Metronidazole co-crystal, and preparation method and application thereof

Abstract

The application discloses a metronidazole co-crystal and a preparation method and application thereof, and a structure formula of the co-crystal is shown as formula I: the metronidazole co-crystal has a faster dissolution rate and a higher apparent solubility, improves a peak concentration thereof, and can reach a higher blood drug concentration in a short time, so that rapid control on infection symptoms is realized.

Description

Technical Field

[0001] This invention relates to the field of biomedical technology, and in particular to a metronidazole cocrystal, its preparation method, and its application. Background Technology

[0002] Metronidazole is a widely used, inexpensive, and effective antibiotic and antiprotozoal active pharmaceutical ingredient used for the treatment or prevention of systemic or local infections caused by anaerobic bacteria. Since being identified by the World Health Organization in 1978 as a specific drug against anaerobic infections, its therapeutic efficacy has stood the test of time.

[0003] However, metronidazole is soluble in organic solvents such as ethanol, but only slightly soluble in water, with a solubility of approximately 10 mg / mL. This low solubility limits its bioavailability in vivo. Metronidazole is also difficult to form polymorphs, limiting the optimization of bioavailability through polymorph selection and indicating that the unit cell of the metronidazole molecule has a low lattice energy. To improve its oral efficacy, researchers have developed various drug delivery systems, including polymer gels and cyclodextrin encapsulations, to enhance efficacy through rapid drug dissolution. Other researchers have developed benzoyl metronidazole compositions to accelerate dissolution and shorten the time to peak plasma concentration for rapid control of infection symptoms. However, to improve the unfavorable physical properties of metronidazole, designing a supramolecular crystal structure (i.e., multi-component co-crystal) using intermolecular forces without altering its chemical structure, while simultaneously preserving the metronidazole molecular configuration, is a potential method to improve the apparent solubility or dissolution performance of metronidazole. However, the regulatory mechanism by which this method alters the direction of apparent solubility is currently unclear. Summary of the Invention

[0004] The present invention aims to at least solve one of the aforementioned technical problems existing in the prior art. Therefore, the object of the present invention is to provide a metronidazole cocrystal, its preparation method, and its application. This metronidazole cocrystal has a faster dissolution rate and higher apparent solubility, improving its peak concentration and achieving a high blood drug concentration in a short time, thereby achieving rapid control of infection symptoms.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] In a first aspect, the present invention provides a cocrystal of metronidazole and 3,5-dihydroxyacetophenone, the structural formula of which is shown in Formula I:

[0007]

[0008] In some embodiments of the present invention, the molar ratio of metronidazole to 3,5-dihydroxyacetophenone in the metronidazole-3,5-dihydroxyacetophenone cocrystal is 1:1.

[0009] In some embodiments of the present invention, the metronidazole and 3,5-dihydroxyacetophenone cocrystal exhibits characteristic peaks in X-ray powder diffraction measured by Cu Kα rays at diffraction angles 2θ of 10.935±0.2°, 11.776±0.2°, 17.078±0.2°, 22.216±0.2°, 25.141±0.2°, and 25.552±0.2°.

[0010] In some embodiments of the present invention, the metronidazole and 3,5-dihydroxyacetophenone cocrystal, as measured by Cu Kα rays, exhibit characteristic peaks at at least one location with diffraction angles 2θ of 26.369±0.2° and 27.703±0.2°.

[0011] In some embodiments of the present invention, the X-ray powder diffraction pattern of the metronidazole and 3,5-dihydroxyacetophenone cocrystal is as follows: Figure 2 As shown.

[0012] Due to different measurement conditions, the 2θ angle and relative intensity of each peak on the PXRD diffraction pattern will vary. Generally, the 2θ angle varies within ±0.2°, but it can also slightly exceed this range. Those skilled in the art should understand that the relative intensity of diffraction can depend on, for example, the sample formulation or the equipment used.

[0013] In some embodiments of the present invention, the metronidazole and 3,5-dihydroxyacetophenone cocrystal is a monoclinic crystal system with space group P21 / n and cell parameters of [missing information]. α = 90°; β = 100.669(2)°; γ = 90°, and the unit cell volume is

[0014] In some embodiments of the present invention, the single-crystal structure (SC-XRD) of the metronidazole and 3,5-dihydroxyacetophenone co-crystal is shown in the figure. Figure 1 As shown.

[0015] In some embodiments of the present invention, the unit cell of the metronidazole and 3,5-dihydroxyacetophenone cocrystal contains 4 metronidazole molecules and 4 3,5-dihydroxyacetophenone molecules.

[0016] In some embodiments of the present invention, the crystal structure parameters of the metronidazole and 3,5-dihydroxyacetophenone cocrystal are shown in Table 1:

[0017] Table 1

[0018]

[0019] In some embodiments of the present invention, an endothermic peak appears at 135.03±0.5℃ in the differential scanning calorimeter of the metronidazole and 3,5-dihydroxyacetophenone cocrystal.

[0020] In some embodiments of the present invention, the differential scanning calorimeter of the metronidazole and 3,5-dihydroxyacetophenone cocrystal is as follows: Figure 3 As shown.

[0021] In some embodiments of the present invention, the average particle size of the metronidazole and 3,5-dihydroxyacetophenone cocrystal is 30-100 nm.

[0022] In some embodiments of the present invention, the metronidazole and 3,5-dihydroxyacetophenone cocrystal is a cocrystal.

[0023] In a second aspect, the present invention provides a pharmaceutical composition comprising the metronidazole and 3,5-dihydroxyacetophenone cocrystal.

[0024] In some embodiments of the present invention, the pharmaceutical composition is an aqueous suspension composition; the aqueous suspension composition comprises the metronidazole and 3,5-dihydroxyacetophenone cocrystal and water, wherein the metronidazole and 3,5-dihydroxyacetophenone cocrystal is suspended in water in particulate form.

[0025] In some embodiments of the present invention, the mass of the metronidazole and 3,5-dihydroxyacetophenone cocrystal in the aqueous suspension composition is 1% to 6% w / w of water.

[0026] In some embodiments of the present invention, the pharmaceutical composition is a dried composition; the dried composition is obtained by drying the aqueous suspension composition.

[0027] In some embodiments of the present invention, the metronidazole and 3,5-dihydroxyacetophenone cocrystal in the dried composition exists in particulate form, and the particulates are micron-sized particles; preferably, the particulates are spherical or near-spherical with an average particle size of 0.8 to 4 μm.

[0028] In some embodiments of the present invention, the pharmaceutical composition further includes at least one of a stabilizer, a surfactant, a suspending agent, and a preservative.

[0029] In some embodiments of the present invention, the stabilizer and / or surfactant are present in an amount of 1% to 5% w / w of water.

[0030] In some embodiments of the present invention, the pharmaceutical composition further includes at least one of Tween 20, Tween 60, Tween 80, Span 20, Span 60, Span 80, Metz 35, sodium lauryl sulfate, sodium dodecyl sulfate, lecithin, polyvinyl alcohol, vinylpyrrolidone-vinyl acetate copolymer, ethylene-vinyl acetate copolymer, poloxamer, polyethylene glycol, hydroxypropyl cellulose, hydroxypropyl methylcellulose, sodium carboxymethyl cellulose, and carbomer.

[0031] In some embodiments of the present invention, the suspending agent includes at least one of methylcellulose, ethylcellulose, hydroxypropylcellulose, hydroxypropyl methylcellulose, carboxymethylcellulose, sodium carboxymethylcellulose, sodium carboxymethyl starch, gum arabic, tragacanth gum, carbomer, polyethylene glycol, colloidal silica, and sodium alginate.

[0032] A third aspect of the present invention provides a method for preparing the metronidazole and 3,5-dihydroxyacetophenone cocrystal, comprising the following steps: stirring and suspending metronidazole and 3,5-dihydroxyacetophenone, filtering and drying to obtain the metronidazole and 3,5-dihydroxyacetophenone cocrystal.

[0033] In some embodiments of the present invention, the mass ratio of metronidazole to 3,5-dihydroxyacetophenone is 0.75 to 1.22:1.

[0034] A fourth aspect of the present invention provides a method for preparing the pharmaceutical composition, comprising the following steps: obtaining the aqueous suspension composition by wet grinding or suspension method of the solution of metronidazole and 3,5-dihydroxyacetophenone cocrystallization; or obtaining the dried composition by centrifuging and drying the aqueous suspension composition.

[0035] In some embodiments of the present invention, the wet grinding speed is 2500-3500 rpm; the time is 60-120 min.

[0036] In some embodiments of the present invention, the wet grinding is performed using zirconia grinding beads; preferably, the average particle size of the zirconia grinding beads is 0.1 to 0.3 mm; preferably, the volume ratio of the zirconia grinding beads to the aqueous suspension composition is 1:3 to 5.

[0037] In some embodiments of the present invention, the centrifugation speed is 2000 to 4000 rpm.

[0038] In some embodiments of the present invention, the drying includes blower drying and / or freeze drying.

[0039] In some embodiments of the present invention, the drying time is 6 to 12 hours.

[0040] A fifth aspect of the invention provides for the use of the metronidazole cocrystal with 3,5-dihydroxyacetophenone or the pharmaceutical composition thereof in the preparation of a medicament for treating bacterial infections.

[0041] In some embodiments of the present invention, the bacteria include at least one of anaerobic Gram-negative bacilli (such as Bacteroides fragilis and / or Fusobacterium), anaerobic Gram-positive bacilli (such as Clostridium species and / or susceptible strains of Eubacterium), or anaerobic Gram-positive cocci (such as Peptococcus niger and / or Peptostreptococcus).

[0042] The beneficial effects of this invention are:

[0043] (1) The metronidazole and 3,5-dihydroxyacetophenone cocrystal of the present invention has better solubility behavior than metronidazole.

[0044] (2) In the aqueous suspension composition of the present invention, the stabilizer and / or surfactant can control the size of metronidazole eutectic particles at the nano-micron scale, and have good uniformity and storage stability.

[0045] (3) The dried composition of the present invention has a higher dissolution rate and apparent solubility, which improves its peak concentration and can achieve a higher blood drug concentration in a short time, thereby achieving rapid control of infection symptoms.

[0046] (4) The method for preparing high-dissolution metronidazole nano-eutectic of the present invention is simple, has good repeatability, and is suitable for industrial production. Attached Figure Description

[0047] Figure 1 This is a cell structure diagram of the metronidazole-3,5-dihydroxyacetophenone cocrystal of the present invention.

[0048] Figure 2 The X-ray diffraction patterns are those of metronidazole, 3,5-dihydroxyacetophenone and the cocrystals of Examples 1-5 of this invention.

[0049] Figure 3 The differential scanning calorimetry (DSC) comparison spectra of metronidazole, 3,5-dihydroxyacetophenone and eutectic of this invention are shown.

[0050] Figure 4 This is a 5K magnification electron microscope image of the dried eutectic particles in Example 2 of the present invention.

[0051] Figure 5 This is a 5K magnification electron microscope image of the dried eutectic particles in Example 3 of the present invention.

[0052] Figure 6 This is a 5K magnification electron microscope image of the dried eutectic particles in Example 4 of the present invention.

[0053] Figure 7 This is a 5K magnification electron microscope image of the dried eutectic particles in Example 5 of the present invention.

[0054] Figure 8 The diagram shows the particle size variation of the particulate suspensions in Examples 2-5 of this invention.

[0055] Figure 9 The stability diagrams are for the particle suspensions in Examples 2-5 of this invention.

[0056] Figure 10 Comparison of dissolution rates of metronidazole and the dry eutectic from Examples 1-2. Detailed Implementation

[0057] The present invention will be further described in detail below through specific embodiments. Unless otherwise specified, the raw materials, reagents, or apparatus used in the embodiments and comparative examples are all available from conventional commercial sources or can be obtained by existing technical methods. Unless otherwise specified, the test or experimental methods are conventional methods in the art.

[0058] In the following examples, the detection instruments and methods are:

[0059] X-ray powder diffraction was performed using a Pixel 1D array detector (Bruker D8 ADVANCE, DE) under 3 kW Cu Ka radiation. The scanning angle was between 5° and 60° with a step size of 0.013°.

[0060] The sample was measured using a differential scanning calorimeter (TA DSC 25, US) at an equilibrium temperature of 25°C, an endpoint temperature of 310°C, and a heating rate of 10 K / min. The flow pressure of the nitrogen purge gas was set to 0.1 MPa.

[0061] The absolute configuration of the eutectic single crystal was analyzed using a single-crystal diffractometer (Rigaku Supernova, JP). A 250W liquid Ga target light source was used, with a scanning accuracy of 0.0006° and a scanning speed of 20° / s at 150K.

[0062] High-performance liquid chromatography (Shimadzu SIL-20A, JP) was used to analyze the liquid phase composition of eutectic in an aqueous system. The detection wavelength was set to 270 nm, and the mobile phase consisted of 30% methanol and 70% water (v / v).

[0063] Particle size analysis (using a Malvern Mastersizer 3000, UK) was performed by taking suspension samples from the mill hopper at regular intervals during the grinding process. The cumulative particle size distribution D50 of the measured results was used to represent the average particle size. The particle refractive index was set to 1.618, the absorptivity to 0.01, and the dispersion speed to 2000 rpm.

[0064] An ultra-high resolution field emission scanning electron microscope (Hitachi Su8220, JP) was used to observe the surface morphology of the polished products. All samples were sputtered with a thin gold film prior to testing. Measurements were performed using an accelerating voltage of 5 kV.

[0065] Example 1

[0066] In this embodiment, a metronidazole cocrystal was prepared. The specific process is as follows:

[0067] Add 200g of deionized water, 6.35g of metronidazole, and 5.64g of 3,5-dihydroxyacetophenone to a clean beaker. Turn on the magnetic stirrer and stir for 24 hours at room temperature. Filter the solid and place it in a forced-air drying oven to obtain a cocrystal of metronidazole and 3,5-dihydroxyacetophenone.

[0068] Example 2

[0069] In this embodiment, a metronidazole cocrystal was prepared. The specific process is as follows:

[0070] 1) Add 200g deionized water, 6.35g metronidazole, 5.64g 3,5-dihydroxyacetophenone, and 2g Tween 20 to a clean beaker, and stir with a magnetic stirrer at room temperature for 24 hours.

[0071] 2) Pour the suspension prepared in step 1) into the hopper of a wet grinding mill for grinding, using 0.3 mm yttrium-stabilized zirconia grinding beads, a grinding speed of 3000 rpm, and a grinding time of 1.5 h. During the grinding process, samples are taken periodically for particle size analysis of the suspension (Malvin, Mastersizer 3000). Grinding is stopped when the average particle size of the suspension no longer decreases, and the suspension is collected and stored at 4°C.

[0072] 3) Centrifuge the suspension at 2500 rpm for 20 min, place the resulting solid in liquid nitrogen for freeze-drying, and then freeze-dry under vacuum for 10 h to obtain the freeze-dried product.

[0073] X-ray powder diffraction (XRD) analysis was performed on the obtained lyophilized product, such as... Figure 2 As shown, its spectrum is consistent with that of the unground metronidazole eutectic, indicating that no crystal transformation occurred during the grinding process.

[0074] Example 3

[0075] In this embodiment, a metronidazole cocrystal was prepared. The specific process is as follows:

[0076] 1) Add 200g deionized water, 7g metronidazole, 5.64g 3,5-dihydroxyacetophenone, and 10g Tween 20 to a clean beaker, and turn on the magnetic stirrer to stir for 24 hours at room temperature.

[0077] 2) Pour the suspension prepared in step 1) into the hopper of a wet grinding mill for grinding, using 0.3 mm yttrium-stabilized zirconia grinding beads, a grinding speed of 3000 rpm, and a grinding time of 1.5 h. During the grinding process, samples are taken periodically for particle size analysis of the suspension (Malvin, Mastersizer 3000). Grinding is stopped when the average particle size of the suspension no longer decreases, and the suspension is collected and stored at 4°C.

[0078] 3) Centrifuge the suspension at 2500 rpm for 20 min, place the resulting solid in a forced-air drying oven, set the drying temperature to 80℃ and dry for 10 h to obtain the dried product.

[0079] The dried product was analyzed by X-ray powder diffraction (XRD), such as... Figure 2 As shown, its spectrum is consistent with that of the unground metronidazole eutectic, indicating that no crystal transformation occurred during the grinding process.

[0080] Example 4

[0081] In this embodiment, a metronidazole cocrystal was prepared. The specific process is as follows:

[0082] 1) Add 200g deionized water, 6.35g metronidazole, 5.64g 3,5-dihydroxyacetophenone, and 2g sodium dodecyl sulfate to a clean beaker, and turn on the magnetic stirrer to stir for 24 hours at room temperature.

[0083] 2) Pour the suspension prepared in step 1) into the hopper of a wet grinding mill for grinding, using 0.3 mm yttrium-stabilized zirconia grinding beads, a grinding speed of 3000 rpm, and a grinding time of 1.5 h. During the grinding process, samples are taken periodically for particle size analysis of the suspension (Malvin, Mastersizer 3000). Grinding is stopped when the average particle size of the suspension no longer decreases, and the suspension is collected and stored at 4°C.

[0084] 3) Centrifuge the suspension at 2500 rpm for 20 min, place the resulting solid in a forced-air drying oven, set the drying temperature to 80℃ and dry for 10 h to obtain the dried product.

[0085] The dried product was analyzed by X-ray powder diffraction (XRD), such as... Figure 2 As shown, its spectrum is consistent with that of the unground metronidazole eutectic, indicating that no crystal transformation occurred during the grinding process.

[0086] Example 5

[0087] In this embodiment, a metronidazole cocrystal was prepared. The specific process is as follows:

[0088] 1) Add 200g of deionized water, 6.35g of metronidazole, and 5.64g of 3,5-dihydroxyacetophenone to a clean beaker, and turn on the magnetic stirrer to stir for 24 hours at room temperature.

[0089] 2) Pour the suspension prepared in step 1) into the hopper of a wet grinding mill for grinding, using 0.3 mm yttrium-stabilized zirconia grinding beads, a grinding speed of 3000 rpm, and a grinding time of 1.5 h. During the grinding process, samples are taken periodically for particle size analysis of the suspension (Malvin, Mastersizer 3000). Grinding is stopped when the average particle size of the suspension no longer decreases, and the suspension is collected and stored at 4°C.

[0090] 3) Centrifuge the suspension at 2500 rpm for 20 min, place the resulting solid in a forced-air drying oven, set the drying temperature to 80℃ and dry for 10 h to obtain the dried product.

[0091] The dried product was analyzed by X-ray powder diffraction (XRD), such as... Figure 2 As shown, its spectrum is consistent with that of the unground metronidazole eutectic, indicating that no crystal transformation occurred during the grinding process.

[0092] Experimental Example 1

[0093] The surface morphology of the dried products obtained in Examples 2-5 was observed using an electron microscope (Hitachi, SU8220) at high magnification. Figures 4-7 .

[0094] from Figures 4-7 It can be seen that the eutectic particles, after being dried by wet grinding, agglomerate into micron-sized aggregates with an average particle size of about 0.8 to 4 μm, and have a larger specific surface area than the metronidazole raw material.

[0095] Experimental Example 2

[0096] The suspensions obtained after grinding in Examples 2-5 were subjected to wet particle size analysis using a laser particle size analyzer (Malvin, Mastersizer 3000). The results are shown in […]. Figure 8 .

[0097] from Figure 8It can be seen that the stabilizer is crucial to the particle size of the eutectic particles during the grinding process. The final particle size D50 of the eutectic particles obtained in Example 5 without any stabilizer was 153 nm, while the eutectic particles obtained in Examples 2 and 3 with stabilizers were all smaller than 153 nm. At the same time, comparing the effects of different stabilizers on the eutectic particles during the grinding process, it was found that Tween 20 was better than sodium dodecyl sulfate in dispersing the eutectic particles and reducing their particle size.

[0098] Experimental Example 3

[0099] The nano-eutectic suspensions prepared in Examples 2-5 were placed at 4°C, and wet particle size analysis was performed using a laser particle size analyzer (Malvin, Mastersizer 3000) during the first and third weeks. The results are shown in the figure. Figure 9 .

[0100] from Figure 9 It can be seen that the eutectic suspension prepared in Example 5 without the addition of stabilizer agglomerated during storage, resulting in an increase in the particle size of the eutectic particles. However, Examples 2 and 3 with Tween 20 as a stabilizer maintained the same particle size as at the beginning after 3 weeks, indicating that Tween 20 has a good inhibitory effect on the agglomeration of eutectic particles.

[0101] Test Example 4

[0102] The dissolution rates of metronidazole raw material, the metronidazole eutectic obtained in Example 1, and the dried product obtained in Example 2 were tested under the same temperature conditions, and the content was analyzed by high performance liquid chromatography (Shimadzu, SIL-20A). The results are shown in Table 2. Figure 10 .

[0103] Table 2

[0104] Time (min) / Content (mg / mL) Metronidazole raw materials Example 1 Example 2 0 0 0 0 1 6.722 8.721 9.642 3 8.817 9.126 9.660 6 9.315 9.429 10.346 10 9.268 9.570 10.374 15 9.313 9.663 10.516 20 9.351 9.883 10.196 40 8.976 9.759 10.774 60 9.133 9.730 10.084

[0105] From Table 2, Figure 10 It can be seen that, compared with the metronidazole raw material, the metronidazole eutectic obtained in Example 1 has superior solubility. The freeze-dried product obtained in Example 2 showed a 43.4% increase in dissolution rate in the first minute and a 10.4% increase in apparent solubility after 1 hour.

[0106] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A cocrystal of metronidazole and 3,5-dihydroxyacetophenone, characterized in that: The structural formula of the eutectic is shown in Formula I: ； The metronidazole-3,5-dihydroxyacetophenone cocrystal is a monoclinic crystal with space group P21 / n. Its unit cell parameters are a = 11.5848(6) Å; b = 11.1148(6) Å; c = 11.7684(5) Å; α = 90°; β = 100.669(2)°; γ = 90°, and its unit cell volume is 1489.14(13) Å. 3 .

2. The metronidazole and 3,5-dihydroxyacetophenone cocrystal according to claim 1, characterized in that: The cocrystal of metronidazole and 3,5-dihydroxyacetophenone exhibits characteristic peaks in X-ray powder diffraction measured by Cu Kα radiation at diffraction angles 2θ of 10.935±0.2°, 11.776±0.2°, 17.078±0.2°, 22.216±0.2°, 25.141±0.2°, and 25.552±0.2°.

3. The metronidazole and 3,5-dihydroxyacetophenone cocrystal according to claim 1, characterized in that: An endothermic peak appeared at 135.03±0.5℃ in the differential scanning calorimeter of the metronidazole and 3,5-dihydroxyacetophenone cocrystal.

4. A pharmaceutical composition, characterized in that: The cocrystal of metronidazole and 3,5-dihydroxyacetophenone as described in any one of claims 1 to 3 is included.

5. The pharmaceutical composition according to claim 4, characterized in that: The pharmaceutical composition is an aqueous suspension composition; the aqueous suspension composition comprises the metronidazole and 3,5-dihydroxyacetophenone cocrystal and water, wherein the metronidazole and 3,5-dihydroxyacetophenone cocrystal is suspended in water in particulate form.

6. The pharmaceutical composition according to claim 4, characterized in that: The pharmaceutical composition is a dried composition; the dried composition is prepared by suspending metronidazole and 3,5-dihydroxyacetophenone cocrystals in water in particulate form and then drying them.

7. The pharmaceutical composition according to claim 4, characterized in that: The pharmaceutical composition further includes at least one stabilizer, surfactant, suspending agent, and preservative.

8. A method for preparing the cocrystal of metronidazole and 3,5-dihydroxyacetophenone according to any one of claims 1 to 3, comprising the following steps: Metronidazole and 3,5-dihydroxyacetophenone were stirred and suspended, filtered and dried to obtain the metronidazole and 3,5-dihydroxyacetophenone cocrystal.

9. The use of the metronidazole and 3,5-dihydroxyacetophenone cocrystal as described in any one of claims 1 to 3, or the pharmaceutical composition as described in any one of claims 4 to 7, in the preparation of a medicament for treating bacterial infections.

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