Traditional Chinese medicine compound microemulsion gel for treating atopic dermatitis and preparation method thereof

Abstract

The invention provides a traditional Chinese medicine compound microemulsion gel for treating atopic dermatitis and a preparation method thereof, and belongs to the technical field of biological medicines. The traditional Chinese medicine compound microemulsion gel for treating atopic dermatitis comprises Wenqing drink microemulsion and a gel skeleton, the Wenqing drink microemulsion is loaded on the gel skeleton, and the gel skeleton is carbomer-940. The warm clearing drink microemulsion comprises 2.55% of oleic acid, 12.73% of castor oil polyoxyethylene ether, 12.73% of 1, 2-pentanediol and 72% of a water phase. The microemulsion gel is prepared from 3.5 percent of CP940, 10 percent of glycerol and 1 percent of triethanolamine. The traditional Chinese medicine compound for treating atopic dermatitis is remarkable in effect and small in side effect, and the microemulsion gel is applied through skin and has the advantages that administration and withdrawal are convenient, the first-pass effect of the liver is avoided, gastrointestinal irritation is reduced and the like.

Description

Technical Field

[0001] The present invention relates to the field of biomedical technology, and particularly relates to a traditional Chinese medicine compound microemulsion gel for treating atopic dermatitis and a preparation method thereof. Background Art

[0002] Atopic dermatitis (AD), also known as atopic eczema, is a chronic recurrent skin disease characterized by dryness, itching, and inflammation. According to statistics, the global prevalence of AD in children is as high as 20%, and in adults is 10%, and the number of AD patients is still increasing year by year. Currently, Western medicine mainly uses corticosteroids, antibiotics, dupilumab, and other immunosuppressants to treat AD. However, because moderate and severe AD is extremely prone to recurrence and requires continuous treatment, long-term use of the above drugs will cause various side effects, such as skin atrophy, hypertension, and diarrhea, etc., and at the same time, drug resistance and dependence will also occur. Therefore, it is crucial to find safe, effective, and less side-effect drugs for the treatment of AD.

[0003] Wenqing Decoction comes from "Wanbing Huichun" written by Gong Tingxian in the Ming Dynasty, which can promote blood circulation and nourish blood, clear heat and detoxify. Modern pharmacological research shows that it has anti-ulcer, anti-inflammatory, analgesic, antipyretic, sedative, and hemostatic immune regulatory effects, and is commonly used in clinical treatment of various skin diseases, such as facial hormone-dependent dermatitis, chronic eczema, chronic urticaria, psoriasis, acne, AD, etc. The transdermal drug delivery system refers to a drug delivery system in which drugs are absorbed through the skin into the human blood circulation at a certain controlled rate to produce systemic or local therapeutic effects. It can overcome the disadvantages of traditional oral administration and injection administration, and has the advantages of convenient administration and withdrawal, avoiding the first-pass elimination of the liver, and maintaining the blood drug concentration for a long time. Currently, the form of Wenqing Decoction in the treatment of skin diseases mainly focuses on oral administration. Therefore, it is of great significance to develop an external preparation of Wenqing Decoction for the treatment of AD.

[0004] Microemulsion (ME) is a thermodynamically stable, isotropic, and clear colloidal dispersion system in which emulsion droplets with a particle size of 10 - 100 nm are dispersed in another liquid, which can enhance the solubility of poorly soluble drugs and enhance drug stability. However, due to the strong fluidity of microemulsion, when applied to transdermal drug delivery, it is not easy to coat and retain on the skin. Preparing it into a microemulsion gel can effectively increase the viscosity of the microemulsion and play a sustained-release role.

[0005] In the present invention, the extract of Wenqing Decoction with definite curative effect is innovatively combined with microemulsion technology and gel technology to prepare a microemulsion gel for transdermal drug delivery to treat AD. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a traditional Chinese medicine compound microemulsion gel for treating atopic dermatitis and a preparation method thereof in view of the deficiencies of the above-mentioned prior art. This gel can combine the dual advantages of microemulsion and gel, improve the solubility of various complex traditional Chinese medicine components in the preparation of topical preparations, effectively increase the cumulative transdermal amount of drugs compared with the single WENQINGYIN gel, effectively play the role of treating AD, and have fewer adverse reactions.

[0007] The present invention provides a traditional Chinese medicine compound microemulsion gel for treating atopic dermatitis, which includes WENQINGYIN microemulsion and a gel matrix, and the WENQINGYIN microemulsion is loaded on the gel matrix.

[0008] The gel matrix is carbomer-940 (CP940).

[0009] The WENQINGYIN microemulsion includes 2.546% oleic acid, 12.727% polyoxyethylene castor oil ether, 12.727% 1,2-pentanediol, and 72% aqueous phase.

[0010] Preferably, the microemulsion gel contains 2%-4.5% CP940, 0%-15% glycerol, and 0.5%-2% triethanolamine.

[0011] Preferably, the microemulsion gel contains 3.5% CP940, 10% glycerol, and 1% triethanolamine.

[0012] Another technical solution of the present invention is a preparation method of a traditional Chinese medicine compound microemulsion gel for treating atopic dermatitis, which includes the following steps:

[0013] S1. Extraction and concentration of the water extract of WENQINGYIN;

[0014] S2. Using the water extract of WENQINGYIN extracted in step S1 as the aqueous phase to prepare WENQINGYIN microemulsion;

[0015] S3. Adding the WENQINGYIN microemulsion prepared in step S2 to the gel matrix CP940 to make it fully swell, and preparing it into a microemulsion gel.

[0016] Preferably, step S1 is specifically: weighing the cut pieces of Angelica sinensis, Ligusticum chuanxiong, Paeonia lactiflora, Rehmannia glutinosa, Scutellaria baicalensis, Coptis chinensis, Phellodendron amurense, and Gardenia jasminoides, soaking them in 47% ethanol at a material-liquid ratio of 1:25 for 30 minutes, refluxing and extracting for 115 minutes, filtering while it is hot with four layers of gauze, repeating the extraction 2 times, finally combining the extraction solutions, and rotary evaporating and concentrating at 60°C as the aqueous phase of the microemulsion.

[0017] Preferably, step S2 is specifically:

[0018] S2.1. Screening of oil phase, surfactant, and co-surfactant;

[0019] S2.2. Starting from Km = 1:1, extend the surfactant and cosurfactant to both sides (3:1, 2:1, 1:1, 1:2, 1:3), mix and stir evenly, and then mix evenly with the oil phase at a mass ratio of 1:9 - 9:1 respectively. Use the method of titrating with distilled water, adding and stirring simultaneously to prepare the Wenqingyin microemulsion;

[0020] S2.3. Centrifuge the Wenqingyin extract at 4000 r / min for 10 min, collect the supernatant, and concentrate it under reduced pressure to an appropriate amount as the water phase of the microemulsion. Determine 0.75 g / mL of the water extract as the optimal water extract concentration.

[0021] Preferably, in step S2.1, the oil phase is oleic acid, the surfactant is castor oil polyoxyethylene ether, and the cosurfactant is 1,2 - pentanediol.

[0022] Preferably, in step S2.2, the heating temperature for preparing the microemulsion is 35 °C, the stirring speed is 600 r / min, and the stirring time is 0.5 h.

[0023] Preferably, step S3 is specifically as follows:

[0024] S3.1. Take an appropriate amount of Wenqingyin microemulsion, add the gel matrix CP940 to make it fully swell;

[0025] S3.2. Dropwise add 1% triethanolamine and continuously stir to form a gel;

[0026] S3.2. Add 10% glycerol and continuously stir to form the finished gel agent.

[0027] Compared with the prior art, the present invention achieves the following technical effects:

[0028] The present invention innovatively combines the Wenqingyin extract with definite curative effect with microemulsion technology and gel technology, and prepares a microemulsion gel for transdermal administration to treat AD; the traditional Chinese medicine compound of the present invention has a significant effect and small side effects in treating atopic dermatitis, and the microemulsion gel is administered by skin application, which has the advantages of convenient administration and withdrawal, avoiding the first - pass effect of the liver and reducing gastrointestinal irritation. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] For ease of explanation, the present invention is described in detail by the following specific embodiments and drawings.

[0030] Figure 1 It is a screening diagram of the surfactant.

[0031] Figure 2 It is a screening diagram of the cosurfactant.

[0032] Figure 3 It is a screening diagram for determining the Km value.

[0033] Figure 4 It is a diagram showing the clear and transparent state of the clear drink microemulsion.

[0034] Figure 5 It is a diagram for identifying the microemulsion type by staining method.

[0035] Figure 6 It is a diagram for identifying the microemulsion type by dilution method.

[0036] Figure 7 It is a diagram of the microscopic morphology of the microemulsion.

[0037] Figure 8 It is a diagram of the measurement results of the moisture retention rate of glycerol at different concentrations.

[0038] Figure 9 It is a diagram of the measurement results of the water loss rate of glycerol at different concentrations.

[0039] Figure 10 It is a diagram of the appearance characteristics of the microemulsion gel.

[0040] Figure 11 It is a diagram of the in vitro transdermal absorption results.

[0041] Figure 12 It is a diagram of the modeling and drug administration time schedule.

[0042] Figure 13 It is a diagram of the skin condition of mice on the back and the severity score of dermatitis.

[0043] Figure 14 It is a diagram comparing the spleen size and index of mice in each group.

[0044] Figure 15 It is a diagram of the pathological changes of mouse skin tissue.

[0045] Figure 16 It is a diagram of the levels of inflammatory factors in mouse serum, where (n = 6) (p* < 0.05, p** < 0.01, p*** < 0.001).

[0046] Figure 17 It is a diagram of the levels of inflammatory factors in mouse skin tissue, where (n = 6) (p* < 0.05, p** < 0.01, p*** < 0.001).

[0047] Figure 18 It is a flowchart of the present invention. Detailed implementation manners

[0048] The following are specific embodiments of the present invention and, in combination with the accompanying drawings, further describe the technical solutions of the present invention. However, the present invention is not limited to these embodiments. In the following description, providing specific details such as specific configurations is only to help comprehensively understand the embodiments of the present invention. Therefore, those skilled in the art should clearly understand that various changes and modifications can be made to the embodiments described here without departing from the scope and spirit of the present invention.

[0049] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0050] The materials, practices, and experimental equipment involved in the embodiments of the present invention, unless otherwise specified, all conform to commercially available products in the relevant chemical engineering and biotechnology fields.

[0051] Example 1 Extraction and Concentration of Wenqing Drinking Water Extract

[0052] Weigh 3 g each of the cut pieces of Angelica sinensis, Ligusticum chuanxiong, Paeonia lactiflora, Rehmannia glutinosa, Scutellaria baicalensis, Coptis chinensis, Phellodendron amurense, and Gardenia jasminoides. Soak them in 47% ethanol at a material-liquid ratio of 1:25 for 30 min, reflux and extract for 115 min, filter while it is hot through four layers of gauze, repeat the extraction 2 times, and finally combine the extraction solutions, and rotary evaporate and concentrate at 60 °C to obtain the aqueous phase of the microemulsion. Among them, through the previous research of the research group, the total content of 5 index components, namely geniposide, ferulic acid, baicalin, berberine hydrochloride, and wogonoside, was used as the investigation of the active ingredients of Wenqingyin, and the liquid phase conditions were determined as follows: Agilent Polaris 3 C18-A chromatographic column (250 mm × 4.6 mm, 5 μm); mobile phase 0.2% phosphoric acid (A)-acetonitrile (B), gradient elution (0 - 8 min, 5% - 20% B; 8 - 30 min, 20% - 38% B; 30 - 40 min, 38% - 50% B; 40 - 50 min, 50% - 90% B); volume flow rate 0.6 mL / min; column temperature 40 °C; detection wavelength 254 nm; injection volume 10 μL.

[0053] Example 2 Preparation of Wenqingyin Microemulsion

[0054] 2.1 Selection of Oil Phase

[0055] The oil phase is an important component in the formation of microemulsions. Within a certain range, the smaller the relative molecular mass of the oil phase, the stronger its solubility for drugs. Macromolecular oil phases are not easily embedded in the surfactant to form an interfacial film, while small-molecular oil phases are easily embedded. Therefore, in order to increase the drug solubility and enlarge the microemulsion formation region, short-chain oil phases should preferably be selected. Currently, common oil phases used for preparing microemulsions include soybean oil, oleic acid, ethyl oleate, olive oil, isopropyl palmitate, etc. Oleic acid is a naturally occurring fatty acid, similar to the composition of human cell membranes, with good biocompatibility and low interfacial tension. Moreover, its unsaturated double bond helps to form a stable microemulsion structure, which can not only improve the solubility of drugs in the oil phase but also increase the area of the microemulsion formation region. Therefore, after preliminary screening, oleic acid is designated as the oil phase.

[0056] 2.2 Screening of Surfactants

[0057] Tween-60, Tween-80, Span-80, and castor oil polyoxyethylene ether (EL-40) were respectively mixed with absolute ethanol at a Km of 1:1 ( Figure 1 as shown). After stirring evenly with a magnetic stirrer, they were respectively mixed evenly with oleic acid at a mass ratio of 1:9 to 9:1. Using the distilled water titration method, while adding and stirring, microemulsions were prepared. Taking the critical point of the system changing from clear to turbid as the critical point of microemulsion formation, the water addition amount at the critical point was recorded, and the pseudo-ternary phase diagram was drawn using origin software to screen out the best surfactant.

[0058] The results showed that when EL-40 was used as the surfactant, the area of the microemulsion region formed was the largest. Therefore, EL-40 was selected as the surfactant.

[0059] 2.3 Screening of Cosurfactants

[0060] Absolute ethanol, 1,2-propanediol, glycerol, 1,2-pentanediol, butanediol, and polyethylene glycol 400 monolaurate (PEG-400) were respectively mixed with the screened surfactant EL-40 at a Km of 1:1 ( Figure 2 as shown). After magnetic stirring evenly, they were respectively mixed evenly with oleic acid at a mass ratio of 1:9 to 9:1. Using the distilled water titration method, while adding and stirring, microemulsions were prepared. Taking the critical point of the system changing from clear to turbid as the critical point of microemulsion formation, the water addition amount at the critical point was recorded, and the pseudo-ternary phase diagram was drawn using origin software to screen out the best cosurfactant.

[0061] The results showed that layering occurred when EL-40 was mixed with glycerol. When absolute ethanol, 1,2-propanediol, 1,2-pentanediol, butanediol, and PEG-400 were used as cosurfactants, the area of the microemulsion region formed by 1,2-pentanediol was the largest. Therefore, 1,2-pentanediol was selected as the cosurfactant.

[0062] 2.4 Selection of Km value

[0063] Start with the surfactant (EL-40) and co-surfactant (1,2-pentanediol) at Km = 1:1 and extend to both sides (3:1, 2:1, 1:1, 1:2, 1:3) and mix and stir evenly ( Figure 3 as shown), then mix evenly with oleic acid at a mass ratio of 1:9 - 9:1 respectively. Using the method of titrating with distilled water, add and stir at the same time to prepare microemulsion. Take the critical point where the system changes from clear to turbid as the formation critical point of the microemulsion, record the amount of water added at the critical point, and then calculate the mass percentage content of the mixed surfactant, oil phase and water phase in the system respectively according to the amount of water added. Use origin software to draw a pseudo-ternary phase diagram, compare the size of the microemulsion region formed, and determine the Km value.

[0064] The results show that when Km is 1:1, the area of the microemulsion region formed is the largest. Therefore, the Km value of the surfactant and co-surfactant is selected as 1.

[0065] 2.5 Determination of the concentration of the extract

[0066] Centrifuge the Wenqingyin extract at 4000 r / min for 10 min, collect the supernatant, and concentrate it under reduced pressure to an appropriate amount as the microemulsion water phase. The preliminary composition ratio of the microemulsion prescription is determined as follows: oil phase: mixed surfactant = 1:9, Km = 1, and water phase 72%. Replace the water phase with the medicinal material extract at different mass concentrations (0.25, 0.5, 0.75, 1, 1.25 g / mL), and investigate the effects of water extracts at different mass concentrations on the particle size and drug loading of the microemulsion, and then determine the optimal extract concentration.

[0067] Table 1 Effects of different extract concentrations on the particle size and drug loading of microemulsion

[0068]

[0069] It can be seen from the above results that water extracts at different mass concentrations have a greater impact on the particle size of the microemulsion. Therefore, on the premise of ensuring the drug loading, 0.75 g / mL water extract is selected as the optimal water extract concentration.

[0070] 2.6 Determination of the optimal prescription

[0071] The determination of the optimal prescription of the microemulsion mainly needs to consider the stability of the microemulsion. Therefore, in the pseudo-ternary phase diagram with Km = 1, appropriate ratios are selected, and the selected points should not be too close to the critical value as much as possible. Otherwise, the microemulsion may stratify or fail to form due to changes in the environment or other factors. Therefore, several points in the center of the microemulsion region and its vicinity are initially selected (oil phase: mixed surfactants are 1:6, 1:7, 1:8, 1:9, 1:10, 1:11 respectively) to prepare the microemulsion, and it is evaluated by particle size and drug loading capacity.

[0072] Table 2 Effects of oil phase and mixed surfactants with different ratios on the particle size and drug loading capacity of the microemulsion

[0073]

[0074] The results show that when the oil phase: mixed surfactant = 1:10, the drug loading capacity of the formed microemulsion is moderate and the particle size is the smallest. Therefore, the oil phase: mixed surfactant = 1:10 is determined.

[0075] To sum up, the final prescription of the Wenqingyin microemulsion obtained is: oleic acid 2.546%, castor oil polyoxyethylene ether 12.727%, 1,2-pentanediol 12.727%, and aqueous phase 72%.

[0076] 2.7 Screening of preparation process conditions

[0077] Taking the particle size and drug loading capacity of the microemulsion as indexes, the single factor test method is used to investigate the effects of temperature, stirring speed, and stirring time on the microemulsion preparation process.

[0078] 2.7.1 Investigation of temperature

[0079] First, fix the rotation speed at 400 r / min and the stirring time at 0.5 h. Compound Wenqingyin microemulsions are prepared at four different temperatures of 25 ± 2 °C, 35 ± 2 °C, 45 ± 2 °C, and 55 ± 2 °C respectively to investigate the effects of temperature on the particle size and drug loading capacity of the microemulsion.

[0080] Table 3 Effects of different temperatures on the particle size and drug loading capacity of the microemulsion

[0081]

[0082] After 35 °C, with the increase of temperature, the drug loading capacity increases, but the particle size of the microemulsion also increases. The increase in drug loading capacity at 45 °C compared with 35 °C is not obvious, and the particle size of the microemulsion at 35 °C is smaller than that at other temperatures. Therefore, the heating temperature is selected as 35 °C.

[0083] 2.7.2 Investigation of stirring speed

[0084] Compound Wenqingyin microemulsion was prepared at a temperature of 35°C, a stirring time of 0.5 h, and four different rotation speeds of 200 r / min, 400 r / min, 600 r / min, and 800 r / min to investigate the effects of rotation speed on the particle size and drug loading of the microemulsion.

[0085] Table 4 Effects of different stirring speeds on the particle size and drug loading of the microemulsion

[0086]

[0087] With the increase of the stirring speed, the drug loading increased and the particle size of the microemulsion decreased. When the rotation speed increased to 800 r / min, the drug loading increased significantly, but the particle size also increased significantly. Therefore, the stirring speed was selected as 600 r / min.

[0088] 2.7.3 Investigation of stirring time

[0089] Compound Wenqingyin microemulsion was prepared at a temperature of 35°C and a rotation speed of 600 r / min at four different times of 0.5 h, 1 h, 1.5 h, and 2 h to investigate the effects of time on the particle size and drug loading of the microemulsion.

[0090] Table 5 Effects of different stirring times on the particle size, PdI, and drug loading of the microemulsion

[0091]

[0092] Before 1.5 h, prolonging the stirring time had little effect on the drug loading and particle size of the microemulsion. When the time increased to 2 h, the drug loading increased significantly, but the particle size also increased significantly. Considering high efficiency and energy conservation, the stirring time was selected as 0.5 h.

[0093] To sum up, the conditions for the preparation process of the microemulsion were determined as a temperature of 35°C, a rotation speed of 600 r / min, and a time of 0.5 h.

[0094] 2.8 Investigation of the physicochemical properties of the microemulsion

[0095] 2.8.1 Appearance

[0096] Observed whether the Wenqingyin microemulsion was in a transparent and clear state and whether there was a Tyndall effect.

[0097] As Figure 4 showed, the Wenqingyin microemulsion presented a transparent and clear state and there was a Tyndall effect.

[0098] 2.8.2 Identification of microemulsion type

[0099] The identification methods of microemulsion type include: centrifugation method, dilution method, and staining method.

[0100] (1) Centrifugation method: Take an appropriate amount of the Wenqingyin microemulsion with a determined prescription and place it in a centrifuge tube. Centrifuge at 10,000 r / min for 15 min to examine whether the sample layers.

[0101] After centrifugation, the Wenqingyin microemulsion did not show any layering phenomenon.

[0102] (2) Staining method (as Figure 4 shown): Take equal amounts of the Wenqingyin microemulsion and add appropriate amounts of methylene blue and Sudan Red III respectively. Observe the diffusion rate and color change of the two dyes in the microemulsion to determine the type of microemulsion.

[0103] The results showed that since methylene blue is a water-soluble dye, it can quickly diffuse in the microemulsion and form a uniform blue solution. While Sudan Red III is a fat-soluble dye, when added to the microemulsion, it was found to float on the upper layer, showing an obvious layering phenomenon.

[0104] (3) Dilution method: Take an appropriate amount of the Wenqingyin microemulsion with a determined prescription, dilute it with water by different multiples and let it stand overnight, then observe the solution state.

[0105] The results showed that after the Wenqingyin microemulsion was diluted with water by different multiples, there was no layering or turbidity phenomenon, and the solutions with different dilution multiples still had no layering and precipitation after standing overnight, indicating that the Wenqingyin microemulsion was a homogeneous and stable solution after being diluted with water.

[0106] In summary, the prepared microemulsion was of the O / W type.

[0107] 2.8.3 Particle size distribution, potential and viscosity of Wenqingyin microemulsion

[0108] The particle size is one of the most important characteristics of the microemulsion. The size of the microemulsion particle size will directly affect the quality of the microemulsion preparation; the potential of the microemulsion is an important indicator reflecting the stability of the microemulsion. Usually, the higher the charge homogeneity of the microemulsion, the better the stability, and there is research showing that the negative charge on the surface of the microemulsion is beneficial to the penetration of droplets through the skin. The particle size and distribution of the microemulsion will affect its viscosity. Usually, the smaller the particle size and the more uniform the distribution, the lower the viscosity of the microemulsion may be. And in the drug delivery system, the microemulsion with low viscosity is more likely to penetrate the skin or mucosal barrier, thereby improving the drug absorption rate and bioavailability. Therefore, in this experiment, a laser particle size analyzer was used to measure the particle size distribution and Zeta potential of the microemulsion, and a rotary viscometer was used to measure the viscosity of the microemulsion.

[0109] The measured particle size of the Wenqingyin microemulsion was 72.93 ± 2.93 nm, which was within the range of 1 - 100 nm for microemulsion particle size; the measured Zeta potential was -16.29 ± 0.63 mv, indicating that the potential distribution of the microemulsion system was negatively charged and the charge homogeneity was good, and the microemulsion had good stability. The viscosity of the Wenqingyin microemulsion measured by a rotary viscometer was 40.48 ± 1.55 mPa·s.

[0110] 2.8.4 Investigation of the Microscopic Morphology of Microemulsion

[0111] Samples were prepared by negative staining method: An appropriate amount of microemulsion was taken and dropped on a copper mesh with a Formvar support film, and negatively stained with 2% phosphotungstic acid solution for 1 - 2 min. The excess liquid on the copper mesh was blotted dry with filter paper and volatilized under natural conditions, and then observed under TEM (transmission electron microscope) for the morphology of the microemulsion.

[0112] It can be seen from Figure 7 that the WQYD microemulsion is spherical or nearly spherical, with a smooth surface, evenly distributed in the field of view and without aggregation phenomenon.

[0113] 2.8.5 Stability Test of Microemulsion

[0114] (1) The microemulsion samples, including blank microemulsion and drug-loaded microemulsion, were centrifuged at 10000 rpm for 30 min, and whether there was phase separation and whether the morphology of the microemulsion was maintained well and remained clear were observed.

[0115] (2) Three batches of microemulsion samples were taken and placed in a refrigerator at -4°C for 12 h, then taken out and restored to room temperature, and whether phenomena such as stratification, oil floating, and oil-water separation occurred were observed.

[0116] (3) Similarly, three batches of microemulsion samples were taken and placed in an oven at 40°C for 12 h, then taken out and restored to room temperature, and whether phenomena such as stratification, oil floating, and oil-water separation occurred were observed.

[0117] The results of the stability experiment showed that after the high-speed centrifugation experiment, cold resistance experiment, and heat resistance experiment, the WQYD microemulsion did not show stratification and still maintained a clear state, indicating that the prepared microemulsion had good thermodynamic stability.

[0118] Example 3 Preparation of WQYD Microemulsion Gel

[0119] The microemulsion drug delivery system can increase the drug loading of poorly soluble drugs and promote the transdermal absorption of drugs. However, as a skin drug delivery preparation, the WQYD microemulsion has low viscosity, large fluidity, and poor adhesion to the skin. Shaping the microemulsion with a suitable gel matrix can effectively increase the viscosity of the microemulsion, make it easy to adhere to the skin, and exert its medicinal effect.

[0120] 3.1 Screening of Gel Matrices

[0121] The commonly used gel matrices Carbopol-940 (CP-940), sodium polyacrylate (NP-700), hydroxypropyl methylcellulose (HPMC), and sodium carboxymethylcellulose (CMC-Na) were selected, and a small amount of water was added to swell them respectively, and solutions with a certain concentration were prepared. Then, an appropriate amount of WQYD microemulsion solution was slowly added to them while stirring, and the appearance and properties of the formed microemulsion gel were observed to screen for suitable gel matrices.

[0122] Table 6 Screening of Gel Matrix

[0123]

[0124] In order to more clearly observe the swelling state and color of these four matrix materials after swelling, the WQ extract with a relatively dark color was not added during the screening of matrix types. Compared with external matrices such as NP-700, HPMC, and CMC-Na, CP940 has a relatively fast swelling rate and a better appearance state. After being neutralized with alkali, the gel can quickly form at a relatively low concentration. Therefore, CP940 was used as the gel material.

[0125] 3.2 Determination of Gel Concentration

[0126] 3.2.1 Preparation of Microemulsion Gel

[0127] Respectively take 4 g of the WQ microemulsion, add the gel skeleton CP940 to make it completely swell, and prepare different concentrations (2%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%). Then add 0.5% triethanolamine and stir continuously to form a gel. By comprehensively scoring the appearance properties, viscosity, ductility, and centrifugal stability of the WQ microemulsion gel, the concentration of the microemulsion gel was determined.

[0128] 3.2.2 Evaluation Indexes

[0129] ① Observe the smoothness, uniformity, and fineness of the formed microemulsion gel; ② Use a rotary viscometer to measure the viscosity of the microemulsion gel; ③ Weigh 0.1 g of the sample, press a 100 g weight on two glass slides, let it stand for about 5 min, and measure the diameter of the formed circle to compare the ductility of each microemulsion gel; ④ Centrifuge at 6000 r / min for 15 min and observe whether the microemulsion gel is layered. According to the above evaluation indexes, the scoring criteria were formulated as shown in Table 3-2 below.

[0130] Table 7 Scoring Criteria for Microemulsion Gel

[0131]

[0132] 3.2.3 Results

[0133] Table 8 Comprehensive Scoring Results of Microemulsion Gel

[0134]

[0135] As can be seen from the table, when the dosage of CP940 is 3.5%, the comprehensive score of the microemulsion gel is relatively high. Therefore, 3.5% CP940 was selected as the gel matrix.

[0136] 3.3 Determination of Glycerol Concentration

[0137] 3.3.1 Preparation of Microemulsion Gel

[0138] The water content of the aqueous gel matrix is relatively large. When the storage conditions are poor or the placement time is too long, it is easy to lose water, resulting in difficulty in spreading on the skin. Therefore, suitable moisturizers are often added. Commonly used moisturizers include: propylene glycol, glycerol, sorbitol, betaine, etc. Research shows that compared with moisturizers such as betaine and sorbitol, the moisturizing performance of propylene glycol and glycerol is more stable, and the moisturizing ability is more persistent. Compared with propylene glycol, glycerol has good moisturizing effect and less irritation to the skin. Therefore, considering safety and adaptability, glycerol is selected as the moisturizer. Since the common dosage of glycerol in the gel is 5% - 15%, with other conditions in the fixed prescription remaining unchanged, 0%, 5.0%, 10%, and 15% are selected as the investigation concentrations of the glycerol addition amount, and the Wenqingyin microemulsion gel is prepared respectively. Using the evaluation criteria, moisturizing rate and water loss rate of the microemulsion gel in Table 3 - 2 as evaluation indicators, the appropriate glycerol concentration range is screened out.

[0139] 3.3.2 Determination of Moisturizing Rate

[0140] The moisturizing rate is the percentage of the mass of retained water in the microemulsion gel at different time points. Weigh an appropriate amount of the microemulsion gel precisely into a glass dish that has been dried to a constant weight (m), and record the total mass as m 0 , evenly spread it on a glass slide, place it in a desiccator at room temperature with a relative humidity of 43%, and measure the mass of the glass dish and the microemulsion gel (m t ) at 0, 6, 12, 24, and 36 h respectively. Calculate the moisturizing rate according to the following formula.

[0141] Moisturizing rate (%) = (m t - m) / (m 0 - m) × 100%

[0142] 3.3.3 Determination of Water Loss Rate

[0143] Take a glass dish dried to a constant weight, record the mass as M 2 , then take an appropriate amount of the microemulsion gel, spread it evenly in the dried glass dish, record the total weight of the microemulsion gel and the glass dish as M 1 , place it in an oven at 60°C for 1 h, take it out, let it cool in a desiccator, and weigh the total mass after drying, denoted as M 3 , and calculate the water loss rate of the microemulsion gel with different concentrations of glycerol according to the formula respectively.

[0144] Water loss rate (%) = (M 3 - M 2 ) / (M 1 - M 2 ) × 100%

[0145] 3.3.4 Results (such as Figure 8 , Figure 9 )

[0146] Table 9 Comprehensive Scoring Results of Microemulsion Gel

[0147]

[0148] In summary, with the increase of glycerol concentration, the moisture retention rate increases and the water loss rate decreases. When the glycerol concentration is 10%, the microemulsion gel has good moisturizing effect, comfortable skin feel and is not sticky. However, when the glycerol concentration continues to increase to 15%, the gel is too viscous and has a greasy feeling. Therefore, the glycerol concentration is determined to be 10%.

[0149] 3.4 Determination of Triethanolamine Concentration

[0150] Take 4 g of Wenqingyin microemulsion respectively, add 3.5% CP940 to make it swell completely, then add 10% glycerol, and finally add 0.5%, 1%, 1.5%, 2.0% triethanolamine respectively, and stir continuously to form a gel. The concentration of the microemulsion gel is determined by comprehensively scoring the appearance properties, viscosity, ductility and centrifugal stability of the Wenqingyin microemulsion gel.

[0151] Table 10 Comprehensive Scoring Results of Microemulsion Gel

[0152]

[0153] It can be seen from the results that with the increase of triethanolamine concentration, the microemulsion gel will liquefy and liquid medicine will precipitate during centrifugation. When the triethanolamine concentration is 1%, the comprehensive score is the highest and the ductility is the best. Therefore, the triethanolamine concentration is determined to be 1%. 3.5. Research on the Quality Evaluation System of Wenqingyin Microemulsion Gel

[0154] Observe the appearance properties of Wenqingyin microemulsion gel, measure its viscosity, pH value and total content of index components, and investigate its preliminary stability, transdermal performance and skin irritation.

[0155] 3.5.1 Appearance Properties

[0156] As Figure 10 shown, the Wenqingyin microemulsion gel is a yellowish-brown, uniform, delicate viscous semi-solid.

[0157] 3.5.2 Determination of Viscosity, pH Value and Total Content of Index Components of Microemulsion Gel

[0158] The viscosity of Wenqingyin microemulsion gel is measured to be 43700.00±0.23 mPa·s using a rotary viscometer; the pH value of the microemulsion gel is measured to be 5.19±0.22 using a pH meter, which is within the optimal skin pH range for humans (4.5 - 6.5); the total content of index components of the microemulsion gel is measured to be 8.760±0.913 mg / g by HPLC.

[0159] 3.5.3 Investigation on the Stability of Microemulsion Gel

[0160] Centrifuge the microemulsion gel at 4000 r / min for 30 min first, and observe whether there is phase separation and whether the morphology of the microemulsion gel remains good.

[0161] Then alternately place the microemulsion gel at room temperature of 25 °C, in a 4 °C refrigerator environment, in a -20 °C refrigerator environment, and in a 40 °C oven environment, each time for about 60 min. Then observe whether there is phase separation under different temperature environment changes and whether the morphology of the microemulsion gel is damaged when returning to the room temperature environment, so as to judge the stability of the microemulsion at different temperatures. Finally, in order to verify the long-term stability of the preparation, seal and store each microemulsion gel that has completed the above tests in a desiccator at room temperature and a relative humidity of 43% for 1 month, and then perform centrifugation again (parameters are the same as before), and observe whether there is phase separation and whether the morphology remains good.

[0162] The results show that the microemulsion gel does not show delamination after centrifugation, and after different temperature environment changes and long-term stability tests, it can still maintain its original state, with uniform and delicate texture during application, indicating that the prepared microemulsion gel has good stability.

[0163] 3.5.4 In Vitro Transdermal Absorption Experiment

[0164] During the experiment, take excised rat skin, thaw it in physiological saline, dry the water on the skin surface with filter paper, place the treated skin with the stratum corneum facing up flat on the receiving pool, fix the diffusion cell on the receiving pool with an iron clamp, add physiological saline containing 30% ethanol as the receiving solution to the receiving pool, add a magnetic stirrer, and finally add 0.3 g of Wenqingyin microemulsion, Wenqingyin gel, and Wenqingyin microemulsion gel respectively to the supply pool. Place the prepared diffusion cell in an in vitro transdermal diffusion instrument, adjust the water bath temperature to (35 ± 1) °C, and keep a constant speed of 300 r·min -1 . At 1, 2, 4, 6, 8, 10, 12, and 24 h after the start of the experiment, take 1 ml of sample from the receiving pool and immediately supplement an equal volume of blank receiving solution. Measure the total content of the index components of the taken samples by HPLC method. Calculate the cumulative amount of permeation per unit area Q of the index components according to the following formula n (μg / cm 2 ). After 24 h of the transdermal experiment, take out the skin, wash the surface drug with physiological saline, and dry the water with filter paper. Then cut the skin into pieces, put them into a centrifuge tube, add an appropriate amount of methanol, ultrasonicate for 30 min, centrifuge at 3500 r / min for 10 min, take the supernatant and measure the total content of the index components by HPLC method, so as to calculate the skin retention amount Q s (μg / cm 2 ).

[0165]

[0166] Among them, C n represents the drug mass concentration measured at the nth sampling point, V represents the total volume of the receiving solution in the receiving pool (15 mL), A represents the effective diffusion area (1.539 cm 2 ), C i represents the drug mass concentration in the receiving solution at the i-th sampling, V i represents the volume of each sampling (1 mL); V s represents the total volume of the skin extract, and C is the drug concentration in the skin extract.

[0167] At 24 h after drug administration, the cumulative permeation amounts Q n of Wenqingyin microemulsion, Wenqingyin gel and Wenqingyin microemulsion gel are respectively (1916.84 ± 1.46) μg·cm -2 , (1685.34 ± 1.22) μg·cm -2 and (1995.93 ± 1.57) μg·cm -2 ; the skin retention amounts Q s of Wenqingyin microemulsion, Wenqingyin gel and Wenqingyin microemulsion gel are respectively (23.76 ± 0.48) μg·cm -2 , (17.62 ± 1.79) μg·cm -2 and (21.56 ± 1.13) μg·cm -2 . The results show that the transdermal amount of the ordinary gel is the lowest and the skin retention amount is also the least; since the microemulsion is a thermodynamically stable nano-system with small particle size, good fluidity, and containing surfactants and co-surfactants, it reduces the skin barrier resistance to a certain extent, so its transdermal rate is fast and the diffusion rate into the skin surface is also fast, and its skin retention amount is the largest; while the microemulsion gel has the structure of the microemulsion, which can promote the drug to enter the skin, but at the same time, because the viscosity of the microemulsion gel is larger than that of the microemulsion, the drug needs to overcome more resistance to release from the preparation into the skin, so the skin retention amount will be less than that of the microemulsion, but the contents of both will be higher than that of the ordinary gel. And through the cumulative transdermal amount results, it is also found that the cumulative transdermal amount of the microemulsion is higher than that of the microemulsion gel before 12 h, and the cumulative transdermal amount of the microemulsion gel increases slowly after 12 h and finally is higher than that of the microemulsion, which also indicates that the active ingredients in the microemulsion show the characteristic of rapid release, and after being prepared into the microemulsion gel, the release of each component is more constant, with a certain sustained-release effect, and basically does not affect the in vitro release of the drug.

[0168] By fitting the transdermal data of Wenqingyin microemulsion gel, its release mechanism was deeply explored, as shown in Table 11. If the drug is released at a constant rate and does not depend on the concentration, it conforms to the zero-order kinetic model, which is often used to describe the drug release process of controlled-release preparations. If the drug release rate is proportional to the drug concentration and slows down with the decrease of the drug concentration, it conforms to the first-order kinetic model; if the drug release is mainly diffusion-based, it conforms to the Higuchi kinetic model, and these two models are often used to describe the drug release process of sustained-release preparations. If the drug release is jointly controlled by diffusion and matrix erosion, it conforms to the Ritger-Peppas kinetic model, and it is necessary to judge whether the drug belongs to sustained-release or controlled-release according to the mechanism. The results showed that the in vitro release of Wenqingyin microemulsion gel within 24 h was most in line with the first-order kinetic model, which also means that Wenqingyin microemulsion gel has a certain sustained-release effect.

[0169] Table 11 Model fitting of in vitro transdermal amount-time of Wenqingyin microemulsion gel

[0170]

[0171] 3.5.5 Skin irritation investigation

[0172] 3.5.5.1 Experimental animal treatment

[0173] Six rats were selected. According to the requirements of the "Technical Guidelines for the Study of Irritation and Hemolysis of Traditional Chinese Medicines and Natural Medicines", the left and right sides of the same body were used for self-comparison. The right side was normal skin, and the left side was damaged skin. The same side was divided by a marker pen. The upper end was the blank group smeared with pure water, and the lower end was the experimental group smeared with Wenqingyin microemulsion gel. Hair was removed 24 h before the experiment, and the hair removal area was 3 cm × 3 cm on each side; the damaged skin was scratched with a sandpaper in a "well" shape after hair removal until bleeding occurred. And the scoring criteria were formulated according to the "Technical Guidelines for the Study of Irritation and Hemolysis of Traditional Chinese Medicines and Natural Medicines".

[0174] Table 12 Scoring criteria for skin irritation reaction

[0175]

[0176]

[0177] Table 13 Evaluation criteria for skin irritation intensity

[0178]

[0179] 3.5.5.2 Investigation of skin irritation after single administration

[0180] Take 0.5 ml of Wenqingyin microemulsion gel and directly apply it to the depilated skin on the lower ends of both sides of the rats. Then cover it with two layers of gauze (3 cm × 3 cm), and fix it with non-irritating adhesive tape; use pure water as a control on the upper ends of both sides of the rats. After applying for 4 h, clean the administration site with warm water, and observe and record with the naked eye whether there are erythema, edema and other conditions at the application site at 24, 48 and 72 h.

[0181] Table 14 Comparison of the results of single-dose skin irritation test

[0182]

[0183]

[0184] 3.5.5.3 Investigation of skin irritation after multiple doses

[0185] Take 0.5 ml of Wenqingyin microemulsion gel and directly apply it to the depilated skin on the lower ends of both sides of the rats. Use pure water as a control on the upper ends. Administer the drug continuously for 7 days. One hour before each administration time point, first wash the drug remaining on the left and right sides of the rats and the skin with warm water, and observe whether there are erythema and edema on the skin at 24 h after administration.

[0186] Table 15 Comparison of the results of multiple-dose skin irritation test

[0187]

[0188] From the above experimental results, it can be seen that in the single-dose skin irritation test and the multiple-dose skin irritation test, no skin irritation reactions such as erythema and edema were observed at the drug application sites on the intact skin and damaged skin of rats for Wenqingyin microemulsion gel, indicating that the Wenqingyin microemulsion gel developed in this project has good safety. The results of this experiment can also provide a basis for safety in later further experimental research and product development.

[0189] Example 4 Pharmacodynamic study of Wenqingyin microemulsion gel

[0190] 4.1 Animal grouping

[0191] Fifty 8-week-old healthy female BALB / c mice, SPF grade, with a body weight of (18 ± 2) g, were randomly divided into 5 groups: blank group, model group, positive group, negative group and treatment group.

[0192] 4.2 Modeling and drug administration methods

[0193] As Figure 12As shown, 50 mice were adaptively fed for one week. One day before the experiment, the back hair of each mouse was shaved off (area 2 cm × 3 cm) using a hair clipper. A sensitizer was prepared by completely dissolving DNCB in a matrix solution (acetone: olive oil = 3:1) to prepare 0.5% and 1% DNCB solutions. Except for the blank control group, in the other groups, on the 1st, 4th, and 7th days of the experiment, 100 μL of 1% DNCB solution was evenly applied to the back skin of the mice using a pipette for sensitization induction, and then from the 9th to the 25th day of the experiment, 100 μL of 0.5% DNCB solution was applied to the back of the mice every other day for re-sensitization. The appearance of AD-like symptoms such as skin erythema, scales, and crusts on the back of the mice in the early stage was regarded as successful modeling. At the same time, from the 13th day of the experiment to the end of the experiment, a drug (0.5 ml / mouse) was applied to the depilated area on the back of the mice once a day. The blank control group and the model group were not given drugs. The positive group was given hydrocortisone butyrate cream, the negative group was applied with a blank microemulsion gel matrix, and the treatment group was applied with Wenqingyin microemulsion gel. Among them, on the day of inducing dermatitis, the drug was given again 4 hours later.

[0194] 4.3 Evaluation of the severity of skin dermatitis

[0195] On the 12th, 19th, and 28th days, the skin of the mice was photographed to compare the treatment process. The EASI scoring system was used to observe and score symptoms such as skin erythema, edema, and dryness (desquamation) on the back skin of the mice. The scores for each parameter were independently scored between 0 - 3 (0 = normal, 1 = mild, 2 = moderate, 3 = severe), thus generating a cumulative score from 0 - 9. The evaluation was independently completed by three researchers. The skin condition scoring criteria are shown in Table 16.

[0196] Table 16 Skin condition scoring criteria

[0197]

[0198] As Figure 13 shown, after DNCB sensitization, symptoms such as epidermal thickening, erythema, and desquamation gradually appeared on the skin of the mice. After one week of treatment with Wenqingyin microemulsion gel, the skin inflammation of the mice gradually subsided, the epidermal thickening was relieved. After two consecutive weeks of treatment, the epidermal thickness of the mice basically returned to normal, and the desquamation situation was greatly improved, and its treatment effect was close to that of the positive group. 4.4 Determination of the spleen index of mice, as Figure 14 shown

[0199] To evaluate the systemic adverse reactions related to the treatment, the body weights and spleens of the mice in each group were weighed and data analysis was performed. Spleen index (mg / g) = spleen weight (mg) / body weight (g) × 100%.

[0200] Compared with the blank group (Control), the spleen indices of the model group (Model) and the negative group (BlankME-gel) increased (p < 0.001), indicating that atopic dermatitis could cause overactivation and proliferation of immune cells in the spleen, infiltration of inflammatory cells, and splenomegaly. After treatment with Wenqingyin microemulsion gel (WQYME-gel), the spleen index of AD mice was significantly decreased (p < 0.001), which was basically close to that of the blank group. After treatment with hydrocortisone butyrate cream (Positive), the spleen index of mice also decreased significantly, but was lower than that of the blank group, indicating that glucocorticoids not only inhibited local reactions but also might overly weaken the systemic immune defense function. This further indicated that traditional Chinese medicine preparations could restore spleen function through immunomodulation rather than broad inhibition, so they might have better safety in long-term treatment.

[0201] 4.5 Histopathological examination of skin lesions Figure 15 as shown

[0202] Skin lesion tissues of mice in each group were taken, fixed with 10% formaldehyde solution, dehydrated with ethanol, cleared with xylene, embedded in paraffin, sectioned, stained with HE and TB, sealed with neutral gum, and the pathological changes of the back skin were observed under a microscope.

[0203] As can be seen from the above pictures, the blank group (Control) was normal skin tissue, and the epidermis and dermis were regular. The HE staining results of the model group (Model) and the negative group (BlankME-gel) showed hyperkeratosis, epidermal thickening, and downward epidermal projections in the skin of mice, which were typical symptoms of atopic dermatitis. At the same time, the TB staining results also showed a significant increase in the number of mast cells in the dermis of mice. The Wenqingyin microemulsion gel treatment group (WQYME-gel) showed that the degree of keratinization of mice was greatly improved, the epidermal and downward projection phenomena were also significantly reduced, the skin had a tendency to return to the normal state, and the number of mast cells in the dermis was also reduced compared with the model group. The results were similar to those of the positive group, indicating that Wenqingyin microemulsion gel could significantly improve the skin condition of AD mice and promote recovery.

[0204] 4.6 ELISA was used to detect the levels of inflammatory factors in the serum and back skin of mice Figure 16 、 Figure 17 as shown

[0205] (1) Blood was collected from the orbital sinus of mice and allowed to stand at room temperature for 2 h, then centrifuged at 3000 r / min for 15 min. The serum was collected and stored at -20 °C. The levels of IL-4, IL-6, IL-1β, TNF-α and IgE in each group were detected by ELISA. Specimens, standards and detection antibodies labeled with HRP were successively added to the coated microwells pre-coated with mouse plasma antibodies, incubated and washed thoroughly. TMB substrate was used for color development. TMB was converted into blue under the catalysis of peroxidase and into the final yellow under the action of acid. The color depth was positively correlated with the concentration of inflammatory cytokines in the mouse plasma to be measured in the sample. The absorbance (OD value) was measured at a wavelength of 450 nm with an enzyme-linked immunosorbent assay reader, and the concentration of inflammatory factors was calculated according to the standard curve.

[0206] (2) The back tissue of mice was homogenized and centrifuged to obtain the supernatant. An enzyme-linked immunosorbent assay plate pre-coated with specific capture antibodies was used. After washing, non-specific sites were blocked with BSA. Subsequently, standards and samples diluted in gradients were added, incubated to allow the target factor to bind to the capture antibody, washed, and then detection antibodies labeled with HRP were added successively. After each incubation, thorough washing was performed to remove unbound substances. TMB substrate was added for color development. After terminating the reaction, the absorbance (OD value) was measured at 450 nm, and the concentration of inflammatory factors was calculated according to the standard curve.

[0207] The results showed that the levels of IgE, IL-4, IL-6, IL-1β and TNF-α in the serum and skin tissues of the mice in the model group were significantly higher than those of the mice in the blank group after modeling, and the difference was statistically significant (P < 0.05). After local administration of Wenqingyin microemulsion gel, the IgE level in the serum and skin tissues could be significantly reduced, the expression of Th2-type immune factors IL-4 and IL-6 was inhibited, and the concentration of pro-inflammatory mediator IL-1β was down-regulated, and the differences were all statistically significant (P < 0.05). However, after treatment with Wenqingyin microemulsion gel, only the concentration of TNF-α in the serum could be significantly reduced, and the concentration of TNF-α in the skin could not be reduced.

[0208] 4.7 Detection of the expression of proteins related to the PI3K / AKT and MAPK signaling pathways in the back tissue by Western blot

[0209] Approximately 100 mg of skin tissue samples were weighed, ground into powder, and homogenate was added to the lysis buffer and lysed on ice for 30 min. The lysate was collected with 1.5 mL Eppendorf tubes, centrifuged at 10000 rpm for 15 min at 4 °C, the supernatant was collected, aliquoted and stored at -80 °C for later use. The protein content was measured by the BCA method, and protein bands were separated by SDS-PAGE. The proteins on the gel were transferred to a PVDF membrane, blocked with 5% skim milk powder for 1 h, and then incubated. Finally, ECL chemiluminescent reagent was used for developing and imaging.

[0210] Those skilled in the art to which this application pertains can make various modifications, supplements, or use similar means of substitution to the described specific embodiments, but will not deviate from the inventive concept of this application or exceed the scope defined by the appended claims.

Claims

1. A Chinese medicine compound microemulsion gel for treating atopic dermatitis, characterized in that: It comprises a Wenqingyin microemulsion and a gel skeleton, wherein the Wenqingyin microemulsion is loaded on the gel skeleton, and the gel skeleton is Carbomer-940; The Wenqingyin microemulsion comprises 2.546% oleic acid, 12.727% castor oil polyoxyethylene ether, 12.727 1,2-pentanediol and 72% aqueous phase.

2. The Chinese medicine compound microemulsion gel for treating atopic dermatitis according to claim 1, characterized in that: The microemulsion gel comprises 2%-4.5% of CP940, 0%-15% of glycerol and 0.5%-2% of triethanolamine.

3. The Chinese medicine compound microemulsion gel for treating atopic dermatitis according to claim 2, characterized in that: The microemulsion gel comprises 3.5% of CP940, 10% of glycerol and 1% of triethanolamine.

4. A method for preparing a Chinese medicine compound microemulsion gel for treating atopic dermatitis, characterized in that: The following steps are involved: S1. Extraction and concentration of warm and clear drinking water extract; S2. The Wenqingyin water extract extracted in step S1 is used as the aqueous phase to prepare the Wenqingyin microemulsion; S3. Add the Wenqingyin microemulsion prepared in step S2 to the gel skeleton CP940 to completely swell and prepare a microemulsion gel.

5. The method for preparing a Chinese medicine compound microemulsion gel for treating atopic dermatitis according to claim 4, characterized in that: The step S1 specifically comprises: weighing pieces of Chinese Angelica sinensis, Chuanxiong, White Peony Root, Rehmannia Glutinosa, Scutellaria baicalensis, Coptis chinensis, Phellodendron amurense, and Gardenia jasminoides, soaking them in 47% ethanol at a solid-liquid ratio of 1:25 for 30 min, refluxing extraction for 115 min, filtering through four layers of gauze while hot, repeating the extraction twice, and finally combining the extracts, concentrating them by rotary evaporation at 60° C., and using them as the aqueous phase of the microemulsion.

6. The method for preparing a Chinese medicine compound microemulsion gel for treating atopic dermatitis according to claim 5, characterized in that: The step S2 is specifically as follows: S2.

1. Screening of oil phase, surfactant and co-surfactant; S2.

2. Start with Km=1:1, extend the surfactant and co-surfactant to both sides and mix them evenly, then mix them evenly with the oil phase at a mass ratio of 1:9-9:1, and use distilled water titration method while adding and stirring to prepare warm and clear drink microemulsion; S2.

3. Centrifuge the Wenqingyin extract at 4000 r / min for 10 min, collect the supernatant, and concentrate it under reduced pressure to an appropriate amount as the microemulsion aqueous phase. Determine 0.75 g / mL of aqueous extract as the optimal aqueous extract concentration.

7. The method for preparing a Chinese medicine compound microemulsion gel for treating atopic dermatitis according to claim 6, characterized in that: In the step S2.1, the oil phase is oleic acid, the surfactant is castor oil polyoxyethylene ether, and the co-surfactant is 1,2-pentanediol.

8. The method for preparing a Chinese medicine compound microemulsion gel for treating atopic dermatitis according to claim 7, characterized in that: In step S2.2, the heating temperature for preparing the microemulsion is 35°C, the stirring speed is 600 r / min, and the stirring time is 0.5 h.

9. The method for preparing a Chinese medicine compound microemulsion gel for treating atopic dermatitis according to claim 8, characterized in that: The step S3 is specifically as follows: S3.

1. Take an appropriate amount of Wenqingyin microemulsion and add the gel skeleton CP940 to make it completely swollen; S3.

2. Add 1% triethanolamine dropwise and stir continuously to form a gel; S3.

2. Add 10% glycerol and stir continuously to form a finished gel.

Images