Novel long-acting slow-release fluralan solution as well as preparation method and application thereof

Abstract

The invention discloses a novel long-acting slow-release type fluralan solution as well as a preparation method and application of the novel long-acting slow-release type fluralan solution. The solution comprises the following components: 8-12% of fluralan and 55-70% of a composite slow-release carrier, and the composite slow-release carrier comprises chitosan subjected to denaturation treatment, polycaprolactone and pentaerythritol bis [bis (2-ethylhexyl) phosphate]. The preparation method comprises the steps of raw material pretreatment, microfluidic mixing, post-treatment and preparation. According to the invention, a long-acting slow-release system with uniform structure and stable performance is constructed by synergistically compounding the modified chitosan, the polycaprolactone and the pentaerythritol bis [bis (2-ethylhexyl) phosphate] in combination with a micro-fluidic precision process. According to the system, the release stability and the action durability of the medicine are remarkably improved, the burst release problem of a conventional preparation is effectively avoided, and long-acting protection of single administration is realized. Meanwhile, the product is excellent in storage stability, application tests show that the composition has a thorough control effect on red mites of laying hens, the administration frequency can be reduced, and the medication economy is effectively improved.

Description

Technical Field

[0001] This invention relates to the field of veterinary drug technology, and more specifically, to a novel long-acting sustained-release fluranar solution, its preparation method, and its application. Background Technology

[0002] With the rapid development of livestock and poultry farming towards intensification and large-scale operations, the prevention and control of parasitic diseases has become a key aspect of ensuring animal health and improving farming efficiency. Flurana, a broad-spectrum and highly effective isoxazoline antiparasitic drug, is widely used in the livestock industry due to its excellent killing activity against various internal and external parasites (such as mites, ticks, lice, and some nematodes).

[0003] Currently available commercially available fluranal solutions mostly use conventional formulations, and their drug release often exhibits a "burst release" pattern, meaning a large amount is released in a short period of time, making it difficult to maintain a long-term effective therapeutic concentration in the body. For example, when treating ectoparasites in sheep, conventional solutions usually need to be repeated every 7-10 days to maintain effective protection. This not only significantly increases the cost and labor intensity for farmers, but frequent dosing may also cause stress in animals and affect growth performance. Related studies have also confirmed this limitation. For example, the Chinese literature "Advances in the Application of Fluranal in the Control of Animal Parasitic Diseases" (Chinese Journal of Veterinary Drugs, September 2022, Vol. 56, No. 9) points out that when using fluranal to treat mites in laying hens, a regimen of two doses every 7 days is required to achieve good results, indicating that existing formulations cannot achieve long-term protection with a single dose.

[0004] Meanwhile, the chemical structure of fluranarin is quite sensitive to environmental factors such as light and temperature. Under actual storage conditions in farms, especially during hot seasons, the active ingredients in conventional formulations are prone to degradation. Data shows that after one month of storage at temperatures above 35°C, the content of the active ingredient in some products may decrease by 15% to 20%. This instability not only leads to drug waste but may also result in insufficient actual dosage, thus affecting the deworming effect.

[0005] From a formulation technology perspective, traditional fluranarine solution formulations typically rely on simple solubilizers and surfactant systems, lacking advanced sustained-release design and stability protection mechanisms. While such formulations can achieve basic drug delivery, they are significantly deficient in terms of long-acting sustained release and improved stability.

[0006] Therefore, there is an urgent need in this field to develop a novel fluranarine formulation that can achieve long-lasting sustained release and improved stability in order to enhance the parasite control effect, reduce drug costs, and promote the sustainable development of the aquaculture industry. Summary of the Invention

[0007] Therefore, it is necessary to address the above-mentioned technical problems by providing a novel long-acting sustained-release fluranar solution, its preparation method, and its application.

[0008] To address the aforementioned technical problems, the first aspect of this invention provides a long-acting sustained-release fluranarine solution, which, by mass percentage, comprises the following components: Freranal 8~12%, Composite sustained-release carrier 55-70%, The composite sustained-release carrier comprises denatured chitosan, polycaprolactone, and pentaerythritol bis[di(2-ethylhexyl)phosphate].

[0009] Furthermore, based on the total mass of the solution, the mass percentages of the modified chitosan, polycaprolactone, and pentaerythritol bis[di(2-ethylhexyl)phosphate] are (45~50)%, (5~10)%, and (5~10)%, respectively.

[0010] Furthermore, the particle size of the modified chitosan is less than 20 μm, and the particle size of the fluranar is 1~5 μm.

[0011] Furthermore, the polycaprolactone has a weight-average molecular weight of 10,000 to 50,000 Da.

[0012] Furthermore, it also contains 10-15% by weight of a surfactant, wherein the surfactant is polysorbate 80.

[0013] Furthermore, it also contains 0.05-0.15% by weight of an antioxidant, 0.05-0.15% by weight of a pH buffer, and 3-8% by weight of glucose; the antioxidant is tert-butylhydroquinone, and the pH buffer is a mixture of citric acid and sodium citrate.

[0014] A second aspect of this invention provides a method for preparing the above-mentioned long-acting sustained-release fluranar solution, comprising the following steps: S1. Raw material pretreatment: Grind the flurana technical grade to a particle size of 1~5μm; dry and pulverize the modified chitosan; cut the polycaprolactone after vacuum heating treatment; dissolve pentaerythritol bis[di(2-ethylhexyl) phosphate] in anhydrous ethanol to prepare a stock solution; S2. Microfluidic Mixing: The pretreated fluranar, modified chitosan, polycaprolactone, pentaerythritol bis[di(2-ethylhexyl)phosphate] stock solution, and surfactant are dissolved or dispersed in organic solvents respectively, and then mixed through a microfluidic chip. The microchannel width of the microfluidic chip is 50~100μm and the depth is 30~50μm. The flow rate of each solution is controlled so that it is injected into the microchannel at a specific flow rate to form a homogeneous emulsion. The Reynolds number in the microchannel is controlled between 1 and 10. S3. Post-processing and preparation: Remove the organic solvent from the emulsion obtained in S2, add deionized water, adjust the pH value to 6.8~7.2, and fill into bottles to obtain the final product.

[0015] Furthermore, in step S2, the organic solvent is propylene glycol; in step S3, the organic solvent is removed by rotary evaporation at a temperature of 40-50°C and a vacuum of -0.08 to -0.09 MPa.

[0016] The third aspect of this invention proposes the application of the above-mentioned long-acting sustained-release fluranarine solution in the preparation of a drug for the prevention and treatment of red mites in laying hens by single-drinking administration.

[0017] Furthermore, the dosage for a single oral administration via drinking water is 8-12 mg / kg body weight, calculated as fluranarine.

[0018] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a novel long-acting sustained-release fluranarine solution, its preparation method, and its applications. By employing a synergistic composite carrier design of modified chitosan, polycaprolactone, and pentaerythritol bis[di(2-ethylhexyl)phosphate], combined with microfluidic precision mixing technology, a structurally homogeneous and stable long-acting sustained-release system was successfully constructed. The system provided by this invention significantly improves the release stability and duration of action of fluranarine, with a significantly prolonged in vitro release time, effectively avoiding the burst release problem of conventional formulations and achieving long-term protection with a single dose. Simultaneously, the composite system of this invention significantly improves the storage stability of the product through multiple stabilization mechanisms. In accelerated testing, the retention rate of the active ingredient far exceeds that of conventional products, avoiding efficacy decline due to storage degradation. Furthermore, the process of this invention effectively ensures the consistency of product quality. Application tests show that it has a thorough and long-lasting effect on the control of red mites in laying hens, avoiding the operational costs and animal stress of frequent dosing, and improving the economy of medication while ensuring efficacy. Detailed Implementation

[0019] To enable those skilled in the art to better understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0020] Specifications and pretreatment of key raw materials in embodiments of the present invention 1. Fluoranal technical grade: High-quality fluoranal technical grade with a purity of not less than 99.95% is selected to ensure the high efficacy of the active pharmaceutical ingredient. Before use, the technical grade needs to be finely ground (air jet milling or ball milling) to control its final particle size within the range of 1~5μm.

[0021] 2. Preparation of modified chitosan micropowder S1. Loading: Add 50g of chitosan powder, 200g of agate balls with a diameter of 5mm (ball-to-powder mass ratio of 4:1) and 50mL of anhydrous ethanol (grinding aid) to the ball mill jar.

[0022] S2. Grinding: Set the ball mill speed to 300 r / min, and use intermittent mode (grind for 30 min, pause for 10 min), for a total of 2 hours.

[0023] S3. Separation: After grinding, wash with anhydrous ethanol, collect the suspension, centrifuge at 3000 r / min for 10 minutes, separate the solid and dry to obtain chitosan micro powder with a particle size of <20 μm, for later use.

[0024] 3. Preparation of synthetic polycaprolactone (PCL) (ring-opening polymerization method) S1. Feeding: In a dry reaction flask, add ε-caprolactone monomer, stannous octoate catalyst (Sn(Oct)2), and anhydrous toluene solvent. As an example, a typical feeding ratio is: 10g ε-caprolactone monomer, corresponding to 0.05g (i.e., 0.5% of the monomer mass) stannous octoate, and 1L anhydrous toluene.

[0025] S2. Polymerization: Under nitrogen protection, the reaction is carried out in an oil bath at 130~140℃ with stirring for 12~24 hours.

[0026] S3. Purification and Molecular Weight Control: After the reaction is complete, the product is dissolved in dichloromethane and slowly added dropwise to ice-cold diethyl ether to precipitate (e.g., 1 L of dichloromethane corresponds to 10 L of ice-cold diethyl ether). The white solid is collected by filtration and dried under vacuum to obtain polycaprolactone.

[0027] By precisely adjusting the initial molar ratio of ε-caprolactone monomer to the initiator stannous octoate, polycaprolactone with a specific molecular weight can be synthesized. To achieve the desired sustained-release backbone performance, this invention requires that the weight-average molecular weight (Mw) of the polycaprolactone used be controlled within the range of 10,000 to 50,000 Da. In the embodiments of this invention, the weight-average molecular weight of the polycaprolactone used is 15,000 Da.

[0028] 4. Synthesis of pentaerythritol bis[di(2-ethylhexyl)phosphate] S1. Feeding: Add [di(2-ethylhexyl) phosphate] and pentaerythritol to the reactor at a molar ratio of 2:1, and add an appropriate amount of p-toluenesulfonic acid catalyst.

[0029] S2. Reaction: Under nitrogen protection, heat to 120~130℃ and stir for 6~8 hours.

[0030] S3. Purification: After the reaction is complete, remove unreacted substances and byproducts by vacuum distillation to obtain a pale yellow transparent liquid product for later use.

[0031] Example 1 This embodiment provides a novel long-acting sustained-release fluranarine solution, the formulation of which is shown in Table 1 below by mass.

[0032] Table 1: Formulation Table for Example 1 Raw material name Dosage (g) Freranar 10 Denatured chitosan 50 Synthetic polycaprolactone 10 Pentaerythritol bis[di(2-ethylhexyl)phosphate] 5 Citric acid + sodium citrate 0.1 glucose 5 Polysorbate 80 15 Deionized water 4.8 tert-butylhydroquinone 0.1 total 100 Its preparation method includes the following steps: S1. Raw material pretreatment: (1) Grind 10g of fluranal technical material to make its particle size reach about 3μm.

[0033] (2) Place 50g of the modified chitosan at 70°C and dry for 2.5 hours, then crush and pass through an 80-mesh sieve.

[0034] (3) 10g of synthetic polycaprolactone was subjected to vacuum heating treatment, and after cooling, it was cut into small pieces.

[0035] (4) Dissolve 5g pentaerythritol bis[di(2-ethylhexyl) phosphate] in 10ml anhydrous ethanol to prepare a stabilizer stock solution.

[0036] S2, Microfluidic mixing: (1) Dissolve or disperse the pretreated components in step S1, including Freranil, chitosan powder, polycaprolactone blocks, stabilizer stock solution, 15g polysorbate 80, 0.05g citric acid, 0.05g sodium citrate and 0.1g tert-butylhydroquinone, in propylene glycol to form a uniform solution or suspension.

[0037] (2) Inject each of the above solutions into different syringes and install them on the injection pump.

[0038] (3) Start the syringe pump to simultaneously inject each solution into the microchannel of the microfluidic chip at a specific flow rate. The channel width is 50~100μm and the depth is 30~50μm. Under laminar flow conditions, the components are rapidly and uniformly mixed within the microchannel to form a homogeneous emulsion. During the mixing process, the Reynolds number within the microchannel is controlled between 1 and 10. Specifically, in this embodiment, the channel width is approximately 80μm, the depth is approximately 40μm, and the flow rate of each flow path is controlled within the range of 5~50μL / h, resulting in an emulsion with a uniform particle size distribution at the outlet.

[0039] S3. Post-processing and preparation: (1) Transfer the emulsion collected in step S2 to a rotary evaporator and evaporate it at 40~50℃ and vacuum degree -0.08 to -0.09 MPa. The rotation speed is controlled at 30~50 rpm to completely remove organic solvents such as propylene glycol until the solvent residue is less than 0.1%.

[0040] (2) Add 4.8g of deionized water to the evaporated concentrate, stir and mix evenly, and adjust the pH of the system to 6.8~7.2 with citric acid-sodium citrate buffer.

[0041] (3) The content of fluorellana in the prepared solution was determined by high performance liquid chromatography. After the test was qualified, it was dispensed into brown glass bottles by aseptic filling process.

[0042] (4) Immediately seal the bottle mouth with a rubber stopper and tighten it with an aluminum cap to obtain a 10% long-acting sustained-release fluranar solution.

[0043] S4. Storage: Store the packaged product in a cool, dry, and well-ventilated environment, with the storage temperature controlled between 2 and 8°C. Avoid high temperature, high humidity, and direct sunlight.

[0044] Example 2 This embodiment provides a novel long-acting sustained-release fluranar solution, the formulation of which is shown in Table 2 below by mass.

[0045] Table 2: Formulation Table for Example 2 Raw material name Dosage (g) Freranar 8 Denatured chitosan 45 Synthetic polycaprolactone 5 Pentaerythritol bis[di(2-ethylhexyl)phosphate] 10 Citric acid + sodium citrate 0.1 glucose 5 Polysorbate 80 10 Deionized water 16.8 tert-butylhydroquinone 0.1 total 100 Its preparation method includes the following steps: S1. Raw material pretreatment: (1) Grind 8g of fluranal technical material to make its particle size reach about 5μm.

[0046] (2) Place 45g of the modified chitosan at 70°C and dry for 2.5 hours, then crush and pass through an 80-mesh sieve.

[0047] (3) 5g of synthetic polycaprolactone was subjected to vacuum heating treatment, and after cooling, it was cut into small pieces.

[0048] (4) Dissolve 10g pentaerythritol bis[di(2-ethylhexyl) phosphate] in 10ml anhydrous ethanol to prepare a stock solution.

[0049] S2, Microfluidic mixing: Microfluidic mixing was performed according to the method described in Example 1. The raw materials for mixing were the components pretreated in S1 of this Example, as well as 10g (different amounts) of polysorbate 80, 0.05g of citric acid, 0.05g of sodium citrate and 0.1g of tert-butylhydroquinone.

[0050] S3. Post-processing and preparation: (1) Rotary evaporation was performed according to the method described in Example 1 to remove the organic solvent.

[0051] (2) Add 16.8g of deionized water to the evaporated concentrate, stir and mix well, and adjust the pH to 6.8~7.2 with buffer solution.

[0052] (3) The subsequent quality inspection, aseptic filling and sealing steps are the same as in Example 1.

[0053] S4. Storage: The storage conditions are the same as in Example 1.

[0054] Example 3 This embodiment provides a novel long-acting sustained-release fluranarine solution, the formulation of which is shown in Table 3 below by mass.

[0055] Table 3: Formulation Table for Example 3 Raw material name Dosage (g) Freranar 12 Denatured chitosan 47 Synthetic polycaprolactone (PCL) 8 Pentaerythritol bis[di(2-ethylhexyl)phosphate] 8 Citric acid + sodium citrate 0.1 glucose 5 Polysorbate 80 12 Deionized water 7.9 tert-butylhydroquinone 0.1 total 100 Its preparation method includes the following steps: S1. Raw material pretreatment: (1) Grind 12g of fluranal technical material to make its particle size reach about 2μm.

[0056] (2) Place 47g of the denatured chitosan at 70°C and dry for 2.5 hours, then crush and pass through an 80-mesh sieve.

[0057] (3) 8g of synthetic polycaprolactone was subjected to vacuum heating treatment, and after cooling, it was cut into small pieces.

[0058] (4) Dissolve 8g of pentaerythritol bis[di(2-ethylhexyl)phosphate] in an appropriate amount (about 16ml) of anhydrous ethanol to prepare a stock solution.

[0059] S2, Microfluidic mixing: Microfluidic mixing was performed according to the method described in Example 1. The raw materials for mixing were the components pretreated in Example S1, as well as 12g (different amounts) of polysorbate 80, 0.05g of citric acid, 0.05g of sodium citrate, and 0.1g of tert-butylhydroquinone.

[0060] S3. Post-processing and preparation: (1) Rotary evaporation was performed according to the method described in Example 1 to remove the organic solvent.

[0061] (2) Add 7.9g of deionized water to the evaporated concentrate, stir and mix well, and adjust the pH to 6.8~7.2 with buffer solution.

[0062] (3) The subsequent quality inspection, aseptic filling and sealing steps are the same as in Example 1.

[0063] S4. Storage: The storage conditions are the same as in Example 1.

[0064] Comparative Example 1 This comparative example provides a comparative fluranar solution, which differs from Example 1 only in that it does not contain pentaerythritol bis[di(2-ethylhexyl)phosphate], and its corresponding mass fraction is made up by an equal amount of deionized water.

[0065] In this comparative example, modified chitosan and polycaprolactone were used as the composite carrier, without the crosslinking and stabilizing effect of pentaerythritol bis[di(2-ethylhexyl)phosphate]. Except for the substitutions mentioned above, all other components and process parameters in the formulation are completely consistent with those in Example 1 of this invention.

[0066] Comparative Example 2 This comparative example provides a comparative fluranar solution, which differs from Example 1 only in that it does not contain polycaprolactone, and its corresponding mass fraction is made up by an equal amount of deionized water.

[0067] This comparative example uses modified chitosan as a carrier and pentaerythritol phosphate as a crosslinking agent, without the skeletal support of polycaprolactone. Except for the substitutions mentioned above, all other components and process parameters are completely consistent with those in Example 1 of this invention.

[0068] Comparative Example 3 This comparative example provides a comparative fluranar solution, which differs from Example 1 of the present invention only in that ordinary chitosan (undenatured) is used instead of the denatured chitosan in Example 1.

[0069] This comparative example uses common chitosan as a carrier, pentaerythritol phosphate as a crosslinking agent, and PCL as a skeleton reinforcing agent. Except for the substitutions mentioned above, all other components and process parameters are completely consistent with those in Example 1 of this invention.

[0070] Comparative Example 4 This comparative example provides a comparative fluranar solution, which differs from Example 1 only in that conventional mechanical stirring and mixing technology is used instead of microfluidic mixing technology, while the rest of the formulation, raw materials and process parameters are completely consistent with Example 1.

[0071] Specifically, step S2 involves conventional mechanical mixing: (1) All the solid components after the pretreatment in step S1 (including Freranar, modified chitosan powder, polycaprolactone blocks), as well as polysorbate 80, citric acid, sodium citrate and tert-butylhydroquinone, are added to a reaction vessel containing propylene glycol.

[0072] (2) Use a high shear dispersion emulsifier and stir continuously for 30 to 45 minutes at a speed of 5000 r / min.

[0073] (3) Subsequently, the anhydrous ethanol stock solution of pentaerythritol bis[di(2-ethylhexyl)phosphate] was slowly added dropwise to the above mixture. After the addition was complete, stirring was continued for 15 to 20 minutes to finally form a crude emulsion.

[0074] The subsequent S3 post-processing and preparation, and S4 storage steps are the same as in Example 1.

[0075] Verification Example This verification example tested the in vitro release performance of the solutions from Examples 1-3 and Comparative Examples 1-4. The test was conducted to verify the sustained-release effect and synergistic effect of the long-acting sustained-release fluranar solution provided by this invention, and to simultaneously verify its stability under storage conditions.

[0076] 1. In vitro release performance experiment 1.1 Basic Experimental Conditions Release medium: simulating the internal environment of livestock and poultry, using phosphate-buffered saline (PBS) at pH 7.4.

[0077] Experimental parameters: The temperature was kept constant at 37 ± 0.5℃, and the stirring speed was 50 ± 5 r / min to ensure the consistency and repeatability of the experimental conditions.

[0078] Detection method: High performance liquid chromatography (HPLC) was used to sample at preset time points, detect the concentration of fluranar in the release medium, calculate the cumulative release rate, and plot the release curve.

[0079] Release time: The time (in hours) required for the cumulative release rate to reach 80% is used as the sustained-release endpoint to evaluate the long-lasting effect.

[0080] Release stability: Measured by the coefficient of variation (CV, which is the ratio of the standard deviation to the mean of the release rate) of the release curve. The smaller the CV value, the more stable the release.

[0081] 1.2 Experimental Data The in vitro release performance data of Examples 1-3 and Comparative Examples 1-4 of the present invention are summarized in Table 4, and their detailed release kinetic data, i.e., the cumulative release rate at each time point, are shown in Table 5.

[0082] Table 4. Comparison of in vitro release core performance data of each group Group Release time (T80%, h) Release stability (CV value) Example 1 60.2±2.3 7.8±0.9 Example 2 68.5±2.7 6.3±0.7 Example 3 72.1±3.1 5.9±0.6 Comparative Example 1 18.5±1.5 22.6±1.8 Comparative Example 2 24.3±1.9 19.4±1.5 Comparative Example 3 30.7±2.1 16.8±1.3 Comparative Example 4 42.5±2.5 13.2±1.1 Table 5: Cumulative release rate (%, Mean ± SD, n=3) of each group at different time points Time (h) Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 0.5 8.2±0.6 7.5±0.5 7.1±0.4 28.5±1.3 22.3±1.1 20.3±1.1 19.3±1.1 1 10.5±0.7 9.8±0.6 9.2±0.5 36.7±1.5 29.4±1.3 26.4±1.3 23.4±1.3 2 14.3±0.8 13.5±0.7 12.8±0.6 48.2±1.8 38.6±1.5 32.6±1.5 29.8±1.5 4 19.6±1.0 18.7±0.9 17.9±0.8 62.5±2.1 51.3±1.8 45.3±1.8 40.8±1.8 6 24.2±1.1 23.3±1.0 22.5±0.9 71.8±2.3 60.3±2.0 50.3±2.0 45.6±2.0 8 28.5±1.2 27.6±1.1 26.8±1.0 78.3±2.5 67.9±2.2 55.9±2.2 51.4±2.2 12 35.8±1.4 34.9±1.3 34.1±1.2 82.1±2.6 74.3±2.3 62.3±2.3 56.9±2.3 16 42.3±1.5 41.5±1.4 40.7±1.3 (Taiwan has reached 80%) 79.6±2.4 68.98±2.4 61.8±2.4 20 48.5±1.6 47.8±1.5 47.0±1.4 / 83.5±2.5 75.8±2.5 66.8±2.5 24 54.2±1.7 53.5±1.6 52.8±1.5 / (Taiwan has reached 80%) 82.7±2.6 72.9±2.6 36 65.8±1.9 65.1±1.8 64.5±1.7 / / (Taiwan has reached 80%) 81.8±2.7 48 73.6±2.1 72.9±2.0 72.3±1.9 / / / (Taiwan has reached 80%) 60 80.5±2.3 78.3±2.1 77.6±2.0 / / / / 68 (Taiwan has reached 80%) 80.8±2.2 79.5±2.1 / / / / 72 / (Taiwan has reached 80%) 80.3±2.2 / / / / Based on the data in Tables 4 and 5, the in vitro release behavior of Examples 1-3 of the present invention is significantly better than that of Comparative Examples 1-4. The examples of the present invention exhibit excellent sustained-release performance, with the time required to reach a cumulative release rate of 80% significantly extended (60.2-72.1 hours), and the release process is stable with coefficients of variation all below 8%. Specifically, there is no burst release in the initial stage (0.5-2 hours), uniform release in the middle stage (24-48 hours), and stable achievement of the target in the later stage (60-72 hours), meeting the design requirements of long-acting sustained-release formulations. Examples 2 and 3, through further optimization of the carrier ratio and process parameters, further extended the release time and improved the release stability, demonstrating the synergistic optimization effect of the formulation and process.

[0083] Each comparative example showed significant performance deficiencies: Comparative example 1 lacked pentaerythritol bis[di(2-ethylhexyl)phosphate], resulting in insufficient release stability; Comparative example 2 lacked polycaprolactone, leading to large release fluctuations; Comparative example 3 used ordinary chitosan (without denaturation treatment), resulting in rapid drug release and decreased stability; Comparative example 4 used conventional mechanical stirring, leading to a significant decrease in sustained-release performance. The coefficients of variation for all comparative examples were higher than 13%, further verifying the synergistic sustained-release effect of the system of the present invention.

[0084] This invention utilizes a ternary composite carrier composed of modified chitosan, polycaprolactone, and pentaerythritol bis[di(2-ethylhexyl)phosphate] to achieve a synergistic effect of a multi-stage sustained-release mechanism: modified chitosan provides the initial release impetus, polycaprolactone constructs the long-acting sustained-release framework, and pentaerythritol bis[di(2-ethylhexyl)phosphate] optimizes carrier compatibility and enhances drug locking ability through plasticizing, coordination, and dispersing effects. The three components synergistically form a sustained-release system with rapid onset, long duration of action, and stable release, suitable for veterinary formulations requiring long-acting administration, reducing dosing frequency, lowering breeding costs, and avoiding drug residues.

[0085] 2. Storage stability verification experiment 2.1 Experimental Conditions Samples: Samples from Examples 1-3 and Comparative Examples 1-4.

[0086] Storage conditions: Following the relevant guidelines in the Chinese Veterinary Pharmacopoeia, the samples were sealed and packaged, and then subjected to accelerated testing at high temperature (40 ± 2℃).

[0087] Testing time points: Samples were taken and tested on storage day 0 (initial), day 30, day 60, and day 90.

[0088] Test indicators: appearance, pH value, and freranel content (determined by HPLC, expressed as a percentage of the initial content).

[0089] 2.2 Experimental Results The data on the changes in the content of freranil in each sample during the high-temperature accelerated stability test are summarized in Table 6.

[0090] Table 6: Retention rate of fluranarane content in each sample under high temperature accelerated conditions (%, Mean ± SD, n=3) Group 0 days 30 days 60 days 90 days Example 1 100±0.1 98.7±0.3 97.5±0.4 96.8±0.5 Example 2 100±0.2 98.5±0.2 97.3±0.3 96.5±0.4 Example 3 100±0.1 98.6±0.2 97.4±0.3 96.6±0.4 Comparative Example 1 100±0.1 96.2±0.5 92.8±0.6 89.5±0.7 Comparative Example 2 100±0.1 95.8±0.4 91.7±0.5 87.3±0.6 Comparative Example 3 100±0.1 93.1±0.6 88.2±0.7 83±0.8 Comparative Example 4 100±0.1 91.5±0.7 85.6±0.8 79.2±0.9 Table 6 shows that, during the 90-day accelerated stability test at high temperature, the products of Examples 1-3 of this invention all exhibited excellent stability, with the retention rate of fluorellana content consistently exceeding 96%. Example 1, in particular, maintained a retention rate of over 96.8% after 90 days. The stability differences among the examples were minimal (SD ≤ 0.5%), indicating that the products possess good stability and reproducibility under the formulation and process conditions provided by this invention.

[0091] In contrast, the content retention rates of Comparative Examples 1-4 were significantly lower than those of the embodiments of the present invention, and showed a more pronounced decreasing trend with prolonged storage time. For example, the content of Comparative Example 1 was only 89.5% after 90 days, while that of Comparative Example 4 dropped to 79.2%. This indicates that the present invention, through optimizing the excipient composition and employing precision processes such as microfluidics, effectively inhibits the oxidation and hydrolytic degradation of fluoranal under high-temperature conditions, thereby significantly improving the storage stability of the formulation and further verifying the advantages of the present invention in terms of stability.

[0092] Application Example 1 This application example aims to evaluate the efficacy of the product of this invention and commercially available products in preventing and controlling severe red mange in laying hens and their impact on production performance.

[0093] 1. Experimental Design Experimental animals: One hundred 300-day-old Hy-Line Brown laying hens were selected, all naturally infected with red mites, with an average infection count of 15 ± 3 mites / chicken. They were randomly divided into two groups of 50 each.

[0094] Experimental grouping: The participants were divided into an experimental group and a control group. The experimental group consumed the long-acting sustained-release fluranarine solution (10% mass concentration) prepared in Example 1 of this invention, while the control group consumed a commercially available conventional fluranarine solution (10% mass concentration) without a sustained-release carrier.

[0095] Dosing regimen: Single-dose administration via drinking water. Chickens were kept dry for 2 hours prior to administration. The calculated dosage of 10 mg / kg body weight of the active ingredient was dissolved in an appropriate amount of drinking water, ensuring the chickens consumed it within 4 hours. Both the experimental and control groups received this single-dose administration. The control group received a second dose on day 10 following the initial administration, following the same method.

[0096] Efficacy evaluation: On days 1, 3, and 7 after administration, and after a second administration to the control group, 20 chickens were randomly selected from each group to check the number of surviving mites on their body surface and calculate the kill rate.

[0097] 2. Experimental Results The main observation data during the experiment are recorded in Table 7 below.

[0098] Table 7: Application Example 1 (Severe Infection) Trial Results Evaluation indicators Observation time point experimental group control group Mite eradication rate (%) Day 1 after administration 80 80 Day 3 after administration 90 85 Day 7 after administration 98 90 After the second dose (day 10) / 98 Production performance Average egg production rate (%) 90 86 Average egg weight throughout the process (g) 48 45 As shown in Table 7, under severe red mite infestation conditions, the mite eradication rate reached 98% on day 7 after a single administration of the product of Example 1 of this invention via drinking water, and maintained a consistently high eradication effect. In contrast, commercially available products, at the same dosage, only achieved a maximum eradication rate of 90% after a single administration, failing to achieve complete control and requiring a second administration on day 10 to reach a 98% eradication rate. Furthermore, the experimental group using the product of this invention showed superior performance compared to the control group (86%, 45g) in both average egg production rate (90%) and average egg weight (48g), indicating that the product of this invention has no negative impact on laying hen performance and may even have a certain improving effect. This fully demonstrates that the product of this invention has significant advantages in preventing and treating severe infections, including more thorough efficacy, longer-lasting effects, and reduced administration frequency.

[0099] Application Example 2 This application example aims to verify the effectiveness of the product of the present invention in preventing and controlling moderate red mite infection in laying hens.

[0100] Experimental animals: One hundred 300-day-old Lohmann Brown laying hens were selected, all naturally infected with red mites, with an average infection count of 10 ± 2 mites / chicken. They were randomly divided into an experimental group and a control group, with 50 birds in each group.

[0101] Experimental grouping and administration: The experimental group drank the long-acting sustained-release fluranarine solution (10% concentration) prepared in Example 1 of this invention, while the control group drank commercially available conventional fluranarine solution (10% mass concentration) without a sustained-release carrier. The administration regimen was the same as in Example 1, and the experimental results are shown in Table 8 below.

[0102] Table 8: Results of Application Example 2 (Moderate Infection) Trial Evaluation indicators Observation time point experimental group control group Mite eradication rate (%) Day 1 after administration 80 80 Day 3 after administration 90 82 Day 7 after administration 98 86 After the second dose (day 10) / 92 Production performance Average egg production rate (%) 86 82 Average egg weight throughout the process (g) 48 44 As shown in Table 8, under moderate infection conditions, the product of Example 1 of this invention also exhibits excellent single-dose prevention and control capabilities, while commercially available products still cannot eradicate infection with a single dose and require secondary intervention.

[0103] Application Example 3 This embodiment aims to verify the rapid elimination and sustained protection effect of the product of the present invention on mild red mite infestation.

[0104] Experimental animals: One hundred Hy-Line Brown chickens aged 280 days were selected, all naturally infected with red mites, with an average infection count of 5 ± 2 mites / chicken. They were randomly divided into an experimental group and a control group, with 50 chickens in each group.

[0105] Experimental grouping and administration: The experimental group drank the long-acting sustained-release fluranarane solution (10% mass concentration) prepared in Example 1 of this invention, while the control group drank commercially available conventional fluranarane solution (10% mass concentration) without a sustained-release carrier. The administration regimen was the same as in Application Example 1, and the experimental results are shown in Table 9 below.

[0106] Table 9: Application Example 3 (Mild Infection) Trial Results Evaluation indicators Observation time point experimental group control group Mite eradication rate (%) Day 1 after administration 85 85 Day 3 after administration 90 88 Day 7 after administration 99 90 After the second dose (day 10) / 96 Production performance Average egg production rate (%) 92 88 Average egg weight throughout the process (g) 49 43 Table 9 shows that, under mild infection conditions, the mite-killing rate of the product of this invention reached 99% on day 7 after a single administration, which is higher than the 90% of commercially available products at the same time. Furthermore, the production performance indicators of the experimental group were also superior to those of the control group. This further demonstrates that the product of this invention maintains excellent rapid and sustained efficacy in a mild infection model and has no negative impact on laying hen production.

[0107] Based on the combined results of the three tests with different infection levels, compared with existing commercially available products, the long-acting sustained-release fluranarol solution prepared in Example 1 of this invention has the following outstanding advantages: rapid onset of action and thorough eradication; long-term effective protection can be achieved with only a single dose, reducing the dosing frequency by more than 50%; no negative impact on laying hen production performance, and good safety. These advantages significantly improve the convenience, economy, and animal welfare of medication, fully demonstrating the important value of the formulation of this invention in practical applications.

[0108] Obviously, the embodiments described above are merely some embodiments of this application, not all embodiments, and do not limit the patent scope of this application. This application can be implemented in many different forms; on the contrary, the purpose of providing these embodiments is to make the disclosure of this application more thorough and comprehensive. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing specific embodiments, or make equivalent substitutions for some of the technical features. Any equivalent structures made using the content of this application's specification, directly or indirectly applied to other related technical fields, are similarly within the patent protection scope of this application.

Claims

1. A long-acting sustained-release fluranarine solution, characterized in that, By weight percentage, it contains the following components: Freranal 8~12%, Composite sustained-release carrier 55-70%, The composite sustained-release carrier comprises denatured chitosan, polycaprolactone, and pentaerythritol bis[di(2-ethylhexyl)phosphate].

2. The long-acting sustained-release fluranarine solution according to claim 1, characterized in that, Based on the total mass of the solution, the mass percentages of the modified chitosan, polycaprolactone and pentaerythritol bis[di(2-ethylhexyl)phosphate] are (45~50)%, (5~10)% and (5~10)%, respectively.

3. The long-acting sustained-release fluranarine solution according to claim 2, characterized in that, The modified chitosan has a particle size of less than 20 μm, and the fluranar has a particle size of 1~5 μm.

4. The long-acting sustained-release fluranarine solution according to claim 2, characterized in that, The polycaprolactone has a weight-average molecular weight of 10,000 to 50,000 Da.

5. The long-acting sustained-release fluranarine solution according to claim 1, characterized in that, It also contains 10-15% by weight of a surfactant, wherein the surfactant is polysorbate 80.

6. The long-acting sustained-release fluranarine solution according to claim 1, characterized in that, It also contains 0.05-0.15% by weight of an antioxidant, 0.05-0.15% by weight of a pH buffer, and 3-8% by weight of glucose; the antioxidant is tert-butylhydroquinone, and the pH buffer is a mixture of citric acid and sodium citrate.

7. A method for preparing a long-acting sustained-release fluranar solution as described in any one of claims 1 to 6, characterized in that, Includes the following steps: S1. Raw material pretreatment: Grind the flurana technical grade to a particle size of 1~5μm; dry and pulverize the modified chitosan; cut the polycaprolactone after vacuum heating treatment; dissolve pentaerythritol bis[di(2-ethylhexyl) phosphate] in anhydrous ethanol to prepare a stock solution; S2. Microfluidic Mixing: The pretreated fluranar, modified chitosan, polycaprolactone, pentaerythritol bis[di(2-ethylhexyl)phosphate] stock solution, and surfactant are dissolved or dispersed in organic solvents respectively, and then mixed through a microfluidic chip. The microchannel width of the microfluidic chip is 50~100μm and the depth is 30~50μm. The flow rate of each solution is controlled so that it is injected into the microchannel at a specific flow rate to form a homogeneous emulsion. The Reynolds number in the microchannel is controlled between 1 and 10. S3. Post-processing and preparation: Remove the organic solvent from the emulsion obtained in S2, add deionized water, adjust the pH value to 6.8~7.2, and fill into bottles to obtain the final product.

8. The method according to claim 7, characterized in that, In step S2, the organic solvent is propylene glycol; in step S3, the organic solvent is removed by rotary evaporation at a temperature of 40-50°C and a vacuum of -0.08 to -0.09 MPa.

9. The use of a long-acting sustained-release fluranarine solution as described in any one of claims 1 to 6 in the preparation of a drug for the prevention and treatment of red mites in laying hens by single-drinking administration.

10. The application according to claim 9, characterized in that, The dosage for a single oral administration via drinking water is 8-12 mg / kg body weight, calculated as fluranarine.