Soluble gabapentin microneedle patches, methods of making and using the same

Abstract

This invention belongs to the field of pharmaceutical technology, specifically relating to soluble gabapentin microneedle patches, their preparation methods, and applications. The microneedles provided by this invention are prepared by negative pressure centrifugation using gabapentin, hyaluronic acid, anesthetic, and water in a specific ratio. These microneedles can penetrate the stratum corneum of the skin, rapidly dissolving and releasing the drug within 10 minutes, effectively solving the problems of slow onset and low bioavailability in traditional drug administration. They also possess excellent mechanical strength and safety, with no skin irritation or organ toxicity, and are specifically designed to relieve or treat symptoms of stress, anxiety, fear, and epilepsy, providing sedation, adjunctive analgesia, and emotional calming effects, significantly improving the convenience and compliance of drug administration.

Description

Technical Field

[0001] This invention belongs to the field of pharmaceutical technology, specifically relating to soluble gabapentin microneedle patches, their preparation methods, and applications. Background Technology

[0002] Stress is a non-specific response of an organism to external or internal stimuli. This response is universal in all animals, including humans and other mammals. However, prolonged or excessive stress can negatively impact an organism's health, leading to conditions such as urinary tract disorders and behavioral abnormalities. Therefore, medications or other interventions may be used when necessary to alleviate stress and anxiety in organisms.

[0003] Transdermal drug delivery is a method of drug administration in which drugs are absorbed through the skin, enter the bloodstream, and reach effective blood concentrations to treat or prevent diseases. Traditional transdermal drug delivery primarily relies on skin patches; however, due to the barrier effect of the stratum corneum, drug permeability is limited, making it difficult to achieve the effective drug concentrations required for treatment. To improve drug permeability, researchers have developed various transdermal drug delivery technologies using physical and chemical methods, among which microneedle delivery technology has emerged as a novel and effective approach. Microneedles are typically made of materials such as metals, silicon, and polymers, and are shaped like symmetrical cones or asymmetrical bevels. These tiny needle tips can penetrate the outermost layer of the skin (stratum corneum), providing a direct channel for drugs to enter the skin.

[0004] Gabapentin (GBP) is a structural analog of γ-aminobutyric acid (GABA), but its pharmacological effects are not directly mediated by GABA receptors. Instead, it exerts its effects by binding to the α2δ subunit of voltage-gated calcium channels and is mainly used as an antiepileptic drug.

[0005] In clinical practice, stress, anxiety, and pain are common problems. Oral gabapentin has problems such as slow onset of action, inconvenient administration, and easy to cause gastrointestinal reactions, which limit its application. Summary of the Invention

[0006] Based on the above technical problems, the purpose of this invention is to provide soluble gabapentin microneedle patches, their preparation methods, and applications.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] This invention provides a soluble gabapentin microneedle, which is composed of a substrate layer and microneedles perpendicular to the substrate layer. The microneedles are made of gabapentin, a curing agent, an anesthetic, and water. The mass-volume ratio of gabapentin, curing agent, anesthetic, and water is 0.5~2g:2~4g:0.02~0.5g:5~15mL.

[0009] The microneedles provided by this invention are prepared by negative pressure centrifugation using gabapentin, hyaluronic acid, anesthetic and water in a specific ratio. These microneedles can penetrate the stratum corneum of the skin and rapidly dissolve and release the drug within 10 minutes, effectively solving the problems of slow onset and low bioavailability of traditional drug administration. They also have excellent mechanical strength and safety, with no skin irritation or organ toxicity, and can be used to treat or relieve symptoms such as stress and anxiety, playing a sedative, analgesic and mood-soothing role, and significantly improving the convenience of drug administration.

[0010] Furthermore, the needle matrix is ​​one or more of the following: hyaluronic acid, polyvinyl alcohol, sodium carboxymethyl cellulose, polyvinylpyrrolidone, alginate, chondroitin sulfate, chitosan, polylactic acid, polylactic acid-glycolic acid copolymer, methacrylamide gelatin, methacrylamide hyaluronic acid, and gelatin.

[0011] Furthermore, the anesthetic drug is one or more of the following: procaine, lidocaine, bupivacaine, benzocaine, promecaine, ropivacaine, dexmedetomidine, fentanyl, tramadol, butorphanol, and meloxicam.

[0012] Furthermore, the substrate layer is one or more of pullulan, polyvinyl alcohol, chitosan, and sodium carboxymethyl cellulose.

[0013] The present invention also provides a method for preparing the soluble gabapentin microneedles, comprising the following steps:

[0014] S1. Gabapentin, curing agent and anesthetic are mixed with water and centrifuged to remove air bubbles to obtain a mixture;

[0015] S2. Add the mixture to the microneedle mold and remove bubbles. After adding the substrate solution, solidify and demold to obtain gabapentin microneedles.

[0016] The present invention also provides the application of the soluble gabapentin microneedles in the preparation of drugs or medical devices for treating stress.

[0017] The present invention also provides the use of the soluble gabapentin microneedles in the preparation of drugs or medical devices for treating epilepsy.

[0018] The present invention also provides the application of the soluble gabapentin microneedles in the preparation of sedative drugs or medical devices.

[0019] The present invention also provides the application of the soluble gabapentin microneedles in the preparation of adjuvant analgesic drugs or medical devices.

[0020] The present invention has the following beneficial effects:

[0021] The soluble gabapentin microneedles provided by this invention can overcome the transdermal drug delivery barrier, penetrate the stratum corneum of the skin, and form a drug channel, overcoming the low penetration rate of traditional patches and the gastrointestinal problems caused by oral formulations. They completely dissolve within 10 minutes of insertion into the skin, achieving rapid drug release. Excellent mechanical properties and drug-load balance allow them to withstand a pressure of 0.4 N / needle, ensuring they do not break upon skin insertion. High safety and biocompatibility are demonstrated; no significant skin irritation was observed in a skin irritation test on New Zealand white rabbits. No significant abnormalities were found in serum biochemical indicators and pathological examinations of the heart, liver, spleen, lungs, kidneys, and skin tissues in mice, indicating good in vivo biocompatibility. The patch design allows for drug delivery within 5 minutes of pressing, significantly improving administration convenience. Attached Figure Description

[0022] Figure 1 Force-displacement curves for different types of microneedles.

[0023] Figure 2 The diagram shows the in vitro insertion performance of different types of microneedles.

[0024] Figure 3 This is a diagram showing the drug loading capacity of different types of microneedles.

[0025] Figure 4 This is a graph showing the cumulative release of different types of microneedles.

[0026] Figure 5 Force-displacement curves for microneedles with different GBP solubilities.

[0027] Figure 6 The in vitro insertion performance of microneedles with different GBP solubilities is shown in the figure.

[0028] Figure 7 This is a graph showing the drug loading of microneedles with different GBP solubilities.

[0029] Figure 8 This is a graph showing the cumulative release of microneedles with different GBP solubilities.

[0030] Figure 9 The images show the appearance of GBP-MNs, where A is the lower view under an optical microscope, B is the top view, and C is the side view.

[0031] Figure 10 Here are the SEM images of GBP-MNs, where A is the top view, B is the top magnified view, and C is the side view.

[0032] Figure 11 The images show fluorescence images of microneedles. In the image, A is a 4× microscope image of the fluorescence pattern of microneedles loaded with Rhodamine B, and B is the magnified view.

[0033] Figure 12The images show staining of mouse skin with trypan blue microneedles, where A is a magnified view from the epidermal side and B is a view from the medial side.

[0034] Figure 13 H&E staining image of GBP-MNs after insertion into the skin.

[0035] Figure 14 Morphological images of GBP-MNs at different times after insertion into the skin.

[0036] Figure 15 In vivo imaging of mice after application of Rhodamine B microneedles.

[0037] Figure 16 The images show mouse organ imaging, where A is an imaging image of the main organs of the mouse 24 hours after the application of Rhodamine B microneedles, and B is the mean signal value of the mouse over 24 hours.

[0038] Figure 17 This image shows the effect of GBP-MNs on rabbit skin.

[0039] Figure 18 The graphs show the effects of various biochemical parameters on mouse serum. In the graphs, A represents ALT expression, B represents AST expression, C represents UREA expression, and D represents CREA expression.

[0040] Figure 19 This image shows the histopathological staining results of major organs in mice after the application of GBP-MNs.

[0041] Figure 20 The image shows the skin pathological staining results of mice 24 hours after the application of GBP-MNs. Detailed Implementation

[0042] The present invention will now be described in detail with reference to specific embodiments, but these should not be construed as limiting the invention. Unless otherwise specified, the technical means used in the following embodiments are conventional means well known to those skilled in the art, and the materials, reagents, etc. used in the following embodiments can be obtained commercially unless otherwise specified.

[0043] Example 1

[0044] I. Determination of microneedle specifications.

[0045] 1. Experimental Setup: 1g of gabapentin (GBP) and 0.1g of lidocaine were dissolved in 10mL of pure water to obtain a GBP-lidocaine solution. The needle matrix was hyaluronic acid (HA). 3g of hyaluronic acid was weighed and added to the 10mL GBP-lidocaine solution in three portions. After shaking until completely dissolved, the solution was centrifuged to remove air bubbles, obtaining a GBP-HA solution. The GBP-HA solution was added to a polydimethylsiloxane (PDMS) mold and defoamed under negative pressure at room temperature for 2 minutes. Remaining air bubbles were removed with a 10μL pipette tip. The solution was then placed in a 50mL centrifuge tube with a base and centrifuged at 3000rpm for 4 minutes. This process of vacuum defoaming and centrifugation was repeated twice. After scraping off the surface GBP-HA solution, pullulan solution with a concentration of 250mg / mL was added (according to 1.3mg / mL). 2 The mass-area concentration was added to the mold groove, and after heating and drying for 24 hours, the gabapentin microneedles (GBP-MNs) were demolded. Four different types of microneedle molds were prepared using the same method, and the main dimensions are shown in Table 1.

[0046] Table 1: Parameters of four different sizes of microneedles

[0047]

[0048] 2. Experimental Testing:

[0049] (1) Mechanical strength test: The mechanical strength of GBP-MNs was tested using a texture analyzer. First, the GBP-MNs microneedle patch was fixed on the aluminum plate below the texture analyzer. The initial distance between the microneedle tip and the aluminum plate was set to 3 mm. The aluminum plate above the texture analyzer was moved downward at a speed of 5 mm / min until the microneedle broke or the maximum force of 50 N was reached. The instrument recorded the displacement and instantaneous force every 0.1 s to obtain the relevant force-displacement curve.

[0050] (2) In vitro insertion performance determination: Parafilm M ® As a skin mimic, the in vitro insertion characteristics of GBP-MNs microneedles were evaluated. The specific procedures are as follows: Parafilm M... ® The film was folded into eight layers and placed on a stainless steel plate. Then, using a 500g weight, the GBP-MNs microneedles were aligned with the folded Parafilm M... ® Press the film down. After holding for 3 minutes, remove the GBP-MNs microneedle patch from the Parafilm M. ® The microneedles of GBP-MNs were removed from the film and observed using an optical microscope on each layer of Parafilm M. ® The number of microchannels formed on the film was used to calculate the ratio of insertion holes. The experiment was repeated three times and the average value was taken.

[0051] (3) Determination of drug loading: The GBP content in GBP-MNs was determined. The microneedles and substrate of GBP-MNs were separated by a scalpel, and the needles were dissolved in 1 mL of pure water. After complete dissolution, GBP-MNs extract was obtained. The extract was filtered through a 0.22 μm microporous membrane, diluted 100 times, and the GBP concentration was determined by LC-MS / MS.

[0052] (4) In vitro transdermal release capacity determination: The in vitro transdermal release capacity of GBP-MNs microneedles was studied using the Franz diffusion cell method. GBP-MNs were inserted into the skin surface of isolated rats (2.5cm × 2.5cm) using a microneedle syringe and fixed with a medical surgical membrane, and placed on a receiving cell. 20mL of physiological saline was added to the receiving cell as the receiving medium, and air bubbles under the skin were removed to ensure full contact between the receiving medium and the skin. The device was placed in a constant temperature water bath set at 37.5±0.5℃ and a stirring speed of 300rpm to simulate in vivo release conditions. 2mL of solution was taken from the receiving cell at 5min, 15min, 30min, 1h, 2h, 4h, 6h, 12h, and 24h, and isothermal and equal amounts of receiving medium were added simultaneously. Each group was tested in triplicate. The freshly extracted receptor solution was filtered through a 0.22 μm filter membrane and then the concentration and cumulative release (Q) of GBP in the receptor cell solution were determined by liquid chromatography-mass spectrometry (LC-MS / MS).

[0053] 3. Experimental Results: Mechanical properties are a key factor in whether microneedles can effectively penetrate the skin in practical applications. During the testing process, gradually increasing pressure was applied to each type of microneedle until the microneedles broke or deformed to simulate the pressure that microneedles might withstand. Figure 1 The mechanical strength results of different microneedle models showed that GBP-MNs #1 had the best mechanical strength, withstanding a higher maximum pressure than the other three models, and exhibiting the highest resistance at half the needle length. This indicates that GBP-MNs #1 is more likely to maintain its structural stability in practical use, thus better fulfilling its drug delivery function.

[0054] Insertion testing uses a sealing film to simulate skin to assess the penetration ability of microneedles, allowing for a direct comparison and quantitative analysis of the penetration capabilities of different microneedle models. Figure 2The results showed that GBP-MNs #1 exhibited the most ideal insertion depth, maintaining over 90% penetration at the third sealing film (405 μm) and penetrating the fifth sealing film (675 μm). Its structure remained intact during insertion without any breakage. In contrast, GBP-MNs #2 and GBP-MNs #3 could only penetrate the third sealing film; while GBP-MNs #4, although similar in penetration depth to GBP-MNs #1, only achieved 10% penetration at the fourth sealing film. In conclusion, GBP-MNs #1 demonstrated the best performance in in vitro insertion.

[0055] Drug loading capacity is an important indicator of the amount of drug a microneedle can carry, and it has a direct impact on treatment efficacy. Figure 3 The data show that the drug loading of GBP-MNs#1 was 0.5116±0.0476 mg / Patch, significantly lower than that of GBP-MNs#3 (0.6160±0.0922 mg / Patch). However, both #1 and #3 microneedle models were significantly higher than GBP-MNs#2 and GBP-MNs#4 (P<0.01). Although GBP-MNs#3 had the highest drug loading, its mechanical properties were relatively weak, which may prevent it from effectively penetrating the skin in practical applications.

[0056] To evaluate the drug release efficiency of different microneedle models, an in vitro release test was conducted using a Franz diffusion cell. Figure 4 Drug release curves for four different microneedle models are presented. Within 4 hours, all models showed rapid drug release, with GBP-MNs#3 exhibiting the fastest release rate, followed by GBP-MNs#1. Release gradually stabilized after 10 hours. The cumulative release of GBP-MNs#1 within 24 hours reached 2952.49 μg / cm³. 2 The cumulative release was 4195.61 μg / cm³, second only to GBP-MNs#2. 2 .

[0057] 4. Experimental Conclusions: This study selected and evaluated microneedles based on mechanical properties, drug loading capacity, and in vitro drug release efficiency. First, the mechanical properties of the microneedles were crucial to ensure smooth and effective skin insertion, a fundamental prerequisite for drug delivery. GBP-MNs#1 demonstrated excellent performance in both aspects, outperforming other models. Second, the drug loading capacity of the microneedles was evaluated to maximize drug loading capacity while maintaining mechanical stability, thereby improving drug delivery efficiency. GBP-MNs#3 had the highest drug loading capacity, but its shortcomings in mechanical properties limited its application potential. In contrast, while GBP-MNs#1 had a slightly lower drug loading capacity than GBP-MNs#3, its advantages in mechanical properties were more significant. Finally, the drug release characteristics of the microneedles were examined to achieve rapid drug release and the highest possible cumulative release within a given time. GBP-MNs#2 showed the best cumulative release within 24 hours, but its limitations in mechanical properties and drug loading capacity restricted its potential as the preferred model. GBP-MNs#1 exhibits a faster initial release rate and a cumulative release rate second only to GBP-MNs#2, giving it a similar advantage in drug release efficiency. Therefore, considering the evaluation results from these three aspects, GBP-MNs#1 was ultimately selected as the microneedle for subsequent trials in this study.

[0058] II. Determination of drug loading capacity on microneedles

[0059] 1. Experimental Setup: Based on the successful screening of GBP-MNs #1, a systematic evaluation of the drug loading capacity of GBP-MNs under different GBP solubilities was further conducted. Different solubilities refer to dissolving 1g, 1.5g, and 2g of GBP in 10ml of pure water to obtain GBP solutions of different concentrations, which were then made into microneedles to compare their mechanical strength, insertion performance, drug loading capacity, and release efficiency.

[0060] 2. Experimental testing: The methods for mechanical performance testing, drug loading determination, and diffusion cell release efficiency testing are as shown above.

[0061] 3. Experimental Results: Mechanical strength tests were conducted on GBP-MNs#1 with different GBP solubilities, such as... Figure 5 The results showed that microneedles with three different drug loading capacities could withstand forces exceeding 0.3 N without breaking. Among them, the microneedle with a solubility of 1 g exhibited the best mechanical stability and could withstand a higher maximum force than microneedles under other drug loading conditions.

[0062] The results of the sealing film insertion test are as follows: Figure 6The results showed that microneedles with a solubility of 1g maintained a 90% penetration rate at the third sealing film (405μm) and could penetrate the fifth sealing film (675μm) without breakage or deformation during insertion. In contrast, GBP-MNs with solubilities of 1.5g and 2g showed reduced insertion depths, with penetration rates of less than 10% at the fifth sealing film (675μm).

[0063] The GBP content in the microneedle extract was determined by liquid chromatography-mass spectrometry (LC-MS), thus determining the drug loading capacity of GBP-MNs under different GBP solubilities. Figure 7 The results showed that when the solubility reached 1.5g and 2g, the drug loading was 0.5299±0.0043mg / Patch and 0.5370±0.0087mg / Patch, respectively. The drug loading of 1g of GBP-MNs was 0.5148±0.0084mg / Patch, which was not significantly different from 1.5g (P>0.05), but significantly lower than that of microneedles with a GBP solubility of 2g (P<0.05).

[0064] like Figure 8 The release efficiency results showed that the cumulative release amounts of GBP-MNs with solubilities of 1.5 g and 2 g were comparable over 24 h (4098.2639 ± 156.6209 μg / cm³, respectively). 2 and 3838.5824±95.9039μg / cm 2 (P>0.05), slightly higher than the solubility of GBP-MNs (3430.4413±359.4853μg / cm³) at 1g. 2 This means that, under conditions of excessive dissolution, the drug release efficiency also improves with the increase in the drug loading of GBP-MNs.

[0065] 3. Experimental Conclusions: In this study, microneedles with different solubilities were comprehensively evaluated. The results showed that microneedles with a solubility of 1g exhibited the best mechanical properties. Although there was a significant difference in drug loading compared to microneedles with a solubility of 2g (P < 0.05), in practical applications, this difference only resulted in a 0.0222μg difference in drug content per microneedle, which was insufficient to significantly increase blood drug concentration. Furthermore, the release efficiency test results revealed a clear correlation between drug release and drug loading. However, given that the skin penetration ability of microneedles is crucial for their clinical application, mechanical strength should be prioritized during microneedle preparation to ensure effective skin insertion and drug release. Therefore, considering the experimental results of mechanical properties, drug loading, and diffusion cell release efficiency, GBP-MNs with a GBP solubility of 1g were ultimately selected as the optimal addition amount for subsequent experiments.

[0066] III. Morphological Observation and Trial Use of Microneedles

[0067] 1. The morphology of GBP-MNs was observed using a camera and optical microscope, such as... Figure 9 As shown in the image, the overall size of the prepared GBP-MNs observed by the camera is 11.0 mm × 11.0 mm. The entire patch is intact and free of air bubbles. Optical microscopy reveals that the needles of the GBP-MNs are intact, with no broken tips. The spacing between each microneedle is equal, exhibiting a uniform conical shape, proving the successful preparation of GBP-MNs.

[0068] 2. The morphology of GBP-MNs was observed using SEM, such as... Figure 10 As shown, the prepared GBP-MNs have a height of 1000 μm, with intact needle bodies and sharp tips, facilitating skin insertion. Each microneedle is evenly spaced, exhibiting a uniform conical shape, consistent with the mold specifications, proving the successful preparation of GBP-MNs.

[0069] 3. The morphology of the microneedles loaded with Rhodamine B was observed using a fluorescence stereomicroscope. Rhodamine B, as a commonly used fluorescent dye, can clearly reveal the structural features of the microneedles. Figure 11 The morphology of the microneedles loaded with Rhodamine B is shown under a fluorescence stereomicroscope. Figure 11 The overall morphology of the microneedle array shows that the microneedles are arranged regularly and densely, which is beneficial for improving drug loading and release efficiency. Furthermore, the sharp needle-like tips of the microneedles help reduce resistance and improve penetration when inserted into the skin. Figure 11 This is a high-magnification image of the microneedles, each approximately 1000 μm in length. Rhodamine B is uniformly distributed within the microneedles, and the substrate exhibits almost no fluorescence, demonstrating that the prepared microneedles can effectively encapsulate the drug within the needle body without diffusing to the substrate, thus improving drug utilization.

[0070] 4. Microneedles loaded with 0.4% trypan blue solution were used to perform penetration tests on isolated mouse skin, and the trypan blue staining results after penetration were observed using an optical microscope. The distribution of trypan blue in the tissue can visually reflect the penetration path and effect of the microneedles. Figure 12 The images show staining after the trypan blue microneedles were inserted into isolated mouse skin. Figure 12 As shown in Figure A, the hair on the back of the mouse had been shaved, and the microneedles formed obvious puncture points on the skin surface. Trypan blue solution penetrated into the skin through these puncture points, indicating that the microneedles were able to successfully penetrate the epidermal layer of the skin. Figure 12 The B-line diagram shows that the microneedles also create corresponding puncture points on the inner side of the skin, enabling them to penetrate the skin and further confirming that the microneedles can penetrate the entire skin layer.

[0071] 5. To assess the insertion of GBP-MNs into mouse skin, mouse skin samples were stained with hematoxylin and eosin (H&E) 15 min after insertion, and the insertion depth of GBP-MNs was observed using an optical microscope. Figure 13 The images shown reveal a depression corresponding to the needle, with a depth of approximately 294 μm. Furthermore, the skin tissue structure in the microneedle insertion area remains relatively intact, with no obvious tissue damage or inflammatory response. The boundary between the epidermis and dermis is clear, and the cells are arranged in an orderly manner, indicating that the microneedle insertion process has minimal impact on the tissue.

[0072] 6. For example Figure 14 As shown, GBP-MNs were inserted into the skin of mice, and the in vitro dissolution results of GBP-MNs were observed at different time points (3 min, 5 min, 10 min). The dissolution process of the microneedles in the skin was recorded using an optical microscope.

[0073] Before insertion, the microneedles were structurally intact with no significant changes. At 3 minutes post-insertion, signs of dissolution were observed, with some microneedle tips becoming blunt, indicating the start of drug release. At 5 minutes post-insertion, dissolution intensified, with the microneedle tips almost completely disappearing and becoming blunt, reaching approximately half the original needle height. At 10 minutes post-insertion, most of the microneedle body was completely dissolved, and the drug was almost entirely released, while the base of the microneedle remained visible. These results demonstrate that GBP-MNs exhibit rapid dissolution in isolated mouse skin, completely dissolving within 10 minutes.

[0074] 7. To evaluate the distribution and metabolism of GBP-MNs in mice, as well as the changes in fluorescence intensity at different time points, Rhodamine B-loaded microneedles were prepared for in vivo imaging in mice. Rhodamine B was used instead of GBP and loaded into the microneedles to simulate its release. Figure 15 and Figure 16 Figure B shows the fluorescence imaging results and corresponding mean signal values ​​of the mouse backs from before application to 24 hours. One hour before microneedle application, there was no fluorescence on the mouse backs, with a mean signal of 0 p / s / cm² / sr / (μw / cm²). Upon application of MNs, strong red fluorescence signals appeared on the mouse backs, with a mean signal reaching 3.52E+11 p / s / cm² / sr / (μw / cm²). The fluorescence intensity gradually decreased over time. At 24 hours, the fluorescence signal significantly decreased to 0 p / s / cm² / sr / (μw / cm²), the same as before microneedle application.

[0075] Figure 16 Figure A shows fluorescence imaging of the major organs of the mouse, namely the heart, liver, spleen, lungs, and kidneys, after 24 hours. Figure 16The B-results showed that no fluorescence signal was observed in any of the tested organs after 24 hours, and the fluorescence intensity of all major organs was measured to be 0 p / s / cm² / sr / (μw / cm²). Based on these results, it is preliminarily determined that the prepared GBP-MNs can avoid the first-pass effect and improve drug bioavailability.

[0076] IV. Safety Evaluation of Microneedles

[0077] Skin irritation test: Select 3 healthy adult New Zealand white rabbits, weighing no less than 2.0 kg. Each rabbit was housed individually in a cage, clearly labeled and numbered, and allowed to acclimatize to the test environment for 7 days. 24 hours prior to the test, the fur on both sides of the rabbit's spine was removed, creating an area of ​​approximately 15 cm × 15 cm, which will be used for testing and observation.

[0078] 0.9% saline and 1% Triton X-100 solution were applied to the skin on both sides of the rabbit's spine as negative and positive control groups, respectively. Medical tape was cut into approximately 3cm × 3cm pieces, and GBP-MNs were directly applied to the skin and secured with the tape. Skin erythema and edema were observed after microneedle removal. Skin reactions were scored (see Table 2), and the average score for each group's skin reaction at each observation time point was calculated. Stimulus intensity was evaluated according to Table 3.

[0079] Table 2: Skin Irritation Response Scoring Criteria

[0080]

[0081] Table 3: Evaluation Criteria for Skin Irritation Intensity

[0082]

[0083] Safety in mice: KM mice were anesthetized using a respiratory anesthesia device. After complete anesthesia, the fur on the backs of the mice was completely shaved using a small animal shaver. For the GBP-MNs group, medical tape with GBP-MNs was applied to the shaved area on the back of the mice and left for 5 minutes before removal. The behavior and mental state of the mice were observed for 24 hours, and any abnormalities were recorded. 24 hours after treatment, mice in the GBP-MNs group and the control group (without GBP-MNs) were selected. Blood was collected, allowed to stand at room temperature for 30 minutes, and then centrifuged to obtain serum for biochemical analysis. This included measuring alanine aminotransferase (ALT), aspartate aminotransferase (AST), blood urea nitrogen (UREA), and creatinine (CREA). The experiment was repeated three times, and the average value was taken. Heart, liver, spleen, lung, kidney, and skin tissues were collected, fixed in 10% formaldehyde solution, embedded in paraffin, sectioned, stained with H&E, and subjected to histopathological evaluation.

[0084] 3. Experimental Results:

[0085] Healthy New Zealand white rabbits were divided into a negative control group, a GBP-MNs group, an application treatment group, and a positive control group.

[0086] The negative control group was treated with saline solution, the GBP-MNs group was treated with GBP-MNs applied for 5 minutes and then removed, the application treatment group was treated with GBP-MNs applied to New Zealand white rabbits (the negative control group) for 5 minutes and then removed, and the positive control group was treated with 1% Triton solution to assess the potential skin irritation of GBP-MNs. Figure 17 Table 4 shows actual photographs of rabbit skin after different treatments and skin irritation scores, where the effects of different treatments on the skin can be observed.

[0087] Table 4: Skin Irritation Score (n=3)

[0088]

[0089] The skin on the backs of New Zealand white rabbits in the control group and the GBP-MNs group remained intact, without erythema or edema. The average skin irritation score for all rabbits was 0.00 ± 0.00, indicating no skin irritation from the control group or GBP-MNs application. After GBP-MNs application, one rabbit had a skin irritation score of 1.00, indicating a slight increase in skin irritation, but the overall irritation remained low, with an average score of 0.33 ± 0.58. The positive control group, tested with 1% Triton, showed severe erythema and mild edema on the backs of all rabbits; the average skin irritation score was 3.67 ± 0.58, indicating strong skin irritation. These results show that the control group, GBP-MNs application, and GBP-MNs application all showed no irritation with no significant difference (P > 0.05); the 1% Triton application resulted in moderate irritation, which was significantly different from the other three groups (P < 0.01), indicating that GBP-MNs has good skin compatibility and low irritation.

[0090] In the in vivo safety assessment of mice, biochemical indicators in mouse serum, including alanine aminotransferase (ALT), aspartate aminotransferase (AST), blood urea nitrogen (UREA), and creatinine (CREA), were first measured 24 h after GBP-MNs administration. Figure 18 As shown, there were no significant differences in ALT, AST, UREA, and CREA levels between the control group and the GBP-MNs treatment group (P > 0.05). The ALT and AST results indicated that GBP-MNs did not cause significant liver damage in mice. The UREA and CREA results also showed that GBP-MNs had no significant adverse effects on kidney function. These results demonstrate that GBP-MNs have good safety profiles in the major metabolic organs of mice at the tested doses.

[0091] The effects of GBP-MNs on major organs (including heart, liver, spleen, lungs and kidneys) and skin tissues in mice were assessed using H&E staining histopathology. Figure 19 This study demonstrates the histopathological changes in major organs of mice 24 hours after GBP-MNs treatment. No significant pathological changes were observed in the heart, liver, spleen, lungs, and kidneys in either the GBP-MNs-treated group or the control group. The histological characteristics were similar between the two groups, with orderly cell arrangement, intact tissue structure, and no inflammatory cell infiltration, tissue necrosis, or other abnormal pathological phenomena. This further confirms that GBP-MNs have good biocompatibility under the tested conditions and did not induce significant tissue damage or inflammatory response.

[0092] Figure 20Pathological sections of mouse skin tissue 24 h after GBP-MNs application were shown. Compared with the control group, there were no significant changes in the GBP-MNs group. Both groups of skin sections showed loose connective tissue, intact adipose tissue, a distinct basal layer, abundant and clearly visible collagen fibers, clear blood vessels, and no inflammatory cell infiltration. In conclusion, the results of serum biochemical indicators and histopathological examination in mice indicate that GBP-MNs exhibit good biocompatibility in mice, providing a research basis for further preliminary clinical application.

[0093] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

Claims

1. A soluble gabapentin microneedle, characterized by, The soluble gabapentin microneedle is composed of a substrate layer and microneedles perpendicular to the substrate layer, the microneedles are made of gabapentin, a curing agent, an anesthetic and water, the mass-volume ratio of the gabapentin, the curing agent, the anesthetic and water is 0.5-2 g:2-4 g:0.02-0.5 g:5-15 mL, the curing agent is hyaluronic acid, the anesthetic is lidocaine, and the substrate layer is pullulan.

2. The method of making the soluble gabapentin microneedle of claim 1, wherein, The method comprises the following steps: S1, centrifuging to remove bubbles after mixing gabapentin, a curing agent and an anesthetic with water to obtain a mixed solution; S2, adding the mixed solution into a microneedle mold and defoaming, adding a substrate layer solution and then curing and demolding to obtain gabapentin microneedles.

3. The soluble gabapentin microneedle of claim 1 is used for preparing a drug or a medical device for treating epilepsy.

4. The soluble gabapentin microneedle of claim 1 is used for preparing a sedative drug or a medical device.

5. The soluble gabapentin microneedle of claim 1 is used for preparing an auxiliary analgesic drug or a medical device.

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