Preparation method of cefquinome sulfate nanocrystal freeze-dried powder

Abstract

The invention discloses a preparation method of cefquinome sulfate nanocrystal freeze-dried powder, which is characterized in that after nanoscale cefquinome sulfate is prepared by using a solvent-anti-solvent precipitation method, cefquinome sulfate nanocrystals with the particle size of 17.4 + / -0.2623 nm, the PDI of 0.193 + / -0.017 and uniform particles can be obtained in combination with an optimized freeze-drying method. The cefquinome sulfate nanocrystal can be stably stored for at least 30 days in an environment of 4 DEG C, and has good stability; the dissolvability is obviously superior to that of a commercially available preparation, and the defect that the commercially available preparation is poor in needle passing performance can be effectively improved; the release performance is good, and rapid dissolution of the medicine is facilitated.

Description

Technical Field

[0001] The invention relates to a cefquinome sulfate preparation for veterinary medicine, in particular to a preparation method of cefquinome sulfate nanocrystalline freeze-dried powder. Background Art

[0002] In livestock and poultry farming, veterinary antibiotics play an important role in ensuring animal health and breeding efficiency, but drug residues and drug resistance caused by abuse have seriously threatened food safety and public health.

[0003] As the world's first fourth-generation cephalosporin specifically for animals, cefquinome has become an important drug for the treatment of respiratory infections, sepsis and other diseases in livestock and poultry due to its advantages such as broad-spectrum antibacterial properties, low toxicity and lack of drug resistance. However, its existing sulfate suspension injection has significant defects: on the one hand, the large particle size during injection leads to slow absorption and low bioavailability. At the same time, the uneven dispersion of the suspension causes high needle resistance and strong muscle irritation. On the other hand, the particle size limitation during transdermal administration can easily lead to low skin penetration, seriously affecting the efficacy. The limitation of the dosage form with excessively large particle size has seriously restricted the improvement of the efficacy of cefquinome and the prevention and control of drug resistance.

[0004] Nanocrystal dosage forms offer a new approach to overcoming the limitations of existing formulations. Directly nanosizing drugs can significantly enhance solubility and bioavailability, while also improving dispersibility and stability. Compared to carrier-dependent nanocarrier systems, nanocrystal formulations offer advantages such as high drug loading, simplified processing, and excellent stability. Currently, over 20 nanocrystal drugs are marketed, and their potential to enhance efficacy and expand drug delivery routes has been widely recognized. Summary of the Invention

[0005] Purpose of the invention: The purpose of the present invention is to provide a method for preparing a highly uniform and easily soluble lyophilized powder of cefquinome sulfate nanocrystals.

[0006] Technical solution: The method for preparing the cefquinome sulfate nanocrystalline freeze-dried powder of the present invention comprises the following steps:

[0007] (1) dissolving cefquinome sulfate in an organic solvent to obtain a cefquinome sulfate solution having a concentration of 0.3-3.0 g / mL;

[0008] (2) adding 11-12 times the volume of the cefquinome sulfate solution obtained in step 1 and having a concentration of 0.04 g / mL of a nonionic surfactant solution, mixing, and filtering to obtain a suspension;

[0009] (3) adding 1-10 times the mass of cefquinome sulfate contained in the suspension obtained in step 2 to a cryoprotectant, and simultaneously adding 1-5 times the volume of the suspension to a nonionic surfactant solution having a concentration of 0.04 g / mL, and mixing to obtain a suspension;

[0010] (4) The suspension obtained in step 3 is frozen below -70°C and then freeze-dried to obtain cefquinome sulfate nanocrystal freeze-dried powder.

[0011] Preferably, the organic solvent in step 1 is any one or more of dimethyl sulfoxide, methanol, ethanol, acetonitrile, acetone, and acetic acid.

[0012] Preferably, the organic solvent dissolving cefquinome sulfate in step 1 is specifically: using dimethyl sulfoxide to dissolve cefquinome sulfate at room temperature in the dark.

[0013] Preferably, the nonionic surfactant solution in step 2 or 3 is a polysorbate-phosphate buffer solution with a pH of 3.0-4.0.

[0014] Preferably, the polysorbate-phosphate buffer solution is a Tween 80-phosphate buffer solution.

[0015] Preferably, the method of adding the nonionic surfactant solution in step 2 is to add it dropwise at a rate of 1-2 drops / 5s, and the method of mixing is to stir and mix at 500-1000 rpm for 50-70 minutes.

[0016] Preferably, the cryoprotectant in step 3 is any one or more of mannitol, sucrose, and trehalose.

[0017] Preferably, the method of adding the nonionic surfactant solution in step 3 is to add it dropwise at a rate of 1-2 drops / 5s, and the method of mixing is 80-100W ultrasound for 2-5min.

[0018] Preferably, the freezing step in step 4 is freezing below -70°C for no less than 20 hours.

[0019] Preferably, the freeze-drying procedure in step 4 includes:

[0020] (41) Freeze-dry for 18-22 h under a vacuum of no more than 10 Pa, with a cold trap temperature no higher than -55°C and a plate temperature no higher than -40°C;

[0021] (42) Under a vacuum of 10-30 Pa, the cold trap temperature is no higher than -55°C, the plate temperature is linearly and uniformly raised to no higher than -10°C, and freeze-dried for 18-22 h;

[0022] (43) Under a vacuum of no more than 5 Pa, the cold trap temperature is no more than -55°C, the plate temperature is linearly and uniformly raised to no more than 35°C, and freeze-dried for 4-8 h;

[0023] (44) Return to normal temperature and pressure within 1-3 hours.

[0024] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: 1. The particle size of the cefquinome sulfate nanocrystalline freeze-dried powder is 17.4±0.2623nm, the PDI is 0.193±0.017, and the particles are uniform; 2. It can be stably stored for at least 30 days at 4°C and has good stability; 3. Its solubility is significantly better than that of commercially available preparations, and it can effectively improve the needle-passing property; 4. It has good release performance, which is conducive to the rapid dissolution of the drug. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a graph showing the particle size distribution test results of cefquinome sulfate nanocrystals;

[0026] Figure 2 This is a transmission electron microscope image of cefquinome sulfate nanocrystal freeze-dried powder;

[0027] Figure 3 This is the morphology of cefquinome sulfate nanocrystalline freeze-dried powder;

[0028] Figure 4 This is the particle size distribution test result of cefquinome sulfate nanocrystalline freeze-dried powder after reconstitution with water;

[0029] Figure 5 Figure 2 shows the particle size distribution test results of cefquinome sulfate nanocrystal freeze-dried powder after being reconstituted with water after being stored at different temperatures for 30 days. A shows the result of storage at 4°C, and B shows the result of storage at -20°C.

[0030] Figure 6 This is a graph showing the release performance test results of cefquinome sulfate nanocrystalline freeze-dried powder;

[0031] Figure 7 This is the antibacterial performance result of cefquinome sulfate nanocrystalline freeze-dried powder. DETAILED DESCRIPTION

[0032] The technical solution of the present invention is further described below.

[0033] Example 1

[0034] (1) Preparation of cefquinome sulfate solution

[0035] 10 mg of cefquinome sulfate raw material (purchased from Qilu Shenghua Pharmaceutical) was weighed and dissolved in 0.032 mL of dimethyl sulfoxide (DMSO). The mixture was stirred at room temperature in the dark until completely dissolved to obtain a light yellow slightly viscous solution.

[0036] (2) Preparation of anti-solvent system

[0037] After adjusting the pH value of phosphate buffer saline (PBS) to 3.6 with 1 M HCl solution, 100 mL was taken, 4 g of Tween-80 was added, and stirred for 1 hour until completely dissolved to obtain a 4% (w / v) Tween-80 / PBS solution.

[0038] (3) Preparation of Cefquinome Sulfate Nanocrystalline Suspension

[0039] The cefquinome sulfate solution prepared in (1) was added dropwise into 0.368 mL of the Tween-80 / PBS solution prepared in (2) at a rate of 2 drops per 5 seconds using a syringe, stirred for 60 minutes, and then filtered through a 0.22 μm nylon filter membrane to obtain a cefquinome sulfate nanocrystal suspension.

[0040] (4) Preparation of Cefquinome Sulfate Nanocrystalline Lyophilized Powder

[0041] 10 mg of D-mannitol was added to the suspension of cefquinome sulfate nanocrystals in (3), and 2 mL of the Tween-80 / PBS solution prepared in (2) was dripped into the suspension at a rate of 1 drop every 5 seconds using a syringe. The suspension was dissolved by ultrasonication at 80 W for 3 min to obtain a pre-frozen solution of cefquinome sulfate nanocrystals.

[0042] The sample was placed in an ultra-low temperature freezer at -80°C for pre-freezing for 24 h, and then freeze-dried using the freeze-drying program shown in Table 1 to obtain cefquinome sulfate nanocrystal freeze-dried powder.

[0043] Table 1 Freeze-drying procedure

[0044] Time (h) Vacuum degree (Pa) Cold trap temperature (℃) Plate temperature (℃) 0-20 ≤10 -60 -40 20-40 10-30 -60 -35→-10 40-46 ≤5 -60 25→35 46-48 / Return to room temperature Room temperature

[0045] Example 2

[0046] (1) Preparation of cefquinome sulfate solution

[0047] Weigh 25 mg of cefquinome sulfate API and dissolve it in 0.08 mL of dimethyl sulfoxide. Stir at room temperature in the dark until it is completely dissolved to obtain a light yellow, slightly viscous solution.

[0048] (2) Preparation of anti-solvent system

[0049] After adjusting the pH value of phosphate buffer saline (PBS) to 3.6 with 1 M HCl solution, 100 mL was taken, 4 g of Tween-80 was added, and stirred for 1 hour until completely dissolved to obtain a 4% (w / v) Tween-80 / PBS solution.

[0050] (3) Preparation of Cefquinome Sulfate Nanocrystalline Suspension

[0051] The cefquinome sulfate solution prepared in (1) was added dropwise into 0.92 mL of the Tween-80 / PBS solution prepared in (2) at a rate of 2 drops per 5 seconds using a syringe, stirred for 60 minutes, and then filtered through a 0.22 μm nylon filter membrane to obtain a cefquinome sulfate nanocrystal suspension.

[0052] (4) Preparation of Cefquinome Sulfate Nanocrystalline Lyophilized Powder

[0053] 500 mg of D-mannitol was added to the cefquinome sulfate nanocrystal suspension in (3), and 5 mL of the Tween-80 / PBS solution prepared in (2) was dripped into the suspension at a rate of 1 drop every 5 seconds using a syringe. The suspension was dissolved by ultrasonication at 90 W for 4 min to obtain a pre-frozen solution of cefquinome sulfate nanocrystals.

[0054] The sample was placed in an ultra-low temperature freezer at -80°C for pre-freezing for 24 h, and then freeze-dried using the freeze-drying program shown in Table 1 to obtain cefquinome sulfate nanocrystal freeze-dried powder.

[0055] Example 3

[0056] (1) Preparation of cefquinome sulfate solution

[0057] 50 mg of cefquinome sulfate API was weighed and dissolved in 0.16 mL of dimethyl sulfoxide. The mixture was stirred at room temperature in the dark until completely dissolved to obtain a light yellow, slightly viscous solution.

[0058] (2) Preparation of anti-solvent system

[0059] After adjusting the pH value of phosphate buffer saline (PBS) to 3.6 with 1 M HCl solution, 100 mL was taken, 4 g of Tween-80 was added, and stirred for 1 hour until completely dissolved to obtain a 4% (w / v) Tween-80 / PBS solution.

[0060] (3) Preparation of Cefquinome Sulfate Nanocrystalline Suspension

[0061] The cefquinome sulfate solution prepared in (1) was added dropwise into 1.84 mL of the Tween-80 / PBS solution prepared in (2) at a rate of 2 drops per 5 seconds using a syringe, stirred for 60 minutes, and then filtered through a 0.22 μm nylon filter membrane to obtain a cefquinome sulfate nanocrystal suspension.

[0062] (4) Preparation of Cefquinome Sulfate Nanocrystalline Lyophilized Powder

[0063] 500 mg of D-mannitol was added to the suspension of cefquinome sulfate nanocrystals in (3), and 2 mL of the Tween-80 / PBS solution prepared in (2) was dripped into the suspension at a rate of 1 drop every 5 seconds using a syringe. The suspension was dissolved by ultrasonication at 90 W for 4 min to obtain a pre-frozen solution of cefquinome sulfate nanocrystals.

[0064] The sample was placed in an ultra-low temperature freezer at -80°C for pre-freezing for 24 h, and then freeze-dried using the freeze-drying program shown in Table 1 to obtain cefquinome sulfate nanocrystal freeze-dried powder.

[0065] Example 4

[0066] (1) Preparation of cefquinome sulfate solution

[0067] 100 mg of cefquinome sulfate API was weighed and dissolved in 0.32 mL of dimethyl sulfoxide. The mixture was stirred at room temperature in the dark until completely dissolved to obtain a light yellow, slightly viscous solution.

[0068] (2) Preparation of anti-solvent system

[0069] After adjusting the pH value of phosphate buffer saline (PBS) to 3.6 with 1 M HCl solution, 100 mL was taken, 4 g of Tween-80 was added, and stirred for 1 hour until completely dissolved to obtain a 4% (w / v) Tween-80 / PBS solution.

[0070] (3) Preparation of Cefquinome Sulfate Nanocrystalline Suspension

[0071] The cefquinome sulfate solution prepared in (1) was added dropwise into 3.68 mL of the Tween-80 / PBS solution prepared in (2) at a rate of 2 drops per 5 seconds using a syringe, stirred for 60 minutes, and then filtered through a 0.22 μm nylon filter membrane to obtain a cefquinome sulfate nanocrystal suspension.

[0072] (4) Preparation of Cefquinome Sulfate Nanocrystalline Lyophilized Powder

[0073] 1000 mg of D-mannitol was added to the suspension of cefquinome sulfate nanocrystals in (3), and 20 mL of the Tween-80 / PBS solution prepared in (2) was dripped into the suspension at a rate of 1 drop every 5 seconds using a syringe. The suspension was dissolved by ultrasonication at 100 W for 5 min to obtain a pre-frozen solution of cefquinome sulfate nanocrystals.

[0074] The sample was placed in an ultra-low temperature freezer at -80°C for pre-freezing for 24 h, and then freeze-dried using the freeze-drying program shown in Table 1 to obtain cefquinome sulfate nanocrystal freeze-dried powder.

[0075] Example 5

[0076] (1) Preparation of cefquinome sulfate solution

[0077] 2.5 g of cefquinome sulfate API was weighed and dissolved in 0.8 mL of dimethyl sulfoxide. The mixture was stirred at room temperature in the dark until completely dissolved to obtain a light yellow, slightly viscous solution.

[0078] (2) Preparation of anti-solvent system

[0079] After adjusting the pH value of phosphate buffer saline (PBS) to 3.6 with 1 M HCl solution, 100 mL was taken, 4 g of Tween-80 was added, and stirred for 1 hour until completely dissolved to obtain a 4% (w / v) Tween-80 / PBS solution.

[0080] (3) Preparation of Cefquinome Sulfate Nanocrystalline Suspension

[0081] The cefquinome sulfate solution prepared in (1) was added dropwise into 9.2 mL of the Tween-80 / PBS solution prepared in (2) at a rate of 2 drops per 5 seconds using a syringe, stirred for 60 minutes, and then filtered through a 0.22 μm nylon filter membrane to obtain a cefquinome sulfate nanocrystal suspension.

[0082] (4) Preparation of Cefquinome Sulfate Nanocrystalline Lyophilized Powder

[0083] 1000 mg of D-mannitol was added to the suspension of cefquinome sulfate nanocrystals in (3), and 20 mL of the Tween-80 / PBS solution prepared in (2) was dripped into the suspension at a rate of 1 drop every 5 seconds using a syringe. The suspension was dissolved by ultrasonication at 100 W for 5 min to obtain a pre-frozen solution of cefquinome sulfate nanocrystals.

[0084] The sample was placed in an ultra-low temperature freezer at -80°C for pre-freezing for 24 h, and then freeze-dried using the freeze-drying program shown in Table 1 to obtain cefquinome sulfate nanocrystal freeze-dried powder.

[0085] Test Example 1 Characterization of Cefquinome Sulfate Nanocrystals

[0086] 1. Determination of particle size of cefquinome sulfate nanocrystals

[0087] The particle size of the cefquinome sulfate nanocrystals prepared in Example 1 was measured using a Malvern Zetasizer Nano ZS90 particle size analyzer. The results are as follows: Figure 1 As shown, the particle size of the cefquinome sulfate nanocrystals is 17.4 nm ± 0.2623 nm, and the PDI is 0.193 ± 0.017. The particle size of this preparation meets the nanocrystal size requirements, and the PDI is less than 0.3, indicating excellent preparation uniformity.

[0088] 2. Transmission electron microscopy imaging of cefquinome sulfate nanoparticles

[0089] The microscopic morphology of cefquinome sulfate nanocrystals was photographed using a transmission electron microscope. Figure 2 As shown, the nanocrystals of cefquinome sulfate observed under transmission electron microscopy were about 20 nm in size and were regular spherical, which was consistent with the results of Malvern particle size analyzer.

[0090] Test Example 2 Characterization of Cefquinome Sulfate Nanocrystalline Lyophilized Powder

[0091] 1. Morphology of Cefquinome Sulfate Nanocrystalline Lyophilized Powder

[0092] The results of the experiment were as follows: Figure 3 As shown, the freeze-dried powder has a loose, porous, non-collapsed structure and good properties.

[0093] 2. Particle size determination of cefquinome sulfate nanocrystalline freeze-dried powder after reconstitution

[0094] The lyophilized powder of cefquinome sulfate nanocrystals was reconstituted to a concentration of 20 mg / mL. The difficulty of reconstitution was observed and the particle size after reconstitution was measured. The lyophilized powder was very easy to reconstitute. After adding solvent (water), slight shaking and standing for 1 minute, a clear and transparent suspension of cefquinome sulfate nanocrystals was obtained. The particle size test results are as follows: Figure 4 As shown in the figure, the particle size of the nanocrystalline freeze-dried powder was stable at 11.92nm±0.4013 after reconstitution, with no significant difference from that before freeze-drying.

[0095] Test Example 3: Stability Study of Freeze-dried Powder of Cefquinome Sulfate Nanocrystals

[0096] The lyophilized powder of cefquinome sulfate nanocrystals was stored at 4°C and -20°C, respectively. After 30 days, samples were taken and re-dissolved to a concentration of 20 mg / mL. The difficulty of re-dissolution was observed and the particle size was measured.

[0097] The freeze-dried powders stored under both conditions were easy to reconstitute. After adding solvent (water), slight shaking and standing for 1 minute, a clear and transparent cefquinome sulfate nanocrystalline suspension could be obtained.

[0098] The particle size test results are as follows Figure 5 As shown in the figure, the reconstituted particle size can be kept stable after storage at 4°C and -20°C for 30 days.

[0099] Test Example 4: Determination of the Needle-Permeability of Cefquinome Sulfate Nanocrystals

[0100] Use a 5mL disposable syringe with a 4.5, 5, 6, 7, 8, or 16 gauge needle to draw the 20 mg / mL nanocrystal reconstituted solution prepared in Example 1 and the 20 mg / mL reference reagent. 2 mL of cefquinome sulfate suspension injection (purchased from Hefei Zhonglong Shenli Animal Pharmaceutical Co., Ltd.) was used, and the extraction time was recorded. The results are shown in Table 2 below.

[0101] Table 2 Time required to extract 2 mL

[0102]

[0103] When drawing the same volume of liquid using needles ranging from 4.5 to 16, the drawing time of the cefquinome sulfate nanocrystal complex solution obtained in the example is significantly shorter than that of the commercially available suspension injection, and the solution has excellent needleability.

[0104] Test Example 5 Determination of in vitro release performance of cefquinome sulfate nanocrystals

[0105] Take a nanocrystalline preparation containing 20 mg of cefquinome sulfate, Commercially available cefquinome sulfate suspension injection, Cefquinome sulfate lyophilized injection (purchased from Xinxiang Huaxu Trading Co., Ltd.) was prepared to ensure that the cefquinome sulfate content of all three preparations was 20 mg. After precise weighing, the mixture was placed into the dissolution cup, and three replicates were set for each preparation.

[0106] The paddle method was used at a speed of 500 rpm. The dissolution medium was PBS (pH = 7.4) with a volume of 900 mL and the temperature was maintained at 37 ± 0.5°C. 5 mL of the dissolution solution was drawn from each dissolution cup at 5, 15, 30, 60, and 180 minutes, and an equal amount of dissolution medium at the same temperature was immediately added.

[0107] The extracted dissolution solution was filtered using a 0.45 μm microporous filter membrane and used as the test solution. The absorption peak of the test solution was measured at 270 nm by high performance liquid chromatography, and the concentration of the drug in the dissolution solution was calculated according to the standard curve.

[0108] Chromatographic conditions: CORTECS Premier C18 column ( 2.7μm, 4.6mm*150mm), 0.05% formic acid aqueous solution: acetonitrile (V / V = 90:10), flow rate 1mL / min, column temperature 35°C, detection wavelength 270nm. Set the above chromatographic conditions, inject and test, and draw a concentration standard curve.

[0109] Standard curve formula: Y = 39061.4 × C - 139567, R 2 =0.9997, where Y is the peak response area and C is the drug concentration. The drug release amount at each time point is calculated based on the measured drug concentration to obtain the release percentage.

[0110] The results are as follows Figure 6 As shown in the data, the nanocrystalline preparation can achieve almost complete release in the release medium within 15 minutes, the commercially available injectable lyophilized powder can achieve complete release within 30 minutes, and the commercially available suspension injection requires 3 hours to achieve complete release; compared with the suspension injection, the nanocrystalline preparation and the commercially available injectable lyophilized powder have faster release rates, among which the nanocrystalline preparation has the fastest release rate, which may be due to its smaller particle size, which is conducive to drug dissolution.

[0111] Test Example 6 Determination of Antibacterial Properties of Cefquinome Sulfate Nanocrystals

[0112] Escherichia coli CMCC(B)44102 was used as a representative of Gram-negative bacteria, and Staphylococcus aureus ATCC6538 was used as a representative of Gram-positive bacteria.

[0113] 20 μL of a concentration of 5 × 10 5 CFU / mL Escherichia coli CMCC(B)44102 bacterial solution or Staphylococcus aureus ATCC6538 bacterial solution was mixed with 20 μL of 25 μg / mL cefquinome sulfate nanocrystal complex solution obtained in Example 1 or PBS, spread on a sterile LB plate, incubated in a 37°C incubator for 12 hours, and then taken out for observation.

[0114] The results are as follows Figure 7 As shown, no bacteria grew on the plates containing the cefquinome sulfate nanocrystal complex solution, indicating that the nanocrystals have a good inhibitory effect on both Gram-positive and Gram-negative bacteria.

Claims

1. A method for preparing cefquinome sulfate nanocrystalline freeze-dried powder, characterized in that the steps include: (1) dissolving cefquinome sulfate in an organic solvent to obtain a cefquinome sulfate solution having a concentration of 0.3-3.0 g / mL; (2) adding 11-12 times the volume of the cefquinome sulfate solution obtained in step 1 and having a concentration of 0.04 g / mL of a nonionic surfactant solution, mixing, and filtering to obtain a suspension; (3) adding 1-10 times the mass of cefquinome sulfate contained in the suspension obtained in step 2 to a cryoprotectant, and simultaneously adding 1-5 times the volume of the suspension to a nonionic surfactant solution having a concentration of 0.04 g / mL, and mixing to obtain a suspension; (4) The suspension obtained in step 3 is frozen below -70°C and then freeze-dried to obtain cefquinome sulfate nanocrystal freeze-dried powder.

2. The method for preparing cefquinome sulfate nanocrystalline freeze-dried powder according to claim 1, wherein The organic solvent in step 1 is any one or more of dimethyl sulfoxide, methanol, ethanol, acetonitrile, acetone, and acetic acid.

3. The method for preparing cefquinome sulfate nanocrystalline freeze-dried powder according to claim 1, wherein: The step 1 of dissolving cefquinome sulfate with an organic solvent specifically comprises: using dimethyl sulfoxide to dissolve cefquinome sulfate at room temperature in the dark.

4. The method for preparing cefquinome sulfate nanocrystalline freeze-dried powder according to claim 1, wherein: The nonionic surfactant solution in step 2 or 3 is a polysorbate-phosphate buffer solution with a pH of 3.0-4.

0.

5. The method for preparing cefquinome sulfate nanocrystalline freeze-dried powder according to claim 4, wherein: The polysorbate-phosphate buffer solution is a Tween 80-phosphate buffer solution.

6. The method for preparing cefquinome sulfate nanocrystalline freeze-dried powder according to claim 1, wherein: The method of adding the nonionic surfactant solution in step 2 is to add it dropwise at a rate of 1-2 drops / 5s, and the method of mixing is to stir and mix at 500-1000 rpm for 50-70 minutes.

7. The method for preparing cefquinome sulfate nanocrystalline freeze-dried powder according to claim 1, wherein: The cryoprotectant in step 3 is any one or more of mannitol, sucrose, and trehalose.

8. The method for preparing cefquinome sulfate nanocrystalline freeze-dried powder according to claim 1, wherein: The method of adding the nonionic surfactant solution in step 3 is to add it dropwise at a rate of 1-2 drops / 5s, and the method of mixing is 80-100W ultrasound for 2-5min.

9. The method for preparing cefquinome sulfate nanocrystalline freeze-dried powder according to claim 1, wherein: The freezing step in step 4 is freezing below -70°C for no less than 20 hours.

10. The method for preparing cefquinome sulfate nanocrystalline freeze-dried powder according to claim 1, wherein: The freeze-drying procedure of step 4 includes: (41) Freeze-dry for 18-22 h under a vacuum of no more than 10 Pa, with a cold trap temperature no higher than -55°C and a plate temperature no higher than -40°C; (42) Under a vacuum of 10-30 Pa, the cold trap temperature is no higher than -55°C, the plate temperature is linearly and uniformly raised to no higher than -10°C, and freeze-dried for 18-22 h; (43) Under a vacuum of no more than 5 Pa, the cold trap temperature is no more than -55°C, the plate temperature is linearly and uniformly raised to no more than 35°C, and freeze-dried for 4-8 h; (44) Return to normal temperature and pressure within 1-3 hours.

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