A Milrinone-Saccharin Crystal Form

Abstract

This invention provides a milrinone-saccharin crystal form. The crystal form, when subjected to Cu-Kα radiation, exhibits characteristic peaks in its X-ray diffraction pattern (expressed as 2θ) at at least 11.3±0.2°, 12.0±0.2°, 12.9±0.2°, 15.8±0.2°, 22.8±0.2°, and 26.1±0.2°. It belongs to the triclinic crystal system, with space group P-1 and cell parameters of α=81.5282(10)°, β=79.5254(12)°, and γ=68.9492(13)°. The milrinone-saccharin crystal form provided by this invention has good stability and high solubility. It has a long half-life, rapid onset of action after oral administration, and can significantly improve the oral bioavailability of milrinone, while also improving the taste of oral milrinone formulations.

Description

Technical Field

[0001] This invention belongs to the technical field of medicinal chemistry, specifically relating to a milrinone-saccharin crystal form, its preparation method, and its application. Background Technology

[0002] Milrinone (Formula I), chemically named 1,6-dihydro-2-methyl-6-oxo-[3,4-bispyridine]-5-carboxynitrile, has the molecular formula C1. 12 H9N3O, with a molecular weight of 211.22, is a white or off-white crystalline powder with the following structural formula:

[0003]

[0004] Milrinone was originally developed by Sterling in the United States as an anti-heart failure drug. It was first approved by the FDA in the United States in 1987 and officially launched in the United States in 1992. Subsequently, it was launched and sold in the United Kingdom, France, Germany, the Netherlands, Belgium and other countries.

[0005] Milrinone is a phosphodiesterase inhibitor, a derivative of amrinone, with the same mechanism of action. It is effective both orally and intravenously, exhibiting both positive inotropic and vasodilatory effects. It is suitable for short-term treatment of severe congestive heart failure unresponsive to conventional maintenance therapy, with efficacy 10-30 times stronger than amrinone, better tolerability, and fewer adverse reactions. Its positive inotropic effect is mainly achieved by inhibiting phosphodiesterase, increasing intracellular cyclic adenosine monophosphate (cAMP) concentration, increasing intracellular calcium, strengthening myocardial contractility, and increasing cardiac output. It is generally considered a highly effective, low-toxicity, non-digitalis, non-sympathomimetic cardiotonic drug, showing significant efficacy against severe heart failure and pulmonary edema caused by ischemic heart disease and dilated cardiomyopathy, superior to dopamine derivatives, with fewer adverse reactions and no increase in heart rate. Therefore, this drug plays an increasingly important role in the treatment of congestive heart failure (CHF) and peripheral vasodilation.

[0006] However, milrinone is almost insoluble in water, has poor water solubility, and poor absorption in the body. Furthermore, existing milrinone injection solutions suffer from poor stability and are prone to degradation, requiring the addition of various excipients. For example, patent CN106361710A discloses a method of first precipitating crystals in a solvent of ethanol + acetone + water, then using lactic acid as a co-solvent, and adding a certain amount of vitamin E and glutathione as antioxidants to improve the stability of the injection solution. However, the new crystal form itself does not overcome the problem of poor milrinone solubility. Moreover, lactic acid is a racemic mixture composed of L-lactic acid and D-lactic acid. Since the human body only has enzymes to metabolize L-lactic acid and its metabolic capacity is limited, excessive intake of D-lactic acid can cause metabolic disorders or even acidosis. Another example is patent CN19151919A, which discloses a method of preparing a freeze-dried formulation by salting milrinone with hydrochloric acid, phosphoric acid, sulfuric acid, methanesulfonic acid, sodium hydroxide, and potassium hydroxide. However, the solubility and stability of the milrinone salt itself remain poor.

[0007] Furthermore, according to the disclosure of patent CN105663034A, because milrinone is almost insoluble in water, large-scale production can lead to problems such as long dissolution time, incomplete dissolution, and excessive levels of insoluble particles. Current milrinone injection preparation technology uses activated carbon adsorption to remove pyrogens. Activated carbon has a large adsorption capacity for milrinone; with 0.05% activated carbon, it can adsorb approximately 14% milrinone, requiring excessive addition to ensure the milrinone injection content meets regulations. However, excessive addition significantly increases production costs, and while adsorbing pyrogens, activated carbon itself can introduce excessive amounts of unknown substances, affecting product quality.

[0008] Furthermore, existing purification / crystallization methods for milrinone crystals have low yields. For example, patent CN104387320A crystallizes crude milrinone using an ethanol-water system, obtaining white milrinone crystals with a purity of 99.7% and a yield of 83.8%; patent CN102558044A uses a mixed solvent (DMF plus water at a certain temperature) for crystallization, first dissolving it in dimethylformamide (DMF) by heating, then adding hot water while stirring, and slowly crystallizing, producing uniform white crystals with a purity of 99.98% and a yield of 82.6%; patent CN104744357A uses a mixed solvent composed of water, ethanol, and DMF for purification, achieving a purity of 99.90%, but also with a low yield; patent CN103965101B dissolves it under reflux with 50 wt% ethanol, filters it, and stirs the filtrate at -5 to 10°C to crystallize, obtaining white solid milrinone with a purity of 99.97% and a yield of 82.8%. Summary of the Invention

[0009] To address the shortcomings of existing milrinone crystal technologies, such as poor solubility, poor stability, and low yield, this invention aims to provide a new milrinone crystalline form with higher solubility and stability: the milrinone-saccharin crystalline form. Furthermore, this invention provides a method for preparing the milrinone-saccharin crystalline form that is simple, has a high yield, is convenient, and suitable for industrial production.

[0010] The specific technical content of this invention is as follows:

[0011] On one hand, the present invention provides a Milrinon-saccharin crystal form, which, using Cu-Kα radiation, has characteristic peaks in its X-ray diffraction pattern represented by 2θ at at least 11.3±0.2°, 12.0±0.2°, 12.9±0.2°, 15.8±0.2°, 22.8±0.2°, and 26.1±0.2°.

[0012] Preferably, the Milrinon-saccharin crystal form, when subjected to Cu-Kα radiation, exhibits characteristic peaks in its X-ray diffraction pattern (expressed as 2θ) at at least 11.3±0.2°, 12.0±0.2°, 12.9±0.2°, 15.8±0.2°, 21.2±0.2°, 22.8±0.2°, 24.1±0.2°, 24.5±0.2°, 26.1±0.2°, 26.2±0.2°, and 32.1±0.2°.

[0013] Preferably, the milrinon-saccharin crystal form, when subjected to Cu-Kα radiation, exhibits characteristic peaks that conform to... Figure 1 The X-ray powder diffraction pattern shown is shown.

[0014] Preferably, the milrinone-saccharin crystalline form has the molecular formula C1. 19 H 14 N4O4S, crystallographic parameters: triclinic crystal system, space group P-1, unit cell parameters: α = 81.5282(10)°, β = 79.5254(12)°, γ = 68.9492(13)°, cell volume

[0015] On the other hand, the present invention provides a method for preparing milrinone-saccharin crystal form, comprising the following steps:

[0016] Milrinone and saccharin were dissolved in a mixed solvent, heated and stirred, filtered, cooled to crystallize, filtered again, and dried to obtain the milrinone-saccharin crystal form.

[0017] Preferably, the mixed solvent is a mixture of methanol and other organic solvents, wherein the other organic solvents are selected from ethanol, acetonitrile, acetone and trifluoroethanol.

[0018] More preferably, the mixed solvent is a mixture of methanol and trifluoroethanol, or a mixture of methanol and acetone.

[0019] Preferably, in the mixed solvent, the volume ratio of methanol to other organic solvents is 1:1 to 3, more preferably 1:1.5 to 2.5.

[0020] Preferably, the mass-to-volume ratio of milrinone to the mixed solvent is 4.0–21.0:1, more preferably 6.0–10.5:1; wherein the mass of milrinone is expressed in mg and the volume of the mixed solvent is expressed in ml.

[0021] Preferably, the molar ratio of milrinone to saccharin is 1:0.8 to 1.1, more preferably 1:1 to 1.1.

[0022] Preferably, the heating temperature is 50-70°C, and more preferably 60°C.

[0023] The cooling crystallization temperature is 0–30°C, preferably 0–8°C.

[0024] The crystallization time is 8 to 48 hours.

[0025] The drying temperature is 50-65℃, and the drying time is 8-10 hours.

[0026] Milrinone, the raw material used in the preparation method, can be prepared according to any method in the prior art or purchased from commercially available products.

[0027] Finally, the present invention provides an oral pharmaceutical composition containing the milrinone-saccharin crystal form described herein and other pharmaceutically feasible components.

[0028] Preferably, the other pharmaceutically feasible components may be co-operable active pharmaceutical ingredients and / or pharmaceutically acceptable excipients.

[0029] Confirmation of crystal structure

[0030] The X-ray crystal data for the Milrinon-saccharin crystal form test described in this invention 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 an ω-scan mode with Lp correction. The structure was analyzed using a direct method, and all non-hydrogen atoms were identified using the difference Fourier method. All hydrogen atoms on carbon and nitrogen were obtained through theoretical hydrogenation. The structure was refined using the least squares method.

[0031] The crystallographic data (as shown in Table 1) of the milrinone-saccharin crystalline form prepared by this invention were tested and analyzed. The crystal system is triclinic, space group is P-1, and the cell parameters are: α = 81.5282(10)°, β = 79.5254(12)°, γ = 68.9492(13)°, cell volume

[0032] Table 1. Major crystallographic data of milrinon-saccharin crystal forms

[0033]

[0034] The ORTEP diagram of the milrinone-saccharin crystalline form of the present invention shows that this crystalline form contains one molecule of milrinone and one molecule of saccharin, as shown in the attached diagram. Figure 2 As shown. The packing diagram of the Milrinone-Saccharin 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.

[0035] Table 2 PXRD peaks of milrinon-saccharin crystal form

[0036]

[0037]

[0038] Compared with the prior art, the technical effects achieved by the present invention are as follows:

[0039] This invention provides a milrinone-saccharin crystalline form, the preparation method of which is simple to operate, the crystallization process is easy to control, and it has good reproducibility. The milrinone-saccharin crystalline form has good stability and high solubility, a long half-life, and rapid onset of action after oral administration, which can significantly improve the oral bioavailability of milrinone and has strong pharmaceutical value. Attached Figure Description

[0040] Figure 1 PXRD pattern of Milrinone-saccharin crystal form.

[0041] Figure 2 ORTEP diagram of Milrinone-saccharin crystal form.

[0042] Figure 3 Stacking diagram of Milrinone-saccharin crystal form. Detailed Implementation

[0043] 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.

[0044] Example 1

[0045] 211.1 mg milrinone and 183.2 mg saccharin were dissolved in a mixed solvent of 10 mL methanol and 15 mL trifluoroethanol. The solution was heated and stirred in a water bath at 60 °C until completely dissolved. The solution was filtered, cooled to 0–5 °C for 48 h to crystallize, filtered again, and dried at 55 °C for 8 h to obtain milrinone-saccharin crystal form with a yield of 94.2% and a purity of 99.95%.

[0046] Example 2

[0047] 211.1 mg milrinone and 201.7 mg saccharin were dissolved in a mixed solvent of 10 mL methanol and 25 mL acetone. The solution was heated in a water bath at 60 °C and stirred until completely dissolved. The solution was filtered, cooled to 0–5 °C for 36 h to crystallize, filtered again, and dried at 50 °C for 10 h to obtain the milrinone-saccharin crystalline form. The yield was 95.5% and the purity was 99.97%.

[0048] Example 3

[0049] 211.1 mg milrinone and 146.5 mg saccharin were dissolved in a mixed solvent of 10 mL methanol and 10 mL trifluoroethanol. The solution was heated and stirred in a water bath at 60 °C until completely dissolved. The solution was filtered, cooled to 5–8 °C for 12 h to crystallize, filtered again, and dried at 55 °C for 8 h to obtain milrinone-saccharin crystal form with a yield of 90.3% and a purity of 99.93%.

[0050] Example 4

[0051] 211.1 mg milrinone and 201.7 mg saccharin were dissolved in a mixed solvent of 10 mL methanol and 30 mL acetone. The solution was heated in a water bath at 60 °C and stirred until completely dissolved. The solution was filtered, cooled to 0–5 °C for 36 h to crystallize, filtered again, and dried at 50 °C for 10 h to obtain the milrinone-saccharin crystalline form. The yield was 91.6% and the purity was 99.94%.

[0052] Example 5

[0053] 211.1 mg milrinone and 201.7 mg saccharin were dissolved in a mixed solvent of 10 mL methanol and 25 mL acetonitrile. The solution was heated in a water bath at 60 °C and stirred until completely dissolved. The solution was filtered, cooled to 0–5 °C for 36 h to crystallize, filtered again, and dried at 50 °C for 10 h to obtain the milrinone-saccharin crystalline form. The yield was 92.4% and the purity was 99.92%.

[0054] Example 6

[0055] 211.1 mg milrinone and 146.5 mg saccharin were dissolved in a mixed solvent of 10 mL methanol and 40 mL trifluoroethanol. The mixture was heated in a water bath at 60 °C and stirred until completely dissolved. After filtration, the mixture was cooled to 5–8 °C and allowed to crystallize for 12 h. After filtration, the mixture was dried at 55 °C for 8 h to obtain the milrinone-saccharin crystalline form, with a yield of 86.2% and a purity of 99.91%.

[0056] Example 7

[0057] 211.1 mg milrinone and 183.2 mg saccharin were dissolved in a mixed solvent of 10 mL methanol and 15 mL trifluoroethanol. The mixture was heated and stirred in a water bath at 60 °C until completely dissolved. After filtration, the mixture was allowed to crystallize at room temperature for 48 h. After filtration, the mixture was dried at 55 °C for 8 h to obtain the milrinone-saccharin crystalline form, with a yield of 89.5% and a purity of 99.92%.

[0058] Example 8

[0059] 211.1 mg milrinone and 228.9 mg saccharin were dissolved in a mixed solvent of 5 mL methanol and 5 mL trifluoroethanol. The solution was heated and stirred in a water bath at 60 °C until completely dissolved. The solution was filtered, cooled to 5–8 °C for 12 h to crystallize, filtered again, and dried at 55 °C for 8 h to obtain milrinone-saccharin crystal form with a yield of 87.1% and a purity of 99.91%.

[0060] Comparative Example 1: Mirinon recrystallization

[0061] Add 20 times the mass of crude milrinone to a mixed solvent (volume ratio, ethanol:water:dimethylformamide = 4:4:1), and slowly heat to 60°C until the crude product is completely dissolved. Add 15% of the crude product mass of activated carbon for decolorization for 1 hour, and filter while hot to remove the activated carbon. Cool the filtrate to room temperature with slow stirring to allow crystallization, filter again, wash the filter cake with ethanol, and then dry at 60°C to obtain off-white crystals. Add 20 times the mass of the above mixed solvent to these white crystals, and slowly heat to 60°C until the off-white crystals are completely dissolved. Cool to room temperature with slow stirring to allow crystallization, and obtain white milrinone crystals with a purity of 99.90% and a yield of 80.5%.

[0062] Comparative Example 2

[0063] 10g of milrinone was placed in a 500ml beaker, and 0.1N sodium hydroxide aqueous solution was added dropwise while stirring until dissolved. The solution was brought to a pH of 7-8, and then acetone (5 times its volume) was added. After cooling, a white precipitate formed. The precipitate was filtered, washed twice with acetone, and dried. Then, it was dried at 105℃ for 2 hours to obtain sodium milrinone. The yield was 90.2%, and the purity was 99.89%.

[0064] Comparative Example 3

[0065] 10 g of milrinone was placed in a 500 mL beaker, and 0.1 N hydrochloric acid solution was added dropwise while stirring to dissolve it, adjusting the pH of the solution to 4–4.5. Five times the volume of acetone was added, and the mixture was cooled, resulting in a white precipitate. The precipitate was filtered, washed twice with acetone, and dried. Then, it was dried at 105 °C for 2 hours to obtain milrinone hydrochloride. The yield was 91.0%, and the purity was 99.91%.

[0066] Comparative Example 4

[0067] 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 slurry for 45 minutes. The ground powder sample was dissolved in a minimum amount of methanol / acetonitrile / H₂O mixed solvent (methanol:acetonitrile:water volume ratio 2:1:1) and rapidly and vigorously stirred at 60 °C for approximately 3 hours. After cooling to room temperature, the resulting reaction mixture was filtered. The powder 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. Yield: 83.5%, Purity: 99.90%.

[0068] Verification of Examples

[0069] 1. Stability test

[0070] The specific stability test methods were carried out in accordance with the guidelines for stability studies in Part IV of the Chinese Pharmacopoeia. Purity was determined by HPLC, and the specific test results are shown in Table 3.

[0071] Table 3. Stability test results of different milrinone crystal forms under light, high temperature and high humidity conditions.

[0072]

[0073] Note: The milrinone-saccharin crystal forms prepared in Examples 1-8 of this invention have similar stability effects. Table 3 shows the milrinone-saccharin crystals...

[0074] The stability of the saccharin crystal form was tested using the crystal form prepared in Example 2 as an example.

[0075] 2. Solubility test

[0076] 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.

[0077] Table 4. Solubility of milrinone crystals in different media (mg / mL)

[0078]

[0079] Note: The milrinone-saccharin prepared in Examples 1-8 of this invention all have similar solubility. The solubility of the milrinone-saccharin crystal form in Table 4 is tested using the crystal form prepared in Example 2 as an example.

[0080] 3. Pharmacokinetic studies

[0081] Methods: In vivo pharmacokinetic (PK) experiments were conducted using a single oral dose administration method. Male SD rats (220-260g) were fed in a quiet environment with constant humidity of 0%-60% at 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 test 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 administration status to detect the blood concentration of milrinone. The results are shown in Table 5.

[0082] Table 5. Pharmacokinetic Study Results of Different Milrinone Crystals

[0083]

[0084] Note: Compared with Comparative Example 1 crystal, *P<0.05, the difference is statistically significant.

[0085] Experimental results show that the milrinon-saccharin crystalline form provided by this invention has a faster onset of action, a longer half-life, and higher oral bioavailability compared to other milrinon crystalline forms. Furthermore, saccharin, due to its high sweetness, can improve the palatability of oral milrinon formulations.

Claims

1. A Milrinone-saccharin crystalline form, characterized in that, The crystallographic parameters of the crystal form are: triclinic crystal system, space group P-1, cell parameters: a=7.40637(12)Å, b=8.52739(10)Å, c=15.91233(10)Å, α=81.5282(10)°, β=79.5254(12)°, γ=68.9492(13)°, cell volume V=918.59(2)Å. 3 .

2. The crystal form according to claim 1, characterized in that, Using Cu-Kα radiation, the X-ray diffraction pattern, expressed as 2θ, has characteristic peaks at least at 11.3±0.2°, 12.0±0.2°, 12.9±0.2°, 15.8±0.2°, 22.8±0.2°, and 26.1±0.2°.

3. The crystal form according to claim 1, characterized in that, Using Cu-Kα radiation, the X-ray diffraction pattern, expressed as 2θ, has characteristic peaks at at least 11.3±0.2°, 12.0±0.2°, 12.9±0.2°, 15.8±0.2°, 21.2±0.2°, 22.8±0.2°, 24.1±0.2°, 24.5±0.2°, 26.1±0.2°, 26.2±0.2°, and 32.1±0.2°.

4. The crystal form according to claim 1, characterized in that, Using Cu-Kα radiation, its characteristic peaks conform to the X-ray powder diffraction pattern shown in Figure 1.

5. A method for preparing the milrinone-saccharin crystalline form according to any one of claims 1-4, characterized in that, The process includes the following steps: dissolving milrinon and saccharin in a mixed solvent, heating and stirring, filtering, cooling to crystallize, filtering again, and drying to obtain the milrinon-saccharin crystal form.

6. The preparation method according to claim 5, characterized in that, The mixed solvent is a mixture of methanol and other organic solvents, wherein the other organic solvents are selected from ethanol, acetonitrile, acetone and trifluoroethanol.

7. The preparation method according to claim 5, characterized in that, The mass-to-volume ratio of milrinone to the mixed solvent is 4.0 to 21.0:1, wherein the mass of milrinone is expressed in mg and the volume of the mixed solvent is expressed in ml.

8. The preparation method according to claim 5, characterized in that, The molar ratio of milrinone to saccharin is 1:0.8-1.

1.

9. The preparation method according to claim 5, characterized in that, The cooling and crystallization temperature is 0-8℃.

10. An oral pharmaceutical composition, characterized in that, The composition comprises the milrinone-saccharin crystal form as described in claim 1 and other pharmaceutically acceptable components.

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