Soluble florfenicol powder and preparation method thereof

Abstract

The invention relates to soluble florfenicol powder and a preparation method thereof, and aims to improve the solubility and bioavailability of florfenicol. The method comprises the following steps: dissolving florfenicol powder in deionized water, and sequentially adding an emulsifier and a surfactant to form a stable emulsion; dissolving the pretreated chitosan in an acetic acid solution, and adding an antioxidant; and adding the florfenicol emulsion into the chitosan solution to form a microcapsule suspension, then adding a curing agent to carry out a cross-linking reaction, and finally carrying out freeze drying to obtain the soluble florfenicol powder. According to the method, the solubility and the bioavailability of florfenicol are remarkably improved, the stability and the oxidation resistance of the medicine are enhanced, the medicine release is controlled through a microcapsule technology, and the method has an important application prospect.

Description

Technical Field

[0001] The invention relates to the technical field of florfenicol powder, in particular to soluble florfenicol powder and a preparation method thereof. Background Art

[0002] Florfenicol is a broad-spectrum antibiotic widely used in the veterinary field for the treatment and prevention of bacterial infections in livestock and aquaculture. With the widespread application of florfenicol in agriculture and aquaculture, its formulation forms and preparation processes are also constantly evolving. At present, the formulation forms of florfenicol mainly include injections, oral solutions, powders and premixes. These preparations have their own advantages and disadvantages in terms of therapeutic effects, but they generally have a common problem, that is, the solubility of florfenicol in water is low, resulting in limited bioavailability.

[0003] In order to solve this problem, researchers are constantly exploring various methods to improve the solubility of florfenicol. Among them, nanotechnology, micronization technology, solid dispersion technology, self-emulsifying drug delivery system (SEDDS), etc. have been widely studied and applied. These technologies have improved the solubility and bioavailability of florfenicol to varying degrees, but there are still some limitations. For example, although nanotechnology and micronization technology can significantly increase the specific surface area of ​​the drug and thus improve solubility, their processes are complex and costly; while solid dispersion and SEDDS technologies improve drug solubility, there are also challenges in stability and production process control.

[0004] Although the above-mentioned technologies have made certain progress in improving the solubility and bioavailability of florfenicol, the existing technologies still have some shortcomings, especially the improvement effect in solubility and bioavailability is not significant and stable enough. First of all, while traditional formulation forms and processes improve drug solubility, they are often accompanied by the problem of reduced drug stability. For example, although nano- and micron-sized technologies can improve solubility by reducing particle size, nano- and micron-sized particles have high surface energy and are prone to aggregation and agglomeration, resulting in unstable solubility and bioavailability improvement effects.

[0005] Secondly, although solid dispersion and SEDDS technologies have performed well in improving the solubility of florfenicol, their preparation process is complex, the production cost is high, and the components are prone to separation and degradation during long-term storage, affecting the effectiveness and stability of the drug. In addition, these technologies also require strict control of process parameters such as temperature, humidity, selection and dosage of emulsifiers and co-solvents, otherwise it is difficult to ensure product consistency and quality stability.

[0006] In contrast, microencapsulation technology, as an emerging drug delivery system, can not only effectively improve the solubility and bioavailability of drugs by encapsulating drugs in soluble materials to form microcapsules, but also protect drugs from the influence of the external environment to a certain extent, prolong the shelf life of drugs, and improve their taste and compliance with taking. Therefore, the use of microencapsulation technology to prepare soluble florfenicol powder has significant advantages and potential application prospects. By encapsulating florfenicol in soluble materials to form microcapsules, it can not only improve its water solubility and bioavailability, but also overcome the shortcomings of the existing technology to a certain extent, providing a more stable and effective formulation form. Summary of the invention

[0007] As an emerging drug delivery system, microencapsulation technology can effectively improve the solubility and bioavailability of drugs by encapsulating drugs in soluble materials to form microcapsules, and can also protect drugs from the influence of the external environment to a certain extent, prolong the shelf life of drugs, and improve their taste and compliance. Therefore, the use of microencapsulation technology to prepare soluble florfenicol powder has significant advantages and potential application prospects.

[0008] The present application provides a method for preparing soluble florfenicol powder, comprising the following steps:

[0009] S1. dissolving florfenicol powder in deionized water, and adding emulsifier and surfactant in sequence; S2. dissolving pretreated chitosan in 1wt% acetic acid solution, stirring evenly, and then adding antioxidant to the pretreated chitosan solution, stirring evenly; S3. adding a solubilizer to the florfenicol emulsion in step S1, stirring evenly, so as to further improve the solubility of the drug; S4. adding the florfenicol emulsion in step S3 dropwise to the chitosan solution in step S2, and continuing to stir to form a preliminary microcapsule suspension; S5. adding a curing agent solution dropwise to the microcapsule suspension, performing a cross-linking reaction, so that the chitosan forms a stable capsule shell; S6. freeze-drying the obtained microcapsule suspension to obtain a soluble florfenicol powder.

[0010] By adopting the above technical scheme, first, florfenicol powder is dissolved in deionized water. Since florfenicol itself has poor solubility, a stable emulsion system can be formed by adding emulsifiers and surfactants. Emulsifiers and surfactants increase the compatibility between drug molecules and water molecules by reducing surface tension, and promote the dispersion and dissolution of florfenicol in water. Pretreated chitosan dissolves in acetic acid solution to form a solution, because acetic acid can help open the polymerization chain of pretreated chitosan and increase its solubility in water. The addition of antioxidants is to prevent the oxidation reaction that may occur in florfenicol during subsequent treatment, and to protect the chemical stability of the drug. The solubilizer changes the solvation environment of the drug by forming hydrogen bonds or other weak interactions with drug molecules, thereby improving its solubility in an aqueous environment. The florfenicol emulsion in step S3 is slowly added to the pretreated chitosan solution in step S2, and continuously stirred, and the pretreated chitosan molecules are gradually wrapped in the florfenicol emulsion by electrostatic action or hydrophilic-hydrophobic interaction to form the preliminary structure of microcapsules. Through the cross-linking reaction of sodium tripolyphosphate (STPP), a more stable microcapsule structure is formed, which prolongs the shelf life of the drug and enhances the protective effect of the drug.

[0011] As a preferred technical solution for the preparation of a soluble florfenicol powder, the emulsifier is polysorbate 80 and the surfactant is poloxamer.

[0012] By adopting the above technical solution, polysorbate 80 is mainly responsible for the initial emulsification to form a uniform emulsion, while poloxamer further stabilizes the emulsion and encapsulates the drug molecules through its micellar structure to prevent droplet aggregation. Polysorbate 80 and poloxamer work together to significantly reduce the surface tension of the interface between the aqueous phase and the oil phase, forming a more stable emulsion, thereby improving the solubility and bioavailability of florfenicol powder.

[0013] As a preferred technical solution for the preparation of a soluble florfenicol powder, the emulsifier accounts for 0.1 to 5 wt % of the weight of florfenicol, and the surfactant accounts for 0.5 to 10 wt % of the weight of florfenicol.

[0014] By adopting the above technical solution, the addition amount of emulsifier and surfactant is optimized, and the solubility and bioavailability of florfenicol powder are improved.

[0015] As a preferred technical solution for the preparation of a soluble florfenicol powder, the antioxidant is vitamin E and the solubilizer is polyethylene glycol.

[0016] By adopting the above technical solution, vitamin E, as an antioxidant, can capture and neutralize free radicals generated during drug preparation and storage, preventing drug molecules from being oxidized and degraded. PEG provides a hydrophilic environment in this process, enhancing the dispersibility of vitamin E, making it more effective in capturing free radicals, thereby enhancing the antioxidant properties and bioavailability of florfenicol powder.

[0017] As a preferred technical solution for the preparation of a soluble florfenicol powder, the antioxidant accounts for 1 wt% of the weight of the pretreated chitosan, and the solubilizer accounts for 0.5 to 10 wt% of the weight of the florfenicol.

[0018] By adopting the above technical solution, the addition amount of antioxidant and solubilizer is optimized, and the antioxidant property and bioavailability of florfenicol powder are improved.

[0019] As a preferred technical solution for the preparation of soluble florfenicol powder, the curing agent is sodium tripolyphosphate, and the curing agent is 0.1 to 2 times the weight of the pretreated chitosan.

[0020] By adopting the above technical solution, a more stable microcapsule structure is formed by cross-linking reaction through sodium tripolyphosphate (STPP), thereby extending the shelf life of the drug and enhancing the protective effect of the drug.

[0021] As a preferred technical solution for the preparation of a soluble florfenicol powder, the freeze-drying comprises the following steps:

[0022] The microcapsule suspension was quickly frozen using liquid nitrogen at a temperature of -80°C for 1 hour. The pre-frozen microcapsule suspension was transferred to a freeze dryer. The initial vacuum degree was set to 30 Pa, and the temperature was gradually increased to -40°C and maintained for 4 hours. The temperature was further increased to -20°C and maintained for 8 hours. Finally, the temperature was increased to 0°C and maintained for 6 hours. The temperature was gradually increased to 25°C, and the vacuum degree was maintained below 10 Pa for 12 hours to remove residual moisture.

[0023] By adopting the above technical scheme, the rapid freezing temperature is -80°C and the duration is 1h, which can prevent ice crystals from forming inside and outside the microcapsule and avoid destroying the structure and integrity of the microcapsule. The initial vacuum degree is set to 30Pa. When the temperature gradually rises to -40°C, the frozen water will directly sublimate into water vapor and leave the microcapsule, thereby improving the drying efficiency and maintaining the stability of the drug. Then, by slowly heating to -20°C, the sublimation of the remaining water is promoted, and the water in the microcapsule is effectively removed, thereby avoiding the destruction of the microcapsule structure due to rapid temperature changes. Finally, the temperature is raised to 0°C and maintained for 6 hours to further remove residual water, prevent the collapse of the microcapsule structure, and ensure the integrity of the microcapsule. The temperature is slowly raised to 25°C and maintained for a long time. At a higher temperature and low vacuum degree, the water adsorbed in the microcapsule is removed to ensure the dryness of the microcapsule and stabilize the microcapsule structure.

[0024] As a preferred technical solution for the preparation of a soluble florfenicol powder, the pretreated chitosan comprises the following steps: taking a certain amount of chitosan, dissolving it in a mixed solution of isopropanol and deionized water, heating and stirring until the chitosan is completely dissolved to form a uniform chitosan solution; adding a 10wt% sodium hydroxide solution dropwise to the chitosan solution, maintaining the pH value of the solution at 12, stirring continuously for 1 hour to ensure that the chitosan is completely reacted, and then slowly adding a 20wt% chloroacetic acid solution to the chitosan solution, maintaining the pH value of the solution between 8 and 9, and controlling the addition speed. , stir the reaction vigorously to prevent the reaction for 3-5 hours, control the reaction temperature at 60-70°C, after the reaction is completed, cool the reaction mixture to room temperature, use an acid-base regulator to gradually neutralize the reaction mixture, adjust the pH value to about 7, terminate the reaction, wash the reaction mixture with ethanol and deionized water for multiple times, remove unreacted chloroacetic acid and by-products, use a vacuum filtration device to precipitate carboxymethyl chitosan, place the obtained carboxymethyl chitosan precipitate in a drying oven, set the temperature at 40-50°C, and dry for 24 hours until completely dry to obtain pure carboxymethyl chitosan powder.

[0025] By adopting the above technical solution, isopropanol plays a role in assisting dissolution and stabilizing the solution during the dissolution process, and sodium hydroxide acts as a strong base to react with the amino groups (-NH 2 ) reacts with hydroxyl (-OH) to form ionized amino (-NH 2 + ) and hydroxyl groups (-O-), which improve the reactivity of chitosan. At the same time, the alkaline environment is conducive to the carboxymethylation reaction. Chloroacetic acid (Cl-CH 2 -COOH) will generate sodium chloroacetate (Cl-CH 2-COONa), reacts with amino and hydroxyl groups in chitosan molecules to generate carboxymethyl chitosan by nucleophilic substitution reaction. The pH value is controlled between 8 and 9 to ensure the reaction and avoid degradation of chitosan caused by excessive alkalinity. After cooling the reaction mixture, the remaining alkaline substances in the solution are neutralized by gradually adding an acid-base regulator, and the pH value is adjusted to neutrality to terminate the reaction to prevent product degradation caused by excessive reaction. The residual chloroacetic acid and other by-products in the reaction solution are removed by multiple washings to ensure that pure carboxymethyl chitosan is obtained. Vacuum filtration helps to quickly separate the precipitate and obtain a clean solid product. Low-temperature drying ensures that thermal degradation of the carboxymethyl chitosan will not be caused. Mild drying conditions help to maintain the physical and chemical stability of the product.

[0026] The florfenicol powder prepared by the above preparation method is encapsulated in microcapsules formed by chitosan, the microcapsules are spherical, and the particle size of the microcapsules ranges from 50um to 400um.

[0027] By adopting the above technical solution, the prepared microcapsules are spherical, and the particle size range of the microcapsules is strictly controlled between 50um and 400um during the preparation process, ensuring the uniformity and consistency of the microcapsules, having better fluidity and operability when used, and also helping to control the release rate of the drug.

[0028] The preparation method provided by the present invention significantly improves the solubility and bioavailability of florfenicol; the specific advantages include:

[0029] 1. Improve solubility: By encapsulating florfenicol in microcapsules formed by chitosan and utilizing the synergistic effect of emulsifiers and surfactants, the water solubility of the drug is significantly improved;

[0030] 2. Enhanced stability: The microcapsule structure effectively protects the drug from the influence of the external environment and prolongs the shelf life of the drug;

[0031] 3. Improve bioavailability: Use solubilizers and antioxidants to optimize the drug dissolution environment and stability, significantly improving the absorption efficiency of the drug in the body;

[0032] 4. Controlled drug release: The spherical structure and strictly controlled particle size range of the microcapsules make the drug have better fluidity and operability during use, and also help control the release rate of the drug. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a graph of the particle size of the florfenicol powder prepared in Examples 1 to 4; DETAILED DESCRIPTION

[0034] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0035] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0036] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0037] Preparation Example

[0038] Take a certain amount of chitosan and dissolve it in a mixed solution of isopropanol and deionized water.

[0039] The method comprises the steps of heating and stirring until the chitosan is completely dissolved to form a uniform chitosan solution; adding a prepared 10 wt % sodium hydroxide solution dropwise into the chitosan solution, maintaining the pH value of the solution at 12, continuously stirring for 1 hour to ensure that the chitosan is completely reacted, slowly adding a prepared 20 wt % chloroacetic acid solution into the chitosan solution, maintaining the pH value of the solution at 8-9, controlling the adding speed to prevent a violent reaction, stirring the reaction for 3-5 hours, controlling the reaction temperature at 60-70° C., cooling the reaction mixture to room temperature after the reaction is completed, gradually neutralizing the reaction mixture with ethanol, adjusting the pH value to about 7, terminating the reaction, washing the reaction mixture with ethanol and deionized water for multiple times to remove unreacted chloroacetic acid and byproducts, using a vacuum filtration device to precipitate the carboxymethyl chitosan, placing the obtained carboxymethyl chitosan precipitate in a drying oven, setting the temperature at 40-50° C., drying for 24 hours until it is completely dried, and finally obtaining pure carboxymethyl chitosan powder.

[0040] Example 1

[0041] A method for preparing soluble florfenicol powder comprises the following steps:

[0042] S1. Dissolve florfenicol powder in deionized water, and add polysorbate 80 and poloxamer in turn; wherein polysorbate 80 accounts for 3wt% of the weight of florfenicol and poloxamer accounts for 3wt% of the weight of florfenicol;

[0043] S2. The pretreated chitosan was dissolved in a 1wt% acetic acid solution and stirred, and then vitamin E was added to the pretreated chitosan solution and stirred; wherein vitamin E accounted for 1wt% of the weight of the pretreated chitosan;

[0044] S3. Adding polyethylene glycol to the florfenicol emulsion in step S1 and stirring evenly to further improve the solubility of the drug; wherein the polyethylene glycol accounts for 5wt% of the weight of florfenicol;

[0045] S4. The florfenicol emulsion in step S3 is added dropwise to the chitosan solution in step S2, and stirring is continued to form a preliminary microcapsule suspension;

[0046] S5. A sodium tripolyphosphate solution is added dropwise to the microcapsule suspension to perform a cross-linking reaction to form a stable capsule shell of chitosan; wherein the sodium tripolyphosphate is 1 times the weight of the pretreated chitosan;

[0047] S6. freeze-drying the obtained microcapsule suspension to obtain soluble florfenicol powder; wherein the freeze-drying comprises the following steps:

[0048] The microcapsule suspension was quickly frozen using liquid nitrogen at a temperature of -80°C for 1 hour. The pre-frozen microcapsule suspension was transferred to a freeze dryer. The initial vacuum degree was set to 30 Pa, and the temperature was gradually increased to -40°C and maintained for 4 hours. The temperature was further increased to -20°C and maintained for 8 hours. Finally, the temperature was increased to 0°C and maintained for 6 hours. The temperature was gradually increased to 25°C, and the vacuum degree was maintained below 10 Pa for 12 hours to remove residual moisture.

[0049] Example 2

[0050] A method for preparing soluble florfenicol powder comprises the following steps:

[0051] S1. Dissolve florfenicol powder in deionized water, and add polysorbate 80 and poloxamer in turn; wherein polysorbate 80 accounts for 0.1wt% of the weight of florfenicol and poloxamer accounts for 0.5wt% of the weight of florfenicol;

[0052] S2. The pretreated chitosan was dissolved in a 1wt% acetic acid solution and stirred, and then vitamin E was added to the pretreated chitosan solution and stirred; wherein vitamin E accounted for 1wt% of the weight of the pretreated chitosan;

[0053] S3. Adding polyethylene glycol to the florfenicol emulsion in step S1 and stirring evenly to further improve the solubility of the drug; wherein the polyethylene glycol accounts for 0.5wt% of the weight of florfenicol;

[0054] S4. The florfenicol emulsion in step S3 is added dropwise to the chitosan solution in step S2, and stirring is continued to form a preliminary microcapsule suspension;

[0055] S5. sodium tripolyphosphate solution is added dropwise to the microcapsule suspension to perform a cross-linking reaction to form a stable capsule shell of chitosan; wherein the sodium tripolyphosphate is 0.1 times the weight of the pretreated chitosan;

[0056] S6. freeze-drying the obtained microcapsule suspension to obtain soluble florfenicol powder; wherein the freeze-drying comprises the following steps:

[0057] The microcapsule suspension was quickly frozen using liquid nitrogen at a temperature of -80°C for 1 hour. The pre-frozen microcapsule suspension was transferred to a freeze dryer. The initial vacuum degree was set to 30 Pa, and the temperature was gradually increased to -40°C and maintained for 4 hours. The temperature was further increased to -20°C and maintained for 8 hours. Finally, the temperature was increased to 0°C and maintained for 6 hours. The temperature was gradually increased to 25°C, and the vacuum degree was maintained below 10 Pa for 12 hours to remove residual moisture.

[0058] Example 3

[0059] A method for preparing soluble florfenicol powder comprises the following steps:

[0060] S1. Dissolving florfenicol powder in deionized water, and sequentially adding polysorbate 80 and poloxamer; wherein polysorbate 80 accounts for 5wt% of the weight of florfenicol, and poloxamer accounts for 10wt% of the weight of florfenicol;

[0061] S2. The pretreated chitosan was dissolved in a 1wt% acetic acid solution and stirred, and then vitamin E was added to the pretreated chitosan solution and stirred; wherein vitamin E accounted for 1wt% of the weight of the pretreated chitosan;

[0062] S3. Adding polyethylene glycol to the florfenicol emulsion in step S1 and stirring evenly to further improve the solubility of the drug; wherein the polyethylene glycol accounts for 10wt% of the weight of florfenicol;

[0063] S4. The florfenicol emulsion in step S3 is added dropwise to the chitosan solution in step S2, and stirring is continued to form a preliminary microcapsule suspension;

[0064] S5. A sodium tripolyphosphate solution is added dropwise to the microcapsule suspension to perform a cross-linking reaction to form a stable capsule shell of chitosan; wherein the sodium tripolyphosphate is twice the weight of the pretreated chitosan;

[0065] S6. freeze-drying the obtained microcapsule suspension to obtain soluble florfenicol powder; wherein the freeze-drying comprises the following steps:

[0066] The microcapsule suspension was quickly frozen using liquid nitrogen at a temperature of -80°C for 1 hour. The pre-frozen microcapsule suspension was transferred to a freeze dryer. The initial vacuum degree was set to 30 Pa, and the temperature was gradually increased to -40°C and maintained for 4 hours. The temperature was further increased to -20°C and maintained for 8 hours. Finally, the temperature was increased to 0°C and maintained for 6 hours. The temperature was gradually increased to 25°C, and the vacuum degree was maintained below 10 Pa for 12 hours to remove residual moisture.

[0067] Comparative Example 1

[0068] The difference between this comparative example and Example 1 is that poloxamer is used to replace an equal amount of polysorbate 80 in this comparative example.

[0069] Comparative Example 2

[0070] The difference between this comparative example and Example 1 is that in this comparative example, polysorbate 80 is used to replace an equal amount of poloxamer.

[0071] Comparative Example 3

[0072] The difference between this comparative example and Example 1 is that vitamin E is used to replace an equal amount of polyethylene glycol in this comparative example.

[0073] Comparative Example 4

[0074] The difference between this comparative example and Example 1 is that in this comparative example, polyethylene glycol is used to replace an equal amount of polyethylene glycol vitamin E.

[0075] Comparative Example 5

[0076] The difference between this comparative example and Example 1 is that the chitosan used in this comparative example is not pretreated.

[0077] Performance Testing

[0078] Particle size testing method: Laser particle size analysis

[0079] Laser particle size analysis uses a laser beam to illuminate particles suspended in a liquid medium, and calculates the particle size distribution by measuring the angle and intensity of the scattered light. The following are the detailed steps: disperse the prepared microcapsule powder in an appropriate liquid medium (such as deionized water or ethanol), use an ultrasonic processor to treat the sample to ensure that the sample is evenly dispersed and avoid particle agglomeration, calibrate according to the instrument operation manual, ensure that the laser particle size analyzer is in good working condition, inject the dispersed sample into the sample cell, ensure that there are no bubbles in the sample cell, adjust the sample concentration so that the scattered light intensity is moderate when the laser passes through the sample, start the laser particle size analyzer, and start measuring. The instrument will automatically record the angle and intensity of the scattered light and calculate the particle size distribution. The test results are as follows: Figure 1 shown.

[0080] Solubility test method:

[0081] The samples of the embodiments and comparative examples were added to a known volume of solvent, and the container containing the sample and the solvent was placed in a constant temperature water bath, and the solution was stirred using a magnetic stirrer for generally 24 hours to ensure that the dissolution equilibrium was reached. After reaching equilibrium, the solution was filtered using a filter membrane to remove undissolved drug particles, and the filtrate was injected into an HPLC system, and the drug concentration was detected using an appropriate chromatographic column and mobile phase, and the solubility (mg / mL) = the measured drug concentration (mg / mL). The results are shown in Table 1.

[0082] Table 1

[0083]

[0084] Antioxidant test method: DPPH free radical scavenging method

[0085] Prepare DPPH solution (0.1 mM) in methanol or ethanol, prepare sample solutions of Examples and Comparative Examples of different concentrations, add 2 mL of DPPH solution to a test tube, add 0.1 mL of Example or Comparative Example sample solution to a test tube, mix well, place the mixture in a dark place for 30 minutes, measure the absorbance of the sample at 517 nm using a spectrophotometer, and calculate the scavenging rate of DPPH free radicals using the following formula:

[0086]

[0087] Wherein, Acontrol is the absorbance of the blank control group, and Asample is the absorbance of the sample. The test results are shown in Table 2.

[0088] Table 2

[0089]

[0090]

[0091] Testing methods for single-dose pharmacokinetic studies:

[0092] Select appropriate animal models (such as rats, rabbits) or healthy volunteers, fast for a certain period of time (usually 12 hours) before the experiment, give the subjects a single oral or injection of the drug according to the experimental design, record the administration time and dosage, collect blood samples at predetermined time points (such as 0.5, 1, 2, 4, 6, 8, 12, 24 hours, etc.), collect a certain volume of blood (such as 0.5-1mL) at each time point, centrifuge the collected blood samples, separate the plasma, transfer the separated plasma to a clean test tube, mark the time point, pretreat the plasma sample (such as protein precipitation, liquid-liquid extraction) to remove interfering substances, use the treated sample for analysis, use high performance liquid chromatography (HPLC) or mass spectrometer (MS) to determine the concentration of the drug in the plasma sample, draw the plasma drug concentration-time curve, and calculate the drug's pharmacokinetic parameters, such as C_max (maximum blood drug concentration ng / mL), T_max (time to reach maximum blood drug concentration h), etc. The test results are shown in Table 3.

[0093] Table 3

[0094]

[0095]

[0096] Combining Examples 1 to 4 and Figure 1 It can be seen that the particle size of the florfenicol powder prepared in Examples 1 to 4 ranges from 50 um to 400 um, which ensures the uniformity and consistency of the microcapsules, has better fluidity and operability when used, and also helps to control the release rate of the drug.

[0097] Combining Examples 1 to 4, Comparative Examples 1 and 2 and Table 1, it can be seen that the solubility of the florfenicol powder prepared by the scheme of the present application in Examples 1 to 4 is between 10.6 mg / ml and 11.5 mg / ml. From the comparison between Example 1 and Comparative Examples 1 and 3, it can be seen that polysorbate 80 and poloxamer have a synergistic enhancing effect on the solubility of florfenicol powder.

[0098] Combining Examples 1 to 4, Comparative Examples 3 and 4 and Table 2, it can be seen that the florfenicol powder prepared by the scheme of the present application in Examples 1 to 4 has good antioxidant properties, and the average clearance rate is between 73.44% and 88.80%. From the comparison of Example 1, Comparative Example 3 and Comparative Example 4, it can be seen that vitamin E and polyethylene glycol have a synergistic enhancing effect on the antioxidant properties of florfenicol powder.

[0099] Combining Examples 1 to 4, Comparative Examples 1 to 5 and Table 3, it can be seen that the bioavailability of the florfenicol powder prepared by the scheme of the present application in Examples 1 to 4 is relatively good, with C_max between 22.4 mg / ml and 27.6 mg / ml, and T_max between 1.5h and 2.8; from the comparative examples of Example 1 and Comparative Examples 1 to 5, it can be seen that poloxamer, polysorbate 80, vitamin E, polyethylene glycol and pretreated chitosan all have an effect on the bioavailability of florfenicol powder.

[0100] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention is described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing soluble florfenicol powder, characterized in that: The steps include: S1. Dissolve florfenicol powder in deionized water, and add an emulsifier and a surfactant in sequence; S2. The pretreated chitosan was dissolved in a 1wt% acetic acid solution and stirred, and then an antioxidant was added to the pretreated chitosan solution and stirred; S3. Adding a solubilizer to the florfenicol emulsion in step S1 and stirring evenly to further improve the solubility of the drug; S4. The florfenicol emulsion in step S3 is added dropwise to the chitosan solution in step S2, and stirring is continued to form a preliminary microcapsule suspension; S5. Adding a curing agent solution dropwise to the microcapsule suspension to perform a cross-linking reaction so that chitosan forms a stable capsule shell; S6. freeze-drying the obtained microcapsule suspension to obtain soluble florfenicol powder.

2. The method for preparing soluble florfenicol powder according to claim 1, characterized in that: The emulsifier is polysorbate 80, and the surfactant is poloxamer.

3. The method for preparing the soluble florfenicol powder according to claim 1 or 2, characterized in that: The emulsifier accounts for 0.1 to 5 wt % of the weight of florfenicol, and the surfactant accounts for 0.5 to 10 wt % of the weight of florfenicol.

4. The method for preparing soluble florfenicol powder according to claim 1, characterized in that: The antioxidant is vitamin E, and the solubilizer is polyethylene glycol.

5. The method for preparing the soluble florfenicol powder according to claim 1 or 4, characterized in that: The antioxidant accounts for 1 wt % of the weight of the pretreated chitosan, and the solubilizer accounts for 0.5 to 10 wt % of the weight of florfenicol.

6. The method for preparing soluble florfenicol powder according to claim 1, characterized in that: The curing agent is sodium tripolyphosphate, and the curing agent is 0.1 to 2 times the weight of the pretreated chitosan.

7. The method for preparing soluble florfenicol powder according to claim 1, characterized in that: The freeze drying comprises the following steps: The microcapsule suspension was quickly frozen using liquid nitrogen at a temperature of -80°C for 1 hour. The pre-frozen microcapsule suspension was transferred to a freeze dryer. The initial vacuum degree was set to 30 Pa, and the temperature was gradually increased to -40°C and maintained for 4 hours. The temperature was further increased to -20°C and maintained for 8 hours. Finally, the temperature was increased to 0°C and maintained for 6 hours. The temperature was gradually increased to 25°C, and the vacuum degree was maintained below 10 Pa for 12 hours to remove residual moisture.

8. The method for preparing soluble florfenicol powder according to claim 1, characterized in that: The pretreated chitosan treatment steps include: taking a certain amount of chitosan, dissolving it in a mixed solution of isopropanol and deionized water, heating and stirring until the chitosan is completely dissolved to form a uniform chitosan solution; adding a prepared 10wt% sodium hydroxide solution dropwise to the chitosan solution, maintaining the pH value of the solution at 12, stirring continuously for 1 hour to ensure that the chitosan is completely reacted, and then slowly adding a prepared 20wt% chloroacetic acid solution to the chitosan solution, maintaining the pH value of the solution between 8-9, controlling the addition speed to prevent a violent reaction, and stirring the reaction for 3- 5 hours, controlling the reaction temperature at 60-70°C, after the reaction is completed, cooling the reaction mixture to room temperature, using an acid-base regulator to gradually neutralize the reaction mixture, adjusting the pH value to about 7, terminating the reaction, washing the reaction mixture with ethanol and deionized water for multiple times to remove unreacted chloroacetic acid and by-products, using a vacuum filtration device to precipitate carboxymethyl chitosan, placing the obtained carboxymethyl chitosan precipitate in a drying oven, setting the temperature at 40-50°C, and drying for 24 hours until completely dry, and finally obtaining pure carboxymethyl chitosan powder.

9. Florfenicol powder prepared by the preparation method according to any one of claims 1 to 8, characterized in that: The florfenicol powder is encapsulated in microcapsules formed by chitosan, and the microcapsules are spherical.

10. Florfenicol powder prepared according to the preparation method of claim 9, characterized in that: The particle size of the microcapsules ranges from 50um to 400um.

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