Colchicine external nano latex agent as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of pharmaceutical preparations, and particularly discloses a colchicine external nano latex agent as well as a preparation method and application thereof.The colchicine external nano latex agent is prepared from the following raw materials in percentage by mass: 0.1%-1.2% of colchicine, 0.5%-25% of an oil phase matrix, 2%-20% of a surfactant, 2%-15% of a cosurfactant, 0%-15% of a transdermal absorption enhancer, 3%-3.5% of a gel matrix, 0%-0.5% of a pH regulator and the balance of water, totaling 100%. According to the colchicine external nano latex agent, the optimal prescription is obtained by applying a pseudo-ternary phase diagram and combining with D-optimal mix design, the particle size of the nano emulsion is stably controlled to be about 14 nm, and the small particle size means faster Brownian movement and stronger penetration of skin cuticle gaps or improvement of the infiltration capacity through appendages such as hair follicles, so that the colchicine external nano latex agent has a good application prospect. The skin penetration efficiency is higher than that of other prescriptions with larger particle sizes, and the nanoemulsion with small particle size hardly shows lag time.

Description

Technical Field

[0001] This invention relates to the field of pharmaceutical formulation technology, specifically to colchicine topical nano-emulsion, its preparation method, and its application. Background Technology

[0002] Acute gouty arthritis, one of the most common inflammatory arthritis worldwide, is caused by the deposition of urate crystals within the joints. Acute gouty arthritis typically manifests as rapid onset of joint redness, swelling, heat, pain, and functional impairment. The severe pain and sudden onset place a significant burden on patients' quality of life and daily activities. Controlling the acute inflammatory response and rapidly relieving pain to shorten attack duration and improve treatment efficacy are the main goals of clinical management of gouty arthritis. Clinically, colchicine is recommended as a first-line treatment for acute gouty arthritis. It effectively inhibits the activation of the NLRP3 inflammasome, the phagocytosis of neutrophils by urate crystals, chemotactic migration, and the release of inflammatory mediators, thus providing long-term prevention and treatment of acute gouty arthritis. Unfortunately, despite its potent anti-inflammatory effects, colchicine's severe gastrointestinal and systemic toxicity greatly limits its clinical application. Its plasma concentration range is only 0.5–3 ng / mL, with a narrow therapeutic index; therefore, precise dosage control is crucial. Although intravenous administration can have a rapid onset of action, this route was banned by the U.S. Food and Drug Administration in 2008 due to the associated serious systemic toxicity risks, including multiple organ failure.

[0003] Currently, colchicine is primarily administered orally, with a bioavailability of only 45%. More seriously, colchicine's microtubule depolymerization activity can directly damage the cytoskeleton of gastrointestinal epithelial cells. Even at recommended doses, gastrointestinal adverse reactions such as nausea, vomiting, and diarrhea are observed in approximately 20% of patients, and up to 10% require discontinuation of treatment due to intolerance. Therefore, there is an urgent need to develop an alternative colchicine administration strategy with high efficacy and safety.

[0004] Given the severe gastrointestinal and systemic toxicity of oral colchicine formulations, transdermal drug delivery strategies are highly competitive due to their ability to bypass first-pass metabolism and reduce systemic exposure, particularly for drugs with low recommended doses and narrow therapeutic indications. Several existing transdermal formulations, such as patches, emulsions, gels, vesicles, and microneedles, have shown good feasibility, but certain limitations remain. Traditional patches may detach prematurely during joint activity, limiting transdermal delivery time. Oil-based formulations, including water-in-oil microemulsions, often leave oily residues, causing skin discomfort. Hydrogel systems, lacking hydrophobic transdermal facilitators, exhibit poor skin penetration. Nanocarrier systems and microneedles typically involve complex fabrication processes and are low-cost, hindering their clinical application.

[0005] To address the gastrointestinal toxicity and systemic exposure issues associated with oral colchicine preparations, this invention develops a topical colchicine nano-latex for the effective and safe treatment of acute gouty arthritis. This latex cleverly combines the advantages of emulsions and hydrogels, exhibiting no gastrointestinal toxicity, significantly reducing systemic colchicine exposure, strong skin adhesion, good biocompatibility, environmental storage capability, and ease of production. It provides patients with a good and safe local treatment strategy, effectively avoiding the systemic toxicity associated with oral colchicine, especially gastrointestinal adverse reactions. Summary of the Invention

[0006] The purpose of this invention is to address the deficiencies of the prior art by providing colchicine-based topical nano-emulsions, their preparation methods, and applications, thereby resolving the problems raised in the background section.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a colchicine topical nano-emulsion, which is composed of colchicine, an oil phase matrix, a surfactant, a co-surfactant, a transdermal absorption enhancer, a gel matrix, a pH adjuster, and water; The composition of the raw materials by mass percentage is as follows: colchicine 0.1%~1.2%, oil phase matrix 0.5%~25%, surfactant 2%~20%, co-surfactant 2%~15%, transdermal absorption enhancer 0%~15%, gel matrix 3%~3.5%, pH adjuster 0%~0.5%, and the balance is water, totaling 100%.

[0008] As a preferred embodiment of the present invention, the oil phase matrix accounts for 0.9% to 1.5% of the total mass of the entire nano-latex agent; the surfactant accounts for 5% to 10% of the total mass of the entire nano-latex agent; and the co-surfactant accounts for 2.5% to 5% of the total mass of the entire nano-latex agent.

[0009] As a preferred embodiment of the present invention, the oil phase matrix is ​​selected from one or more of ethyl oleate, isopropyl myristate, tricaprylic acid glyceride, and liquid paraffin; the surfactant is selected from one or more of Tween 20, Tween 80, Span 80, propylene glycol monolaurate, and polyoxyethylene 40 hydrogenated castor oil; the co-surfactant is selected from one or more of propylene glycol, polyethylene glycol-400, and isopropanol; the transdermal absorption enhancer is isosorbide dimethyl ether; the gel matrix is ​​sodium carboxymethyl cellulose; and the pH adjuster is triethanolamine.

[0010] A method for preparing colchicine topical nano-emulsion as described above includes the following steps: Step 1: Dissolve colchicine, surfactant, and co-surfactant in purified water to obtain an aqueous phase; Step 2: Dissolve the transdermal absorption enhancer in the oil phase matrix to obtain the oil phase; add the obtained oil phase to the aqueous phase obtained in Step 1 and emulsify to obtain colchicine nanoemulsion; Step 3: Add sodium carboxymethyl cellulose to purified water, stir and disperse evenly in a 60°C water bath, and allow it to swell fully to obtain a blank gel; Step 4: Add the colchicine nanoemulsion obtained in Step 2 to the blank gel obtained in Step 3, stir continuously until it is evenly dispersed, and adjust the pH to 6.0-6.5 to obtain colchicine nanoemulsion.

[0011] As a preferred embodiment of the present invention, in step 4, the colchicine nanoemulsion and the blank gel are mixed at 20~25℃.

[0012] As a preferred embodiment of the present invention, in step 2, the particle size of the colchicine nanoemulsion is 14.1~101.4 nm.

[0013] The application of a colchicine topical nano-emulsion as described above in the preparation of a drug for treating acute gouty arthritis.

[0014] Compared with the prior art, the present invention has the following significant advantages: The colchicine topical nanoemulsion of the present invention obtains an optimal formulation by applying a pseudo-ternary phase diagram combined with D-optimal mixture design, and stably controls the nanoemulsion particle size at about 14 nm. Smaller particle size means faster Brownian motion and stronger penetration into the stratum corneum gap or improved permeability through appendages such as hair follicles. Its skin penetration efficiency is higher than other formulations with larger particle sizes, and the small-particle-size nanoemulsion hardly exhibits hysteresis time.

[0015] The colchicine topical nano-emulsion formulation of this invention achieves highly efficient transdermal delivery of colchicine through the synergistic effect of the nano-emulsion drug delivery system and the penetration enhancer. In vitro experiments show that its transdermal rate and cumulative penetration are significantly superior to traditional hydrogel formulations. In vivo efficacy evaluation shows that this formulation has a rapid onset of action and significant anti-inflammatory and analgesic effects in an acute gouty arthritis model; it takes effect rapidly within 1 hour after local administration, and its onset speed and efficacy are superior to oral administration.

[0016] Compared to traditional oral colchicine formulations, the colchicine topical nano-emulsion of this invention delivers colchicine locally through the skin, avoiding gastrointestinal side effects and reducing systemic toxicity risks such as systemic exposure. Skin irritation tests confirmed that the formulation did not cause erythema or edema on the skin, exhibiting high biocompatibility and suitability for long-term use, providing a safer treatment option for patients with acute gouty arthritis.

[0017] The colchicine topical nano-emulsion of this invention exhibits comprehensive advantages compared to other colchicine topical formulations. It integrates the permeation-enhancing and small-particle-size characteristics of the components with the adhesiveness of the gel matrix, resulting in not only higher transdermal efficiency but also better skin adhesion, eliminating the greasiness of creams and the fixation problems of patches. Furthermore, it requires no invasive application, is convenient to apply, and improves patient compliance.

[0018] The colchicine topical nano-emulsion of the present invention adopts a self-emulsification method combined with simple mechanical stirring. The process is simple and efficient, requires no complicated equipment, is easy to scale up, significantly reduces production costs, and provides a solid foundation for clinical translation. Attached Figure Description

[0019] Figure 1 The pseudo-ternary phase diagrams of colchicine nanoemulsions prepared in Example 1 with different excipient compositions and proportions are shown. A is the ethyl oleate-Tween 80-isopropanol system; B is the isopropyl myristate-Tween 80-isopropanol system; C is the tricaprylic acid glyceride-Tween 80-isopropanol system; D is the ethyl oleate-propylene glycol monolaurate-isopropanol system; E is the isopropyl myristate-propylene glycol monolaurate-isopropanol system; F is the tricaprylic acid glyceride-propylene glycol monolaurate-isopropanol system. Figure 2 The rheological analysis diagrams are of the colchicine nano-emulsions prepared in Examples 13-16; A represents strain scan; B represents frequency scan; C represents loss factor; D represents the relationship between shear stress and shear rate; E represents the relationship between viscosity and shear rate; F represents thixotropy. Figure 3 The graph shows the cumulative in vitro transdermal release of colchicine nanoemulsions prepared in Examples 11 and 13-16. Figure 4 The graph shows the changes in joint swelling rate of mice with gout caused by colchicine nano-emulsions prepared in Examples 13 and 15 (n=6). Figure 5 The graph shows the changes in the mechanical paw withdrawal threshold of mice with gout caused by the colchicine nanoemulsions prepared in Examples 13 and 15 (n = 6). Figure 6 The image shows a mouse joint tissue pathology image of the colchicine nanoemulsion prepared in Example 15. Figure 7 The image shows the skin irritation of the colchicine nanoemulsion prepared in Example 15. Detailed Implementation

[0020] The present invention can be better understood from the following embodiments. However, those skilled in the art will readily understand that the descriptions in the embodiments are for illustrative purposes only and should not, and will not, limit the invention as detailed in the claims.

[0021] Example 1: Selection of excipients for nano-emulsions in colchicine topical nano-emulsions, including the following steps: The solubility of colchicine in excipients significantly affects the formulation process, drug loading, formulation stability of nano-latex, and subsequent transdermal properties and therapeutic effects. Therefore, the saturated solubility of colchicine in various excipients was first investigated. Each excipient, including the oil phase (ethyl oleate, isopropyl myristate, glyceryl tricaprylate, liquid paraffin), surfactants (Tween 20, Tween 80, Span 80, propylene glycol monolaurate, polyoxyethylene 40 hydrogenated castor oil), and co-surfactants (propylene glycol, polyethylene glycol-400, isopropanol), was added in 1 mL. Excess colchicine was added to each excipient, and the mixture was shaken on a constant temperature shaker at 25±0.5℃ and 180 rpm for 24 hours. The supernatant was collected, filtered, and diluted. The solubility of colchicine was determined by high-performance liquid chromatography (HPLC). Quantitative analysis was performed using an Agilent 1260 series liquid chromatography system equipped with a UV detector and a Poroshell 120 EC-C18 column (4.6 × 250 mm, 5.0 μm) at 35 °C. The mobile phase was methanol-water (60:40, v / v), with isocratic elution, a flow rate of 1.0 mL / min, a detection wavelength of 230 nm, and an injection volume of 10 μL. The solubility of colchicine in each excipient is shown in the table below.

[0022] Table 1: Solubility of colchicine in different oil phases, surfactants, and co-surfactants (n=3)

[0023] As shown in the table above, the most soluble colchicine compounds in surfactants and co-surfactants are propylene glycol monolaurate, Tween 80, and isopropanol, respectively. Furthermore, the most soluble colchicine compounds in oils are tricaprylic acid glyceride, ethyl oleate, and isopropyl myristate.

[0024] After screening excipients, a pseudo-ternary phase diagram was constructed to evaluate the compatibility and emulsification efficiency of the selected excipient combination. At ambient temperature (25±1℃), a pseudo-ternary phase diagram comprising an oil phase, a surfactant / co-surfactant mixture (Smix), and an aqueous phase was constructed using water titration. Smix was prepared by first mixing the surfactant and co-surfactant at different mass ratios (Km = 1:2, 1:1, 2:1). Then, the oil phase and Smix were mixed at different weight ratios from 1:9 to 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2, and 9:1. After thorough vortex mixing, the oil phase and Smix were slowly titrated with ultrapure water under continuous stirring. The transition from a clear, homogeneous to a turbid appearance of the mixed solution was defined as the phase transition point. The pseudo-ternary phase diagram was then plotted based on the composition of the mixed solution at the phase transition point to visually identify the nanoemulsion regions within the phase diagram. Results are shown below. Figure 1 As shown, the oil phase is isopropyl myristate. When the mass ratio (Km) of Tween 80 to isopropyl alcohol is 2:1, the system exhibits the largest nanoemulsion region, which is a transparent and homogeneous single-phase system. This indicates that the emulsification efficiency is optimal at this ratio. Tween 80 and isopropyl myristate have good compatibility, which helps to reduce interfacial tension and enhance the flexibility of the interfacial film. Therefore, isopropyl myristate was chosen as the oil phase, Tween 80 as the surfactant, and isopropyl alcohol as the co-surfactant.

[0025] Examples 2-10: Preparation method of nanoemulsion in colchicine topical nanoemulsion, including the following steps: First, weigh out 1.2% colchicine by mass. Then, weigh out the remaining amount of isopropyl myristate, Tween 80, and isopropanol (Km = 2:1) according to the mass ratio in Table 2. Dissolve the colchicine, Tween 80, and isopropanol in pure water to form an aqueous phase. Under constant magnetic stirring at 600 rpm and a temperature of 25 ± 1 °C, slowly add isopropyl myristate dropwise to the aqueous phase. After complete addition, continue stirring for 5 minutes to ensure thorough mixing. The sample spontaneously forms a clear and transparent nanoemulsion.

[0026] Example 11: In vitro transdermal experiments and optimization of the colchicine nanoemulsions prepared in Examples 2-10; The method is as follows: Male SD rats (230±20 g) were euthanized by cervical dislocation. Abdominal hair was immediately removed, and abdominal skin was peeled off, subcutaneous fat and connective tissue were removed, and the skin was rinsed with physiological saline. The skin was fixed between the two chambers of the Franz diffusion cell, with the stratum corneum facing the donor chamber, achieving an effective diffusion area of ​​1.79 cm². 7.5 mL of pH 7.4 phosphate buffer was injected into the recipient chamber, maintained at a constant temperature (32 ± 0.5 °C), and continuously stirred magnetically at 200 rpm. 200 mg of each test sample was accurately weighed and evenly applied to the skin surface. 5 mL samples were taken at 0.5, 1, 2, 4, 6, and 8 h, and isothermal and equal-volume fresh buffer was added immediately to maintain the diffusion cell conditions. The samples were filtered through a 0.45 μm microporous membrane, and the COL concentration was determined by HPLC. The cumulative transdermal dose of colchicine over 8 h was calculated, and the results are shown in Table 2.

[0027] Table 2: Cumulative transdermal release of colchicine in different formulation ratios (n=3)

[0028] The experimental results above show that the transdermal effect of the formulation in Example 4 is the best, followed by the formulation in Example 3. All other formulations have lower transdermal absorption rates than these two. Based on the above data, the preferred mass percentages of isopropyl myristate are 2-3%, Tween 80 is 12-20%, and isopropanol is 6-10%. D-optimal mixture design analysis, using particle size as the response value, yielded the optimal formulation as follows: by mass percentage, 2.10% isopropyl myristate, 18.57% Tween 80, 9.28% isopropanol, and 70.05% purified water.

[0029] Example 12: Determination of particle size and zeta potential of colchicine nanoemulsions prepared in Examples 2-11; The method is as follows: The particle size, polydispersity index (PDI) and zeta potential of colchicine nanoemulsion samples were analyzed using a Zetasizer Nano ZS90 (Malvin Company, UK).

[0030] Particle size is considered a key parameter affecting the stability and transdermal behavior of nanoemulsions, typically requiring a particle size of less than 500 nm to ensure effective transdermal delivery. Specifically, smaller particle sizes (< 60 nm) have been shown to significantly improve skin penetration efficiency and shorten hysteresis time. Table 3 shows the particle size, PDI, and Zeta potential of 10 emulsion formulations. All formulations had particle sizes ranging from 14.08 to 101.39 nm, indicating good transdermal delivery potential. PDI values ​​ranged from 0.09 to 0.33, close to the ideal state of monodispersity, reflecting good system homogeneity. Zeta potentials ranged from -27.17 mV to -31.46 mV, indicating good physical stability of the emulsions.

[0031] Table 3: Particle size, PDI, and zeta potential of colchicine nanoemulsions with different formulation ratios (n=3)

[0032] Examples 13-16: Preparation of colchicine topical nano-emulsion according to the optimized formulation obtained in Example 11, including the following steps: Weigh the components according to the mass ratio in Table 4. Dissolve colchicine, Tween 80, and isopropanol (Km=2:1) ​​in pure water to form an aqueous phase. Under constant magnetic stirring at 600 rpm and a temperature of 25 ± 1 °C, slowly add isopropyl myristate, with or without isosorbide dimethyl ether, dropwise to the aqueous phase. After complete addition, continue stirring for 5 minutes to ensure thorough mixing. The sample spontaneously forms a clear and transparent nanoemulsion.

[0033] Sodium carboxymethyl cellulose (6.5%, by mass) was dispersed in pure water in a water bath (60 °C) with stirring to form a clear and uniform hydrogel matrix, which was then cooled to 20–25 °C. The nanoemulsion was added dropwise to the hydrogel matrix at a 1:1 (by mass) ratio and dispersed at room temperature using an HD2010W mechanical stirrer (Shanghai Silai Instrument Co., Ltd.) at 1000 rpm to obtain colchicine nanoemulsion.

[0034] Table 4: Formulation of Colchicine Nano-Emulsion

[0035] Example 17: Rheological analysis of the preferred formulation of the colchicine nano-emulsion prepared in Examples 13-16; The method is as follows: The viscoelastic properties of colchicine nanoemulsion were analyzed using a rotational rheometer (MCR102, Antampere AG, Austria) at 25°C. A parallel plate geometry (PP50, gap: 1 mm) was employed. After loading, the samples were allowed to stand for 2 minutes to eliminate stress history. Strain scans from 0.001% to 1% were performed at a fixed frequency of 1 Hz to determine the linear viscoelastic region (LVR). Then, frequency scans from 0.1–100 rad / s were performed within the LVR range, and the storage modulus (G′) and loss modulus (G″) were recorded. The shear rate was varied from 0.1–100 s⁻¹. -1 To observe the apparent viscosity trend of the sample. Plasticity properties were evaluated using a three-interval plasticity test (3ITT): with a viscosity of 0.1 s⁻¹. -1 The shearing was performed at a rate of 120 seconds to simulate the storage state; at a rate of 100 seconds... -1 The rate was maintained for 120 seconds to simulate the application process; then again at 0.1 seconds. -1 The viscosity was monitored for 120 seconds at a rate that allowed for further observation. The percentage of viscosity recovery was calculated by comparing the viscosity in the third interval with that in the initial interval.

[0036] Test results showed that all samples exhibited a higher G′ than G″ in the low strain range (< 0.1%), confirming that the system was dominated by elastic solid behavior, indicating the integrity of the gel network structure. Beyond the linear viscoelastic region, G′ decreased significantly and converged with G″, marking material yielding and a shift from elastic dominance to viscous fluid dominance. Comparing different formulations, the G′ of the latex was consistently higher than that of the control hydrogel (COL-(CMC-Na)-Gel), indicating that the introduction of nanoemulsions enhanced the mechanical strength of the system. Figure 2 A). During the frequency scan, G′ and G″ for all samples increased with increasing angular frequency, showing a frequency dependence, but G′ was always higher than G″, indicating that the system is dominated by elastic solid behavior. Figure 2 B). Flow curve analysis shows ( Figure 2 D and Figure 2 E), all samples exhibited typical non-Newtonian fluid behavior: shear stress increased with increasing shear rate, while viscosity decreased with increasing shear rate, consistent with pseudoplastic fluid (shear thinning) characteristics. Shear thinning is an ideal property for topical latexes, facilitating application and skin coverage. The 3ITT test was used to evaluate the gel network's post-shear reconstruction ability under high and low shear interaction conditions. The results showed that ( Figure 2 F) The recovery rate of all samples was higher than 68%, and some exceeded 70%, indicating that the formulation could partially reconstruct the structure after simulated application and had good structural integrity.

[0037] Example 18: In vitro transdermal release experiments were conducted on the colchicine nanoemulsions and nano-emulsions prepared in Examples 11 and 13-16; The method is as follows: Male SD rats (230±20 g) were euthanized by cervical dislocation. Abdominal hair was immediately removed, and abdominal skin was peeled off, subcutaneous fat and connective tissue were removed, and the skin was rinsed with physiological saline. The skin was fixed between the two chambers of the Franz diffusion cell, with the stratum corneum facing the donor chamber, achieving an effective diffusion area of ​​1.79 cm². 7.5 mL of pH 7.4 phosphate buffer was injected into the recipient chamber, maintained at a constant temperature (32 ± 0.5°C), and continuously stirred magnetically at 200 rpm. 200 mg of each test sample was accurately weighed and evenly applied to the skin surface. 5 mL samples were taken at 0.5, 1, 2, 4, 6, and 8 h, and isothermal and equal volumes of fresh buffer were added immediately to maintain the diffusion cell conditions. The samples were filtered through a 0.45 μm microporous membrane, and the COL concentration was determined by HPLC. The cumulative transdermal transdermal dose at each time point was calculated, and transdermal curves were plotted. The results are shown below. Figure 3 As shown.

[0038] Test results showed that, compared to the formulations of Example 3 and Example 4, which had larger average particle sizes, the cumulative transdermal absorption rates (CDRs) after 8 hours were 265.0 ± 13.1 μg / cm² and 328.7 ± 11.8 μg / cm², respectively. Example 11, optimized using D-optimal mixture design, showed a significantly reduced average particle size to 14.08 ± 0.86 nm, resulting in a corresponding increase in the cumulative CDR after 8 hours to 375.8 ± 28.9 μg / cm². This data trend clearly indicates that reducing the particle size of nanoemulsions is an effective strategy to enhance their transdermal capabilities. The underlying mechanism may be that smaller particle size implies faster Brownian motion and a stronger ability to penetrate the stratum corneum or pass through appendages such as hair follicles.

[0039] After confirming the advantages of particle size optimization, the colchicine nanoemulsion prepared with the optimized formulation exhibiting the best transdermal performance had a cumulative permeation of 211.1 ± 23.5 μg / cm² after 8 hours. This decrease can be attributed to the increased path resistance of drug diffusion due to the three-dimensional network structure formed by the gel matrix. However, the gel matrix provides better skin adhesion in practical applications, helping to maintain local drug concentration, reduce dosing frequency, and improve patient compliance. To compensate for the potential permeation resistance of the gel matrix, we introduced the permeation enhancer isosorbide dimethyl ether to investigate its synergistic permeation-enhancing effect with isopropyl myristate in the formulation. Isopropyl myristate, as a lipid permeation enhancer, mainly increases the fluidity of the lipid bilayer by embedding into and disrupting the tight arrangement of lipids in the stratum corneum. Isosorbide dimethyl ether, on the other hand, may reduce the resistance of the skin barrier by competitively binding water molecules through its hydrogen-bonding ability, interacting with the polar head groups of keratin or intercellular lipids in the stratum corneum. The two have complementary mechanisms: isopropyl myristate primarily acts on the lipid pathway, while isosorbide dimethyl ether may focus more on polar interactions, thus producing a synergistic effect. Experimental results confirm this: colchicine nanoemulsions containing 5%, 10%, and 15% isosorbide dimethyl ether all showed significantly increased cumulative transdermal release, thereby facilitating faster drug release.

[0040] Example 19: The optimal colchicine nano-latex formulations prepared in Examples 13 and 15 were evaluated for their in vivo anti-inflammatory and analgesic effects using a mouse acute gouty arthritis test. The method was as follows: Male ICR mice weighing 30 ± 2 grams were randomly divided into five groups: a control group (Normal), a model group (Model), an oral colchicine group (Oral COL), a colchicine nano-emulsion group (COL-nEMG), and a colchicine nano-emulsion group loaded with 10% isosorbide dimethyl ether (COL-nEMG-DMI10), with six mice in each group. Except for the Normal group, the mice in the other four groups were injected intramuscularly with 20 μL of sodium urate suspension (50 mg / mL) in the right posterior ankle joint using a sterile syringe. Mice in the control group received an equal volume of saline. Successful induction of acute gouty arthritis was confirmed by the presence of ≥50% ankle swelling and mechanical abnormal pain with a paw retraction threshold ≤4 g 12 hours after injection. Twelve hours after modeling, the Normal and Model groups were given one dose of the control nano-emulsion. The Oral COL group was given one dose of COL (0.8 mg / kg) by gavage. The COL-nEMG group (COL: 0.8 mg / mL) and the COL-nEMG-DMI10 group (COL: 0.8 mg / mL) were obtained by applying the nano-latex agents obtained in Examples 13 and 15 once to the skin of the ankle joint of mice and fixing it with medical tape for 0.5 h.

[0041] (1) Evaluation of ankle swelling in mice The diameter of the mouse ankle joint was measured using digital calipers before modeling (baseline) and at 0.5, 1, 2, 4, 6, and 8 hours after drug administration. To quantify the degree of joint swelling and the efficacy of the drug, the degree of joint swelling (%) and the rate of joint swelling inhibition (%) were calculated.

[0042]

[0043]

[0044] As the results showed, with swelling rate and swelling inhibition rate as the main efficacy indicators, the colchicine topical nano-emulsion of this invention exhibited a rapid and potent anti-inflammatory effect. 0.5 hours after administration, the swelling rate in the COL-nEMG-DMI10 group decreased from 58.9 ± 1.4% to 47.1 ± 2.4%, and further decreased to 25.7 ± 2.7% at 8 hours. Figure 4 The swelling inhibition rate reached 51.2 ± 0.1%, demonstrating sustained and potent anti-inflammatory efficacy. In contrast, the swelling inhibition rates in the Oral COL group were only 7.0 ± 2.6% and 39.1 ± 3.7% at 0.5 hours and 8 hours, respectively, while the swelling inhibition rates in the COL-nEMG group ranged from 11.4 ± 2.8% to 36.3 ± 6.4%. There was no significant difference in joint swelling inhibition rates between the Oral COL group and the COL-nEMG group, but the COL-nEMG-DMI10 group was significantly superior to the Oral COL group. This indicates that the formulation of the present invention has excellent anti-inflammatory properties with rapid onset, significant efficacy, and sustained effects, and has important clinical application value.

[0045] Mechanical pain assessment The effect of colchicine nanoemulsion on improving mechanosensitive hyperalgesia in mice with acute gouty arthritis was evaluated by measuring foot withdrawal threshold (PWT) at baseline (i.e., before modeling) and at 1, 2, 4, 6, and 8 hours after drug administration using a "ZH-ZKL" mechanoresonometer (Zhenghua, Anhui, China). Animals were acclimatized for 30 minutes in a transparent box placed on a metal mesh platform before measuring the PWT. Afterward, the right hind limb ankle region of the mice was vertically stimulated using a probe with an incremental force of 0.1 g (0–10 g). The foot withdrawal reflex threshold (in g) was recorded when rapid foot withdrawal or licking behavior was observed.

[0046] The results show that the threshold of the Model group ( Figure 5The maximum difference in PWT before and after treatment was 0.26 ± 0.01 g, indicating that the latex matrix material could not relieve acute gout inflammation. In the COL-nEMG-DMI10 group, PWT recovered to 59.6% and 85.8% of baseline at 1 h and 8 h, respectively, which was more effective in relieving mechanical abnormal pain than the COL-nEMG group and the Oral COL group.

[0047] Joint histopathological examination Six hours after treatment, mouse ankle joint tissue was harvested and fixed in 10% neutral buffered formalin for 48 hours. After decalcification in 14% EDTA (pH 7.4) for 14 days, the tissue was embedded in paraffin and 5 μm sagittal sections were prepared and stained with hematoxylin and eosin (H&E). The sections were imaged using a Leica DM750 microscope (Leica Microsystems, Germany), focusing on the density of inflammatory cell infiltration in the synovium and joint cavity and the degree of synovial hyperplasia.

[0048] The results show that, Figure 6 As shown, the ankle joints of mice in the Normal group were normal, with no obvious inflammatory infiltration. In contrast, mice in the Model group exhibited thickened articular cartilage and significant inflammatory cell infiltration. Compared to the Model group, the ankle joint pathological damage in mice treated with COL-nEMG-DMI10 was significantly reduced, presumably because COL can inhibit the contact between MSU crystals and monocytes, thus inhibiting the accumulation of leukocytes in the ankle joint. Notably, compared to the Oral COL group, the inflammatory status of mice in the COL-nEMG-DMI10 group showed a more significant improvement, which may be due to the topical formulation acting directly on the lesion site to exert its therapeutic effect.

[0049] Example 20: The safety of the preferred formulation of colchicine nanoemulsion prepared in Example 15 was evaluated using a skin irritation test. The method is as follows: Hair was removed from the back area of ​​female SD rats (n=6) 24 hours before the experiment, exposing approximately 4 cm² of skin. 1.0 g of the corresponding preparation was evenly applied to the shaved area and secured with sterile gauze. Erythema and / or edema were observed at the application site at 1, 6, 12, and 24 hours after application.

[0050] The results showed that no erythema, edema, or other abnormal reactions occurred in the colchicine nanoemulsion treatment group at any of the observation time points of 1, 6, 12, and 24 hours after administration. Figure 7The results indicate that the formulation is non-irritating to the skin and meets the safety requirements for topical preparations. Comprehensive efficacy evaluation and safety studies demonstrate that the colchicine nano-emulsion of this invention not only possesses excellent anti-inflammatory therapeutic efficacy but also exhibits good safety and excellent tolerability, making it a valuable clinical application as a highly effective and safe topical anti-inflammatory treatment.

[0051] The above embodiments merely illustrate implementation methods of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A colchicine-based topical nano-emulsion, characterized in that: This latex is composed of colchicine, oil phase matrix, surfactant, co-surfactant, transdermal absorption enhancer, gel matrix, pH adjuster and water; The composition of the raw materials by mass percentage is as follows: colchicine 0.1%~1.2%, oil phase matrix 0.5%~25%, surfactant 2%~20%, co-surfactant 2%~15%, transdermal absorption enhancer 0%~15%, gel matrix 3%~3.5%, pH adjuster 0%~0.5%, and the balance is water, totaling 100%.

2. The colchicine topical nano-emulsion according to claim 1, characterized in that: The oil phase matrix accounts for 0.9% to 1.5% of the total mass of the nano-latex; the surfactant accounts for 5% to 10% of the total mass of the nano-latex; and the co-surfactant accounts for 2.5% to 5% of the total mass of the nano-latex.

3. The colchicine topical nano-emulsion according to claim 1, characterized in that: The oil phase matrix is ​​selected from one or more of ethyl oleate, isopropyl myristate, tricaprylic acid glyceride, and liquid paraffin; the surfactant is selected from one or more of Tween 20, Tween 80, Span 80, propylene glycol monolaurate, and polyoxyethylene 40 hydrogenated castor oil; the co-surfactant is selected from one or more of propylene glycol, polyethylene glycol-400, and isopropanol; the transdermal absorption enhancer is isosorbide dimethyl ether; the gel matrix is ​​sodium carboxymethyl cellulose; and the pH adjuster is triethanolamine.

4. A method for preparing colchicine topical nano-emulsion as described in any one of claims 1-3, characterized in that: Includes the following steps: Step 1: Dissolve colchicine, surfactant, and co-surfactant in purified water to obtain an aqueous phase; Step 2: Dissolve the transdermal absorption enhancer in the oil phase matrix to obtain the oil phase; add the obtained oil phase to the aqueous phase obtained in Step 1 and emulsify to obtain colchicine nanoemulsion; Step 3: Add sodium carboxymethyl cellulose to purified water, stir and disperse evenly in a 60°C water bath, and allow it to swell fully to obtain a blank gel; Step 4: Add the colchicine nanoemulsion obtained in Step 2 to the blank gel obtained in Step 3, stir continuously until it is evenly dispersed, and adjust the pH to 6.0-6.5 to obtain colchicine nanoemulsion.

5. The colchicine topical nano-emulsion according to claim 4, characterized in that: In step 4, the colchicine nanoemulsion and the blank gel are mixed at 20~25℃.

6. The colchicine topical nano-emulsion according to claim 4, characterized in that: In step 2, the colchicine nanoemulsion has a particle size of 14.1~101.4 nm.

7. The use of a colchicine topical nano-emulsion as described in any one of claims 1-3 in the preparation of a medicament for treating acute gouty arthritis.

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