Sodium hyaluronate gel injectable filling material containing polyester microspheres, and preparation method and application thereof

Abstract

The application provides a hyaluronic acid sodium gel injectable filling material containing polyester microspheres and a preparation method and application thereof, and belongs to the technical field of medical biomaterial preparation. The preparation method comprises the following steps: providing polyester microspheres and a gel carrier, mixing the polyester microspheres and the gel carrier, and then performing first homogenization treatment to obtain a pre-homogenized mixture; performing heat treatment on the pre-homogenized mixture to obtain a heat-treated mixture; performing second homogenization treatment on the heat-treated mixture to obtain a re-homogenized mixture; filling the re-homogenized mixture into a pre-filled syringe, and performing terminal sterilization to obtain the final product of the injectable filling material. The method enables the final product to be sterilized at the terminal in a pre-filled open-use form, and ensures that the polyester microspheres are uniformly dispersed and do not aggregate and block before and after sterilization and during storage, so that the production cost is significantly reduced, and industrialization popularization is easy to realize on the premise of ensuring the safety, convenience and uniformity of the product in clinical use.

Description

Technical Field

[0001] This invention relates to the field of medical biomaterial preparation technology, and in particular to an injectable hyaluronic acid gel containing polyester microspheres, its preparation method, and its application. Background Technology

[0002] With the development of tissue engineering and regenerative medicine, new approaches to induced repair based on regenerative medicine are gradually being applied to the field of injectable minimally invasive cosmetic procedures. Unlike traditional hyaluronic acid, which relies on a physically supported filling mechanism, synthetic microsphere fillers, when combined with a carrier, not only provide initial filling and shaping, but also, due to their slow degradation, stimulate the body's own collagen secretion, thus achieving a collagen-based filling effect. These fillers are known as fillers with collagen regeneration capabilities. These fillers typically consist of a specific ratio of solid microspheres and a carrier gel. The microspheres act as the dispersion medium, and the gel as the dispersant. After injection into the subcutaneous layer, the gel provides initial physical filling. As the carrier gel gradually degrades, the solid microspheres stimulate surrounding cells to secrete collagen, causing fibroblasts to deposit on the surface of the microspheres and attracting fibroblasts to generate collagen fibers, ultimately achieving a long-lasting, natural facial filling and skin tightening effect.

[0003] Polyester microspheres are spherical or near-spherical synthetic microsphere fillers prepared from polyester materials through methods such as melt processing, emulsification, solvent-spraying, surface deposition, and grinding. Due to their good biocompatibility and controllable biodegradability, they have been widely used in the field of regenerative medical aesthetic fillers. Currently, approved polyester microsphere-containing filler products mainly come in two forms: one is provided as a lyophilized powder, which needs to be reconstituted into a suspension with sterile water for injection or 0.9% sodium chloride injection before use; the other is a mixture of microspheres and gel, pre-filled for immediate use. The latter is widely accepted by clinicians due to its convenient clinical operation, good sample homogeneity, and safer clinical use. However, currently marketed products are mainly in the first form. This is because polyester microspheres are thermoplastic polymers. Under the high-temperature conditions of terminal heat sterilization, when the temperature exceeds their glass transition temperature or crystallization temperature, molecular chain movement intensifies, the material softens, and the polymer chains at the contact surfaces of adjacent microspheres intertwine and become entangled, forming irreversible adhesion. Sustained high temperatures make polyester microspheres prone to adhesion and aggregation, leading to needle blockage and difficulty in smooth injection. Aseptic manufacturing processes have drawbacks such as high costs and difficulty in large-scale production. Furthermore, the sterility assurance level of aseptic manufacturing processes is relatively low, and regulatory requirements favor terminal sterilization. Therefore, based on the ease with which these products aggregate during terminal sterilization and the high costs and process control risks of aseptic production, these filler materials are usually produced in lyophilized powder form. However, lyophilized powder products require reconstitution before clinical use, which is cumbersome and carries the risk of inhomogeneity in the suspension after manual reconstitution.

[0004] Based on the above technical challenges, developing a method for preparing a low-cost, easily industrialized sodium hyaluronate gel injectable filler containing polyester microspheres is a problem that urgently needs to be solved in current research. Summary of the Invention

[0005] This invention provides an injectable sodium hyaluronate gel containing polyester microspheres, its preparation method, and its application. The preparation method enables the injectable filler product to achieve terminal sterilization in a pre-filled, ready-to-use form, while ensuring that the polyester microspheres remain uniformly dispersed and do not aggregate or clog during sterilization, as well as during storage. This significantly reduces production costs while ensuring the safety, convenience, and uniformity of the product in clinical use, and enables the industrial-scale promotion of the preparation method.

[0006] To achieve the above objectives, in a first aspect, the present invention provides a method for preparing an injectable filler material of sodium hyaluronate gel containing polyester microspheres, comprising: (1) Provide polyester microspheres and gel carrier, mix them and perform a first homogenization treatment to obtain a pre-homogenized mixture; (2) The pre-homogenized mixture is heat-treated to obtain a heat-treated mixture; (3) The heat-treated mixture is subjected to a second homogenization process to obtain a re-homogenized mixture; (4) Fill the homogenized mixture into a pre-filled syringe and sterilize it at the terminal to obtain the finished product of sodium hyaluronate gel injectable filler containing polyester microspheres.

[0007] To address the technical challenge of polyester microspheres easily agglomerating and clogging needles during terminal moist heat sterilization due to their low glass transition temperature, this invention provides a three-step synergistic preparation method of "pre-homogenization-heat treatment-re-homogenization". This allows the injectable filler material to be pre-filled and sealed for terminal moist heat sterilization. The polyester microspheres are uniformly and stably dispersed in the gel carrier, preventing needle clogging. Furthermore, the displacing force is low, making it convenient and safe for clinical use. The production cost is low, the process is simple, and it is easy to scale up for industrial production.

[0008] In the preparation process of this invention, absorbable polymeric porous polyester microspheres and a gel carrier are added together to an injectable filler material system to form a gradient degradation formula. Through high-speed homogenization and heat treatment, the gel carrier fills the micropores of the polyester microspheres and coats the surface of the microspheres. After the gel carrier degrades, the microsphere structure can induce collagen regeneration and form a fibrous network structure, thereby providing support for the skin. Finally, the filling effect can still be maintained after the polyester microspheres slowly degrade, prolonging the maintenance period of the effect after implantation and achieving long-term support of "material disappearance, tissue preservation".

[0009] Further specified, the polyester microspheres are any one of the following: polylactide microspheres (i.e., polylactic acid, PLA), poly-L-lactide microspheres (PLLA), racemic polylactide microspheres (PDLLA), polylactic acid-polyethylene glycol copolymer microspheres (PLA-PEG), polyhydroxyalkanoate microspheres (PHA), polyhydroxyalkanoate-polyethylene glycol copolymer microspheres (PHA-PEG), and lactide-glycolic acid copolymer microspheres (PLGA). Polyester microspheres provide immediate filling and can stimulate the production of autologous collagen for a long time, and are ultimately degraded in vivo. Because polyester microspheres are typically hydrophobic and often have porous or rough microparticle structures with a large specific surface area and pore volume, the gel carrier can be adsorbed onto the surface of the microspheres or enter the pores. This allows the product to degrade first, then the gel, during degradation. This gradient degradation method prolongs the duration of the effect after implantation.

[0010] Further, the polyester microspheres have a particle size of 20-80 μm. Preferably, the particle size of the polyester microspheres is 20-70 μm. More preferably, the proportion of polyester microspheres with a particle size of 20-50 μm is ≥85%. Selecting microspheres with a specific particle size distribution ensures the stability of the filler material product, excellent injection smoothness, and maintenance of the effect after implantation. Furthermore, the specific particle size has excellent biocompatibility, minimizing the possibility of rejection reactions. If the particle size is too large, the polyester microspheres are prone to poor dispersion within the injectable filler system, resulting in uneven formulation and potentially causing needle blockage or excessive pushing force during injection, making injection difficult and affecting the filling effect and aesthetics. If the particle size is too small, rapid stratification and irreversible aggregation can occur, significantly reducing the consistency of the filler volume and batch-to-batch uniformity. Early degradation rates are also accelerated, leading to filling deformation and displacement in the early stages of injection, significantly shortening the filling maintenance time, and failing to achieve the expected shaping and three-dimensional effect.

[0011] The gel carrier is further configured to be a cross-linked sodium hyaluronate gel, or a composite gel of cross-linked sodium hyaluronate gel and free sodium hyaluronate.

[0012] Preferably, the gel carrier is a compound gel of cross-linked sodium hyaluronate gel and free sodium hyaluronate. More preferably, in the above compound gel, the mass ratio of cross-linked sodium hyaluronate gel to free sodium hyaluronate is 1:(0.05-0.3). The filling effect of the gel carrier is immediate, and it will gradually degrade and metabolize naturally in the body. In the compound gel, the cross-linked sodium hyaluronate gel provides a mechanical support framework, and the free sodium hyaluronate can act as a dispersant and lubricant, greatly improving the uniformity of the formulation and providing a certain degree of lubrication to further ensure a smooth injection process and avoid the risk of needle blockage during injection. At the same time, the degradation cycle of the compound gel system can be flexibly controlled by the ratio to achieve a step-by-step action rhythm of "immediate skin rejuvenation + mid-term support + long-term regeneration", which fully matches the needs of medical aesthetic filling scenarios.

[0013] Further, the degree of cross-linking of the aforementioned cross-linked sodium hyaluronate gel is 8-18%; the molecular weight of the aforementioned free sodium hyaluronate is 1W-200W Da. A moderate degree of cross-linking in the sodium hyaluronate gel provides sufficient cohesion to support the contour while retaining a certain degree of deformability and extensibility, preventing a stiff, "mask-like" appearance after injection. Conversely, excessively low cross-linking prevents long-term anchoring of microspheres, leading to premature degradation and a shorter long-term filling effect. Excessively high cross-linking results in a brittle and hard gel texture, directly increasing injection pressure and leading to poor filling results. The combination of a moderately cross-linked sodium hyaluronate gel and a moderately molecular weight free sodium hyaluronate forms a perfect system of "gradient mechanics + gradient function": the cross-linked gel is responsible for long-term shaping and anchoring, suspending the microspheres, while the free sodium hyaluronate provides lubrication and immediate skin beautification, ultimately achieving the medical aesthetic filler effect of "effortless injection, no microsphere sedimentation, natural shaping, and no long-term risks."

[0014] Further configured, the particle size of the gel carrier is 50-1000 μm. Preferably, the particle size of the gel carrier is 100-800 μm. More preferably, the particle size of the gel carrier is 100-600 μm.

[0015] The mixture is further configured such that the content of the polyester microspheres in the mixture is 50-350 mg / mL, and the content of the gel carrier in the mixture is 10-22 mg / mL.

[0016] Preferably, the content of polyester microspheres in the mixture is 100-300 mg / mL, and the content of gel carrier in the mixture is 12-20 mg / mL. The content of polyester microspheres and gel carrier is related to the expected injection depth of the product. The finished product prepared under these process conditions has moderate and stable extrusion force.

[0017] The solvent is further configured to be water for injection, phosphate solution, or physiological saline.

[0018] Further, the heat treatment temperature is set to 60-100°C, and the heat treatment time is set to 10-60 minutes. Preferably, the heat treatment temperature is higher than the glass transition temperature of the polyester microspheres.

[0019] More preferably, the heat treatment temperature is 70-90℃, and the heat treatment time is 20-50 min. During the heat treatment process, the microspheres soften moderately, the internal stress is released, and the rough surface tends to be smooth. At the same time, the viscosity of the cross-linked sodium hyaluronate gel decreases and the fluidity is enhanced. The softened microspheres are fully wetted by the gel system, and the gel molecules penetrate and fill into the porous structure and rough surface of the microspheres, achieving complete encapsulation of the microspheres. The surface roughness of the microspheres is also improved, and the microspheres are fully isolated by the gel, which improves the dispersion of the microspheres and the uniformity of the mixture.

[0020] The conditions for the first and second homogenization processes were further set as follows: revolution speed of 100-400 rpm, rotation ratio of 1.0-3.0, and time of 10-25 min.

[0021] Preferably, the revolution speed is 100-350 rpm and the rotation ratio is 1.0-2.0.

[0022] More preferably, the revolution speed is 200-350 rpm and the rotation ratio is 1.2-1.8.

[0023] More preferably, the revolution speed is 250-350 rpm and the rotation ratio is 1.2-1.5. The micropores of the aforementioned polyester microspheres are relatively small, making it difficult to disperse the gel system into their micropores using conventional processes. A first homogenization treatment initially disperses and mixes the polyester microspheres with the gel carrier, followed by a second homogenization treatment to further disperse the microspheres within the gel. Through these two different stages of high-speed homogenization, a stable formulation is formed where the microspheres are completely and uniformly dispersed in the gel system, ensuring successful injection of the filler material.

[0024] Further settings include terminal sterilization using moist heat sterilization at a temperature of 120-125℃ for 8-15 minutes.

[0025] Preferably, the sterilization temperature is 121°C and the sterilization time is 10-15 minutes. Terminal moist heat sterilization is performed after filling and sealing, providing a higher level of sterility assurance. The injectable filler material prepared by this method is a pre-filled syringe dosage form, in which the rehomogenized mixture is encapsulated within the syringe and used in conjunction with the pre-filled syringe and a disposable sterile injection needle.

[0026] Secondly, this invention provides an injectable hyaluronic acid gel containing polyester microspheres, prepared by the aforementioned method for preparing the injectable hyaluronic acid gel containing polyester microspheres. This injectable filler is a ready-to-use formulation in the form of a pre-filled syringe. The injectable filler of this invention uses a pre-filled syringe, can withstand terminal moist heat sterilization, is ready for clinical use, and features uniform, stable, and non-aggregated microsphere dispersion. It has moderate injection force, excellent injection smoothness, and is less prone to problems such as needle blockage and material spraying during injection. It also meets the requirements of rapid onset and long-lasting effect, good biocompatibility, high safety, and satisfactory mechanical properties. The filling effect is natural, durable, and aesthetically pleasing.

[0027] Thirdly, this invention provides the application of an injectable hyaluronic acid gel containing polyester microspheres in the preparation of medical or cosmetic injectable filler products. This injectable filler is prepared using the aforementioned method for preparing the sodium hyaluronic acid gel containing polyester microspheres. The injectable filler of this invention incorporates absorbable polymeric porous polyester microspheres and a gel carrier into the injection system, forming a gradient degradation formulation. It possesses cell-inducing properties and can stimulate the secretion of autologous collagen, making it suitable for filling and repairing soft tissue defects.

[0028] The present invention provides an injectable filler material containing polyester microspheres, a preparation method thereof, and its application. Addressing the characteristics of polyester microspheres, such as low glass transition temperature and susceptibility to adhesion or aggregation during moist heat sterilization, a three-step synergistic preparation method of "pre-homogenization-heat treatment-re-homogenization" is designed, which has at least the following beneficial effects: (1) The first homogenization treatment achieves coarse dispersion of polyester microspheres and gel carrier. Utilizing the viscoelasticity and shear thinning properties of the gel carrier itself, the microspheres are uniformly suspended in the gel system. The subsequent heat treatment step should be set at a temperature higher than the glass transition temperature of the polyester microspheres. At this temperature, the microspheres soften moderately, the internal stress is released, the rough surface tends to be smooth, and the viscosity of the gel carrier decreases and the fluidity is enhanced. The softened microspheres are fully wetted by the gel system, and the gel molecules penetrate and fill into the porous structure and rough surface of the microspheres, achieving complete encapsulation of the microspheres. The surface roughness of the microspheres is also improved, and the microspheres are fully isolated from each other by the gel. The second homogenization treatment further redisperses the microspheres that may have aggregated during the heat treatment, so that the gel and microspheres reach a more uniform and stable dispersion state. Through the synergistic effect of the above three steps, the polyester microspheres are effectively isolated and encapsulated by the gel layer. During the subsequent terminal moist heat sterilization process, the gel layer encapsulating the surface of the microspheres forms a physical barrier, effectively preventing direct contact and adhesion between the microspheres due to softening at high temperature. This significantly reduces the risk of needle blockage and ensures the smooth injection of the final product.

[0029] (2) The product is superior in form and convenient and safe for clinical use: The finished product obtained by this invention is filled in the form of a pre-filled syringe, which is a ready-to-use product. When used clinically, there is no need to go through the operation steps of reconstitution and mixing before use, which avoids the risk of contamination caused by the reconstitution operation of the lyophilized powder product and the problem of uneven suspension after reconstitution. It is convenient to use and the sample has good uniformity, which meets the usage preferences of clinicians.

[0030] (3) The process is simple and controllable, and easy to industrialize: absorbable polymeric polyester porous microspheres and gel carriers are added together to the injectable filler material system to form a gradient degradation formula. Through high-speed homogenization, heat treatment and other steps, the gel carrier is filled with the micropores and surface of the polyester microspheres. The polyester microspheres can also be uniformly and stably dispersed in the gel carrier without needle blockage. The pushing force is moderate, the production cost is low, the process is simple to operate, and it is easy to scale up the production on an industrial scale. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 The image shows the surface morphology of PHA microspheres in the pre-homogenized mixture of Example 2.

[0033] Figure 2 The image shows the surface morphology of PHA microspheres in the heat-treated mixture of Example 2.

[0034] Figure 3 The extrusion force test curve of the syringe manufactured in Example 1.

[0035] Figure 4 The extrusion force test curve of the syringe manufactured in Example 2.

[0036] Figure 5 The extrusion force test curve of the syringe manufactured in Example 3.

[0037] Figure 6 The extrusion force test curve of the syringe made in Comparative Example 1.

[0038] Figure 7 The extrusion force test curve of the syringe made in Comparative Example 2 is shown.

[0039] Figure 8 The extrusion force test curve of the syringe made in Comparative Example 3 is shown.

[0040] Figure 9 The syringe extrusion force test curve is for the product manufactured in Comparative Example 4. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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 are also within the scope of protection of the present invention.

[0042] The following examples use conventional instruments and equipment in the art. Unless otherwise specified, the experimental materials and reagents used in the following examples are commercially available and conform to conventional specifications in the art. Any techniques or conditions not specifically described in the following examples can be performed according to the techniques or conditions described in the literature in the art or according to the product instructions.

[0043] It should be noted that, in this invention and the following embodiments, unless otherwise specified, concentration, ratio, etc. are all weight concentration, weight ratio, etc., "%" all represent weight percentage, and "parts" all represent weight parts. These are common writing habits used by those skilled in the art, and therefore will not be repeated in this invention.

[0044] As a preferred embodiment, the preparation method of the sodium hyaluronate gel injectable filler containing polyester microspheres of the present invention specifically includes the following steps: (1) The polyester microspheres are mixed with the gel carrier and solvent to form a mixture. Then, the mixture is subjected to a first homogenization treatment at a revolution speed of 100-400 rpm and a rotation ratio of 1.0-3.0 for 10-25 min to obtain a pre-homogenized mixture.

[0045] The aforementioned polyester microspheres are any one of polylactide microspheres (i.e., polylactic acid, PLA), poly-L-lactide microspheres (PLLA), racemic polylactide microspheres (PDLLA), polylactic acid-polyethylene glycol copolymer microspheres (PLA-PEG), polyhydroxyalkanoate microspheres (PHA), polyhydroxyalkanoate-polyethylene glycol copolymer microspheres (PHA-PEG), and lactide-glycolic acid copolymer microspheres (PLGA).

[0046] The particle size of the aforementioned polyester microspheres is 20-80 μm. Preferably, the particle size of the polyester microspheres is 20-70 μm. More preferably, the proportion of polyester microspheres with a particle size of 20-50 μm is ≥85%.

[0047] The gel carrier is a cross-linked sodium hyaluronate gel, or a composite gel of cross-linked sodium hyaluronate gel and free sodium hyaluronate. Preferably, the gel carrier is a composite gel of cross-linked sodium hyaluronate gel and free sodium hyaluronate. In the above composite gel, the mass ratio of cross-linked sodium hyaluronate gel to free sodium hyaluronate is 1:(0.05-0.3).

[0048] The degree of crosslinking of the above-mentioned crosslinked sodium hyaluronate gel is 8-18%. The molecular weight of the above-mentioned free sodium hyaluronate is 1W-200W Da.

[0049] The particle size of the gel carrier is 50-1000 μm. Preferably, the particle size of the gel carrier is 100-800 μm. More preferably, the particle size of the gel carrier is 100-600 μm.

[0050] The content of the polyester microspheres in the mixture is 50-350 mg / mL, and the content of the gel carrier in the mixture is 10-22 mg / mL. Preferably, the content of the polyester microspheres in the mixture is 100-300 mg / mL, and the content of the gel carrier in the mixture is 12-20 mg / mL.

[0051] Preferably, the revolution speed is 100-350 rpm and the rotation ratio is 1.0-2.0. More preferably, the revolution speed is 200-350 rpm and the rotation ratio is 1.2-1.8. More preferably, the revolution speed is 250-350 rpm and the rotation ratio is 1.2-1.5.

[0052] The solvents mentioned above are water for injection, phosphate solution, or physiological saline.

[0053] (2) The pre-homogenized mixture is heat-treated at a temperature of 60-100℃ for 10-60 min to obtain a heat-treated mixture. Preferably, the heat treatment temperature is 70-90℃ and the heat treatment time is 20-50 min.

[0054] (3) The heat-treated mixture is subjected to a second homogenization treatment at a revolution speed of 100-400 rpm and a rotation ratio of 1.0-3.0 for 10-25 min to obtain a re-homogenized mixture.

[0055] Preferably, the revolution speed is 100-350 rpm and the rotation ratio is 1.0-2.0. More preferably, the revolution speed is 200-350 rpm and the rotation ratio is 1.2-1.8. More preferably, the revolution speed is 250-350 rpm and the rotation ratio is 1.2-1.5.

[0056] (4) The homogenized mixture is filled into a pre-filled syringe and then subjected to terminal moist heat sterilization at a temperature of 120-125℃ for 8-15 minutes to obtain the finished product of sodium hyaluronate gel injectable filler containing polyester microspheres.

[0057] Preferably, the sterilization temperature is 121℃ and the sterilization time is 10-15 min.

[0058] It should be noted that polyester microspheres can be prepared by conventional emulsification methods in the art (such as emulsification-solvent evaporation method, membrane emulsification method, etc.), preferably by the emulsification-solvent evaporation method commonly used in the art, wherein the emulsification step can be carried out by high-speed shearing, ultrasonic or homogenization emulsification commonly used in the art.

[0059] As a preferred embodiment, the preparation process of polyester microspheres is as follows: Polyester material is dissolved in an organic solvent—dichloromethane—at a solid-liquid ratio of 5g:100mL to form an oil phase. This oil phase is then added to an aqueous phase containing 0.5-5wt% emulsifier—polyvinyl alcohol. The volume ratio of the oil phase to the aqueous phase is 1:(2-15). High-speed shear emulsification is performed at 10000rpm for 10-15min to form a primary emulsion. The organic solvent is removed at 60-80℃, promoting the solidification of the emulsion into microspheres. The microspheres are then washed with deionized water, sieved, and dried to obtain the polyester microspheres. During the preparation of the aqueous and oil phases, mixing can be carried out according to conventional stirring conditions in the art, preferably mechanical stirring commonly used in the art.

[0060] The aforementioned polyester materials are any one of polylactide (PLA), poly-L-lactide (PLLA), racemic polylactide (PDLLA), polylactic acid-polyethylene glycol copolymer (PLA-PEG), polyhydroxyalkanoate (PHA), polyhydroxyalkanoate-polyethylene glycol copolymer (PHA-PEG), and lactide-glycolic acid copolymer (PLGA). The molecular weight of the polyester materials is 1000-100000 Da.

[0061] As a preferred embodiment, the preparation process of cross-linked sodium hyaluronate gel is as follows: Sodium hyaluronate is added to the cross-linking reaction medium and stirred to disperse evenly, obtaining a sodium hyaluronate cross-linking reaction system mixture; then, the cross-linking reaction is allowed to stand at 2-8℃ for 24-144 hours, followed by shearing, washing, granulation, and sieving to obtain cross-linked sodium hyaluronate gel. The cross-linking reaction medium includes: 0.5-1.5 wt% sodium hydroxide, 5-15 wt% cross-linking agent, and the balance being water for injection. The concentration of sodium hyaluronate in the cross-linking reaction system mixture is 10-30 wt%. The cross-linking agent is selected from any one of 1,4-butanediol diglycidyl ether (BDDE), divinyl sulfone (DVS), or polyethylene glycol diglycidyl ether. The specific operations of shearing, washing, granulation, and sieving can be performed according to conventional operations in the art. Preferably, washing is performed in multiple stages, and the granulation method includes homogenization and / or sieving.

[0062] It should be noted that in the production process, the homogenization process in steps (1) and (3) can be carried out using the same high-shear homogenizer.

[0063] The present invention will be further described in detail below with reference to embodiments. However, it should be understood that the embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0064] Example 1:

[0065] A method for preparing a sodium hyaluronate gel injectable filler containing lactide-glycolic acid copolymer (PLGA) microspheres includes the following steps: (1) PLGA was dissolved in dichloromethane at a solid-liquid ratio of 5g:100mL to form an oil phase. This oil phase was then added to an aqueous phase containing 2.5wt% polyvinyl alcohol. The volume ratio of the oil phase to the aqueous phase was 1:12. The emulsion was formed by high-speed shearing emulsification at 10000rpm for 10min. The organic solvent was removed at 60℃ to promote the solidification of the emulsion into microspheres. The microspheres were then washed with deionized water, sieved, and dried to obtain polyester microspheres with a particle size of 20-50μm and a proportion of ≥85%.

[0066] (2) Sodium hyaluronate is added to the cross-linking reaction medium and stirred to disperse evenly to obtain a sodium hyaluronate cross-linking reaction system mixture; then the cross-linking reaction is allowed to stand at 8℃ for 72h, and then sheared, washed, granulated and sieved to obtain cross-linked sodium hyaluronate gel with a particle size of 100-600μm; then it is compounded with free sodium hyaluronate at a mass ratio of 1:0.08 to obtain the compounded gel as the gel carrier.

[0067] The cross-linking reaction medium includes: 1.0 wt% sodium hydroxide, 5 wt% cross-linking agent - 1,4-butanediol diglycidyl ether (BDDE), the balance being water for injection, and the concentration of sodium hyaluronate in the cross-linking reaction system mixture is 15 wt%.

[0068] (3) The polyester microspheres were mixed with the gel carrier and solvent-water for injection to form a mixture. The content of polyester microspheres in the mixture was 150 mg / mL and the content of gel carrier in the mixture was 18 mg / mL. Then, the mixture was subjected to the first homogenization treatment at a revolution speed of 250 rpm and a rotation ratio of 1.8 for 15 min to obtain a pre-homogenized mixture.

[0069] (4) The pre-homogenized mixture is heat-treated at a temperature of 85°C for 25 minutes to obtain the heat-treated mixture.

[0070] (5) The heat-treated mixture was subjected to a second homogenization treatment at a revolution speed of 250 rpm and a rotation ratio of 1.8 for 15 min to obtain a re-homogenized mixture.

[0071] (6) The homogenized mixture is filled into a 1mL pre-filled syringe and then subjected to terminal moist heat sterilization at a temperature of 121℃ for 12min to obtain the finished product of sodium hyaluronate gel injectable filler containing polyester microspheres.

[0072] Example 2:

[0073] A method for preparing an injectable hyaluronic acid gel containing polyhydroxyalkanoate (PHA) microspheres includes the following steps: (1) PHA was dissolved in dichloromethane at a solid-liquid ratio of 5g:100mL to form an oil phase. This oil phase was then added to an aqueous phase containing 3.5wt% polyvinyl alcohol. The volume ratio of the oil phase to the aqueous phase was 1:10. The emulsion was formed by high-speed shearing emulsification at 10000rpm for 15min. The organic solvent was removed at 80℃ to promote the solidification of the emulsion into microspheres. The microspheres were then washed with deionized water, sieved, and dried to obtain polyester microspheres with a particle size of 20-50μm and a proportion of ≥85%.

[0074] (2) The cross-linked sodium hyaluronate gel and free sodium hyaluronate are compounded at a mass ratio of 1:0.12 to obtain the compounded gel, which is the gel carrier. The rest is the same as (2) in Example 1.

[0075] (3) The polyester microspheres were mixed with the gel carrier and the solvent-water for injection to form a mixture. The content of the polyester microspheres in the mixture was 200 mg / mL and the content of the gel carrier in the mixture was 20 mg / mL. Then, the mixture was subjected to the first homogenization treatment at a revolution speed of 200 rpm and a rotation ratio of 1.2 for 15 min to obtain a pre-homogenized mixture.

[0076] (4) The pre-homogenized mixture is heat-treated at a temperature of 90°C for 25 minutes to obtain the heat-treated mixture.

[0077] (5) The heat-treated mixture was subjected to a second homogenization treatment at a revolution speed of 200 rpm and a rotation ratio of 1.2 for 15 min to obtain a re-homogenized mixture.

[0078] (6) The homogenized mixture is filled into a 1mL pre-filled syringe and then subjected to terminal moist heat sterilization at a temperature of 121℃ for 15min to obtain the finished product of sodium hyaluronate gel injectable filler containing polyester microspheres.

[0079] Example 3:

[0080] A method for preparing an injectable hyaluronic acid gel containing polylactic acid-polyethylene glycol copolymer (PLA-PEG) microspheres includes the following steps: (1) PLA-PEG was dissolved in dichloromethane at a solid-liquid ratio of 5g:100mL to form an oil phase. This oil phase was then added to an aqueous phase containing 4wt% polyvinyl alcohol. The volume ratio of the oil phase to the aqueous phase was 1:8. The emulsion was formed by high-speed shearing emulsification at 10000rpm for 10min. The organic solvent was removed at 60℃ to promote the solidification of the emulsion into microspheres. The microspheres were then washed with deionized water, sieved, and dried to obtain polyester microspheres with a particle size of 20-50μm and a proportion of ≥85%.

[0081] (2) The cross-linked sodium hyaluronate gel and free sodium hyaluronate are compounded at a mass ratio of 1:0.15 to obtain the compounded gel, which is the gel carrier. The rest is the same as (2) in Example 1.

[0082] (3) The polyester microspheres were mixed with the gel carrier and solvent-water for injection to form a mixture. The content of the polyester microspheres in the mixture was 300 mg / mL and the content of the gel carrier in the mixture was 15 mg / mL. Then, the mixture was subjected to the first homogenization treatment at a revolution speed of 300 rpm and a rotation ratio of 1.5 for 12 min to obtain a pre-homogenized mixture.

[0083] (4) The pre-homogenized mixture is heat-treated at a temperature of 70°C for 45 min to obtain the heat-treated mixture.

[0084] (5) The heat-treated mixture was subjected to a second homogenization treatment at a revolution speed of 300 rpm and a rotation ratio of 1.5 for 12 min to obtain a re-homogenized mixture.

[0085] (6) The homogenized mixture is filled into a 1mL pre-filled syringe and then subjected to terminal moist heat sterilization at a temperature of 121℃ for 10min to obtain the finished product of sodium hyaluronate gel injectable filler containing polyester microspheres.

[0086] Comparative Example 1: A method for preparing an injectable hyaluronic acid gel containing polyhydroxyalkanoate (PHA) microspheres, which does not include the heat treatment + second homogenization step, specifically includes the following steps: (1) Same as (1) in Example 2.

[0087] (2) Same as (2) in Example 2.

[0088] (3) Same as (3) in Example 2.

[0089] (4) Fill the pre-homogenized mixture into a 1mL pre-filled syringe, and finally perform terminal moist heat sterilization at a temperature of 121℃ for 15min to obtain the finished product of sodium hyaluronate gel injectable filler containing polyester microspheres.

[0090] Comparative Example 2: A method for preparing a sodium hyaluronate gel injectable filler containing polyhydroxyalkanoate (PHA) microspheres, wherein the first homogenization treatment is omitted, specifically including the following steps: (1) Same as (1) in Example 2.

[0091] (2) Same as (2) in Example 2.

[0092] (3) The polyester microspheres are mixed with the gel carrier and the solvent-water for injection to form a mixture. The content of the polyester microspheres in the mixture is 200 mg / mL and the content of the gel carrier in the mixture is 20 mg / mL. Then, the mixture is mechanically stirred at 200 rpm for 15 min to obtain a premix.

[0093] (4) The premixed mixture is heat-treated at a temperature of 90°C for 25 minutes to obtain the heat-treated mixture.

[0094] (5) The heat-treated mixture was subjected to a second homogenization treatment at a revolution speed of 200 rpm and a rotation ratio of 1.2 for 15 min to obtain a homogenized mixture.

[0095] (6) The homogeneous mixture is filled into a 1mL pre-filled syringe, and finally subjected to terminal moist heat sterilization at a temperature of 121℃ for 15min to obtain the finished product of sodium hyaluronate gel injectable filler containing polyester microspheres.

[0096] Comparative Example 3: A method for preparing a sodium hyaluronate gel injectable filler containing polyhydroxyalkanoate (PHA) microspheres, wherein the heat treatment temperature is lower than the glass transition temperature or crystallization temperature of polyester microspheres, specifically including the following steps: (1) Same as (1) in Example 2.

[0097] (2) Same as (2) in Example 2.

[0098] (3) Same as (3) in Example 2.

[0099] (4) The pre-homogenized mixture is heat-treated at a temperature of 40°C for 30 minutes to obtain the heat-treated mixture.

[0100] (5) Same as (5) in Example 2.

[0101] (6) Same as (6) in Example 2.

[0102] Comparative Example 4: A method for preparing a sodium hyaluronate gel injectable filler containing polyhydroxyalkanoate (PHA) microspheres, wherein the method does not include a second homogenization process, and specifically includes the following steps: (1) Same as (1) in Example 2.

[0103] (2) Same as (2) in Example 2.

[0104] (3) Same as (3) in Example 2.

[0105] (4) Same as (4) in Example 2.

[0106] (5) The heat treatment mixture is filled into a 1mL pre-filled syringe, and finally terminal moist heat sterilization is carried out at a temperature of 121℃ for 15min to obtain the finished product of sodium hyaluronate gel injectable filler containing polyester microspheres.

[0107] Experimental Example 1: Microsphere surface morphology observation: The pre-homogenized mixture prepared in step (3) of Example 2 and the heat-treated mixture prepared in step (4) were respectively made into thin films and characterized by scanning electron microscopy (SEM). The surface morphology of the PHA microspheres in them was observed as follows: Figure 1 and Figure 2 .

[0108] Figure 1 The image shows the surface morphology of PHA microspheres in the pre-homogenized mixture of Example 2. Figure 2 The images show the surface morphology of the PHA microspheres in the heat-treated mixture of Example 2. As can be seen from the figures, after heat treatment, the PHA microspheres of Example 2 did not exhibit melting, adhesion, or deformation. Furthermore, the surface roughness of the microspheres was significantly improved, indicating that the molecular chains of the gel are embedded in the pores of the microsphere surface. This effectively encapsulates and isolates the microsphere surface by the gel layer, forming a uniformly rough surface morphology. Compared to a simple adsorbed state morphology, this morphology is less prone to relative slippage between the microspheres and the gel layer after shearing and compression, further mitigating the risk of microsphere aggregation and significantly improving the dispersion uniformity of the entire formulation.

[0109] Experimental Example 2: Pushing force test: Take one finished product from Examples 1-3 and Comparative Examples 1-4 respectively, and install a disposable sterile injection needle (27G 1 / 2”). Following the test method in Appendix A of YY / T0962-2021, use a universal testing machine to measure the pushing force (N) at an injection speed of 30 mm / min. Test the maximum / minimum pushing force and the average pushing force. Test 10 products in each group and take the average value. The results are as follows: Figure 3-9 As shown in Table 1.

[0110] Table 1. Pushing Force Data

[0111] As shown in Table 1, the specific sequence of "pre-homogenization-heat treatment-re-homogenization" of the present invention was adopted in Examples 1-3. The polyester microspheres in the resulting products were uniformly dispersed in the gel system without aggregation. After terminal moist heat sterilization, the extrusion force was moderate (12-25N). The products were made in the form of pre-filled syringes, which can be used immediately in clinical use and are easy to operate.

[0112] Comparative Examples 1, 2, and 4 did not undergo the complete "pre-homogenization-heat treatment-re-homogenization" process, and the microspheres aggregated during sterilization, with a blockage rate as high as 45-60%, and the pushing force was relatively large. The heat treatment temperature of Comparative Example 3 was lower than the glass transition temperature or crystallization temperature of polyester microspheres, and the microspheres failed to soften effectively and fully impregnate with the gel. Aggregation still occurred after sterilization, with a blockage rate of 50%.

[0113] Figures 3-5 The extrusion force test curves of the syringes manufactured in Examples 1-3 are shown. Figures 6-9 The extrusion force test curves of the syringes manufactured in Comparative Examples 1-4 are shown. Figures 3-5 The curve in the figure is smooth, with no significant sawtooth fluctuations, and the extrusion continuity is good. In contrast, Figures 6-9 The curves showed significant instability, with multiple peaks and dips (instantaneous blockage / slippage), and the plateau fluctuations intensified, failing to form a stable plateau segment. This manifested as abnormally increased and unstable resistance during extrusion, with the maximum pushing force exceeding 25N multiple times, significantly higher than the clinically desired comfortable pushing force range of 5-20N.

[0114] Experimental Example 3: Rheological parameter testing: For the finished products of Example 2 and Comparative Example 1, a rotational rheometer was used, with the test temperature set at 25°C, small-amplitude oscillating shear (SAOS) mode, and the shear rate range at 0.1 s. -1 -100s -1 Take the shear rate as 1s -1 Shear viscosity values ​​under certain conditions. Frequency sweeps were performed at constant strain within the linear viscoelastic range (LVR), with frequencies varying from 0.1 to 10 Hz. The elastic modulus and viscous modulus values ​​at 1 Hz were compared. The results are shown in Table 2 below.

[0115] Table 2 Rheological data

[0116] As shown in Table 2, the rheological data of the heat-treated and untreated products are not significantly different, indicating that heat treatment has no effect on the rheological properties of the products.

[0117] In summary, this invention achieves the clinical advantages of "pre-homogenization-heat treatment-re-homogenization" without affecting the rheological properties of the product, by using a gel layer to tightly wrap and smooth the surface of the microspheres. This gel layer acts as a physical barrier during terminal moist heat sterilization, effectively preventing the microspheres from agglomerating.

[0118] It should be noted that some detailed steps of the operation are not described in this invention, but are prior art known to those skilled in the art, and therefore will not be repeated here. Furthermore, in this invention, all features defined in the form of numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible secondary ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0119] It should be noted that the detailed structure of some devices is not described in this invention, but is prior art known to those skilled in the art, and therefore will not be elaborated here. In this invention, structures and devices not specifically limited can be purchased commercially, and those skilled in the art only need to install and operate them according to the accompanying instruction manual, without requiring any creative effort from those skilled in the art.

[0120] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. In this invention, not all possible combinations of the various technical features in each embodiment or implementation are described. As long as the combinations of these technical features do not contradict each other, the various technical features in each embodiment or implementation can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing an injectable filler material of sodium hyaluronate gel containing polyester microspheres, characterized in that, include: (1) Provide polyester microspheres and gel carrier, mix them and perform a first homogenization treatment to obtain a pre-homogenized mixture; (2) The pre-homogenized mixture is heat-treated to obtain a heat-treated mixture; (3) The heat-treated mixture is subjected to a second homogenization process to obtain a re-homogenized mixture; (4) Fill the homogenized mixture into a pre-filled syringe and sterilize it at the terminal to obtain the finished product of sodium hyaluronate gel injectable filler containing polyester microspheres.

2. The method for preparing the injectable filler material containing polyester microspheres of sodium hyaluronate gel according to claim 1, characterized in that, The polyester microspheres are any one of polylactide microspheres, poly-L-lactide microspheres, racemic polylactide microspheres, polylactic acid-polyethylene glycol copolymer microspheres, polyhydroxy fatty acid ester microspheres, polyhydroxy fatty acid ester-polyethylene glycol copolymer microspheres, and lactide-glycolic acid copolymer microspheres.

3. The method for preparing the injectable filler material containing polyester microspheres of sodium hyaluronate gel according to claim 1, characterized in that, The gel carrier is a cross-linked sodium hyaluronate gel, or a composite gel of cross-linked sodium hyaluronate gel and free sodium hyaluronate.

4. The method for preparing the injectable filler material containing polyester microspheres of sodium hyaluronate gel according to claim 1, characterized in that, The polyester microspheres have a particle size of 20-80 μm; the gel carrier has a particle size of 50-1000 μm.

5. The method for preparing the injectable filler material containing polyester microspheres of sodium hyaluronate gel according to claim 1, characterized in that, The polyester microspheres in the mixture contain 50-350 mg / mL, and the gel carrier in the mixture contains 10-22 mg / mL.

6. The method for preparing the injectable filler material containing polyester microspheres of sodium hyaluronate gel according to claim 1, characterized in that, The heat treatment temperature is 60-100℃, and the heat treatment time is 10-60min.

7. The method for preparing the injectable filler material containing polyester microspheres of sodium hyaluronate gel according to any one of claims 1-6, characterized in that, The conditions for the first and second homogenization processes are as follows: revolution speed of 100-400 rpm, rotation ratio of 1.0-3.0, and time of 10-25 min.

8. The method for preparing the injectable filler material containing polyester microspheres of sodium hyaluronate gel according to claim 7, characterized in that, The terminal sterilization is performed using moist heat sterilization at a temperature of 120-125℃ for 8-15 minutes.

9. An injectable hyaluronic acid gel containing polyester microspheres, prepared by the method for preparing the injectable hyaluronic acid gel containing polyester microspheres according to any one of claims 1-8, characterized in that, The injectable filler material is a ready-to-use formulation in the form of a pre-filled syringe.

10. The application of a sodium hyaluronate gel injectable filler containing polyester microspheres in the preparation of medical or cosmetic injectable filler products, wherein the injectable filler is prepared by the method for preparing the sodium hyaluronate gel injectable filler containing polyester microspheres according to any one of claims 1-8.

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