Transdermal drug delivery dressing and preparation method thereof

Abstract

The invention relates to the field of medical dressings, in particular to a transdermal drug delivery dressing and a preparation method thereof. The dressing comprises carbomer, carboxymethyl chitosan, sodium polyacrylate, sodium tripolyphosphate, triethanolamine and water, and the content of each component is limited. According to the invention, a'carbomer-triethanolamine 'and'carboxymethyl chitosan-sodium tripolyphosphate' double-gel system is ingeniously constructed, and the moisturizing and enhancing effects of sodium polyacrylate are supplemented; the transdermal delivery hydrogel dressing which integrates excellent adhesion, good mechanical strength, lasting moisturizing capacity, excellent biocompatibility and wide drug adaptability is successfully developed. According to the dressing, the common key problems of poor gel stability, skin irritation risk, limited drug loading, poor process reproducibility and the like in the prior art are effectively solved, and a solution with a great application prospect is provided for developing a new generation of efficient, safe and comfortable transdermal drug delivery products.

Description

Technical Field

[0001] This application relates to the field of pharmaceutical dressings, and in particular to a transdermal drug delivery dressing and its preparation method. Background Technology

[0002] Transdermal drug delivery systems, as a non-invasive drug delivery method, have attracted widespread attention due to their ability to avoid the first-pass effect in the liver, improve patient compliance, and provide sustained and stable blood drug concentrations. Among the various transdermal drug delivery formulations, hydrogel dressings have become a research hotspot in this field due to their unique three-dimensional network structure, excellent biocompatibility, high water content similar to skin tissue, and good drug loading capacity. Ideal hydrogel dressings can not only serve as drug reservoirs and controlled release matrices, but also provide a moist healing environment for wounds, absorb small amounts of exudate, and have certain cooling and soothing effects. However, traditional hydrogel materials still face significant challenges in meeting the comprehensive requirements of transdermal drug delivery. For example, some hydrogels composed of synthetic polymers such as polyvinyl alcohol and polyacrylamide, despite their good mechanical properties, have poor biodegradability and may pose biocompatibility risks; while hydrogels composed solely of natural polymers (such as gelatin and sodium alginate) often suffer from weak mechanical strength, poor stability, and rapid dissolution or degradation in vivo, leading to problems such as drug burst release and shortened duration of action. Therefore, developing a hydrogel dressing that can balance excellent mechanical properties, biocompatibility, controlled drug release characteristics, and user comfort is one of the key issues that urgently need to be addressed in the field of transdermal drug delivery.

[0003] Chitosan, a natural cationic polysaccharide, has shown great potential in the field of biomedical materials due to its excellent biocompatibility, biodegradability, inherent antibacterial activity, and wound-healing ability. However, the strong hydrogen bonding between chitosan molecular chains makes it insoluble in water and most neutral or alkaline solvents, typically requiring dissolution in weakly acidic solutions such as dilute acetic acid to form a gel. This characteristic greatly limits its application in transdermal drug delivery products. First, an acidic environment may threaten the stability of many pH-sensitive active pharmaceutical ingredients (such as peptides, protein-based biopharmaceuticals, or certain chemically unstable small molecules), leading to drug inactivation during storage or use. Second, prolonged application to the skin, especially damaged or sensitive skin, may cause skin irritation, stinging, or allergic reactions due to residual acidic components, affecting safety and comfort. Furthermore, chitosan acid gels formed through physical cross-linking often have weak mechanical properties and unstable gel network structures, making them prone to collapse or rapid dissolution under body temperature or fluid conditions, hindering the long-term, controlled release of drugs. Although chemical cross-linking (such as using cross-linking agents like glutaraldehyde) can enhance the mechanical strength and stability of medical dressings, these chemical cross-linking agents often have certain cytotoxicity, introducing new biosafety risks and failing to meet the high safety standards required for medical dressings.

[0004] To overcome the limitations of single-material hydrogels, researchers have turned their attention to composite hydrogel systems, aiming to achieve synergistic effects through the physical or chemical combination of two or more polymeric materials. One important direction is the composite of synthetic and natural polymers. For example, carbomer (a common synthetic polyacrylic acid anionic polymer) can be combined with certain natural polysaccharides. Carbomer itself possesses excellent thickening and hydrophilic properties, forming a transparent gel after neutralization; however, its gel network is sensitive to ionic strength and has limited bioactivity. Theoretically, combining it with natural polymers could combine the structural strength of synthetic materials with the functional activity of natural materials. However, existing composite strategies often suffer from poor interfacial compatibility and inhomogeneous network structures. For example, directly mixing unmodified chitosan with carbomer can easily lead to electrostatic complexation, forming precipitates or coarse phase-separated structures due to their opposite charges, rather than forming a uniform and stable interpenetrating or double-network structure. This results in poor gel appearance, unstable physical properties (such as elasticity and adhesion), and unpredictable and uncontrollable drug distribution and release behavior in such heterogeneous systems. Furthermore, existing technologies often lack systematic optimization of process parameters such as the order of component addition and cross-linking timing. Even subtle process differences can lead to significant fluctuations in the final product's performance, resulting in poor reproducibility and hindering large-scale, standardized industrial production.

[0005] Existing transdermal hydrogel dressings, especially those combining natural polysaccharides with synthetic polymers, generally suffer from one or more of the following drawbacks: First, the natural polysaccharides used (such as chitosan) have poor solubility, requiring acidic solvents and posing potential risks of skin irritation and drug incompatibility. Second, the microstructure of the composite gel is difficult to control, easily leading to phase separation and resulting in poor gel mechanical properties, stability, and drug release performance. Third, the preparation process significantly affects the performance of the final product, but existing methods lack universality and robustness, making it difficult to achieve simple and controllable production while ensuring performance. Therefore, there is an urgent need in this field to develop a novel hydrogel dressing and its preparation method that can fundamentally solve the above-mentioned problems, obtaining an ideal transdermal drug delivery platform that is structurally stable, has excellent performance, is safe and comfortable to use, and is suitable for various drug carriers, without introducing biosafety risks. Summary of the Invention

[0006] To address the aforementioned problems with existing transdermal drug delivery dressings, this application provides a transdermal hydrogel dressing. This dressing, through the synergistic effect of specific components and processes, exhibits excellent biocompatibility, good adhesion, long-lasting moisturizing effect, and controllable drug release performance, making it suitable for the transdermal delivery of various pharmaceutical ingredients.

[0007] A transdermal hydrogel dressing, characterized in that it comprises carbomer, carboxymethyl chitosan, sodium polyacrylate, sodium tripolyphosphate, triethanolamine and water.

[0008] Preferably, the transdermal hydrogel dressing comprises the following components, in parts by weight: - Carbomer 0.1~5 parts; - 0.1 to 5 parts of carboxymethyl chitosan; - Sodium polyacrylate 0.2~1 part; - Sodium tripolyphosphate 0.1~5 parts; - Triethanolamine 0.5 to 8 parts; - 76-99 parts water.

[0009] More preferably, each component comprises, by weight: - Carbomer 0.5~1.5 parts; - 0.5~2.0 parts of carboxymethyl chitosan; - Sodium polyacrylate 0.3~0.5 parts; - Sodium tripolyphosphate 0.5~2 parts; - Triethanolamine 1-4 parts; - 90-97 parts water.

[0010] Furthermore, the transdermal hydrogel dressing also contains a pharmaceutically active ingredient.

[0011] Preferably, the active pharmaceutical ingredient is selected from one or more of the following: antifungal drugs, glucocorticoids, active substances of traditional Chinese medicine, nonsteroidal anti-inflammatory drugs, local anesthetics, anti-acne drugs, vitamins and their derivatives, and growth factors for skin repair.

[0012] On the other hand, this application provides a method for preparing the transdermal hydrogel dressing as described above.

[0013] A method for preparing a transdermal hydrogel dressing, characterized by comprising the following steps: - (1) Prepare aqueous solutions of sodium tripolyphosphate and triethanolamine, respectively; - (2) Mix carbomer, carboxymethyl chitosan and sodium polyacrylate with water to form mixed solution A; - (3) Add sodium tripolyphosphate aqueous solution to mixed solution A, mix well to form mixture B; - (4) Add triethanolamine aqueous solution dropwise to mixture B, mix well to form the hydrogel; - (5) Spread the obtained hydrogel on the surface of the mold, and after degassing and drying, obtain sheet or film hydrogel dressing.

[0014] Preferably, step (2) specifically includes: - Carbomer and sodium polyacrylate are dispersed in a portion of water under high-speed shear, and allowed to swell by standing to obtain a swollen solution; - Dissolve carboxymethyl chitosan in another portion of water to obtain an aqueous solution of carboxymethyl chitosan; - The carboxymethyl chitosan aqueous solution is mixed with the swelling solution and stirred until homogeneous to form the mixed solution A; The high-speed shearing speed is 1000~5000 rpm, and the shearing time is 3~10 minutes; the static swelling time is 0.5~2 hours.

[0015] Preferably, the mass percentage concentration of the sodium tripolyphosphate aqueous solution is 1% to 10%, and the mass percentage concentration of the triethanolamine aqueous solution is 5% to 20%; and in step (4), after adding the triethanolamine aqueous solution, the pH value of the system is adjusted to 6.2 to 7.5.

[0016] Preferably, the method further includes the step of adding a pharmaceutically active ingredient to the mixed solution A.

[0017] This application also relates to the use of the aforementioned transdermal hydrogel dressing in the preparation of gel patches. Beneficial effects

[0018] The core concept of the transdermal hydrogel dressing of the present invention lies in constructing a dual gel system of "carbomer-triethanolamine" and "carboxymethyl chitosan-sodium tripolyphosphate" and synergizing with the unique properties of sodium polyacrylate, thereby achieving complementary advantages and functional enhancement of multiple polymer materials, and ultimately obtaining a dressing that is structurally stable, has comprehensive performance, and is safe and comfortable.

[0019] Its beneficial effects are specifically reflected in the following aspects: 1. Synergistic Crosslinking of a Dual-Gel System for Structural Stability and Performance Optimization: This invention creatively integrates two independent gel-forming mechanisms. On one hand, the anionic polymer carbomer is ionized under the neutralization of triethanolamine, and its molecular chains extend to form a primary three-dimensional network structure through hydrogen bonds and van der Waals forces. This network provides excellent initial tack and long-lasting adhesion between the dressing and the skin, and imparts basic transparency and moisturizing properties to the gel. On the other hand, water-soluble carboxymethyl chitosan and the anionic crosslinking agent sodium tripolyphosphate undergo physical crosslinking through electrostatic interactions to form a second, stable network structure. This network not only significantly enhances the overall mechanical strength, elastic modulus, and tear resistance of the gel, overcoming the shortcomings of single carbomer gels such as stickiness and insufficient strength, but also introduces the inherent bioactivity of natural polysaccharides, such as antibacterial and healing-promoting functions. These two networks interpenetrate and support each other at the microscopic level, forming a stable interpenetrating polymer network structure. Their synergistic effect enables the dressing to have good adhesion while possessing mechanical properties and structural stability that surpass those of a single-component system, effectively preventing damage or deformation caused by stretching or friction during use.

[0020] 2. Sodium polyacrylate enhances hydration, ensuring long-lasting moisturization and a comfortable feel: In the aforementioned dual-network framework, sodium polyacrylate, as a highly efficient water-soluble thickener and water-absorbing resin, contains numerous hydrophilic groups on its molecular chain, enabling it to rapidly absorb and lock in water far exceeding its own weight. Its addition acts like countless "miniature reservoirs" embedded in the dual-network structure, significantly increasing the dressing's water content and retention capacity. This not only creates a long-lasting moist healing environment for the skin, reducing the dressing's drying due to moisture evaporation, but also ensures good solubility and migration of drug molecules within the gel matrix by maintaining a high hydration state, thus facilitating stable drug release. Simultaneously, ample moisture provides a cooling and refreshing feel, enhancing the user experience.

[0021] 3. Fundamentally Solving Biocompatibility and Drug Compatibility Issues: This invention uses water-soluble carboxymethyl chitosan to completely replace the chitosan that needs to be dissolved under acidic conditions in traditional processes. This crucial substitution completely eliminates the dependence on acidic solvents, allowing the pH of the final gel product to be precisely adjusted to a neutral range (6.2-7.5) similar to that of healthy skin. This not only eliminates the safety hazards such as skin irritation and allergies that may be caused by acidic environments, making it particularly suitable for damaged or sensitive skin, but also avoids the risk of many pH-sensitive active pharmaceutical ingredients (such as certain peptides, growth factors, or chemically unstable anti-inflammatory analgesics) being inactivated under acidic conditions, greatly expanding the drug-carrying capacity of the dressing. The entire system is mainly based on physical cross-linking, eliminating the need to introduce toxic chemical cross-linking agents such as glutaraldehyde, further ensuring the product's biosafety and cell compatibility.

[0022] 4. The sophisticated preparation process ensures structural uniformity and reproducible performance: The preparation method of this invention is not a simple material mixing process, but rather a carefully designed step-by-step approach to ensure the successful construction of the dual-gel system. Carbomer and sodium polyacrylate are first dispersed and swollen in water under high-speed shear, ensuring sufficient hydration and dispersion of the hydrophobic polymer groups and preventing the formation of "fish eyes." Subsequently, a pre-dissolved carboxymethyl chitosan solution is mixed with it, and finally, sodium tripolyphosphate crosslinking agent and triethanolamine neutralizing agent are introduced stepwise. This sequential addition method effectively avoids the instantaneous electrostatic complexation and phase separation that may occur when positively charged chitosan comes into direct contact with negatively charged carbomer, ensuring that each component is uniformly distributed in the solution. This allows for the formation of a uniform and dense composite gel network during the crosslinking and neutralization reactions. Clearly defined process parameters (such as shear rate, swelling time, and pH control) ensure good reproducibility and controllability of the preparation process, laying a solid foundation for large-scale, standardized production.

[0023] This invention, through the ingenious construction of a dual-gel system of "carbomer-triethanolamine" and "carboxymethyl chitosan-sodium tripolyphosphate," coupled with the moisturizing and enhancing effect of sodium polyacrylate, has successfully developed a transdermal drug delivery hydrogel dressing that combines excellent adhesion, good mechanical strength, long-lasting moisturizing ability, outstanding biocompatibility, and broad drug compatibility. This dressing effectively solves key problems commonly found in existing technologies, such as poor gel stability, risk of skin irritation, limited drug loading, and poor process reproducibility, providing a highly promising solution for developing a new generation of efficient, safe, and comfortable transdermal drug delivery products. Detailed Implementation Example 1

[0024] (1) Prepare sodium tripolyphosphate aqueous solution: Take 1.0 g of sodium tripolyphosphate, dissolve it in 10 mL of deionized water, stir until completely dissolved, and set aside.

[0025] (2) Prepare triethanolamine aqueous solution: Take 1.0 g of triethanolamine, dissolve it in 10 mL of deionized water, stir until completely dissolved, and set aside.

[0026] (3) Formation of mixed solution A: 2.0 g of carbomer and 0.4 g of sodium polyacrylate were dispersed in 50 mL of deionized water under high-speed shear (3000 rpm) and allowed to swell for 1 hour to obtain a swollen solution. Separately, 2.0 g of carboxymethyl chitosan was dissolved in 40 mL of deionized water to obtain an aqueous solution of carboxymethyl chitosan. The aqueous solution of carboxymethyl chitosan was mixed with the swollen solution and stirred evenly to form mixed solution A.

[0027] (4) Add the sodium tripolyphosphate aqueous solution prepared in step (1) to the mixed solution A, mix well to form mixture B.

[0028] (5) Slowly add the triethanolamine aqueous solution prepared in step (2) to mixture B while stirring until it is evenly mixed and forms a uniform and transparent hydrogel.

[0029] (6) The obtained hydrogel is spread on the surface of the mold, and after degassing and drying, a sheet or film hydrogel dressing is obtained. Example 2

[0030] (1) Prepare sodium tripolyphosphate aqueous solution: Take 0.1 g of sodium tripolyphosphate, dissolve it in 10 mL of deionized water, stir until completely dissolved, and set aside.

[0031] (2) Prepare triethanolamine aqueous solution: Take 0.5 g of triethanolamine, dissolve it in 10 mL of deionized water, stir until completely dissolved, and set aside.

[0032] (3) Formation of mixed solution A: 0.1 g of carbomer and 0.2 g of sodium polyacrylate were dispersed in 40 mL of deionized water under high-speed shear (1000 rpm) and allowed to swell for 0.5 hours to obtain a swollen solution. Separately, 0.1 g of carboxymethyl chitosan was dissolved in 30 mL of deionized water to obtain an aqueous solution of carboxymethyl chitosan. The aqueous solution of carboxymethyl chitosan was mixed with the swollen solution and stirred evenly to form mixed solution A.

[0033] (4) Add the sodium tripolyphosphate aqueous solution prepared in step (1) to the mixed solution A, mix well to form mixture B.

[0034] (5) Slowly add the triethanolamine aqueous solution prepared in step (2) to mixture B while stirring until the mixture is uniform and forms a hydrogel.

[0035] (6) The obtained hydrogel is spread on the surface of the mold, and after degassing and drying, a sheet or film hydrogel dressing is obtained. Example 3

[0036] (1) Prepare sodium tripolyphosphate aqueous solution: Take 5 g of sodium tripolyphosphate, dissolve it in 50 mL of deionized water, stir until completely dissolved, and set aside.

[0037] (2) Prepare triethanolamine aqueous solution: Take 8 g of triethanolamine, dissolve it in 40 mL of deionized water, stir until completely dissolved, and set aside.

[0038] (3) Formation of mixed solution A: Disperse 5 g of carbomer and 1 g of sodium polyacrylate in 50 mL of deionized water under high-speed shear (5000 rpm), and let it swell for 2 hours to obtain a swollen solution. Separately, dissolve 5 g of carboxymethyl chitosan in 40 mL of deionized water to obtain a carboxymethyl chitosan aqueous solution. Mix the carboxymethyl chitosan aqueous solution with the swollen solution and stir evenly to form mixed solution A.

[0039] (4) Add the sodium tripolyphosphate aqueous solution prepared in step (1) to the mixed solution A, mix well to form mixture B.

[0040] (5) Slowly add the triethanolamine aqueous solution prepared in step (2) to mixture B while stirring until the mixture is uniform and forms a hydrogel.

[0041] (6) The obtained hydrogel is spread on the surface of the mold, and after degassing and drying, a sheet or film hydrogel dressing is obtained. Example 4

[0042] (1) Prepare sodium tripolyphosphate aqueous solution: Take 1.2 g of sodium tripolyphosphate, dissolve it in 10 mL of deionized water, stir until completely dissolved, and set aside.

[0043] (2) Prepare triethanolamine aqueous solution: Take 2.5 g of triethanolamine, dissolve it in 10 mL of deionized water, stir until completely dissolved, and set aside.

[0044] (3) Formation of mixed solution A: Disperse 0.1 g of carbomer and 0.4 g of sodium polyacrylate in 50 mL of deionized water under high-speed shear (3000 rpm) and allow to swell for 1 hour to obtain a swollen solution. Separately, dissolve 5 g of carboxymethyl chitosan in 40 mL of deionized water to obtain a carboxymethyl chitosan aqueous solution. Mix the carboxymethyl chitosan aqueous solution with the swollen solution and stir evenly to form mixed solution A.

[0045] (4) Add the sodium tripolyphosphate aqueous solution prepared in step (1) to the mixed solution A, mix well to form mixture B.

[0046] (5) Slowly add the triethanolamine aqueous solution prepared in step (2) to mixture B while stirring until the mixture is uniform and forms a hydrogel.

[0047] (6) The obtained hydrogel is spread on the surface of the mold, and after degassing and drying, a sheet or film hydrogel dressing is obtained. Example

[0048] (1) Prepare sodium tripolyphosphate aqueous solution: Take 1.2 g of sodium tripolyphosphate, dissolve it in 10 mL of deionized water, stir until completely dissolved, and set aside.

[0049] (2) Prepare triethanolamine aqueous solution: Take 2.5 g of triethanolamine, dissolve it in 10 mL of deionized water, stir until completely dissolved, and set aside.

[0050] (3) Formation of mixed solution A: Disperse 5 g of carbomer and 0.4 g of sodium polyacrylate in 50 mL of deionized water under high-speed shear (3000 rpm), and let it stand to swell for 1 hour to obtain a swollen solution. Separately, dissolve 0.1 g of carboxymethyl chitosan in 40 mL of deionized water to obtain a carboxymethyl chitosan aqueous solution. Mix the carboxymethyl chitosan aqueous solution with the swollen solution and stir evenly to form mixed solution A.

[0051] (4) Add the sodium tripolyphosphate aqueous solution prepared in step (1) to the mixed solution A, mix well to form mixture B.

[0052] (5) Slowly add the triethanolamine aqueous solution prepared in step (2) to mixture B while stirring until the mixture is uniform and forms a hydrogel.

[0053] (6) The obtained hydrogel is spread on the surface of the mold, and after degassing and drying, a sheet or film hydrogel dressing is obtained. Example 5

[0054] (1) Prepare sodium tripolyphosphate aqueous solution: Take 1.2 g of sodium tripolyphosphate, dissolve it in 10 mL of deionized water, stir until completely dissolved, and set aside.

[0055] (2) Prepare triethanolamine aqueous solution: Take 2.5 g of triethanolamine, dissolve it in 10 mL of deionized water, stir until completely dissolved, and set aside.

[0056] (3) Formation of Mixed Solution A: 1.0 g of carbomer and 0.4 g of sodium polyacrylate were dispersed in 50 mL of deionized water under high-speed shear (3000 rpm) and allowed to swell for 1 hour to obtain a swollen solution. Separately, 1.2 g of carboxymethyl chitosan was dissolved in 40 mL of deionized water to obtain an aqueous solution of carboxymethyl chitosan. The aqueous solution of carboxymethyl chitosan was mixed with the swollen solution and stirred evenly to form mixed solution A.

[0057] (4) Add 0.1 g of salicylic acid, the active ingredient in the medicine, to mixed solution A and stir until completely dissolved.

[0058] (5) Add the sodium tripolyphosphate aqueous solution prepared in step (1) to the mixed solution A, mix well to form mixture B.

[0059] (6) Slowly add the triethanolamine aqueous solution prepared in step (2) to mixture B while stirring until the mixture is homogeneous and forms a hydrogel.

[0060] (7) The obtained hydrogel is spread on the surface of the mold, and after degassing and drying, a sheet or film hydrogel dressing is obtained.

[0061] Comparative Example 1 (1) Prepare sodium tripolyphosphate aqueous solution: Take 2.0 g of sodium tripolyphosphate, dissolve it in 10 mL of deionized water, stir until completely dissolved, and set aside.

[0062] (2) Formation of mixed solution A: Disperse 0.4 g of sodium polyacrylate in 50 mL of deionized water under high-speed shear (3000 rpm) and allow it to swell for 1 hour to obtain a swollen solution. Separately, dissolve 4.0 g of carboxymethyl chitosan in 40 mL of deionized water to obtain an aqueous solution of carboxymethyl chitosan. Mix the aqueous solution of carboxymethyl chitosan with the swollen solution and stir evenly to form mixed solution A.

[0063] (3) Add the sodium tripolyphosphate aqueous solution prepared in step (1) to the mixed solution A, mix well to form mixture B.

[0064] (4) Stir mixture B for 30 minutes to form a gel-like substance.

[0065] (5) Spread the obtained gel on the surface of the mold, and after degassing and drying, obtain a sheet or film dressing.

[0066] Comparative Example 2 (1) Prepare triethanolamine aqueous solution: Take 2.0 g of triethanolamine, dissolve it in 10 mL of deionized water, stir until completely dissolved, and set aside.

[0067] (2) Formation of mixed solution A: Disperse 4.0 g of carbomer and 0.4 g of sodium polyacrylate in 90 mL of deionized water under high-speed shear (3000 rpm), and let it stand to swell for 1 hour to obtain mixed solution A.

[0068] (3) Slowly add the triethanolamine aqueous solution prepared in step (1) to the mixed solution A, stirring while adding, until the mixture is uniform and a hydrogel is formed.

[0069] (4) The obtained hydrogel is spread on the surface of the mold, and after degassing and drying, a sheet or film hydrogel dressing is obtained.

[0070] Comparative Example 3 (1) Prepare sodium tripolyphosphate aqueous solution: Take 1.2 g of sodium tripolyphosphate, dissolve it in 10 mL of deionized water, stir until completely dissolved, and set aside.

[0071] (2) Prepare triethanolamine aqueous solution: Take 2.5 g of triethanolamine, dissolve it in 10 mL of deionized water, stir until completely dissolved, and set aside.

[0072] (3) Formation of mixed solution A: Disperse 1.0 g of carbomer in 50 mL of deionized water under high-speed shear (3000 rpm) and allow it to swell for 1 hour to obtain a swollen solution. Separately, dissolve 1.2 g of carboxymethyl chitosan in 40 mL of deionized water to obtain an aqueous solution of carboxymethyl chitosan. Mix the aqueous solution of carboxymethyl chitosan with the swollen solution and stir evenly to form mixed solution A.

[0073] (4) Add the sodium tripolyphosphate aqueous solution prepared in step (1) to the mixed solution A, mix well to form mixture B.

[0074] (5) Slowly add the triethanolamine aqueous solution prepared in step (2) to mixture B while stirring until the mixture is uniform and forms a hydrogel.

[0075] (6) The obtained hydrogel is spread on the surface of the mold, and after degassing and drying, a sheet or film hydrogel dressing is obtained.

[0076] Mechanical property testing: Using a universal testing machine, the samples were cut into standard dumbbell-shaped specimens (50 mm in length, 10 mm in width, and 2 mm in thickness) and tested at a tensile speed of 50 mm / min. The tensile strength (kPa) and elongation at break (%) were recorded. Each sample was tested 5 times, and the average value was taken.

[0077] Water retention performance test: The sample was cut into circular pieces with a diameter of 20 mm, and the initial weight was recorded as W0. The sample was then placed in a constant temperature and humidity chamber (temperature 37°C, relative humidity 50%), and weighed after 24 hours, recorded as W1. The water retention rate was calculated using the formula: Water retention rate (%) = (W1 / W0) × 100%. Each sample was tested 3 times, and the average value was taken.

[0078] According to the data in the table above, the transdermal hydrogel dressing prepared in Example 1 of this invention shows significant advantages in tensile strength, elongation at break, and water retention, which fully demonstrates the synergistic effect of the "carbomer-triethanolamine" and "carboxymethyl chitosan-sodium tripolyphosphate" dual gel system and sodium polyacrylate.

[0079] Example 1 exhibits a tensile strength of 185 kPa and an elongation at break of 213%, significantly higher than all comparative examples. This indicates that the hydrogel dressing of Example 1 possesses excellent flexibility and tensile strength, enabling it to withstand mechanical stress during use without easily breaking. Comparative Example 1 (lacking the carbomer and triethanolamine system, relying solely on carboxymethyl chitosan-sodium tripolyphosphate crosslinking) has the lowest tensile strength (45 kPa) and elongation at break (75%). This reveals the crucial role of the carbomer-triethanolamine system in constructing the primary network structure: carbomer, after neutralization by triethanolamine, forms an ionized network, providing basic adhesion and structural strength; the absence of this system leads to a fragile gel network and a significant decrease in mechanical properties. Comparative Example 2 (lacking the carboxymethyl chitosan and sodium tripolyphosphate crosslinking system, using only carbomer-triethanolamine and sodium polyacrylate) has a tensile strength (95 kPa) and elongation at break (156%) superior to Comparative Example 1, but still significantly lower than Example 1. This highlights the importance of the second network formed by carboxymethyl chitosan and sodium tripolyphosphate: this network enhances the rigidity and toughness of the overall gel through electrostatic crosslinking, compensating for the insufficient strength of a single carbomer gel. The mechanical properties (tensile strength 143 kPa, elongation at break 175%) of Comparative Example 3 (lacking sodium polyacrylate, retaining only the dual-gel system) are between Comparative Example 2 and Example 1, but still inferior to Example 1. This indicates that sodium polyacrylate, as a thickener and water-absorbing resin, can fill the voids in the gel network, improving overall density and elasticity, and further optimizing mechanical properties.

[0080] Example 1 exhibited a high water retention rate of 92.5%, demonstrating excellent moisture-locking ability, providing a long-lasting moisturizing environment for the skin, enhancing user comfort, and improving drug release stability. Comparative Example 1 had a lower water retention rate (83.0%), stemming from the lack of a hydrophilic network in the carbomer system and the water-absorbing properties of sodium polyacrylate, resulting in insufficient moisture retention. Comparative Example 2 achieved a better water retention rate (85.3%) than Comparative Example 1, but its water retention performance was still limited due to the lack of a carboxymethyl chitosan network. Carboxymethyl chitosan itself possesses hydrophilic groups that can form hydrogen bonds with water molecules, enhancing the water retention effect. Comparative Example 3 had the lowest water retention rate (80.5%), retaining the dual-gel system but lacking the "micro-reservoir" effect of sodium polyacrylate. Sodium polyacrylate can absorb and lock in large amounts of water; its absence directly led to a decrease in water retention rate, confirming the crucial contribution of sodium polyacrylate in moisturizing.

[0081] This invention achieves a comprehensive improvement in both mechanical and water-retention properties through the synergistic effect of a dual-gel system and sodium polyacrylate. In Example 1, the carbomer-triethanolamine network provides initial tack and basic structure, while the carboxymethyl chitosan-sodium tripolyphosphate network enhances mechanical strength through electrostatic crosslinking. The two form an interpenetrating polymer network (IPN), avoiding the limitations of a single system (as in Comparative Examples 1 and 2). This structure ensures the uniformity and stability of the gel, allowing the dressing to remain intact during stretching and bending. Sodium polyacrylate not only improves water retention but also enhances the hydration state of the gel through its high water absorption, thereby improving drug solubility and migration, while also imparting a cooling sensation to the dressing.

[0082] The hydrogel dressing of Example 1 significantly outperformed the comparative examples in tensile strength, elongation at break, and water retention, demonstrating the effectiveness of the "dual gel system + sodium polyacrylate" strategy employed in this invention. Data from Comparative Examples 1-3 further validated the indispensability of the carbomer system, carboxymethyl chitosan system, and sodium polyacrylate: the absence of any one component leads to performance degradation. This invention successfully solves the problems of weak mechanical strength, poor water retention, and structural instability in traditional hydrogel dressings, providing a high-performance, safe, and comfortable dressing solution for transdermal drug delivery.

[0083] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A transdermal hydrogel dressing, characterized in that, It contains carbomer, carboxymethyl chitosan, sodium polyacrylate, sodium tripolyphosphate, triethanolamine, and water.

2. The transdermal hydrogel dressing according to claim 1, characterized in that, It contains the following components, in parts by weight: - Carbomer 0.1~5 parts; - 0.1 to 5 parts of carboxymethyl chitosan; - Sodium polyacrylate 0.2~1 part; - Sodium tripolyphosphate 0.1~5 parts; - Triethanolamine 0.5 to 8 parts; - 76-99 parts water.

3. The transdermal hydrogel dressing according to claim 2, characterized in that, Each component, by weight, includes: - Carbomer 0.5~1.5 parts; - 0.5~2.0 parts of carboxymethyl chitosan; - Sodium polyacrylate 0.3~0.5 parts; - Sodium tripolyphosphate 0.5~2 parts; - Triethanolamine 1-4 parts; - 90-97 parts water.

4. The transdermal hydrogel dressing according to any one of claims 1-3, characterized in that, It also contains medicinal active ingredients.

5. The transdermal hydrogel dressing according to claim 4, characterized in that, The active pharmaceutical ingredient is selected from one or more of the following: antifungal drugs, glucocorticoids, active substances of traditional Chinese medicine, nonsteroidal anti-inflammatory drugs, local anesthetics, anti-acne drugs, vitamins and their derivatives, and growth factors for skin repair.

6. A method for preparing a transdermal hydrogel dressing as described in any one of claims 1-5, characterized in that, Includes the following steps: - (1) Prepare aqueous solutions of sodium tripolyphosphate and triethanolamine, respectively; - (2) Mix carbomer, carboxymethyl chitosan and sodium polyacrylate with water to form mixed solution A; - (3) Add sodium tripolyphosphate aqueous solution to mixed solution A, mix well to form mixture B; - (4) Add triethanolamine aqueous solution dropwise to mixture B, mix well to form the hydrogel; - (5) Spread the obtained hydrogel on the surface of the mold, and after degassing and drying, obtain sheet or film hydrogel dressing.

7. The method according to claim 6, characterized in that, Step (2) specifically includes: - Carbomer and sodium polyacrylate are dispersed in a portion of water under high-speed shear, and allowed to swell by standing to obtain a swollen solution; - Dissolve carboxymethyl chitosan in another portion of water to obtain an aqueous solution of carboxymethyl chitosan; - The carboxymethyl chitosan aqueous solution is mixed with the swelling solution and stirred until homogeneous to form the mixed solution A; The high-speed shearing speed is 1000~5000 rpm, and the shearing time is 3~10 minutes; the static swelling time is 0.5~2 hours.

8. The method according to claim 6, characterized in that, The sodium tripolyphosphate aqueous solution has a mass percentage concentration of 1% to 10%, and the triethanolamine aqueous solution has a mass percentage concentration of 5% to 20%; and in step (4), after adding the triethanolamine aqueous solution, the pH value of the system is adjusted to 6.2 to 7.

5.

9. The method according to claim 6, characterized in that, It also includes the step of adding the active pharmaceutical ingredient to the mixed solution A.

10. The use of the transdermal hydrogel dressing as described in any one of claims 1-5 in the preparation of gel patches.

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