Anhydrous self-emulsifying drug-loaded emulsion based on deep eutectic solvent and preparation method of anhydrous self-emulsifying drug-loaded emulsion

Abstract

The invention belongs to the technical field of anhydrous emulsions, and discloses an anhydrous self-emulsifying drug-loaded emulsion based on a deep eutectic solvent and a preparation method thereof.The preparation method comprises the following steps that 1, betaine and a hydrogen bond donor are mixed, the deep eutectic solvent is prepared through a mixed heating method, a drug is dissolved in the deep eutectic solvent, and a drug solution is prepared; the hydrogen bond donor is levulinic acid or lactic acid; (2) mixing Tween 80 and Span 80 according to a mass ratio of (1-2): 1 to obtain a surfactant, adding absolute ethyl alcohol as a co-emulsifier, adding isopropyl myristate, and uniformly stirring and mixing to obtain a dispersion liquid; and (3) dropwise adding the drug solution in the step (1) into the dispersion liquid in the step (2), and stirring at the same time to finally form the anhydrous self-emulsifying drug-loaded emulsion. According to the invention, the loading capacity, the stability and the bioavailability of the medicine can be obviously improved; in addition, the efficiency of transdermal drug delivery of the emulsion is high, and the emulsion can be applied to skin external preparations.

Description

Technical Field

[0001] The present invention belongs to the field of anhydrous self-emulsifying emulsion drug-carrying systems, and mainly relates to a preparation method and application of an anhydrous self-emulsifying drug-carrying emulsion based on a deep eutectic solvent. Background Art

[0002] Traditional water-in-oil (W / O) self-emulsifying systems, due to the presence of an internal aqueous phase, are unable to effectively load hydrophobic drugs and are prone to drug precipitation. Existing oil-in-oil (O / O) anhydrous emulsions, on the other hand, suffer from high emulsifier costs and complex processes. Existing technologies struggle to achieve a high drug loading capacity, stable emulsification, and industrial feasibility.

[0003] Currently, traditional oil-in-water (O / W) or water-in-oil (W / O) emulsions are unable to effectively improve the solubility and dissolution rate of poorly soluble drugs, thereby enhancing their bioavailability. For example, rutin, also known as vitamin P and rutin, is chemically known as 3',4',5,7-tetrahydroxyflavone-3-rutin. It is a flavonoid compound widely found in plants and exhibits various biological activities and pharmacological effects. In recent years, with the deepening of research on rutin, its antioxidant, anti-inflammatory, anti-cancer, and cardiovascular protective effects have gradually been revealed, showing broad application prospects. However, previous studies have shown that rutin is poorly soluble in both water and most oils, making it a poorly soluble component in both oil and water. Therefore, its application is subject to certain limitations.

[0004] Self-emulsifying drug delivery systems (SEDDS) spontaneously form microemulsions or nanoemulsions in the gastrointestinal tract through the spontaneous emulsification of an oil phase, surfactants, and co-surfactants, increasing the specific surface area of ​​the drug and thus significantly improving the solubility and absorption rate of the drug. However, its traditional structure that relies on an aqueous phase (such as W / O or O / W systems) has bottlenecks such as low hydrophobic drug loading and easy degradation of water-sensitive components. To address this technical pain point, anhydrous emulsions break through the limitations of traditional emulsion systems through innovative design: completely replacing the aqueous phase with an immiscible non-aqueous two-phase (such as an oil-in-oil O / O structure), combining multiple mechanisms such as the directional arrangement of surfactant molecules, polymer spatial stabilization, and solid particle interface anchoring, to construct a highly stable anhydrous self-emulsifying system (N-SEDDS). This not only increases the hydrophobic drug loading to 2-3 times that of traditional systems, but also improves the 24-hour controlled release rate and drug content retention rate, while avoiding the risk of drug hydrolysis caused by the aqueous phase. Although this technology has made breakthroughs in drug loading performance, its industrialization still needs to optimize long-term stability (such as inhibiting Ostwald ripening) and reduce process costs. For example, Jaitely et al. studied the effects of different emulsifiers on the stability of castor oil / silicone oil anhydrous emulsions. The results showed that the stability of oil-in-oil emulsions prepared by Tween 80, Spann 60, polyoxyethylene (10) hexadecyl ether (Brij 56) and polyoxyethylene (2) hexadecyl ether (Brij 52) and triethanolamine oleate can only be maintained for 12 hours, and octylphenyl poly (n) ethylene oxide Triton X 100 and Triton X114 can only be maintained for 7 days. ([1]. Jaitely V, Sakthivel T, Magee G, et al. Formulation of oil in oil emulsions: Potential drug reservoirs for slow release [J]. Journal of Drug Delivery Science and Technology, 2004, 14 (2): 113-117). Summary of the Invention

[0005] To address these issues, the present invention proposes a novel anhydrous self-emulsifying drug delivery system (N-SEDDS) that utilizes a deep eutectic solvent (DES) to replace the internal aqueous phase of traditional self-emulsifying emulsions. This system utilizes DES as the internal phase, isopropyl myristate as the external oil phase, Tween 80 and Span 80 as mixed surfactants, anhydrous ethanol as a co-emulsifier, and rutin as a drug model. This system significantly improves the solubility, in vitro release, and skin permeability of rutin, and is widely applicable in the food, pharmaceutical, and cosmetics industries.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for preparing an anhydrous self-emulsifying drug-loaded emulsion based on a deep eutectic solvent comprises the following steps:

[0008] (1) mixing betaine and a hydrogen bond donor, preparing a deep eutectic solvent using a mixing heat method, and dissolving the drug in the deep eutectic solvent to prepare a drug solution; the hydrogen bond donor is levulinic acid or lactic acid;

[0009] (2) Tween 80 and Span 80 were mixed in a mass ratio of (1-2):1 as a surfactant, anhydrous ethanol was added as a co-emulsifier, and isopropyl myristate (IPM) was added, and the mixture was stirred and mixed to obtain a dispersion;

[0010] (3) The drug solution of step (1) is added dropwise to the dispersion of step (2) while stirring, to finally form an anhydrous self-emulsifying drug-loaded emulsion.

[0011] Preferably, in step (1), betaine and the hydrogen bond donor are mixed in a molar ratio of 1:2.

[0012] Preferably, in step (2), the mass ratio of Tween 80 to Span 80 is 2:1.

[0013] Preferably, in step (2), the mass ratio of surfactant to anhydrous ethanol is 2:1.

[0014] Preferably, the concentration of isopropyl myristate in the dispersion in step (2) is 20±5%.

[0015] Preferably, the mass ratio of the drug solution to the dispersion in step (3) is 1:(4±1).

[0016] Preferably, the drug in step (1) is rutin or luteolin; the concentration of the drug is 60-80 mg / g.

[0017] Preferably, in step (1), the deep eutectic solvent is prepared by mixing betaine and a hydrogen bond donor in a sealed container and continuously heating and stirring until a uniform transparent liquid is formed, and then storing the mixture at 70-90° C. for 1±0.5 hours to obtain a deep eutectic solvent, and the stirring speed is 600-800 r / min.

[0018] Preferably, the mixing condition of Tween 80 and Span 80 in step (2) is stirring at 60±20° C.; and the stirring condition of step (3) is stirring at a rotation speed of 600±100 r / min for 15±5 min.

[0019] Preferably, the anhydrous self-emulsifying drug-loaded emulsion based on the deep eutectic solvent can be used in the preparation of external skin preparations.

[0020] The present invention's anhydrous oil-in-DES (DES / O) self-emulsifying system, using DES as the internal phase, overcomes the limitations of traditional oil-in-water (O / W) or water-in-oil (W / O) emulsions, significantly improving the solubility and bioavailability of poorly soluble drugs. The resulting anhydrous drug-loaded self-emulsifying emulsion exhibits excellent stability while increasing drug solubility, bioavailability, and transdermal penetration.

[0021] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0022] (1) The particle size of the R-NSEDDS prepared in the present invention is 35.01±0.19 nm, and the polydispersity index (PDI=0.2037±0.0009) indicates that it has good monodispersity. The microscopic morphology confirms that the emulsion droplets after self-emulsification show the characteristics of multiple emulsions (multiple small droplets are enclosed in a large droplet), and the appearance is a regular spherical structure with uniform distribution.

[0023] (2) The system significantly improved the solubility and drug loading of rutin: 1:2 [Bet: Aa] DES increased the solubility of rutin by 166 times compared with the aqueous phase, with a rutin encapsulation efficiency of 77.3% and a drug loading of 0.932%. Dissolution experiments showed that the cumulative release of NSEDDS in simulated gastrointestinal fluid (58.48% in gastric fluid and 90.53% in intestinal fluid) was significantly higher than that of the raw drug. The in vitro release behavior was consistent with the first-order kinetic model (n = 0.51626), indicating that it achieved controlled release through a non-Fickian diffusion mechanism. Simulated digestion studies showed that the percentage of NSEDDS drug dissolution was 75.11 ± 1.5%, which was 1.26 times that of the rutin powder group, demonstrating good bioavailability optimization.

[0024] (3) The system has high transdermal delivery efficiency: using experimental Bama pig skin (thickness 0.8-1.0 mm) for transdermal experiments, the cumulative transdermal amount of NSEDDS in 24 hours reached 38.58±0.94μg / cm 2, which is twice that of rutin-PBS solution, and the retention rate of each layer of the skin is significantly improved (6.38% in the stratum corneum and 2.3% in the epidermis), and it is further verified that the smaller the emulsion particle size, the higher the efficiency of transdermal drug delivery.

[0025] (4) The system has high stability: the optimal formula anhydrous emulsion was stored at room temperature for more than 15 days without lipid aggregation, floating, stratification, or rutin precipitation. The particle size and dispersibility of the emulsion remained stable within the range of 30-70°C and pH = 1-9, and it exhibited good drug loading stability.

[0026] (5) Safety verification: Electron microscopy and histological analysis of pig skin structure after transdermal delivery of rutin showed that NSEDDS had no significant damaging effect on the skin surface and had excellent biocompatibility, providing safety assurance for its clinical application. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Pseudo-ternary phase diagrams of Examples 4 and 5; (a) is Example 4, and (b) is Example 5.

[0028] Figure 2 is the colostrum stability index of the emulsions of Examples 1 to 6.

[0029] Figure 3 These are comparison diagrams of the appearance of the emulsions of Examples 6 to 8 after 15 days of storage at room temperature; (a) is the appearance diagram on the first day; (b) is the appearance diagram after 15 days of storage.

[0030] Figure 4 (a) is an optical microscope image and (b) is a transmission electron microscope image of the emulsions of Examples 6 to 8.

[0031] Figure 5 Graphs showing (a) particle size change, (b) polydispersity index change, (c) zeta potential value change, and (d) rutin content change of Examples 6 to 8 after treatment at different temperatures.

[0032] Figure 6 Graphs showing (a) particle size change, (b) polydispersity index change, (c) zeta potential value change, and (d) rutin content change of Examples 6 to 8 after treatment with different pH values.

[0033] Figure 7 The rutin loading (LC) and encapsulation efficiency (EE) of the emulsions of Examples 6 to 8 are shown.

[0034] Figure 8 The dissolution rates of the emulsion of Example 8 and pure rutin in simulated gastric fluid (a) and simulated intestinal fluid (b) are shown.

[0035] Figure 9is the in vitro release of the emulsions of Example 8 and Example 10.

[0036] Figure 10 The cumulative permeation amount of rutin permeated through the skin of the emulsions of Examples 6 and 8 and the solution of Example 11 (a) and the retention rate of rutin in each layer of the skin (b) are shown.

[0037] Figure 11 It is a biological scanning electron micrograph of pig skin after the emulsion (a) of Example 8 and the solution (b) of Example 11 were diluted to a certain multiple and then delivered rutin transdermally.

[0038] Figure 12 It is a biological tissue section of pig skin (H&E staining) after the emulsion of Example 8 and the solution of Example 11 were diluted a certain multiple to deliver rutin through the skin. DETAILED DESCRIPTION

[0039] The present invention will be described in further detail below with reference to specific examples, but the embodiments of the present invention are not limited thereto. For process parameters not particularly noted, conventional techniques may be used.

[0040] Example 1

[0041] Betaine (Bet) was used as a hydrogen bond acceptor, and levulinic acid (Aa), lactic acid (La), sorbitol (Sor), fructose (Fru), and thymol (Thy) were used as hydrogen bond donors. Betaine was mixed with levulinic acid, lactic acid, ethylene glycol, and fructose in a molar ratio of 1:2 in a sealed glass vial, and betaine was mixed with thymol in a molar ratio of 1:3 in a sealed glass vial. A deep eutectic solvent was prepared using a mixing heat method with a heating temperature of 70-90°C and a magnetic stirring rate of 600-800 r / min until a uniform transparent liquid was formed. The mixture was then kept at this highest temperature for one hour and then returned to room temperature.

[0042] The viscosity of each DES at room temperature was measured using a rheometer.

[0043] Example 2

[0044] An excess of rutin was added to each set of DES from Example 1. The vials were placed in a 30°C water bath in the dark and stirred at 600 rpm for 48 hours. After dissolution equilibrium was reached, the mixture was filtered through a 0.45 μm membrane filter to remove undissolved drug, and the rutin solubility was determined by high-performance liquid chromatography.

[0045] Example 3

[0046] An excess of luteolin was added to each set of DES from Example 1. The vials were placed in a 30°C water bath in the dark and stirred at 600 rpm for 48 hours. After reaching dissolution equilibrium, the mixture was filtered through a 0.45 μm membrane filter to remove undissolved drug, and the solubility of luteolin was determined by high-performance liquid chromatography.

[0047] Table 1 Viscosity, rutin solubility and luteolin solubility of each group of DES in Examples 1-3

[0048]

[0049] Table 1 shows that DES formulations with different viscosity and drug solubility vary significantly. For example, the solubility of rutin in 1:2[Bet][Aa]DES is 91.44 mg / g. While not the highest, its low viscosity makes it suitable for emulsion preparation. While 1:1[Bet:Sor]DE has the highest solubility for rutin, it also has the highest viscosity and virtually no fluidity, limiting its use in emulsion preparation. Furthermore, DES can significantly improve the solubility of luteolin, increasing it by up to 3–4 orders of magnitude.

[0050] Example 4

[0051] The deep eutectic solvent was prepared using the mixed heat method. Betaine and levulinic acid in a molar ratio of 1:2 were mixed in a sealed glass vial, heated at 70-90°C and magnetically stirred at a rate of 600-800 rpm until a homogeneous transparent liquid was formed. The mixture was then kept at this highest temperature for one hour and then returned to room temperature. This was recorded as 1:2[Bet][Aa]DES.

[0052] Tween 80 and Span 80 were mixed in mass ratios of 1:1, 1:2 and 2:1, respectively, and recorded as Smix. Isopropyl myristate (IPM) and Smix were mixed in mass ratios of 1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2 and 9:1. Then, DES was added dropwise to the mixture and magnetic stirring was applied until the solution reached the critical point from clear to turbid. The amount of DES added was recorded and the percentage of the critical point of each component was calculated. A pseudo-ternary phase diagram was drawn with Smix, DES and IPM as the vertices.

[0053] Example 5

[0054] The deep eutectic solvent was prepared using the mixed heat method. Betaine and levulinic acid at a molar ratio of 1:2 were mixed in a sealed glass vial and continuously heated and stirred at 70-90°C until a uniform transparent liquid was formed. The mixture was then kept at this maximum temperature for one hour and then returned to room temperature. This was recorded as 1:2[Bet][Aa]DES.

[0055] Tween 80, Span 80 and anhydrous ethanol were mixed in the mass ratios of 1:1:1, 1:2:1.5 and 2:1:1.5, respectively, and recorded as Smix-EA. Isopropyl myristate and Smix-EA were mixed evenly in the mass ratios of 1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2 and 9:1. Then, DES was added dropwise to the mixture and magnetic stirring was applied until the solution reached the critical point from clear to turbid. The amount of DES added was recorded and the percentage of the critical point of each component was calculated. A pseudo-ternary phase diagram was drawn with Smix-EA, DES and IPM as the vertices.

[0056] from Figure 1 It can be seen that when using anhydrous ethanol as a cosurfactant, the order of the microemulsion area is 2:1 > 1:1 > 1:2, and the maximum amount of DES added is greater than that of the group without DES, allowing for a greater drug loading. This is because the hydroxyl functional group (-OH) in the cosurfactant can improve the fluidity of the oil-water interface film and reduce the droplet size of the microemulsion, thereby improving the drug encapsulation efficiency.

[0057] Example 6

[0058] Weigh 0.26 g of rutin and 4.74 g of 1:2 [Bet][Aa] deep eutectic solvent and stir magnetically at 30°C until the solution becomes clear to prepare R-DES with a rutin concentration of 65 mg / g as the dispersed phase;

[0059] Mix Tween 80 and Span 80 in a mass ratio of 1:1, and then add half the mass of anhydrous ethanol to mix evenly, which is recorded as Smix-EA.

[0060] Weigh 4g of the prepared Smix-EG and 1g of IPM, mix them, and heat and stir at 30-60°C until uniform. This will serve as the continuous phase. Accurately weigh 1.25g of R-DES and add it dropwise to the continuous phase. Stir magnetically at 600-800 rpm for 15 minutes until the emulsion becomes transparent and clear. This yields R-NSEDDS1 with a final rutin concentration of 13 mg / g.

[0061] Example 7

[0062] Weigh 0.26 g of rutin and 4.74 g of 1:2 [Bet][Aa] deep eutectic solvent and stir magnetically at 30°C until the solution becomes clear to prepare R-DES with a rutin concentration of 65 mg / g as the dispersed phase;

[0063] Mix Tween 80 and Span 80 in a mass ratio of 1:2, and then add half the mass of anhydrous ethanol of Smix and mix well, which is recorded as Smix-EA;

[0064] Weigh 4g of the prepared Smix-EG and 1g of IPM, mix, and heat at 30-60°C until uniformly stirred. This serves as the continuous phase. Accurately weigh 1.25g of R-DES and add it dropwise to the continuous phase. Stir magnetically at 600-800 rpm for 15 minutes until the emulsion becomes transparent and clear. This yields R-NSEDDS2 with a final rutin concentration of 13 mg / g.

[0065] Example 8

[0066] Weigh 0.26 g of rutin and 4.74 g of 1:2 [Bet][Aa] deep eutectic solvent and stir magnetically at 30°C until the solution becomes clear to prepare R-DES with a rutin concentration of 65 mg / g as the dispersed phase;

[0067] Mix Tween 80 and Span 80 in a mass ratio of 2:1, and then add half the mass of anhydrous ethanol of Smix and mix well, which is recorded as Smix-EA;

[0068] Weigh 4g of the prepared Smix-EG and 1g of IPM, mix them, and heat and stir at 30-60°C to form the continuous phase. Accurately weigh 1.25g of R-DES and add it dropwise to the continuous phase. Stir magnetically at 600-800 rpm for 15 minutes until the emulsion becomes transparent and clear, yielding R-NSEDDS 3 with a final rutin concentration of 13 mg / g.

[0069] Example 9

[0070] Mix Tween 80 and Span 80 in a mass ratio of 2:1, and then add half the mass of anhydrous ethanol of Smix and mix well, which is recorded as Smix-EA;

[0071] Weigh 4g of the prepared Smix-EG and 1g of IPM, mix them, and heat and stir them at 30-60°C until they are evenly distributed. This serves as the continuous phase. Accurately weigh 1.25g of pure water and add it dropwise to the continuous phase. Stir magnetically at 600-800 rpm for 15 minutes until the emulsion becomes transparent and clear. This yields the traditional water-in-oil self-emulsifying emulsion, W-NSEDDS.

[0072] Example 10

[0073] Weigh 26 mg of rutin and dissolve it in 2 mL of anhydrous ethanol to prepare rutin ethanol solution, R-EA.

[0074] Example 11

[0075] Weigh 2 mg of rutin and dissolve it in 2 mL of PBS to prepare a rutin-PBS solution.

[0076] Example 12

[0077] Examples 6, 7, and 8 were self-emulsified with water at a ratio of 1:100, and then incubated in a water bath at 30°C to 70°C (5°C as a gradient) for 30 min. After cooling to room temperature and storing for 24 h, the particle size, polydispersity index, zeta potential, and rutin content of the samples were measured to investigate the effect of temperature on the emulsion stability and rutin stability.

[0078] Example 13

[0079] Examples 6, 7, and 8 were self-emulsified with water at a ratio of 1:100, and the pH of the emulsions was adjusted to 1-9 using 0.1 mol / L hydrochloric acid solution and NaOH solution. The emulsions were then placed at room temperature for 24 hours and analyzed to test the particle size, polydispersity index, zeta potential, and rutin content of the emulsions. The effects of different pH values ​​on the emulsion stability and rutin stability were investigated.

[0080] Table 2 Rating of self-emulsification efficiency of Examples 6 to 9

[0081]

[0082] Table 2 shows the self-emulsification efficiency ratings of Examples 6 to 9. The data show that the self-emulsification efficiency ratings of Examples 8 and 9 are A (the complete self-emulsification time is 26.74±1.04s and 31.09±3.62s, respectively; the appearance after self-emulsification is transparent, with a bluish glow and no visible flocculent stratification), Example 6 is rated B (self-emulsification time is 68.56±9.89s), and Example 7 is rated C (90.44±6.40s; both have a milky white appearance after self-emulsification, with a layer of white flocculent oil droplets).

[0083] Figure 2 is the colostrum stability index of Examples 6 to 9. It can be seen that the phase separation degree of Example 9 is the largest (ESI≈93%). When the colostrums of each group are not loaded with rutin, no phase separation phenomenon occurs (ESI>99%), while the colostrums loaded with rutin all show a small amount of phase separation. Example 8 has the highest stability (ESI>96%).

[0084] Table 3 Particle size, polydispersity index (PDI) and zeta potential of Examples 6 to 9

[0085]

[0086] From the comparison in Table 3, it can be seen that the droplet particle size of Example 8 is the smallest (35.01±0.19 nm) and the PDI is also the smallest (0.2037±0.0009). The smaller the particle size, the more conducive it is to drug absorption.

[0087] from Figure 3It can be seen that after 15 days of storage at room temperature, the appearance of the emulsion of Example 8 did not change significantly, and it remained clear, with a blue glow, no stratification, and no rutin precipitation. In the subsequent storage process, it remained stable after one month without stratification or rutin precipitation, indicating that the system has good drug encapsulation efficiency and physical stability after drug loading. The emulsion of Example 7 showed obvious flocculation and phase separation from the beginning, and there was obvious rutin solid precipitation at the bottom of the emulsion, indicating that the emulsion had poor stability and did not have good drug encapsulation efficiency and stability. The stability of the emulsion of Example 6 was intermediate.

[0088] Figure 4 The optical microscope images (a) and transmission electron microscope (TEM) images (b) of Examples 6 to 8 show that the interior of the emulsion droplets presents a typical multiple emulsion structure (large droplets encapsulating small droplets). The overall distribution is concentrated, but there is slight heterogeneity in some parts.

[0089] Figure 5 It can be seen that the particle size and polydispersity index (PDI) of Examples 6 to 8 did not change significantly over the entire temperature range, indicating that the size distribution of the emulsion particles remained relatively uniform, without obvious aggregation or uneven dispersion. Among them, Example 8 had a higher rutin loading than the other two groups within the temperature range and had good drug loading stability at medium and low temperatures. However, the rutin content decreased slightly with increasing temperature, which may be due to degradation or solubility changes of rutin at high temperatures.

[0090] Figure 6 It can be seen that the particle size and polydispersity index (PDI) of Examples 6 to 8 do not change significantly over the entire pH range, indicating that the size distribution of the emulsion particles remains relatively uniform, with no obvious aggregation or uneven dispersion. The zeta potential increases significantly with increasing pH, suggesting that the surface charge density of the particles increases, enhancing the electrostatic repulsion between the particles and contributing to the stability of the emulsion. The rutin content of Examples 6 and 8 is stable within the pH range of 3-6, but rutin is released under superacidic or alkaline conditions, which is more conducive to release and absorption in the intestine. However, the drug loading stability of Example 7 is poor.

[0091] Figure 7 The rutin loading capacity (LC) and encapsulation efficiency (EE) of Examples 6 to 8 are shown. The drug loading capacity of Example 8 is 0.932%, which is 1.35 times that of Example 7. There is no obvious difference in the encapsulation efficiency of Examples 6 to 8, which are 76.04±1.68%, 76.00±0.43% and 77.30±0.17%, respectively. Among them, the encapsulation efficiency of Example 8 is the highest.

[0092] Figure 8The solubility of Example 8 and pure rutin in simulated gastrointestinal fluid is shown. In the simulated gastric fluid, the cumulative release of the emulsion of Example 8 within 2 hours is 58.48%, which is significantly higher than the 26.23% of rutin powder. In the simulated intestinal fluid, the cumulative release of the emulsion of Example 8 within 6 hours reaches 90.53%, while that of the rutin powder is only 34.83%. It can be found that the release rate and total amount of the emulsion of Example 8 in intestinal fluid are both higher than those in gastric fluid, indicating that the intestinal fluid environment is more conducive to drug release.

[0093] Figure 9 The in vitro release of the emulsions of Examples 8 and 10 was shown. The experimental data showed that the cumulative release of the emulsion of Example 8 was significantly higher than that of Example 10 at all time points. For example, at 30 minutes, the cumulative release of Example 8 was 4.09%, while that of Example 10 was 1.84%. At 22 hours, the cumulative release of Example 8 reached 87.42%, while that of Example 10 was only 48.96%. This demonstrates that the NSEDDS system can significantly increase the release rate and total amount of rutin.

[0094] Table 4 In vitro release behavior of the emulsions of Examples 8 and 10

[0095]

[0096] Table 4 shows the in vitro release behavior of Examples 8 and 10. The results show that the release behavior of both samples conforms to the first-order kinetic model with a high goodness of fit (r 2 Adjusted values ​​were 0.99916 and 0.9971, respectively), and the AIC values ​​were low (27.61 and 47.38, respectively), indicating that the first-order model best describes the release process. The diffusion exponent n values ​​in the Korsmeyer-Peppas model (0.51626 and 0.53354, respectively) further confirmed the existence of a non-Fickian diffusion mechanism, indicating that drug release may be influenced by both diffusion and matrix erosion. This suggests that R-NSEDDS has potential application in improving drug sustained-release behavior and bioavailability.

[0097] Figure 10 a) Experimental data showed that the cumulative permeation amounts of Examples 6 and 8 at all time points were significantly higher than those of Example 11. After 12 h, the cumulative permeation amounts were 10.97±1.04, 14.01±1.01, and 10.21±1.12 μg / cm, respectively. 2 After 24 hours, the cumulative permeation amounts were 11.43±1.02, 38.58±0.94, and 19.11±0.99μg / cm 2 . Figure 10b) shows that the cumulative permeability of Example 8 is 9.64%, the retention rate in the stratum corneum is 6.38%, and the retention rate in the epidermis is 2.3%, all of which are higher than those of Examples 6 and 11. In summary, the present invention is significantly superior to the traditional rutin-PBS solution in terms of transdermal permeability, and the smaller particle size (Example 8) further improves the drug penetration efficiency.

[0098] from Figure 11 As can be seen from the figure, after transdermal delivery of rutin, some rutin remains on the pig skin surface (red circle), and the rutin residue on the surface of Example 11 is significantly more than that of Example 8. However, the stratum corneum of the skin is intact.

[0099] from Figure 12 It can be seen that the dermis did not undergo any inflammatory reaction, the stratum corneum was clear and intact without flaking, and the collagen fibers in the dermis were evenly arranged and dense, indicating that the invention is safe on the surface of the skin. Therefore, the emulsion of the present invention is a biocompatible and non-toxic drug delivery vehicle.

[0100] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A method for preparing an anhydrous self-emulsifying drug-loaded emulsion based on a deep eutectic solvent, characterized in that: The following steps are involved: (1) mixing betaine and a hydrogen bond donor, preparing a deep eutectic solvent using a mixing heat method, and dissolving the drug in the deep eutectic solvent to prepare a drug solution; the hydrogen bond donor is levulinic acid or lactic acid; (2) Tween 80 and Span 80 were mixed in a mass ratio of (1-2):1 as a surfactant, anhydrous ethanol was added as an emulsifier, and isopropyl myristate was added, and the mixture was stirred and mixed to obtain a dispersion; (3) The drug solution of step (1) is added dropwise to the dispersion of step (2) while stirring, to finally form an anhydrous self-emulsifying drug-loaded emulsion.

2. The preparation method according to claim 1, characterized in that In step (1), betaine and the hydrogen bond donor are mixed in a molar ratio of 1:

2.

3. The preparation method according to claim 2, characterized in that: The mass ratio of Tween 80 to Span 80 in step (2) is 2:

1.

4. The preparation method according to claim 3, characterized in that The mass ratio of the surfactant to anhydrous ethanol in step (2) is 2:

1.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The concentration of isopropyl myristate in the dispersion of step (2) is 20±5%; the drug of step (1) is rutin or luteolin; and the concentration of the drug is 60-80 mg / g.

6. The preparation method according to claim 5, characterized in that: The mass ratio of the drug solution to the dispersion in step (3) is 1:(4±1).

7. The preparation method according to any one of claims 1 to 4, characterized in that: Preparation of the deep eutectic solvent in step (1): betaine and a hydrogen bond donor are mixed in a sealed container and continuously heated and stirred until a uniform transparent liquid is formed, and then the mixture is stored at 70-90°C for 1±0.5 hours to obtain a deep eutectic solvent. The stirring speed is 600-800 r / min.

8. The preparation method according to any one of claims 1 to 4, characterized in that In step (2), the mixing condition of Tween 80 and Span 80 is to stir them evenly at 60±20° C.; and in step (3), the stirring condition is to stir them at a speed of 600±100 r / min for 15±5 min.

9. An anhydrous self-emulsifying drug-loaded emulsion based on a deep eutectic solvent prepared by the method according to any one of claims 1 to 8.

10. Use of the anhydrous self-emulsifying drug-loaded emulsion based on a deep eutectic solvent according to claim 9 in the preparation of a skin external preparation.

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