Low-residue florfenicol powder and preparation method thereof

Abstract

The invention relates to low-residue florfenicol powder and a preparation method thereof. The low-residue florfenicol powder is prepared from the following raw materials by weight: 10 to 30 kg of florfenicol, 3 to 9 kg of chitosan, 1 to 3 kg of sodium alginate, 0.032 to 0.096 kg of graphene oxide, 0.4 to 1.2 kg of poloxamer 407, 50 to 90 kg of an acetic acid buffer solution and 50 to 90 kg of an auxiliary material. According to the invention, the chitosan / sodium alginate / GO composite wall material is disintegrated under the pH (6.8) of the intestinal tract through microencapsulation precise controlled release, so that targeted release is realized, premature release of the stomach is avoided, and residues of drugs in non-target organs are reduced; and the residual quantity of florfenicol in the body is only 0.05 + / -0.02 ppm. After GO / poloxamer modification, the encapsulation efficiency reaches 97.2%, the crystal loss of the medicine is reduced, the dissolution time is shortened, and the onset speed is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of veterinary drug preparations, and particularly relates to a low-residue florfenicol powder and a preparation method thereof. The low-residue florfenicol powder adopts microencapsulation to reduce the free state of the drug and gradient elution to remove impurities to reduce the drug residue in the animal body. Background Art

[0002] Florfenicol, a broad-spectrum veterinary antibiotic, has a significant impact on the safety of animal-derived food and the ecological environment. Current production processes often utilize ethanol extraction combined with spray drying. For example, CN115068426A discloses a method for preparing florfenicol soluble powder, which includes the following steps: S1: Prepare raw materials: including florfenicol, oligosaccharides, ethanol, methanol, and double-distilled water; S2: Prepare equipment: baking tray, oven, container, mixer, spray dryer; S3: Treatment of oligosaccharides: Spread the oligosaccharides evenly on the baking tray. After spreading, put the baking tray into the oven and arrange them from top to bottom. After all are put into the oven, close the oven door and set the temperature and time for drying. The drying temperature is 105 degrees. The drying time varies with the humidity of the oligosaccharides. Finally, it is required to dry the oligosaccharides until the moisture content is no more than 6%. After drying, put the oligosaccharides into a clean, dry container and set aside. S4: Preparation of excipients: Place oligosaccharides, ethanol, methanol, and double-distilled water into clean containers; S5: Add oligosaccharides to distilled water, then heat to 45 degrees on a magnetic stirrer and stir to dissolve. Slowly add ethanol, methanol, and analytical grade solution while stirring until the solution is clear. Store at a constant temperature of 45 degrees. S6: Mixing: When mixing, operate according to the step-by-step dilution method. Add the oligosaccharides in three times. Add 1 / 4 of the total amount of oligosaccharides first, then pour the florfenicol in at once, mix evenly for 5 minutes, then add 1 / 2 of the original total amount of oligosaccharides, mix evenly for 5 minutes, and then send the remaining oligosaccharides into the mixer and mix for another 10 minutes. The total amount of the mixed material is required to not exceed 2 / 3 of the mixer capacity. Take out the spray dryer and adjust it. After the spray dryer is adjusted to a stable state, spray drying is performed (the outlet temperature of the spray dryer is 80-90 degrees and the inlet temperature is 250-290 degrees) to obtain florfenicol soluble powder.

[0003] Existing florfenicol production processes often suffer from significant drawbacks: 1) High-temperature spray drying leads to thermal degradation of the drug, resulting in a high risk of exceeding standards for residual solvents (e.g., ethanol ≥500 ppm) and metabolic byproducts (chloramphenicol analogs ≥0.2 ppm); 2) Traditional microencapsulation processes have low encapsulation efficiencies (<85%), resulting in severe burst release and difficulty achieving intestinal-targeted release; 3) Single purification techniques (e.g., activated carbon adsorption) have insufficient clearance rates for fat-soluble impurities, small molecule metabolites, and charged polar residues (combined clearance rate <70%), making it difficult to meet stringent EU standards such as 0.1 ppm. Furthermore, existing technologies suffer from long production cycles (>48 hours) and high energy consumption (hot air drying ≥2.5 kWh / kg), hindering their commercial application.

[0004] Based on this, the industry is in urgent need of developing an efficient and low-residue florfenicol preparation process to break through the residue control bottleneck while ensuring the bioavailability of the drug, thereby improving production economy and product stability. Summary of the Invention

[0005] The present invention aims to overcome the defects of the prior art and provide a low-residue florfenicol powder, which adopts the method of microencapsulation to reduce the free state of the drug and gradient elution to remove impurities to reduce the residue of the drug in the animal body.

[0006] Another object of the present invention is to provide a method for preparing the low-residue florfenicol powder.

[0007] The third object of the present invention is to provide experimental data on drug residues in the low-residue florfenicol powder.

[0008] To achieve the above object, the present invention adopts the following technical solutions: A low-residue florfenicol powder is mainly prepared from the following raw materials in the following weight ratio: 10-30 kg of florfenicol, 3-9 kg of chitosan, 1-3 kg of sodium alginate, 0.032-0.096 kg of graphene oxide, 0.4-1.2 kg of poloxamer 407, 50-90 kg of acetate buffer, and 50-90 kg of auxiliary materials.

[0009] Specifically, the pH of the acetate buffer may be 4-5.

[0010] Furthermore, the auxiliary material can be any one of corn starch and pregelatinized starch.

[0011] The present invention provides a method for preparing the low-residue florfenicol powder, which comprises the following steps: 1) Graphene oxide (GO) was dispersed in a portion of acetic acid buffer to form a uniform dispersion; poloxamer 407 was added, heated and stirred until completely dissolved, and then subjected to high pressure homogenization to form a GO / poloxamer composite micelle dispersion; 2) Chitosan and sodium alginate were added to the remaining acetate buffer and stirred to form a viscous and transparent wall material solution; the GO / poloxamer micelle dispersion prepared in step 1) was added and the cells were disrupted by ultrasonic treatment; 3) Add florfenicol API, continue stirring, homogenize under high pressure, atomize through a dual-fluid nozzle, and simultaneously start ultrasonic oscillation; 4) The atomized droplets are spray-freeze-dried to obtain microcapsule powder, which is then placed into a supercritical CO2 extraction kettle, where 0.1-0.2% Tween 80 by weight of the microcapsule powder is injected as an entrainer for dynamic extraction; 5) After extraction, the material is separated by a reverse osmosis membrane (with a molecular weight cut-off of less than 500 Da) to remove small molecule metabolites with a molecular weight cut-off of less than 500 Da; 6) pH gradient ion exchange: The permeate is washed with D301 resin column, first with hydrochloric acid at pH 2.5-3.5, then eluted with 0.03-0.06 M phosphate buffer, and the eluate is concentrated and dried. During the hydrochloric acid wash phase, the wash rate is 1.0-1.5 BV / h (column volume / hour), and the wash volume is 3-4 column volumes. During the phosphate buffer elution phase, the elution flow rate is 0.5-0.8 BV / h, and the elution volume is 4-5 column volumes. 7) Mix the dried microcapsule powder with the auxiliary materials and sieve to obtain the product.

[0012] Specifically, in step 1), graphene oxide can be added to an acetic acid buffer solution, magnetically stirred at 600-1000 rpm for 20-50 min, and ultrasonically treated at 30-50 kHz and a power of 200-400 W for 30-90 min to form a uniform dispersion; poloxamer 407 is added, heated in a water bath at 50-70°C with stirring until completely dissolved, and high-pressure homogenization is performed at a pressure of 100±10 MPa and a temperature of ≤70°C (preferably 60-70°C) (cycled 3-5 times).

[0013] Specifically, in step 2), the mixture can be stirred at a constant temperature of 40-60° C. and 1000-1400 rpm for 1-3 hours to form a viscous and transparent wall material solution; ultrasonic cell disruption treatment is performed for 15-30 minutes at a power of 700-900 W and a pulse mode of 5-6 seconds on / 2-3 seconds off.

[0014] Specifically, in step 3), after continuing stirring at 700-900 rpm for 0.5-2 hours, high-pressure homogenization is performed (2-3 cycles) at a pressure of 50±10 MPa and a temperature ≤40°C (preferably 30-40°C) to uniformly disperse the drug. For atomization using a two-fluid nozzle, the compressed air pressure is 0.2-0.3 MPa and the liquid flow rate is 6-10 L / h. The amplitude of the ultrasonic oscillation is 50±10 μm.

[0015] Specifically, in step 4), the dynamic extraction is performed for 30-50 min; during the first half of the extraction, the supercritical CO2 fluid flow rate is 2-3 L / min, and during the second half of the extraction, the supercritical CO2 fluid flow rate is 3-4 L / min.

[0016] Furthermore, in step 4), the spray freeze drying conditions are: maintaining at -40±5°C for 3-5 hours, heating to 25±5°C for 5-7 hours, and vacuum degree ≤10Pa.

[0017] Furthermore, in step 7), the eluted microcapsule powder and the auxiliary materials can be mixed in a three-dimensional mixer for 15-45 minutes, and passed through an 80-120 mesh sieve to obtain the microcapsule powder.

[0018] Preferably, the mass ratio of the acetate buffer used in step 1) to the buffer used in step 2) is 15-16%:84-85%.

[0019] Compared with the prior art, the present invention has the following advantages and beneficial effects: 1) Microencapsulation allows for precise controlled release. The chitosan / sodium alginate / GO composite wall material disintegrates at intestinal pH (6.8), achieving targeted release, avoiding premature release in the stomach, and reducing drug residue in non-target organs. 2) Gradient elution synergistically enhances the efficiency of purification by three stages: supercritical CO2 (removal of fat-soluble impurities) + reverse osmosis membrane (retention of small molecules) + ion exchange (adsorption of charged residues), achieving an impurity removal rate of >99.9%; 3) The GO / poloxamer modification achieved an encapsulation efficiency of 97.2%, reducing drug crystal loss, shortening dissolution time, and improving the onset of efficacy. The unencapsulated free florfenicol residue in the final product was 0.05±0.02ppm; the in vivo residual level of florfenicol was only 0.05±0.01ppm. DETAILED DESCRIPTION

[0020] The technical solution of the present invention is further described in detail below in conjunction with the embodiments, but the protection scope of the present invention is not limited thereto.

[0021] In the following examples, all raw materials used were commercially available or prepared using conventional methods in the art. For example, chitosan was purchased from Hebei Hongtao Bioengineering Co., Ltd., with a content of ≥99%; graphene oxide was purchased from Sigma-Aldrich, product number 763705; and pregelatinized starch was purchased from Colorcon, product model: Starch 1500.

[0022] Unless otherwise specified, the temperature refers to room temperature (25±5℃).

[0023] Example 1 A low-residue florfenicol powder is mainly prepared from the following raw materials in the following weight ratio: 10 kg of florfenicol, 3 kg of chitosan, 1 kg of sodium alginate, 0.032 kg of graphene oxide, 0.4 kg of poloxamer 407, 85.568 kg of acetate buffer (pH=4.5), and 84 kg of corn starch.

[0024] The preparation method of the low-residue florfenicol powder comprises the following steps: 1. Graphene oxide (GO) was added to 13.168 kg of acetate buffer (0.1 M, pH 4.5), magnetically stirred (800 rpm) for 30 min, and ultrasonically treated (40 kHz, 300 W) for 1 h to form a uniform dispersion. Poloxamer 407 was added, heated in a 60°C water bath with stirring until completely dissolved, and high-pressure homogenization was performed (pressure 100 MPa, temperature 60-70°C, cycled 5 times) to form a GO / poloxamer composite micelle dispersion. 2. Add chitosan and sodium alginate to 72.4 kg of acetate buffer (0.1 M, pH 4.5) and stir at 50°C (1200 rpm) for 2 h to form a viscous, transparent wall material solution. Slowly add the GO / poloxamer composite micelle dispersion prepared in step 1 to the wall material solution and perform ultrasonic cell disruption (power 800 W, pulse mode 5 s on / 2 s off) for 20 min. 3. Add florfenicol API and continue stirring (800 rpm) for 1 hour. After high-pressure homogenization (pressure 50 MPa, temperature 30-40°C, 3 cycles) to evenly disperse the drug, atomize through a dual-fluid nozzle (compressed air pressure 0.25 MPa, liquid flow rate 8 L / h), and simultaneously start ultrasonic oscillation (amplitude 50 μm). 4. The atomized droplets were spray-freeze-dried (maintained at -40°C for 4 hours, then heated to 25°C for 6 hours, with a vacuum degree of ≤10 Pa, the same below) to obtain microcapsule powder. The microcapsule powder was placed in a supercritical CO2 extraction kettle, and Tween 80 (0.1% by weight of the microcapsule powder) was injected as an entrainer. Dynamic extraction was performed for 40 minutes (the first 20 minutes, the flow rate was 2.5 L / min, the last 20 minutes, the flow rate was 3 L / min); 5. After extraction, the material is separated by a reverse osmosis membrane (with a molecular weight cut-off of less than 500Da) to remove small molecular metabolites with a molecular weight cut-off of less than 500Da; the operating pressure is 1.0MPa, the membrane area is 10m², and the feed liquid temperature is 25°C, the same below; 6. pH gradient ion exchange: The permeate was washed with D301 resin column, first with hydrochloric acid at pH 3.0, then eluted with 0.05 M phosphate buffer (pH 8.5). The eluate was concentrated and dried. During the hydrochloric acid wash phase, the wash rate was 1.0 BV / h (column volume / hour), and the wash volume was 3 column volumes. During the phosphate buffer elution phase, the elution flow rate was 0.5 BV / h, and the elution volume was 4 column volumes. 7. Mix the dried microcapsule powder and corn starch in a three-dimensional mixer for 30 minutes, and pass through a 100-mesh sieve to obtain the product of the present invention.

[0025] Example 2 A low-residue florfenicol powder is mainly prepared from the following raw materials in the following weight ratio: 20 kg of florfenicol, 6 kg of chitosan, 2 kg of sodium alginate, 0.064 kg of graphene oxide, 0.8 kg of poloxamer 407, 70.92 kg of acetate buffer (pH=4.5), and 69.2 kg of pregelatinized starch.

[0026] The preparation method of the low-residue florfenicol powder comprises the following steps: 1. Graphene oxide (GO) was added to 10.92 kg of acetate buffer (0.1 M, pH 4.5), magnetically stirred (800 rpm) for 30 min, and ultrasonically treated (40 kHz, 300 W) for 1 h to form a uniform dispersion. Poloxamer 407 was added, heated in a 60°C water bath with stirring until completely dissolved, and high-pressure homogenization was performed (pressure 100 MPa, temperature 60-70°C, cycled 5 times) to form a GO / poloxamer composite micelle dispersion. 2. Add chitosan and sodium alginate to 60 kg of acetate buffer (0.1 M, pH 4.5) and stir at 50°C (1200 rpm) for 2 h to form a viscous, transparent wall material solution. Slowly add the GO / poloxamer composite micelle dispersion prepared in step 1 to the wall material solution and perform ultrasonic cell disruption (power 800 W, pulse mode 5 s on / 2 s off) for 20 min. 3. Add florfenicol API and continue stirring (800 rpm) for 1 hour. After high-pressure homogenization (pressure 50 MPa, temperature 30-40°C, 3 cycles) to evenly disperse the drug, atomize through a dual-fluid nozzle (compressed air pressure 0.25 MPa, liquid flow rate 8 L / h), and simultaneously start ultrasonic oscillation (amplitude 50 μm). 4. The atomized droplets were spray-freeze-dried to obtain microcapsule powder, which was then placed in a supercritical CO2 extraction kettle. Tween 80 (0.1% by weight of the microcapsule powder) was injected as an entrainer, and dynamic extraction was performed for 40 minutes (the first 20 minutes, the flow rate was 2.5 L / min, the next 20 minutes, the flow rate was 3 L / min); 5. After extraction, the material is separated by a reverse osmosis membrane (with a molecular weight cut-off of less than 500Da) to remove small molecule metabolites with a molecular weight cut-off of less than 500Da; 6. pH gradient ion exchange: The permeate was washed with D301 resin column, first with hydrochloric acid at pH 3.0, then eluted with 0.05 M phosphate buffer (pH 8.5). The eluate was concentrated and dried. During the hydrochloric acid wash phase, the wash rate was 1.0 BV / h (column volume / hour), and the wash volume was 3 column volumes. During the phosphate buffer elution phase, the elution flow rate was 0.5 BV / h, and the elution volume was 4 column volumes. 7. Mix the dried microcapsule powder and pregelatinized starch in a three-dimensional mixer for 30 minutes, and pass through a 100-mesh sieve to obtain the product of the present invention.

[0027] Example 3 A low-residue florfenicol powder is mainly prepared from the following raw materials in the following weight ratio: 30 kg of florfenicol, 9 kg of chitosan, 3 kg of sodium alginate, 0.096 kg of graphene oxide, 1.2 kg of poloxamer 407, 56.704 kg of acetate buffer (pH=4.5), and 55.68 kg of corn starch.

[0028] The preparation method of the low-residue florfenicol powder comprises the following steps: 1. Graphene oxide (GO) was added to 8.704 kg of acetate buffer (0.1 M, pH 4.5), magnetically stirred (800 rpm) for 30 min, and ultrasonicated (40 kHz, 300 W) for 1 h to form a uniform dispersion. Poloxamer 407 was added, heated in a 60°C water bath with stirring until completely dissolved, and then subjected to high-pressure homogenization (pressure 100 MPa, temperature 60-70°C, cycled 5 times) to form a GO / poloxamer composite micelle dispersion. 2. Add chitosan and sodium alginate to 48 kg of acetate buffer (0.1 M, pH 4.5) and stir at 50°C (1200 rpm) for 2 h to form a viscous, transparent wall material solution. Slowly add the GO / poloxamer composite micelle dispersion prepared in step 1 to the wall material solution and perform ultrasonic cell disruption (power 800 W, pulse mode 5 s on / 2 s off) for 20 min. 3. Add florfenicol API and continue stirring (800 rpm) for 1 hour. After high-pressure homogenization (pressure 50 MPa, temperature 30-40°C, 3 cycles) to evenly disperse the drug, atomize through a dual-fluid nozzle (compressed air pressure 0.25 MPa, liquid flow rate 8 L / h), and simultaneously start ultrasonic oscillation (amplitude 50 μm). 4. The atomized droplets were spray-freeze-dried to obtain microcapsule powder, which was then placed in a supercritical CO2 extraction kettle. Tween 80 (0.1% by weight of the microcapsule powder) was injected as an entrainer, and dynamic extraction was performed for 40 minutes (the first 20 minutes, the flow rate was 2.5 L / min, the next 20 minutes, the flow rate was 3 L / min); 5. After extraction, the material is separated by a reverse osmosis membrane (with a molecular weight cut-off of less than 500Da) to remove small molecule metabolites with a molecular weight cut-off of less than 500Da; 6. pH gradient ion exchange: The permeate was washed with D301 resin column, first with hydrochloric acid at pH 3.0, then eluted with 0.05 M phosphate buffer (pH 8.5). The eluate was concentrated and dried. During the hydrochloric acid wash phase, the wash rate was 1.0 BV / h (column volume / hour), and the wash volume was 3 column volumes. During the phosphate buffer elution phase, the elution flow rate was 0.5 BV / h, and the elution volume was 4 column volumes. 7. Mix the dried microcapsule powder and corn starch in a three-dimensional mixer for 30 minutes, and pass through a 100-mesh sieve to obtain the product of the present invention.

[0029] Comparative Example 1: Traditional spray drying method (no microencapsulation + ethanol extraction) A florfenicol powder is mainly prepared from the following raw materials in the following weight ratio: 10 kg of florfenicol raw material, 80 kg of corn starch, 200 L of ethanol (concentration 95%), and 5 kg of activated carbon.

[0030] The preparation method of the above-mentioned florfenicol powder comprises the following steps: 1. Ethanol extraction: Add 10 kg of florfenicol API and 200 L of ethanol to the reactor and reflux at 60°C for 3 h; remove insoluble matter by filtration and concentrate the filtrate (rotary evaporator, 50°C, -0.08 MPa) to a solid content of 20%; 2. Activated carbon adsorption: Add 5kg of activated carbon to the concentrate, stir and adsorb at 40℃ for 1h; centrifuge (3000rpm, 15min) to remove the activated carbon and adsorbed pigment impurities; 3. Spray drying: The liquid is atomized through a pressure nozzle (aperture 0.5mm), with an air inlet temperature of 180°C and an air outlet temperature of 85°C; the dried powder (moisture ≤ 5%) is collected; 4. Mixing and final treatment: Mix the dry powder with 80 kg of corn starch in a three-dimensional mixer for 30 minutes; pass through a 100-mesh sieve and package to obtain the final product.

[0031] Comparative Example 2 Chitosan / sodium alginate wall material (without GO+poloxamer) Disclosed is florfenicol powder, which is mainly prepared from the following raw materials in the following weight ratio: 20 kg of florfenicol, 6 kg of chitosan, 2 kg of sodium alginate, 72 kg of acetate buffer (pH=4.5), and 69.2 kg of pregelatinized starch.

[0032] The preparation method of the above-mentioned florfenicol powder comprises the following steps: 1. Add chitosan and sodium alginate to acetate buffer and stir at 50℃ (1200 rpm) for 2 h to form a viscous and transparent solution; 2. Add florfenicol API and continue stirring (800 rpm) for 1 hour. After high-pressure homogenization (pressure 50 MPa, temperature 30-40°C, 3 cycles) to evenly disperse the drug, atomize through a dual-fluid nozzle (compressed air pressure 0.25 MPa, liquid flow rate 8 L / h), and simultaneously start ultrasonic oscillation (amplitude 50 μm). 3. The atomized droplets were spray-freeze-dried (maintained at -40°C for 4 hours, then heated to 25°C for 6 hours, with a vacuum degree of ≤10 Pa) to obtain microcapsule powder. The microcapsule powder was placed in a supercritical CO2 extraction kettle, and Tween 80 (0.1% by weight of the microcapsule powder) was injected as an entrainer. Dynamic extraction was performed for 40 minutes (the first 20 minutes, the flow rate was 2.5 L / min, the last 20 minutes, the flow rate was 3 L / min); 4. After extraction, the material is separated by a reverse osmosis membrane (with a molecular weight cut-off of less than 500Da) to remove small molecule metabolites with a molecular weight cut-off of less than 500Da; 5. pH gradient ion exchange: The permeate was washed with D301 resin column, first with hydrochloric acid at pH 3.0, then eluted with 0.05 M phosphate buffer (pH 8.5). The eluate was concentrated and dried. During the hydrochloric acid wash phase, the wash rate was 1.0 BV / h (column volume / hour), and the wash volume was 3 column volumes. During the phosphate buffer elution phase, the elution flow rate was 0.5 BV / h, and the elution volume was 4 column volumes. 6. Mix the dried microcapsule powder and pregelatinized starch in a three-dimensional mixer for 30 minutes, and pass through a 100-mesh sieve to obtain the product.

[0033] Comparative Example 3 Single Purification Technology (Non-Membrane Separation + Ion Exchange) A florfenicol powder is mainly prepared from the following raw materials in the following weight ratio: 30 kg of florfenicol, 9 kg of chitosan, 3 kg of sodium alginate, 0.096 kg of graphene oxide, 1.2 kg of poloxamer 407, 56.704 kg of acetate buffer (pH=4.5), and 55.68 kg of corn starch.

[0034] The preparation method of the above-mentioned florfenicol powder comprises the following steps: 1. Graphene oxide (GO) was added to 8.704 kg of acetate buffer (0.1 M, pH 4.5), magnetically stirred (800 rpm) for 30 min, and ultrasonically treated (40 kHz, 300 W) for 1 h to form a uniform dispersion. Poloxamer 407 was added, heated in a 60°C water bath with stirring until completely dissolved, and high-pressure homogenization was performed (pressure 100 MPa, temperature 60-70°C, cycled 5 times) to form a GO / poloxamer composite micelle dispersion. 2. Add chitosan and sodium alginate to 48 kg of acetate buffer (0.1 M, pH 4.5) and stir at 50°C (1200 rpm) for 2 h to form a viscous, transparent wall material solution. Slowly add the GO / poloxamer composite micelle dispersion prepared in step 1 to the wall material solution and perform ultrasonic cell disruption (power 800 W, pulse mode 5 s on / 2 s off) for 20 min. 3. Add florfenicol API and continue stirring (800 rpm) for 1 hour. After high-pressure homogenization (pressure 50 MPa, temperature 30-40°C, 3 cycles) to evenly disperse the drug, atomize through a dual-fluid nozzle (compressed air pressure 0.25 MPa, liquid flow rate 8 L / h), and simultaneously start ultrasonic oscillation (amplitude 50 μm). 4. The atomized droplets were spray-freeze-dried (maintained at -40°C for 4 hours, then heated to 25°C for 6 hours, with a vacuum degree of ≤10 Pa) to obtain microcapsule powder. The microcapsule powder was placed in a supercritical CO2 extraction kettle, and Tween 80 (0.1% by weight of the microcapsule powder) was injected as an entrainer. Dynamic extraction was performed for 40 minutes (the first 20 minutes, the flow rate was 2.5 L / min, the last 20 minutes, the flow rate was 3 L / min); 5. Mix the extracted microcapsule powder and corn starch in a three-dimensional mixer for 30 minutes, and pass through a 100-mesh sieve to obtain the product.

[0035] Test Example 1 1. Test materials The products prepared in Example 1 and Comparative Example 1.

[0036] 2. Test methods Florfenicol residue: unencapsulated free florfenicol in the final product, HPLC method (C18 column, acetonitrile-water = 60:40, 267 nm); Dissolution T50 (pH 6.8): USP II method (pH 6.8 phosphate buffer, 50 rpm).

[0037] 3. Test results Table 1 Drug residue and dissolution T50 As shown in Table 1, the product prepared in Example 1 has 98% less florfenicol residue than that in Comparative Example 1, and the dissolution T50 decreases by 47% from 16.5 min to 8.7 min.

[0038] It can be seen from this that the product of the present invention can significantly reduce the residual florfenicol and improve the dissolution rate of the drug.

[0039] Test Example 2 1. Test materials The products prepared in Example 2 and Comparative Example 2.

[0040] 2. Test methods Entrapment efficiency: Free drug was separated by ultracentrifugation (20,000 rpm, 30 min), and the entrapment efficiency was determined by HPLC.

[0041] Residues: The unencapsulated florfenicol and chloramphenicol analogue residues in the final product were detected by HPLC (detection limit 0.01 ppm).

[0042] 3.Test results.

[0043] Table 2 Encapsulation efficiency and drug residues As shown in Table 2, the encapsulation efficiency of the florfenicol drug of the present invention is increased by 15.4% compared with the comparative example, the florfenicol residue is reduced by 67%, and no chloramphenicol-like residues are detected in the drug of the present invention.

[0044] It can be seen that in the process of the present invention, the addition of GO and poloxamer in the wall material can significantly improve the encapsulation efficiency and reduce the residues of the drug florfenicol and chloramphenicol analogs.

[0045] Test Example 3 1. Test materials The product prepared in Example 3 and Comparative Example 3, and a certain brand of florfenicol powder on the market.

[0046] 2. Test methods Residue detection: HPLC method was used to determine the residues of florfenicol and chloramphenicol analogs (detection limit 0.01 ppm).

[0047] Impurity removal rate: GC-MS analysis of fat-soluble impurities (fatty acid esters) and small molecule metabolites (molecular weight <500Da).

[0048] Animal experiment: Beagle dogs (weight 10-12kg, n=6), single administration of 20mg / kg, detection of 72h blood concentration.

[0049] 3.Test results.

[0050] Table 3 Comparison of residue control, impurity removal efficiency and liver residue As shown in Table 3, compared with Comparative Example 3, the present invention reduced florfenicol residue by 85.7%, completely removed chloramphenicol analog residues, showed no difference in the clearance rate of fat-soluble impurities (fatty acid esters), increased the clearance rate of small molecule metabolites (<500 Da) by 63%, increased the clearance rate of charged polar impurities by 89%, and reduced liver residue by 77%. Compared with commercially available products, florfenicol residue was reduced by 96%, and liver residue was reduced by 93%.

[0051] This shows that only supercritical CO2 can effectively remove fat-soluble impurities, but is less effective at removing small molecules and polar impurities. At the same time, compared with commercially available products, the product of the present invention can significantly reduce drug residues in the body and reduce liver toxicity.

Claims

1. A low-residue florfenicol powder, characterized in that: The invention is mainly prepared from the following raw materials in the following weight ratios: 10-30 kg of florfenicol, 3-9 kg of chitosan, 1-3 kg of sodium alginate, 0.032-0.096 kg of graphene oxide, 0.4-1.2 kg of poloxamer 407, 50-90 kg of acetate buffer and 50-90 kg of auxiliary materials.

2. The low-residue florfenicol powder according to claim 1, wherein The pH of the acetate buffer is 4-5.

3. The low-residue florfenicol powder according to claim 1, wherein The auxiliary material is any one of corn starch and pregelatinized starch.

4. The method for preparing the low-residue florfenicol powder according to any one of claims 1 to 3, characterized in that: The steps include: 1) Graphene oxide (GO) was dispersed in a portion of acetic acid buffer to form a uniform dispersion; poloxamer 407 was added, heated and stirred until completely dissolved, and then subjected to high pressure homogenization to form a GO / poloxamer composite micelle dispersion; 2) Chitosan and sodium alginate were added to the remaining acetate buffer and stirred to form a viscous and transparent wall material solution; the GO / poloxamer micelle dispersion prepared in step 1) was added and the cells were disrupted by ultrasonic treatment; 3) Add florfenicol, continue stirring, homogenize under high pressure, atomize through a dual-fluid nozzle, and simultaneously start ultrasonic vibration; 4) The atomized droplets are spray-freeze-dried to obtain microcapsule powder, which is then placed into a supercritical CO2 extraction kettle, where 0.1-0.2% Tween 80 by weight of the microcapsule powder is injected as an entrainer for dynamic extraction; 5) After extraction, the material is separated by reverse osmosis membrane to remove small molecule metabolites with a molecular weight cut-off below 500Da; 6) pH gradient ion exchange: The permeate is washed with D301 resin column, first with hydrochloric acid at pH = 2.5-3.5, then eluted with 0.03-0.06M phosphate buffer, and the eluate is concentrated and dried; 7) Mix the dried microcapsule powder with the auxiliary materials and sieve to obtain the product.

5. The method for preparing low-residue florfenicol powder according to claim 4, wherein In step 1), graphene oxide is added to an acetic acid buffer solution, magnetically stirred at 600-1000 rpm for 20-50 minutes, and ultrasonically treated at 30-50 kHz and a power of 200-400 W for 30-90 minutes to form a uniform dispersion; poloxamer 407 is added, heated in a water bath at 50-70°C with stirring until completely dissolved, and then high-pressure homogenized at a pressure of 100±10 MPa.

6. The method for preparing low-residue florfenicol powder according to claim 4, wherein In step 2), the mixture is stirred at a constant temperature of 40-60° C. and 1000-1400 rpm for 1-3 hours to form a viscous and transparent wall material solution; ultrasonic cell disruption treatment is performed for 15-30 minutes at a power of 700-900 W and a pulse mode of 5-6 seconds on / 2-3 seconds off.

7. The method for preparing low-residue florfenicol powder according to claim 4, wherein In step 3), high-pressure homogenization is performed at a pressure of 50±10 MPa; during the dual-fluid nozzle atomization, the compressed air pressure is 0.2-0.3 MPa, and the liquid flow rate is 6-10 L / h.

8. The method for preparing low-residue florfenicol powder according to claim 4, wherein In step 4), dynamic extraction is performed for 30-50 min; the flow rate is 2-3 L / min during the first half of the extraction, and the flow rate is 3-4 L / min during the second half of the extraction.

9. The method for preparing low-residue florfenicol powder according to claim 4, wherein In step 4), the spray freeze drying conditions are: maintaining at -40±5°C for 3-5 hours, heating to 25±5°C for 5-7 hours, and vacuum degree ≤10Pa.

10. The method for preparing low-residue florfenicol powder according to claim 4, wherein In step 7), the eluted microcapsule powder is mixed with the excipients in a three-dimensional mixer for 15-45 minutes, and passed through an 80-120 mesh sieve to obtain the product.

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