Mylrigol-amino acid crystals and methods of making

Abstract

This invention belongs to the technical field of medicinal chemistry and provides a high-purity milrinone-sulfamic acid crystal. The preparation method is simple, the crystallization process is easy to control, and it has good reproducibility. The prepared milrinone-sulfamic acid crystals exhibit significantly enhanced stability and solubility compared to the free base and its crystal form, thus facilitating product storage, transportation, and application in formulation preparation. Furthermore, it possesses enhanced bioavailability and absorption properties.

Description

Technical Field

[0001] This invention belongs to the technical field of medicinal chemistry, specifically relating to milrinone-aminosulfonic acid crystals and their preparation method. Background Technology

[0002] Milrinone, chemically named 1,6-dihydro-2-methyl-6-oxo-[3,4-bispyridine]-5-carboxynitrile, has the molecular formula C2. 12 H9N3O, with a molecular weight of 211.22, is a white or off-white crystalline powder with the following structural formula:

[0003]

[0004] Cardiovascular disease is the leading cause of death worldwide, claiming more than 17 million lives annually, accounting for nearly 31% of global deaths, and is a key factor severely impacting human life. To reduce the incidence and mortality of cardiovascular disease, research on related drugs, including the development of new drugs and the modification of existing drugs, has received widespread attention from academia and drug developers. However, limitations such as long development cycles and high failure rates cannot meet the market's urgent demand for innovative drug products. Therefore, modifying existing cardiovascular drugs to improve their clinical efficacy is of significant practical importance. Milrinone is a positive inotropic agent with vasodilatory effects, commonly used to treat congestive heart failure and low cardiac output. However, as a Class III drug in the biopharmaceutical drug disposal classification system, milrinone's most serious drawbacks are poor permeability, limited solubility, and severe adverse reactions when taken orally, severely affecting bioavailability and thus limiting its therapeutic effect to some extent. To overcome these shortcomings, various methods have been employed, such as nanotechnology and chemical structure modification. While these efforts have yielded some progress, the complexity and high cost of nanotechnology, coupled with the byproducts generated during chemical synthesis, mean that successful industrial application of these methods remains a long way off. Existing technologies have also disclosed methods attempting to improve the solubility or stability of milrinone, but none have achieved ideal results or mitigated its poor absorption. For example, patent CN1951919A discloses a series of inorganic acid salts of milrinone for the preparation of lyophilized injectable formulations. Although this can improve the solubility of milrinone, stability problems still exist. Another example is patent CN102558044A, which discloses a crystallization method for milrinone. This method yields milrinone with high purity and good crystal form, but it still does not improve the physicochemical properties of milrinone. In addition, patent CN106361710A describes a method to address the problems of poor stability, easy degradation, and significant increase of related substances in lactated milrinone in the prior art. This method increases the stability of the injection solution and reduces the occurrence of degradation reactions by adding a certain amount of vitamin E and glutathione to the formulation and using a new crystal form. However, the use of a new crystal form also does not overcome the problem of poor solubility of milrinone.

[0005] Drug cocrystallization refers to the formation of crystals in which drug molecules are bonded to other physiologically acceptable acids, bases, salts, and nonionic compounds within the same crystal lattice through non-covalent interactions such as hydrogen bonds, π-π stacking, and van der Waals forces. Without disrupting the drug's covalent bonds, cocrystallization can alter the drug's physicochemical properties, including stability, solubility, and bioavailability. Due to its capabilities and advantages in modifying and optimizing active pharmaceutical ingredients (APIs), the development of drug cocrystallization has received increasing attention and emphasis from industry, academia, and regulatory authorities. Therefore, fully leveraging the unique advantages of cocrystallization technology to overcome the serious shortcomings of milrinone is of significant practical importance. Summary of the Invention

[0006] To address the shortcomings of existing technologies in milrinone, such as poor solubility and low stability, this invention aims to provide a new crystalline form of milrinone with higher solubility and stability: milrinone-sulfamic acid crystals. Furthermore, this invention provides a simple, convenient method for preparing milrinone-sulfamic acid crystals suitable for industrial production.

[0007] The specific technical content of this invention is as follows:

[0008] On the one hand, the present invention provides a high-purity milrinone-aminosulfonic acid crystal.

[0009] Preferably, the milrinone-aminosulfonic acid crystal, when subjected to Cu-Kα radiation, exhibits characteristic peaks in its X-ray diffraction pattern (denoted as 2θ) at at least 6.8±0.2°, 10.2±0.2°, 10.4±0.2°, 21.4±0.2°, 24.2±0.2°, 31.1±0.2°, and 38.3±0.2°.

[0010] Preferably, the milrinone-sulfamic acid crystal, when subjected to Cu-Kα radiation, exhibits characteristic peaks in its X-ray diffraction pattern (denoted as 2θ) at at least 6.8±0.2°, 10.2±0.2°, 10.4±0.2°, 17.3±0.2°, 17.7±0.2°, 21.4±0.2°, 24.2±0.2°, 24.8±0.2°, 25.5±0.2°, 25.6±0.2°, 25.9±0.2°, 28.7±0.2°, 31.1±0.2°, and 38.3±0.2°.

[0011] Preferably, the milrinone-sulfamic acid crystals, when subjected to Cu-Kα radiation, exhibit characteristic peaks that conform to the following... Figure 1 The X-ray powder diffraction pattern shown is shown.

[0012] Preferably, the milrinone-sulfamic acid crystals have the molecular formula C2. 12 H 12 N4O4S, crystallographic parameters: monoclinic system, space group P21 / n, unit cell parameters: α = 90°, β = 90.130(2)°, γ = 90°, cell volume

[0013] On the other hand, the present invention provides a method for preparing the milrinone-aminosulfonic acid crystals, comprising the following steps:

[0014] Milrinone and sulfamic acid were dissolved in a mixed solvent, heated and stirred, kept at a constant temperature for reaction, cooled to crystallize, filtered, washed, and dried to obtain milrinone-sulfamic acid crystals.

[0015] Preferably, the mixed solvent is selected from a mixed solvent of DMSO and methanol, ethanol, acetone or acetonitrile, and particularly preferably a mixed solvent of DMSO and ethanol or methanol.

[0016] Preferably, the mass-to-volume ratio of milrinone to organic solvent is 10:0.9 to 1.8; more preferably 10:1 to 1.5, wherein the mass is expressed in mg and the volume in mL.

[0017] Preferably, the molar ratio of milrinone to aminosulfonic acid is 1:0.9 to 1.5, more preferably 1:0.95 to 1.2.

[0018] Preferably, the heating temperature is 50-70°C, and more preferably 60°C.

[0019] Preferably, the cooling crystallization temperature is 10–30°C, and more preferably 15–20°C.

[0020] Preferably, the crystallization time is 48 to 72 hours.

[0021] Preferably, the drying temperature is 55-65°C and the drying time is 8-10 hours.

[0022] In another aspect, the present invention provides a pharmaceutical composition comprising the milrinone-sulfamic acid crystals described herein and other pharmaceutically feasible components.

[0023] Preferably, the other pharmaceutically feasible components may be co-operable active pharmaceutical ingredients and / or pharmaceutically acceptable excipients.

[0024] Compared with the prior art, the technical effects achieved by the present invention are as follows:

[0025] The milrinone-sulfamic acid crystals provided by this invention have a simple preparation method, easy-to-control crystallization process, and good reproducibility. Compared with the free alkali and its crystal form, milrinone-sulfamic acid crystals have significantly enhanced stability and solubility, thus facilitating product storage, transportation, and application in formulation preparation, and also exhibiting enhanced bioavailability and absorption performance. The superior physicochemical properties of the drug polycrystalline material provided by this invention offer a better pharmaceutical raw material for clinical treatment of diseases, and have significant clinical research and development value. Attached Figure Description

[0026] Figure 1 X-ray powder diffraction pattern of milrinone-aminosulfonic acid.

[0027] Figure 2 ORTEP diagram of milrinone-aminosulfonic acid.

[0028] Figure 3Stacking diagram of Milrinone-sulfamic acid. Detailed Implementation

[0029] The present invention will be further illustrated by the following embodiments. It should be understood that the embodiments of the present invention are merely for illustrating the present invention and are not intended to limit the present invention. Therefore, any simple improvements to the present invention under the premise of the method of the present invention are within the scope of protection claimed by the present invention.

[0030] Example 1

[0031] Milrinone (22.3 mg) and sulfamic acid (10.4 mg) were dissolved in a mixed solvent of ethanol (2 mL) and DMSO (0.5 mL). The mixture was heated in a water bath at 60 °C with stirring until completely dissolved. The reaction was maintained at this temperature for 6 h. The temperature was then slowly lowered to 15–20 °C, and the mixture was allowed to stand at this temperature for 52 h to crystallize. The crystals were filtered, and the filter cake was washed with trifluoroethanol. The crystals were then dried under vacuum at 60 °C for 10 h to obtain milrinone-sulfamic acid crystals. The yield was 98.7% and the purity was 99.95%.

[0032] Example 2

[0033] Milrinone (25.2 mg) and sulfamic acid (12.5 mg) were dissolved in a mixed solvent of methanol (3 mL) and DMSO (0.5 mL). The mixture was heated in a water bath at 60 °C with stirring until completely dissolved. The reaction was maintained at this temperature for 6 h. The temperature was then slowly lowered to 15–20 °C, and the mixture was allowed to stand at this temperature for 50 h to crystallize. The crystals were filtered, and the filter cake was washed with trifluoroethanol. The crystals were then dried under vacuum at 60 °C for 10 h to obtain milrinone-sulfamic acid crystals. The yield was 98.1% and the purity was 99.93%.

[0034] Example 3

[0035] Milrinone (46.0 mg) and sulfamic acid (31.7 mg) were dissolved in a mixed solvent of acetone (6 mL) and DMSO (2 mL). The mixture was heated and stirred in a water bath at 60 °C until completely dissolved. The reaction was maintained at this temperature for 6 h. The temperature was then slowly lowered to 15–20 °C, and the mixture was allowed to stand at this temperature for 48 h to crystallize. The crystals were filtered, washed with trifluoroethanol, and dried under vacuum at 60 °C for 10 h to obtain milrinone-sulfamic acid crystals. The yield was 93.1% and the purity was 99.92%.

[0036] Example 4

[0037] Milrinone (50.0 mg) and sulfamic acid (26.7 mg) were dissolved in a mixed solvent of acetonitrile (4.5 mL) and DMSO (1 mL). The mixture was heated and stirred in a water bath at 50 °C until completely dissolved. The reaction was maintained at this temperature for 6 h. The temperature was then slowly lowered to 30 °C, and the mixture was allowed to stand at this temperature for 72 h to crystallize. The crystals were filtered, washed with trifluoroethanol, and dried under vacuum at 60 °C for 10 h to obtain milrinone-sulfamic acid crystals. The yield was 94.1% and the purity was 99.91%.

[0038] Confirmation of crystal structure

[0039] In the crystallization test of milrinone described in this invention, X-ray crystal data were collected on a Rigaku XtaLAB Synergy instrument in Japan at a test temperature of 293(2) K. Cu-Ka radiation was used, and data were collected in ω-scan mode with Lp correction. The structure was resolved using the direct method, and all non-hydrogen atoms were identified using the difference Fourier method. All hydrogen atoms on carbon and nitrogen were obtained by theoretical hydrogenation, and the structure was refined using the least squares method.

[0040] The crystallographic data (as shown in Table 1) for testing and analysis of the crystal form of milrinone-sulfamic acid prepared in this invention are: monoclinic system, space group P21 / n, and cell parameters are: α = 90°, β = 90.130(2)°, γ = 90°, cell volume

[0041] Table 1. Main crystallographic data of milrinone-sulfamic acid crystals

[0042]

[0043]

[0044] The ORTEP diagram of the milrinone-sulfamic acid crystals of the present invention shows that the crystalline form contains one molecule of milrinone and one molecule of sulfamic acid, as shown in the attached diagram. Figure 2 As shown. A packing diagram of the milrinone-aminosulfonic acid crystals of the present invention is attached. Figure 3 As shown. Based on the above crystallographic data, the characteristic peaks in the corresponding X-ray powder diffraction pattern (Cu-Kα) are detailed in the appendix. Figure 1 And Table 2.

[0045] Table 2 PXRD peaks of milrinone-sulfamic acid crystals

[0046]

[0047] Comparative Example 1

[0048] In a 1000 mL three-necked flask, 93.0 g of 4-methylpyridine and 500 mL of chloroform were added. The flask was placed in an ice-water bath and the temperature was controlled below 50 °C. 80.0 g of acetyl chloride was added dropwise. After the addition was complete, the temperature was raised to 55 °C and the reaction was allowed to proceed for 2.5 h. After the reaction was complete, a saturated sodium carbonate aqueous solution was added dropwise to adjust the pH to 5–7 while the system was cooled in an ice bath. Then, 30.0 g of sodium hydroxide solution (30 wt%) was added, and the mixture was stirred at 30–50 °C for 2.5 h. After the reaction was complete, the layers were separated. The aqueous layer was removed, and the mixture was dried over anhydrous sodium sulfate. The solvent was recovered, and the fraction collected at 100–105 °C / 217 kPa, which is 1-(4-pyridyl)-2-propanone, was collected by vacuum distillation.

[0049] Add 60.0 g of 1-(4-pyridyl)-2-propanone to a 500 mL round-bottom flask. While stirring, add 40.5 g of triethyl orthoformate, 92.2 g of acetic anhydride, and 80.0 g of glacial acetic acid to the reaction flask. Stir and react at 35℃–45℃ for 4 hours until the reactants have reacted completely. Concentrate under reduced pressure at 80℃ to remove the solvent, yielding a deep red oily substance. This oil can be used directly in the next reaction without further purification.

[0050] Add 600 mL of anhydrous methanol and the above-mentioned oily substance to 5000 mL of water, and then add 64.0 g of α-cyanoacetamide and 210 g of 50% sodium hydroxide solution while stirring. The reaction time is 1.5 h. After the reaction is complete, adjust the pH to 6.5–7.2 with acetic acid solution to precipitate a solid. Filter to obtain crude milrinone. Recrystallize the solid from an ethanol-water system to obtain white milrinone crystals.

[0051] Comparative Example 2

[0052] Place 10g of milrinone in a 500mL beaker, add 0.1N sodium hydroxide aqueous solution dropwise and stir to dissolve it until the pH value is 7-8. Add acetone in 5 times the volume of the solution, cool, and a white precipitate will precipitate. Filter, wash the filter cake twice with acetone, air dry, and then dry at 105℃ for 2 hours to obtain sodium milrinone.

[0053] Comparative Example 3

[0054] Place 10g of milrinone in a 500mL beaker, add 0.1N hydrochloric acid solution dropwise and stir to dissolve it, so that the pH of the solution is 4-4.5. Add 5 times the volume of acetone, cool, and a white precipitate will precipitate. Filter, wash the filter cake twice with acetone, air dry, and then dry at 105℃ for 2 hours to obtain milrinone hydrochloride.

[0055] Comparative Example 4

[0056] Milrinone (169.0 mg) and gallic acid (136.1 mg) were mixed in an equimolar ratio until homogeneous. 50 μL of water was gradually added, and the mixture was thoroughly ground in a mortar for 45 minutes. The ground powder sample was then dissolved in a minimum amount of a methanol / acetonitrile / H₂O mixed solvent (v... 甲醇:v 乙腈 :v 水 The mixture was stirred rapidly and vigorously at 60°C for approximately 3 hours (ratio 2:1:1). After cooling to room temperature, the resulting reaction mixture was filtered. The powdered sample was added to the filtrate as seed crystals, and the solution was allowed to stand for slow evaporation for 1 day to obtain colorless crystals.

[0057] Stability test

[0058] The specific stability test methods should refer to the guidelines for stability studies in Part IV of the Chinese Pharmacopoeia.

[0059] High temperature test: The test sample is placed in a suitable clean container with the opening open and placed at 60°C for 10 days. Samples are taken on the 5th and 10th days, and the purity is detected by HPLC.

[0060] High humidity test: The test sample is placed in a constant humidity sealed container at 25℃ and a relative humidity of 90% ± 5% for 10 days. Samples are taken on the 5th and 10th days. Purity is determined by HPLC.

[0061] Intense light irradiation test: The test sample is placed in an irradiation device equipped with a fluorescent lamp and placed under an illuminance of 4500 lx ± 500 lx for 10 days. Samples are taken on the 5th and 10th days, and the purity is detected by HPLC.

[0062] Table 3. Stability test results of milrinone-sulfamic acid crystals

[0063]

[0064] Experimental results show that the milrinone-sulfamic acid crystals prepared in the embodiments of the present invention have high purity, and the purity of the samples changes little under high temperature, high humidity and strong light conditions, and the stability is good.

[0065] Solubility test

[0066] Method: Measure 10 ml of medium (water, 0.01 mol / L HCl solution) into a vial, add excess sample, seal the vial and place it in a 25℃ constant temperature water bath and stir for 1 hour. Filter through a filter membrane and collect the filtrate. Measure the absorbance at a wavelength of 270 nm. Calculate the solubility by measuring the absorbance of the standard reference.

[0067] Table 4. Solubility test results of milrinone-sulfamic acid crystals

[0068]

[0069] The experimental results show that the solubility of milrinone-sulfamic acid crystals provided by the present invention in 0.01 mol / L HCl and water is significantly improved compared with other crystal forms of milrinone, which is beneficial to its application in oral formulations.

[0070] Pharmacokinetic studies

[0071] Methods: In vivo pharmacokinetic (PK) assays were conducted using a single oral dose. Male SD rats (220-260g) were fed in a quiet environment with constant humidity (0%-60%) and a temperature of 25±1℃, with rhythmic light exposure from 7:00 AM to 7:00 PM. The PK experiment was strictly conducted in accordance with the "Laboratory Management Guidelines" issued by the Ministry of Science and Technology of China. Before the experiment, the rats were randomly divided into three groups (n=5 per group), allowed free access to water, and fasted overnight. All test samples were suspended in vegetable oil and then administered orally at a single dose of 10 mg / kg milrinone or its equivalent. After administration, 0.5 mL blood samples were collected at the designed time points according to the dosing status, and the blood concentration of milrinone was determined according to the literature method.

[0072] Table 5. Pharmacokinetic Results of Milrinone-Sulfanilic Acid Crystals

[0073]

[0074] Experimental results show that the milrinone-sulfamate crystal form provided by this invention reaches a higher peak concentration at a faster rate compared to other milrinone crystal forms, which is consistent with their dissolution trends, providing conditions for the rapid absorption of milrinone and large amounts of the drug into the bloodstream. Compared to other milrinone crystal forms, the prolonged half-life of the milrinone-sulfamate crystal form allows the drug to remain in the body for a longer period, thus making it possible to achieve long-term therapeutic effects.

Claims

1. A milrinone-aminosulfonic acid crystal, characterized in that, Using Cu-Kα radiation, the X-ray diffraction pattern, expressed in 2θ, exhibits characteristic peaks at at least 6.8±0.2°, 10.2±0.2°, 10.4±0.2°, 21.4±0.2°, 24.2±0.2°, 31.1±0.2°, and 38.3±0.2°; the milrinone-aminosulfonic acid crystal has the molecular formula C. 12 H 12 N4O4S, crystallographic parameters: monoclinic system, space group P21 / n, cell parameters: a=9.24130(10)Å, b=7.48880(10)Å, c=19.2447(3)Å, α=90°, β=90.130(2)°, γ=90°, cell volume V=1331.85(3)Å 3 .

2. The Milrinone-sulfamic acid crystal as described in claim 1, characterized in that, Using Cu-Kα radiation, the X-ray diffraction pattern, expressed as 2θ, has characteristic peaks at at least 6.8±0.2°, 10.2±0.2°, 10.4±0.2°, 17.3±0.2°, 17.7±0.2°, 21.4±0.2°, 24.2±0.2°, 24.8±0.2°, 25.5±0.2°, 25.6±0.2°, 25.9±0.2°, 28.7±0.2°, 31.1±0.2°, and 38.3±0.2°.

3. The Milrinone-sulfamic acid crystal as described in claim 1, characterized in that, Using Cu-Kα radiation, its characteristic peaks conform to the X-ray powder diffraction pattern shown in Figure 1.

4. A method for preparing milrinone-sulfamic acid crystals according to any one of claims 1-3, characterized in that, The specific preparation steps include: dissolving milrinone and aminosulfonic acid in a mixed solvent, heating and stirring, maintaining the temperature for reaction, cooling to crystallize, filtering, washing, and drying to obtain milrinone-aminosulfonic acid crystals.

5. The method for preparing milrinone-sulfamic acid crystals as described in claim 4, characterized in that, The mixed solvent is selected from a mixture of DMSO with methanol, ethanol, acetone or acetonitrile.

6. The method for preparing milrinone-aminosulfonic acid crystals as described in claim 4, characterized in that, The mixed solvent is selected from a mixture of DMSO and ethanol or methanol.

7. The method for preparing Milrinone-sulfamic acid crystals as described in claim 4, characterized in that, The mass-to-volume ratio of milrinone to the mixed solvent is 10:0.9 to 1.8; where mass is expressed in mg and volume in mL.

8. The method for preparing milrinone-sulfamic acid crystals as described in claim 4, characterized in that, The mass-to-volume ratio of milrinone to the mixed solvent is 10:1 to 1.5, where mass is expressed in mg and volume in mL.

9. The method for preparing milrinone-sulfamic acid crystals as described in claim 4, characterized in that, The molar ratio of milrinone to aminosulfonic acid is 1:0.9 to 1.

5.

10. The method for preparing milrinone-aminosulfonic acid crystals as described in claim 4, characterized in that, The molar ratio of milrinone to aminosulfonic acid is 1:0.95 to 1.

2.

11. The method for preparing milrinone-sulfamic acid crystals as described in claim 4, characterized in that, The cooling and crystallization temperature is 10–30°C.

12. The method for preparing milrinone-sulfamic acid crystals as described in claim 4, characterized in that, The cooling crystallization temperature is 15–20°C.

13. The method for preparing milrinone-aminosulfonic acid crystals as described in claim 4, characterized in that, The drying temperature is 55–65°C, and the drying time is 8–10 hours.

14. A pharmaceutical composition, characterized in that, The composition contains milrinone-sulfamic acid crystals as described in any one of claims 1-4, and is mixed with other components.

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