A milrinone-baicalein cocrystal

Abstract

The present invention belongs to the technical field of pharmaceutical chemistry and specifically relates to a milrinone-baicalein cocrystal. The milrinone-baicalein cocrystal has an X-ray diffraction spectrum expressed in 2θ using Cu-Kα radiation, with characteristic peaks at at least 4.7±0.2°, 7.3±0.2°, 7.6±0.2°, 9.4±0.2°, 14.2±0.2°, and 28.6±0.2°.

Description

Technical Field

[0001] The present invention belongs to the technical field of pharmaceutical chemistry, and specifically relates to a new crystal form of milrinone, specifically a co-crystal of milrinone and baicalein, and a preparation method and application thereof. Background Art

[0002] Milrinone (Formula I), chemical name is 1,6-dihydro-2-methyl-6-oxo-[3,4-bipyridine]-5-carbonitrile, molecular formula is C 12 H9N3O, with a molecular weight of 211.22, is a white or off-white crystalline powder with the structural formula:

[0003]

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

[0005] Milrinone is a phosphodiesterase inhibitor and a derivative of amrinone, with the same mechanism of action as amrinone. It is effective both orally and intravenously, exhibiting both positive inotropic and vasodilatory effects. It is indicated for short-term treatment of patients with severe congestive heart failure who have failed conventional maintenance therapy. It is 10-30 times more effective than amrinone, has good tolerability, and offers minimal adverse reactions. Its positive inotropic effect is primarily achieved through phosphodiesterase inhibition, which increases cyclic adenosine monophosphate (CAMP) concentration in myocardial cells, increasing intracellular calcium, strengthening myocardial contractility, and increasing cardiac output. It is generally considered a highly effective, low-toxic, non-digitalis, non-sympathomimetic cardiotonic drug. It is significantly effective for severe heart failure and pulmonary edema caused by ischemic heart disease and dilated cardiomyopathy. It is superior to dopamine, has fewer adverse reactions, and does not increase heart rate. Therefore, this drug has played an increasingly important role in the treatment of congestive heart failure (CHF) and peripheral vasodilation.

[0006] However, milrinone is virtually insoluble in water, so when preparing milrinone formulations, special excipients are required to improve its solubility. Existing formulation methods typically employ the addition of cosolvents and pH adjusters to improve water solubility, often in relatively large quantities. Therefore, the safety and solubility-enhancing properties of cosolvents are crucial. For example, patent CN9151919A discloses a method for preparing a lyophilized formulation using inorganic acids such as hydrochloric acid, phosphoric acid, and sulfuric acid, followed by salt formation. Patent CN106361710A discloses a method for preparing a formulation by first precipitating crystals in an ethanol, acetone, and water solvent, followed by the use of lactic acid as a pH adjuster. However, the poor solubility and stability of milrinone itself have not been completely resolved. For example, when inorganic acids are used as solubilizing agents, the Cl- introduced by hydrochloric acid may cause hyperchloremia, while phosphoric acid, sulfuric acid and other solubilizing agents are not very effective. Among organic acids, lactic acid has a better solubilizing effect, but lactic acid is a racemic form consisting of L-lactic acid and D-lactic acid. Since the human body only has enzymes that metabolize L-lactic acid and its metabolic capacity is limited, excessive intake of D-lactic acid can cause metabolic disorders and even acidosis.

[0007] Furthermore, according to the disclosure of patent CN105663034A, since milrinone is virtually insoluble in water, large-scale production processes can lead to long dissolution times, incomplete dissolution, and excessive amounts of insoluble particulate matter. Existing milrinone injection preparation technology uses activated carbon adsorption to remove pyrogens. However, activated carbon has a high adsorption capacity for milrinone: at a 0.05% activated carbon dosage, it can adsorb approximately 14% milrinone. This requires excessive dosing to ensure the milrinone injection content meets regulatory requirements. However, excessive dosing significantly increases production costs, and while the activated carbon adsorbs pyrogens, it also introduces excessive amounts of unidentified substances, impacting product quality.

[0008] Baicalein is a flavonoid compound with multiple pharmacological effects. For example, it reduces cerebral vascular resistance, improves cerebral circulation, increases cerebral blood flow, and inhibits platelet aggregation. It is clinically used to treat paralysis following cerebrovascular disease. Baicalein is the active ingredient in the body. Upon entering the animal body, baicalein is rapidly converted into baicalin and other metabolites in the blood. However, due to its insolubility in water and poor hydrophilicity, baicalein is difficult to absorb. Poor oral absorption significantly limits its clinical application. Consequently, the development of baicalein formulations presents significant challenges.

[0009] Given the above issues, relying solely on formulation technology to address milrinone's solubility and stability inevitably leads to clinical safety risks caused by excessive amounts of excipients and adjuvants. Therefore, providing a new crystalline form of milrinone with good solubility, high stability, and enhanced safety has become an urgent task for those skilled in the art. Summary of the Invention

[0010] To address the above-mentioned issues, the present invention has discovered through research that the low-water-soluble milrinone and baicalein can form stable co-crystals, and that the resulting crystals exhibit significantly improved solubility and stability. Furthermore, the present invention provides a simple, convenient method for preparing milrinone-baicalein co-crystals, which is suitable for industrial production.

[0011] The specific technical contents of the present invention are as follows:

[0012] In one aspect, the present invention provides a milrinone-baicalein co-crystal, wherein the crystal unit of the co-crystal contains milrinone-baicalein-ethanol molecules in a molar ratio of 2:2:1.

[0013] Preferably, the milrinone-baicalein cocrystal has characteristic peaks at least at 4.7±0.2°, 7.3±0.2°, 7.6±0.2°, 9.4±0.2°, 14.2±0.2°, and 28.6±0.2° in an X-ray diffraction spectrum expressed in 2θ using Cu-Kα radiation.

[0014] Preferably, the milrinone-baicalein cocrystal has an X-ray diffraction spectrum expressed in 2θ using Cu-Kα radiation, and has characteristic peaks at at least 4.7±0.2°, 6.9±0.2°, 7.3±0.2°, 7.6±0.2°, 9.4±0.2°, 12.5±0.2°, 14.2±0.2°, 18.9±0.2°, 23.7±0.2°, 26.1±0.2°, and 28.6±0.2°.

[0015] Preferably, the characteristic peak of the milrinone-baicalein cocrystal using Cu-Kα radiation meets Figure 1 The X-ray powder diffraction pattern is shown.

[0016] Preferably, the milrinone-baicalein cocrystal has a molecular formula of C 56 H 44 N6O 13 , the crystallographic parameters are: triclinic system, space group is P-1, unit cell parameters are: α=78.0950(10)°、β=89.8300(10)°、γ=86.0040(10)°,unit cell volume

[0017] In another aspect, the present invention provides a method for preparing a milrinone-baicalein cocrystal, comprising the following steps:

[0018] Milrinone and baicalein are added to a solvent, ethanol is added, and the mixture is heated and stirred, filtered, cooled, allowed to stand for crystallization, and filtered and dried to obtain a milrinone-baicalein cocrystal.

[0019] Preferably, the solvent is selected from one or a combination of methanol, acetonitrile, acetone, and trifluoroethanol; particularly preferably, one or a combination of methanol and acetone.

[0020] Preferably, the mass-to-volume ratio of milrinone to solvent is 5-30:1, mg / ml; more preferably 10-20:1, mg / ml.

[0021] Preferably, the volume ratio of ethanol to solvent is 1:1-2.

[0022] Preferably, the molar ratio of milrinone to baicalein is 1:0.8-2.0; preferably 1:1.

[0023] Preferably, the heating temperature is 50-70°C, preferably 60°C.

[0024] Preferably, the heating and stirring time is 6 to 24 hours.

[0025] Preferably, the cooling and crystallization temperature is 0-30°C; preferably, the cooling and crystallization temperature is 5-15°C.

[0026] Preferably, the crystallization time is 12 to 72 hours.

[0027] Preferably, the drying temperature is 45 to 65° C., and the drying time is 8 to 24 hours.

[0028] Preferably, the raw material milrinone used in the preparation method can be prepared according to any method in the prior art or purchased from a commercial product.

[0029] Finally, the present invention provides a pharmaceutical composition comprising the milrinone-baicalein cocrystal of the present invention and other pharmaceutically feasible components.

[0030] Preferably, the other pharmaceutically acceptable components may be active pharmaceutical ingredients that can be used in combination and / or pharmaceutically acceptable auxiliary ingredients.

[0031] Confirmation of crystal structure

[0032] X-ray crystallographic data for the milrinone-baicalein cocrystal described herein were collected on a Rigaku XtaLABSynergy instrument at a temperature of 293(2)K using Cu-Ka radiation and ω scanning. Lp correction was performed. The structure was solved using a direct method, with the difference Fourier transform method identifying all non-hydrogen atoms. All hydrogen atoms on carbon and nitrogen were obtained using theoretical hydrogenation, and the structure was refined using the least squares method.

[0033] The crystallographic data of the milrinone-baicalein co-crystal prepared by the present invention (as shown in Table 1) are as follows: triclinic system, space group P-1, unit cell parameters are: α=78.0950(10)°、β=89.8300(10)°、γ=86.0040(10)°,unit cell volume

[0034] Table 1 Main crystallographic data of milrinone-baicalein cocrystal

[0035]

[0036] The ORTEP diagram of the milrinone-baicalein co-crystal of the present invention shows that the crystalline form contains two molecules of milrinone, two molecules of baicalein and one molecule of ethanol, as shown in FIG. Figure 2 The hydrogen bond diagram of the milrinone-baicalein co-crystal of the present invention is shown in FIG. Figure 3 According to the above crystallographic data, the characteristic peaks in the corresponding X-ray powder diffraction pattern (Cu-Kα) are shown in Figure 1 And Table 2.

[0037] Table 2 PXRD peaks of milrinone-baicalein cocrystal

[0038]

[0039]

[0040] Compared with the prior art, the technical effects achieved by the present invention are:

[0041] The present invention provides, for the first time, a milrinone-baicalein cocrystal. Its preparation method is simple, the crystallization process is easily controlled, and reproducibility is excellent. The cocrystal significantly enhances the solubility of milrinone, improving oral bioavailability and possessing strong pharmaceutical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 .PXRD pattern of milrinone-baicalein cocrystal.

[0043] Figure 2 .ORTEP diagram of milrinone-baicalein cocrystal.

[0044] Figure 3 .Hydrogen bond diagram of milrinone-baicalein cocrystal. DETAILED DESCRIPTION

[0045] The present invention is further illustrated by the following examples. It should be understood that the examples of the present invention are merely for illustrating the present invention, rather than for limiting the present invention. Therefore, simple improvements to the present invention based on the method of the present invention fall within the scope of protection claimed by the present invention.

[0046] The milrinone crystals used in the stability and solubility experiments were prepared according to patent CN106361710A.

[0047] Example 1

[0048] 200 mg of milrinone and 256 mg of baicalein were dissolved in 10 mL of methanol, followed by the addition of 10 mL of ethanol. The mixture was heated in a 60°C water bath with stirring for 12 h, filtered, and the filtrate was allowed to stand at 5-10°C for 36 h to crystallize. The filtrate was then filtered and dried at 50°C for 12 h to obtain milrinone-baicalein cocrystals with a yield of 94% and a purity of 99.92%.

[0049] Example 2

[0050] 100 mg of milrinone and 128 mg of baicalein were dissolved in 10 mL of acetone, and then 10 mL of ethanol was added. The mixture was heated in a 50°C water bath with stirring for 12 h, filtered, and the filtrate was allowed to stand at 5-10°C for 48 h to crystallize. The filtrate was filtered and dried at 50°C for 12 h to obtain milrinone-baicalein cocrystals with a yield of 90% and a purity of 99.92%.

[0051] Example 3

[0052] 200 mg of milrinone and 256 mg of baicalein were dissolved in 20 mL of methanol, followed by the addition of 10 mL of ethanol. The mixture was heated in a water bath at 65°C with stirring for 12 h, filtered, and the filtrate was allowed to stand at 10-15°C for 48 h to crystallize, filtered, and dried at 55°C for 12 h to obtain milrinone-baicalein cocrystals with a yield of 89% and a purity of 99.91%.

[0053] Example 4

[0054] 300 mg of milrinone and 383.9 mg of baicalein were dissolved in 10 mL of methanol, followed by the addition of 10 mL of ethanol. The mixture was heated in a water bath at 65°C with stirring for 24 h, filtered, and the filtrate was allowed to stand at 10-15°C for 12 h to crystallize, filtered, and dried at 50°C for 24 h to obtain milrinone-baicalein cocrystals with a yield of 86% and a purity of 99.89%.

[0055] Example 5

[0056] 50 mg of milrinone and 64 mg of baicalein were dissolved in 10 mL of methanol, followed by the addition of 15 mL of ethanol. The mixture was heated in a water bath at 65°C with stirring for 24 h, filtered, and the filtrate was allowed to stand at 10-15°C for 10 h to crystallize, filtered, and dried at 60°C for 8 h to obtain milrinone-baicalein cocrystals with a yield of 79% and a purity of 99.86%.

[0057] Stability test

[0058] The specific stability test method was carried out in accordance with the guidance method for stability investigation in Part IV of the Chinese Pharmacopoeia. The purity test was carried out using HPLC. The specific test results are shown in Table 3.

[0059] Table 3 Milrinone-baicalein cocrystal stability test results

[0060]

[0061] Solubility test

[0062] Method: 10 ml of medium (water, 0.01 mol / L HCl solution) was measured and placed in a vial, and an excess of the sample to be tested was added. The vial was sealed and placed in a 25°C constant temperature water bath with stirring for 1 hour. The solution was filtered through a filter membrane and the filtrate was collected. The HPLC test was performed and the concentration of the saturated solution was calculated according to the external standard method.

[0063] Table 4 Solubility of Milrinone-Baicalein Cocrystal (mg / mL)

[0064]

Claims

1. A milrinone-baicalein cocrystal, characterized in that: The crystal unit of the co-crystal contains milrinone-baicalein-ethanol molecules in a molar ratio of 2:2:

1. The molecular formula of the milrinone-baicalein co-crystal is C 56 H 44 N6O 13 The crystallographic parameters are: triclinic system, space group P-1, unit cell parameters are: a=10.41230(10)Å, b=13.3043(2)Å, c=19.2202(2)Å, α=78.0950(10)°, β=89.8300(10)°, γ=86.0040(10)°, unit cell volume V=2598.76(4)Å 3 .

2. The eutectic according to claim 1, wherein The milrinone-baicalein cocrystal uses Cu-Kα radiation, and the X-ray diffraction spectrum expressed in 2θ has characteristic peaks at at least 4.7±0.2°, 7.3±0.2°, 7.6±0.2°, 9.4±0.2°, 14.2±0.2°, and 28.6±0.2°.

3. The eutectic according to claim 1, wherein The milrinone-baicalein cocrystal has an X-ray diffraction spectrum expressed in 2θ using Cu-Kα radiation, and has characteristic peaks at at least 4.7±0.2°, 6.9±0.2°, 7.3±0.2°, 7.6±0.2°, 9.4±0.2°, 12.5±0.2°, 14.2±0.2°, 18.9±0.2°, 23.7±0.2°, 26.1±0.2°, and 28.6±0.2°.

4. The eutectic according to claim 1, wherein The characteristic peaks of the milrinone-baicalein co-crystal conform to the X-ray powder diffraction pattern shown in FIG1 using Cu-Kα radiation.

5. A method for preparing the milrinone-baicalein cocrystal according to any one of claims 1 to 4, characterized in that: The method comprises the following steps: adding milrinone and baicalein into a solvent, adding ethanol, heating and stirring, filtering, cooling, standing and crystallizing, filtering and drying to obtain the milrinone-baicalein cocrystal.

6. The preparation method according to claim 5, wherein The solvent is selected from one or a combination of methanol, acetonitrile, acetone and trifluoroethanol.

7. The preparation method according to claim 5, wherein The mass volume ratio of the milrinone to the solvent is 5-30:1, mg / ml.

8. The preparation method according to claim 5, wherein The volume ratio of the ethanol to the solvent is 1:1-2.

9. The preparation method according to claim 5, wherein The heating and stirring time is 6 to 24 hours.

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