepared by the method has good stability of the anhydrous crystal form, and the HPLC purity of the methylpyrazine derivative is still higher than 99.85% through stability test detection. The invention has simple preparation process and better industrial application prospect.

Description

Methylpyrazine derivative anhydrous crystal form

Technical Field

The invention belongs to the technical field of crystal form drug molecules, and particularly relates to an anhydrous crystal form of a methylpyrazine derivative.

Background

The acipimox anhydrous crystal form is 5-methylpyrazine-2-carboxylic acid-4-oxide anhydrous crystal form, is white or white-like crystalline powder, and has a structural formula shown as the following formula a:

acipimox is a nicotinic acid derivative, is a broad-spectrum long-acting lipid regulating drug, is used for various primary and secondary hyperlipidemias, mainly acts on adipose tissues, reduces the synthesis of plasma low-density lipoprotein and very low-density lipoprotein by inhibiting the release of free fatty acid from the adipose tissues, thereby reducing the levels of the plasma low-density lipoprotein and the very low-density lipoprotein in the plasma and simultaneously increasing the level of plasma HDL by inhibiting the activity of liver lipase. Acipimox was developed by Farmitalia caro Erba company of italy, marketed in italy in 1985, and then, by virtue of its high safety and remarkable therapeutic effect, it was marketed successively in many countries and regions of germany, chile, switzerland, hong kong, china, etc.

The different crystal forms of the medicine can affect the physicochemical properties of the medicine, directly affect the dissolution and absorption efficiency of the medicine under the condition of physiological pH7.4, and further affect the bioavailability, clinical curative effect and the like of the medicine. Through the mode of drug crystallization, on one hand, the crystallographic parameters of the drug molecules in the crystal form can be determined, and on the other hand, whether the crystal form contains a solvent or not can be determined, which has very important effect on understanding and mastering the spatial arrangement and the physicochemical property of the drug molecules.

At present, a lot of reports about the acipimox exist, but reports about the properties such as preparation, physicochemical property and pharmacology of the acipimox are mainly related, and reports about the crystal form of the acipimox are less, and patents US2005239803A1, CN 103508963A and the like report the preparation method of the acipimox, but the crystal form of the acipimox is not mentioned, so that the acipimox crystal form needs to be provided, the stability, the solubility and other characteristics of the acipimox crystal form are researched, and a better basis is provided for the application of the acipimox crystal form.

The invention provides a simple and easy-to-operate method for preparing high-purity acipimox anhydrous crystal form, provides a product with better chemical stability, solubility and other characteristics, and provides better basis for the application of acipimox in the aspect of drug treatment, thereby more efficiently exerting the medicinal value of the acipimox.

Disclosure of Invention

In view of the defects of the prior art, the application provides an anhydrous crystal form of a methylpyrazine derivative.

The methylpyrazine derivative anhydrous crystal form referred to in the application is an acipimox anhydrous crystal form, and the methylpyrazine derivative is acipimox.

The acipimox serving as the medicinal component of the invention has the chemical name of 5-methylpyrazine-2-carboxylic acid-4-oxide, and is white or off-white crystalline powder. CAS number: 51037-30-0 molecular formula C₆H₆N₂O₃The structural formula is shown as a.

According to a first aspect of the present invention, there is provided an anhydrous crystalline form of a methylpyrazine derivative. According to the methylpyrazine derivative anhydrous crystal form, Cu-Kalpha radiation is used, and an X-ray diffraction spectrogram expressed by 2 theta has characteristic peaks at 5.4 +/-0.2 degrees, 6.2 +/-0.2 degrees, 9.3 +/-0.2 degrees and 27.3 +/-0.2 degrees.

Preferably, the methylpyrazine derivative anhydrous crystal form has characteristic peaks at 5.4 +/-0.2 °, 6.2 +/-0.2 °, 9.3 +/-0.2 °, 16.8 +/-0.2 °, 19.3 +/-0.2 °, 19.6 +/-0.2 °, 27.3 +/-0.2 ° and 27.9 +/-0.2 ° in an X-ray diffraction spectrum expressed by 2 theta by using Cu-Ka radiation.

Preferably, the methylpyrazine derivative in the form of an anhydrous crystal is subjected to Cu-Ka radiation, and the characteristic peaks of the methylpyrazine derivative in the form of an anhydrous crystal accord with an X-ray powder diffraction pattern shown in figure 1.

Preferably, the methylpyrazine derivative has an anhydrous crystal form, and an endothermic peak in a Differential Scanning Calorimetry (DSC) curve, which is 200.97 ℃.

The second aspect of the invention provides a preparation method of an anhydrous crystal form of a methylpyrazine derivative, which comprises the following specific preparation steps: suspending the methylpyrazine derivative in a solvent A, heating for dissolving, stirring for reaction, cooling for crystallization, filtering and drying to obtain the methylpyrazine derivative anhydrous crystal form.

The solvent A is one of tetrahydrofuran or a mixed solution of tetrahydrofuran and a solvent B.

Preferably, the volume ratio of the tetrahydrofuran to the solvent B is preferably 1-10: 9 to 0.

Preferably, the solvent B is selected from one or more of methanol, ethanol, isopropanol, tert-butanol, ethylene glycol, ethyl acetate, acetone and acetonitrile.

More preferably, the solvent B is selected from one or more of methanol, ethanol, acetone and acetonitrile.

The mass-volume ratio of the methylpyrazine derivative to the solvent A is 1: 5-50, wherein the mass is g, and the volume is ml.

The heating and dissolving temperature is 40-70 ℃.

The specific cooling crystallization mode is program cooling, and the cooling speed is 0.1-0.5 ℃/5 min; the temperature of crystallization is-5 to 10 ℃.

The drying mode is vacuum drying, the drying temperature is 40-50 ℃, and the drying time is 3-5 hours.

The following further details the preparation steps of the crystalline form of the invention:

suspending the methylpyrazine derivative in a solvent A, heating to 40-70 ℃ to dissolve the methylpyrazine derivative into a supersaturated solution, stirring to react for 2-6 hours, cooling to-5-10 ℃, standing for crystallization, filtering, and vacuum drying at 40-50 ℃ for 3-5 hours to obtain the methylpyrazine derivative anhydrous crystal form.

Preferably, the volume ratio of the tetrahydrofuran to the solvent B is 1-10: 9 to 0.

Further preferably, all of the solvent a is tetrahydrofuran.

Preferably, the mass-to-volume ratio of the methylpyrazine derivative to the solvent A is 1: 8-20, wherein the mass is g and the volume is ml.

The details of characteristic peaks in an X-ray powder diffraction pattern (Cu-Ka) of an anhydrous crystal form of the methylpyrazine derivative are shown in figure 1 and table 1.

Table 1 PXRD peaks of methylpyrazine derivatives in anhydrous crystalline form

All samples prepared in the examples have the same crystallographic parameters and X-ray powder diffraction patterns.

The TGA/DSC thermal analysis tester and the test conditions in the invention are as follows: TGA/DSC thermogram METTLER TOLEDO TGA/DSC3 +; dynamic temperature section: 30-350 ℃; heating rate: 10 ℃/min; segment gas N₂(ii) a Gas flow rate: 50 mL/min; crucible: an aluminum crucible of 40. mu.l.

The TGA/DSC test result of the acipimox crystal prepared by the method of the invention is shown in figure 2, and the DSC test result only shows that an endothermic melting peak appears at 200.71 ℃. According to the TGA detection result, only one weight loss step exists, the fact that the acipimox crystal does not contain water or other solvents is also shown, and the DSC/TGA detection result shows that the crystal form prepared by the invention is the acipimox anhydrous crystal form.

In a third aspect of the present invention, a pharmaceutical composition is provided, wherein the composition contains the methylpyrazine derivative anhydrous crystal form described in the present invention, and contains other pharmaceutically acceptable adjuvant components.

Preferably, the pharmaceutical composition of the present invention is prepared as follows: the compounds of the present invention are combined with pharmaceutically acceptable solid or liquid carriers and optionally with pharmaceutically acceptable adjuvants and excipients using standard and conventional techniques to prepare useful dosage forms.

Preferably, the other components include other active ingredients, excipients, fillers, etc. that may be used in combination.

Preferably, the pharmaceutical composition is a spray, a tablet, a capsule, a powder injection, a liquid injection and the like.

The fourth aspect of the invention provides an application of an anhydrous crystal form of a methylpyrazine derivative as an active ingredient in preparing a medicament for treating hypolipidemia.

Compared with the currently reported crystal form of the methylpyrazine derivative, the anhydrous crystal form of the methylpyrazine derivative prepared by the method has the following advantages:

(1) the purity is high. The purity of the prepared methylpyrazine derivative anhydrous crystal form is higher than 99.87%, and the purity of the impurity 5-methylpyrazine-2-carboxylic acid is lower than 0.11%.

(2) The solubility is high. The solubility of the methylpyrazine derivative anhydrous crystal form prepared by the invention in a medium is about 3 times of that of the existing crystal form.

(3) The stability is good. After the light test and the high-temperature high-humidity test, the HPLC purity of the methylpyrazine derivative anhydrous crystal form solid prepared by the invention is still higher than 99.7 percent and is far higher than the purity of the existing crystal form after the stability test.

Drawings

FIG. 1: x-ray powder diffraction pattern of the anhydrous crystal form of the methylpyrazine derivative.

FIG. 2: a Differential Scanning Calorimetry (DSC) graph of an anhydrous crystal form of the methylpyrazine derivative.

FIG. 3: x-ray powder diffraction pattern of the crystalline form of comparative example 3.

FIG. 4: PXRD peaks for the comparative example 3 crystalline form.

Detailed Description

The advantageous effects of the present invention will now be further described by the following examples, which are for illustrative purposes only and do not limit the scope of the present invention, and it is within the scope of the present invention to include changes and modifications apparent to those of ordinary skill in the art in light of the present invention, impurity I being 5-methylpyrazine-2-carboxylic acid, and the methylpyrazine derivative being acipimox.

Example 1:

suspending 2.0g of methylpyrazine derivative sample in 20ml of tetrahydrofuran, heating to 60 ℃, stirring and dissolving to obtain a supersaturated solution, stirring and reacting for 3 hours, then stirring and cooling (controlling the cooling rate to be 1 ℃/5min), cooling to 5-10 ℃, standing and crystallizing for 48 hours, filtering, and vacuum drying at 40 ℃ for 3 hours to obtain the methylpyrazine derivative anhydrous crystal form crystal, wherein the yield is 97.55%, the purity is 99.96%, and the impurity I: 0.03 percent.

Example 2:

suspending a 2.0g methylpyrazine derivative sample in 16ml of mixed solution (tetrahydrofuran: methanol ═ 9:1), heating to 50 ℃, stirring and dissolving to obtain a supersaturated solution, stirring and reacting for 4 hours, then stirring and cooling (the cooling speed is controlled to be 2 ℃/5min), cooling to 0-5 ℃, standing and crystallizing for 42 hours, filtering, and drying in vacuum at 45 ℃ for 4 hours to obtain the methylpyrazine derivative anhydrous crystal form crystal, wherein the yield is 96.21%, the purity is 99.94%, and the impurity I: 0.05 percent.

Example 3:

suspending 2.0g of a methylpyrazine derivative sample in 40ml of a mixed solvent (tetrahydrofuran: acetone: 2:8), heating to 40 ℃, stirring and dissolving to obtain a supersaturated solution, stirring and reacting for 5 hours, stirring and cooling (the cooling speed is controlled to be 3 ℃/5min), cooling to-5-0 ℃, standing and crystallizing for 54 hours, filtering, and vacuum drying at 50 ℃ for 3 hours to obtain an anhydrous crystal form crystal of the methylpyrazine derivative, wherein the yield is 95.42%, the purity is 99.93%, and the impurity I: 0.06 percent.

Example 4:

suspending 2.0g of methylpyrazine derivative sample in 10ml of mixed solvent (tetrahydrofuran: ethanol: 7:3), heating to 70 ℃, stirring and dissolving to obtain supersaturated solution, stirring and reacting for 3 hours, then stirring and cooling (the cooling speed is controlled to be 4 ℃/5min), cooling to 5-10 ℃, standing and crystallizing for 42 hours, filtering, and vacuum drying at 50 ℃ for 3 hours to obtain methylpyrazine derivative anhydrous crystal form crystals, wherein the yield is 94.18%, the purity is 99.91%, and the impurity I: 0.08 percent.

Example 5:

suspending 2.0g of methylpyrazine derivative sample in 100ml of mixed solvent (tetrahydrofuran: acetonitrile is 1:9), heating to 60 ℃, stirring and dissolving to obtain supersaturated solution, stirring and reacting for 4 hours, then stirring and cooling (the cooling speed is controlled to be 5 ℃/5min), cooling to-5-0 ℃, standing and crystallizing for 48 hours, filtering, and drying in vacuum at 40 ℃ for 3 hours to obtain the methylpyrazine derivative anhydrous crystal form crystal, wherein the yield is 93.02%, the purity is 99.90%, and the impurity I: 0.09 percent.

Example 6:

suspending 2.0g of a methylpyrazine derivative sample in 110ml of a mixed solvent (tetrahydrofuran: ethylene glycol is 1:9), heating to 80 ℃, stirring and dissolving to obtain a supersaturated solution, stirring and reacting for 2 hours, then stirring and cooling (the cooling speed is controlled to be 5 ℃/5min), cooling to-5-0 ℃, standing and crystallizing for 48 hours, filtering, and drying in vacuum at 40 ℃ for 3 hours to obtain an anhydrous crystal form crystal of the methylpyrazine derivative, wherein the yield is 91.58%, the purity is 99.89%, and the impurity I: 0.10 percent.

Example 7:

suspending a 2.0g methylpyrazine derivative sample in 8ml of mixed solvent (tetrahydrofuran: isopropanol is 5:5), heating to 35 ℃, stirring and dissolving to obtain supersaturated solution, stirring and reacting for 6 hours, then stirring and cooling (the cooling speed is controlled to be 3 ℃/5min), cooling to-10 to-5 ℃, standing and crystallizing for 48 hours, filtering, and drying in vacuum at 40 ℃ for 3 hours to obtain an anhydrous crystal form crystal of the methylpyrazine derivative, wherein the yield is 90.15%, the purity is 99.87%, and the impurity I: 0.11 percent.

Comparative example 1:

adding 2730ml of 98% concentrated sulfuric acid into a 10L glass reaction kettle, adding 910.0g of 5-methylpyrazine-2, 3-dicarboxylic acid under stirring, heating to 60 ℃, heating for reaction for 1h, and slowly adding 5.5kg of water and 164.9g of sodium tungstate (Na)₂WO₄·2H₂O), 623.0g of hydrogen peroxide with the mass concentration of 30 percent, continuously heating and stirring for 8h, cooling and crystallizing for 4h under the ice bath condition, filtering the solid, drying for 12h at 100 ℃ and preparing 595g of acipimox product. The product yield in this reaction was 77.3%; HPLC purity 96.2%, impurity I:2.8％。

comparative example 2:

adding 200ml of water into 100g of the acipimox crude product, heating to 100 ℃, stirring to dissolve, adding 3.0g of activated carbon, continuing to keep the temperature and stirring for 20 minutes, and performing suction filtration; cooling the filtrate to 60 ℃ at a speed of 10 ℃/h, then dropwise adding 220g of acetone into the filtrate, cooling to 5 ℃ at a speed of 10 ℃/h for crystallization for 7h after dropwise adding, performing suction filtration, washing a filter cake with acetone, and drying (0.01MPa, 80 ℃) to obtain the off-white acipimox with a yield of 88.6%. HPLC purity: 98.3%, 5-methylpyrazine-2-carboxylic acid (impurity I): 0.5 percent. Comparative example 3:

330mg (1mmol) of Na₂WO₄·2H₂O was placed in a 50ml flask, dissolved in 16ml of water and fitted with mechanical stirring, reflux cooler and thermometer. 3.75ml of 40% w/v (400g/L) (44mmol) hydrogen peroxide were added to the solution, diluted H₂SO₄The pH was adjusted to 1.5 and 5.52g (40mmol) of 2-carboxy-5-methylpyrazine were then added.

The suspension of water produced by the reaction was heated to 70 ℃ with stirring and maintained at this temperature for 2.5 hours. Thus a gradually solubilised suspension is obtained. Finally, some product was found to precipitate. The mixture was allowed to stand at room temperature overnight to cause precipitation of the reaction product in a crystal form. This product was filtered, washed with ice water and dried on a bisque-fired plate to give 4.62g, corresponding to 4.48g, of partially hydrated (2.83%) 2-carboxy-5-methylpyrazine-4-oxide as an anhydrous product. The yield was 72.0%. HPLC purity: 95.1%, impurity I: 2.3 percent.

Comparative example 4:

250mg (0.75mg) of Na was added₂WO₄·2H₂O was placed in a 50ml flask, dissolved in 13ml of water and fitted with mechanical stirring, reflux cooler and thermometer. 3.23ml of 40% w/v (400g/L) (38mmol) hydrogen peroxide were added to the solution, diluted H₂SO₄The pH was adjusted to 2.0 and then 3.76g of 98% (30mmol) 2-carboxy-5-methylpyrazine were added.

The suspension of water produced in the reaction was heated to 80 ℃ with stirring and maintained at this temperature for 2 hours. And complete solubilization can be obtained after 45minThe suspension of (2). Finally, the solution was allowed to stand at room temperature overnight to cause precipitation of the reaction product in a crystal form. This product was filtered, washed with ice water and dried on a bisque-fired plate to give 3.00g of monohydrate of 2-carboxy-5-methylpyrazine-4-oxide (Experimental value H)₂O-11.35 percent; calculated value of monohydrate product H₂O-11.3%), yield 62.6%. HPLC purity: 94.2%, impurity I: 3.4 percent.

Comparative example 5:

2-carboxy-5-methylpyrazine 4-oxide (2.5g) was added to a mixed solution of methanol (60ml) and ethanolamine (1.1 ml). The mixture was heated at reflux for 20 minutes, then cooled and filtered to give after crystallization from methanol 2-carboxy-5-methylpyrazine 4-oxide ethanolamine salt (2.1g), mp.177 ° -180 ℃, yield: 60.17%, HPLC purity: 96.8%, impurity I: 2.1 percent.

Comparative example 6:

the reaction was carried out in a 500ml.x.4 neck flask equipped with a mechanical stirrer, water condenser (with gas inlet) and thermocouple under nitrogen. Sodium trimethylsilanolate (3.71g) and THF (90g) were added to the reactor, followed by ethyl 5-methylpyrazinecarboxylate-4-oxide (6.00g), the mixture was stirred at room temperature for 4 hours, and the solid was collected by filtration and rinsed with THF (3X45 g). Drying in vacuo (25 inches of mercury, 65 ℃) afforded 5.38g (yield: 92.5%) of the sodium salt as an off-white solid, HPLC purity: 96.8%, impurity I: 2.4 percent.

Stability test

1. Temperature, humidity and light test

The specific stability test method is carried out according to the guidance method of stability investigation in the fourth part of the Chinese pharmacopoeia 2015 edition, the purity is detected by an HPLC method, and the specific test results are shown in Table 2.

Table 2 stability test results of crystal forms of methylpyrazine derivatives under light, high temperature and high humidity conditions

Through tests, all the methylpyrazine derivatives prepared by the scheme of the invention can achieve similar stability effects in the anhydrous crystal forms. As can be seen from table 2, the purity and the appearance of the anhydrous crystal form of the methylpyrazine derivative prepared by the invention are not changed significantly under the conditions of illumination, high temperature and high humidity, while the purity of the crystal forms in comparative examples 1 to 6 is greatly reduced under the same experimental conditions, and the impurity content of the crystal forms is increased significantly, i.e., the crystal forms are deteriorated, so that the anhydrous crystal form of the methylpyrazine derivative prepared by the invention has better chemical stability compared with the existing crystal forms.

Solubility test

The specific solubility test is referred to the chinese pharmacopoeia 2015. The methylpyrazine derivatives prepared in examples 1 to 7 and comparative examples 1 to 6 were weighed precisely, and the obtained mixture was placed in a vial, and water, 0.1mol/L hydrochloric acid, and a phosphate buffer solution having a ph of 7.4 were added to prepare a methylpyrazine derivative saturated solution, which was shaken to dissolve, filtered, and the solubility was calculated by measuring absorbance at a wavelength of 270nm by uv-visible spectrophotometry (general rule 0401), and the results are shown in table 3.

Table 3 solubility of the methylpyrazine derivative crystalline forms in different media

Through tests, all the methylpyrazine derivatives prepared by the scheme of the invention can achieve similar solubility effect in the anhydrous crystal form. As can be seen from table 3, the solubilities of the anhydrous crystal forms of the methylpyrazine derivatives prepared according to the scheme of the present invention in solutions with different pH values are higher than those of the crystal forms of comparative examples 1 to 6, and the crystal forms of the methylpyrazine derivatives prepared according to the present invention have higher solubilities than those of the existing crystal forms.

Claims

1. An anhydrous crystal form of a methylpyrazine derivative, wherein the compound is crystallized by Cu-Ka radiation, and the characteristic peak of the compound accords with an X-ray powder diffraction pattern shown in figure 1; wherein the methylpyrazine derivative is acipimox.

2. The methylpyrazine derivative in the form of an anhydrate according to claim 1, characterised in that it has an endothermic peak at 200.71 ℃ in the differential scanning calorimetry curve.

3. A method for preparing the methylpyrazine derivative in an anhydrous crystal form according to claim 1, comprising the following specific steps: suspending the methylpyrazine derivative in a solvent A, heating for dissolving, stirring for reaction, cooling for crystallization, filtering and drying to obtain an anhydrous crystal form of the methylpyrazine derivative; the solvent A is tetrahydrofuran or a mixed solution of tetrahydrofuran and a solvent B; in the mixed solution, the solvent B is selected from one or more of methanol, ethanol, isopropanol, tert-butanol, ethylene glycol, ethyl acetate, acetone and acetonitrile.

4. The method for preparing the methylpyrazine derivative in the form of an anhydrous crystal according to claim 3, wherein the volume ratio of the tetrahydrofuran to the solvent B in the mixed solution is 1-10: 9 to 0.

5. The method for preparing methylpyrazine derivative in an anhydrous crystalline form according to claim 3, wherein the solvent B is one or more selected from methanol, ethanol, acetone and acetonitrile.

6. The method for preparing the methylpyrazine derivative in the form of an anhydrous crystal according to claim 3, wherein the mass-to-volume ratio of the methylpyrazine derivative to the solvent A is 1: 5-50, wherein the mass is g and the volume is ml.

7. A pharmaceutical composition comprising the methylpyrazine derivative in an anhydrous crystalline form according to any one of claims 1 to 2, together with other pharmaceutically acceptable auxiliary components.

8. Use of an anhydrous crystalline form of a methylpyrazine derivative according to any one of claims 1 to 2 for the manufacture of a medicament for use in the treatment of hypolipidaemia.