A Strychnos nux-vomica hydrogel microneedle drug delivery system, its preparation method and application

Abstract

This invention discloses a strychnine hydrogel microneedle drug delivery system, its preparation method, and its application. The drug delivery system comprises the following components: polyvinyl alcohol, carbomer 934P, strychnine, tartaric acid, and a 40% ethanol solution. The preparation method is as follows: Polyvinyl alcohol and carbomer are placed in a beaker and mixed thoroughly with a 40% ethanol solution containing strychnine until fully swollen. Tartaric acid solution is then added, and after stirring and allowing to stand for full cross-linking, a hydrogel solution with a certain degree of fluidity is prepared. The hydrogel solution is then injected into a microneedle mold, centrifuged, and placed in a desiccator for 24 hours until the moisture is almost completely dried. It is then dried in an oven, removed, cooled to room temperature, and demolded. The prepared hydrogel microneedle drug delivery system exhibits good mechanical properties, swelling properties, sustained-release properties, and safety performance.

Description

Technical Field

[0001] This invention relates to the field of pharmaceutical formulation inventions, and in particular to a strychnine hydrogel microneedle drug delivery system, its preparation method, and its application. Background Technology

[0002] Strychnos nux-vomica L., the dried, mature seed of the plant (Strychnos nux-vomica L.) in the Loganiaceae family, has the effects of clearing the meridians, relieving pain, reducing swelling, and dissipating nodules. It is commonly used to treat injuries from falls and blows, swelling and pain from fractures, stubborn rheumatism, numbness and paralysis, carbuncles and boils, and sore throat. [1-2] Strychnine (Bru) is a traditional anti-RA treatment drug. Derived from the mature seeds and bark of the toxic traditional Chinese medicine *Strychnos nux-vomica*, it possesses various pharmacological effects including anti-inflammatory, analgesic, and anti-tumor properties. It is the second largest alkaloid component of *Strychnos nux-vomica*, accounting for approximately 30%-40% of the total alkaloids, second only to strychnine. However, its toxicity is only 1 / 20th that of strychnine, thus possessing significant development potential. [3] Although Bru has significant pharmacological effects, its therapeutic and toxic doses are close. [4] This limitation restricts its clinical application. Therefore, developing Bru into a safe and efficient new drug delivery system is currently a hot research topic.

[0003] Microneedles (MNs) are a form of drug delivery that falls between subcutaneous injection and traditional transdermal patches (such as patches and films). They can penetrate the stratum corneum of the skin to form micron-sized pores, thereby promoting transdermal drug absorption. Compared to traditional transdermal formulations, MNs can enhance the absorption of poorly water-soluble substances. [5-7] (such as strychnine, tripterygium ether, glycyrrhizin, etc.), biological macromolecules [8-10] (such as polysaccharides, polypeptides, proteins, etc.), hydrophilic small molecules [11-12] The transdermal permeability of drugs such as ibuprofen sodium. Currently, microneedles are mainly classified into five types: solid microneedles, hollow microneedles, coated microneedles, soluble microneedles, and hydrogel-forming microneedles (HFM). HFM, in particular, has the characteristic of rapidly absorbing interdermal fluid after penetrating the stratum corneum, swelling to form continuous, non-blockable hydrogel microporous drug delivery channels. Compared to other microneedles, HFM needle material can be removed from the skin with little or no residue.

[13] The drug release rate can be controlled by changing the degree of cross-linking of the hydrogel material.

[14] There are already studies on its application in arthritis, and the results are significant. [15-16] .

[0004] Prior art document 1, application number 201910134480.3, entitled "A Strychnine Soluble Microneedle, Preparation Method, Detection Method, and Application," discloses a strychnine soluble microneedle composed of 0.012002 to 0.012010 parts of strychnine, 0.998 to 1.006 parts of chondroitin sulfate, and 0.997 to 1.005 parts of polyvinylpyrrolidone. The soluble microneedles are prepared using a vacuum decompression method. The prepared strychnine soluble microneedles exhibit good morphological and mechanical properties, solving the problem of drug penetration through the stratum corneum and addressing the issue that the effective dose and toxic dose of strychnine in treating rheumatoid arthritis are very close, severely limiting its clinical application. Problems; It can significantly reduce synovial epithelial hyperplasia and cartilage erosion in the ankle joint, maintain the joint space, and has a good therapeutic effect on rat RA; however, it has the following defects: (1) The polymer material that makes up the soluble microneedles will gradually dissolve into the skin during the administration process and be absorbed by the human body. This may lead to safety hazards caused by excessive absorption of polymer material by the human body after multiple administrations; (2) The drug loading is small, and there may be drug-loaded matrix residues during in vivo drug administration, which may affect the amount and rate of drug release; (3) The microneedles do not use cross-linking agents, which prevents the microneedles from forming a network structure, which may result in poor mechanical strength, permeation promotion effect, and drug sustained release effect; (4) The curing time is 3-5 days, which is too long.

[0005] Prior art document 2, application number: 201910709653.X, invention title: A strychnine gel preparation and its preparation method, discloses that the gel preparation contains 0.5%-1% strychnine, 0.5%-3% gel skeleton, 10%-30% cosolvent, and the balance is water. The prepared strychnine hydrogel uses simple pharmaceutical excipients, does not use transdermal penetration enhancers but has excellent transdermal effect, is easy to spread, has good biocompatibility, good skin absorption, good drug film adhesion, and is non-irritating to skin and mucous membranes. However, the following defects exist: (1) The preparation does not have a needle structure for piercing the skin, and the skin's barrier function for drug absorption still exists; (2) There will be obvious drug and matrix residues after administration; (3) The gel preparation contains uncontrollable components such as pH adjusters, antioxidants, and antibacterial agents, and long-term use may affect skin safety; (4) The gel preparation prepared by this method cannot be punctured, its permeation-promoting effect is poor, its transdermal sustained-release performance is poor, and its drug bioavailability is greatly reduced.

[0006] To address the problems existing in the prior art, our team has focused on the construction and anti-RA research of drug-loaded soluble microneedles in recent years, discovering that strychnine-soluble microneedles and triptolide-soluble microneedles have significant anti-RA efficacy. However, residues remain on the skin after transdermal drug delivery of soluble microneedles, leading to uncontrollable drug release amounts and rates. Furthermore, the rapid dissolution of the soluble microneedle body also affects the transdermal drug delivery rate of the drug-loaded backing. Therefore, based on previous work and the aforementioned scientific issues, this invention aims to design a hydrogel microneedle drug delivery system with significant slow swelling properties, no matrix dissolution after swelling, obvious long-term drug sustained-release performance, high safety, and good mechanical properties. Summary of the Invention

[0007] The purpose of this invention is to provide a strychnine hydrogel microneedle drug delivery system.

[0008] Another objective of this invention is to provide a method for preparing a strychnine hydrogel microneedle drug delivery system.

[0009] Another object of the present invention is to provide an application of a strychnine hydrogel microneedle drug delivery system in the preparation of anti-RA drug products.

[0010] This invention is achieved by adopting the following technical solution:

[0011] The present invention discloses a strychnine hydrogel microneedle drug delivery system, which is made of the following components: strychnine 0.03-0.07g, polyvinyl alcohol 1-2g, carbomer 934P 0.1-0.2g, tartaric acid 0.1-0.2g, and 40% ethanol solution 10mL.

[0012] Preferably, the strychnine hydrogel microneedle drug delivery system of the present invention is made of the following components: strychnine 0.04-0.06g, polyvinyl alcohol 1.5-2g, carbomer 934P 0.15-0.2g, tartaric acid 0.15-0.2g, and 40% ethanol solution 10mL.

[0013] More preferably, the strychnine hydrogel microneedle drug delivery system of the present invention is made of the following components: 0.05g strychnine, 1.5g polyvinyl alcohol, 0.15g carbomer 934P, 0.2g tartaric acid, and 10mL 40% ethanol solution.

[0014] The preparation method of the strychnine hydrogel microneedle drug delivery system of the present invention includes the following steps:

[0015] (1) Place strychnine in a beaker, add 10 mL of 40% ethanol solution to dissolve it, and use the strychnine solution as a drug loading solvent for later use.

[0016] (2) Place Carbomer 934P in a beaker, add 1-3 mL of the drug loading solvent obtained in step (1), stir evenly and let it stand to swell for 20-40 min; then add polyvinyl alcohol and drug loading solvent 5-7 mL in small amounts several times, stirring while adding until the mixed matrix solution is uniform and free of small lumps, and let it stand overnight in a 4℃ refrigerator to fully swell, to obtain the mixed matrix solution.

[0017] (3) Add tartaric acid to the remaining drug-carrying solvent. After it is completely dissolved, mix it with the mixed matrix solution obtained in step (2). Place it in a 4°C refrigerator overnight for full cross-linking. Take it out and let it cool to room temperature to obtain a hydrogel solution with a certain fluidity.

[0018] (4) Inject the hydrogel solution obtained in step (3) into the microneedle mold, centrifuge at 3000-5000 r / min for 5-30 min, place it in a desiccator for 20-30 h until the moisture is basically completely dried, then place it in an oven to dry for 1.5-2.5 h at a drying temperature of 65-125℃, take it out and let it cool to room temperature, and demold to obtain the strychnine hydrogel microneedle drug delivery system.

[0019] Preferably, the preparation method of the strychnine hydrogel microneedle drug delivery system of the present invention includes the following steps:

[0020] (1) Place strychnine in a beaker, add 10 mL of 40% ethanol solution to dissolve it, and use the strychnine solution as a drug loading solvent for later use.

[0021] (2) Place Carbomer 934P in a beaker, add 2 mL of the drug loading solvent obtained in step (1), stir evenly and let it stand to swell for 30 min; then add 6 mL of polyvinyl alcohol and drug loading solvent in small amounts several times, stirring while adding until the mixed matrix solution is uniform and free of small lumps, and let it stand overnight in a 4°C refrigerator to fully swell, to obtain the mixed matrix solution.

[0022] (3) Add tartaric acid to the remaining drug-carrying solvent. After it is completely dissolved, mix it with the mixed matrix solution obtained in step (2). Place it in a 4°C refrigerator overnight for full cross-linking. Take it out and let it cool to room temperature to obtain a hydrogel solution with a certain fluidity.

[0023] (4) Inject the hydrogel solution obtained in step (3) into the microneedle mold, centrifuge at 4000 r / min for 10-20 min, place it in a desiccator for 24 h until the moisture is basically completely dried, then place it in an oven to dry for 2 h at a drying temperature of 95-115℃, take it out and cool it to room temperature, and demold to obtain the strychnine hydrogel microneedle drug delivery system.

[0024] A further preferred embodiment of the preparation method of the strychnine hydrogel microneedle drug delivery system of the present invention includes the following steps:

[0025] (1) Place strychnine in a beaker, add 10 mL of 40% ethanol solution to dissolve it, and use the strychnine solution as a drug loading solvent for later use.

[0026] (2) Place Carbomer 934P in a beaker, add 2 mL of the drug loading solvent obtained in step (1), stir evenly and let it stand to swell for 30 min; then add 6 mL of polyvinyl alcohol and drug loading solvent in small amounts several times, stirring while adding until the mixed matrix solution is uniform and free of small lumps, and let it stand overnight in a 4°C refrigerator to fully swell, to obtain the mixed matrix solution.

[0027] (3) Add tartaric acid to the remaining drug-carrying solvent. After it is completely dissolved, mix it with the mixed matrix solution obtained in step (2). Place it in a 4°C refrigerator overnight for full cross-linking. Take it out and let it cool to room temperature to obtain a hydrogel solution with a certain fluidity.

[0028] (4) Inject the hydrogel solution obtained in step (3) into the microneedle mold, centrifuge at 4000 r / min for 10 min, place it in a desiccator for 24 h until the moisture is basically completely dried, then place it in an oven to dry for 2 h at a drying temperature of 105℃, take it out and cool it to room temperature, and demold to obtain the strychnine hydrogel microneedle drug delivery system.

[0029] The mass ratio of carbomer 934P to the drug-loaded solvent in this invention is 1.5%.

[0030] The mass ratio of polyvinyl alcohol to drug-loaded solvent in this invention is 15%.

[0031] The mass ratio of tartaric acid to drug-loaded solvent in this invention is 2%.

[0032] The application of the strychnine hydrogel microneedle drug delivery system described in this invention or the strychnine hydrogel microneedle drug delivery system prepared by the preparation method described herein in the preparation of anti-RA drug products.

[0033] The present invention has the following advantages:

[0034] 1. The strychnine hydrogel microneedle drug delivery system of the present invention has good appearance, mechanical strength and swelling performance. It does not dissolve during the swelling process and the drug loading is about 1 mg per tablet.

[0035] 2. The strychnine hydrogel microneedle drug delivery system of this invention exhibits significant drug sustained-release and permeation-enhancing effects. In vivo drug release rate studies show that Bru-HFM has significant sustained-release and permeation-enhancing effects. Bru in the microneedles can achieve sustained release for over 144 hours in vivo, with a release rate of 51.85±11.96% at 144 hours. Under optimal process conditions, Bru-HFM prepared in vitro achieved a release rate of 78.15% after 144 hours. The release rate of the Bru-HFM backing portion in vivo after 144 hours was 57.39±16.65%. The release rate of the microneedles themselves in vivo after 96 hours was 67.43±14.93%, and in vitro drug release reached equilibrium at 48 hours, with a release rate of 78.81%.

[0036] 3. The strychnine hydrogel microneedle drug delivery system of this invention has high safety. Acute toxicity test results show that Bru-HFM transdermal administration has high safety, and no toxic reaction occurs even when the dosage is increased (up to 30 times).

[0037] 4. The preparation process of this invention is simple, easy to implement, stable, and reliable. By characterizing the hydrogel material using infrared spectroscopy and scanning electron microscopy, the optimal material for preparing HFM was identified as PVA / CP hydrogel. After loading Bru onto the hydrogel, the preparation process of Bru-HFM was optimized through single-factor and orthogonal experiments. The optimal preparation parameters for HFM were determined to be: 15% PVA, 1.5% CP, Bru solvent concentration of 5 mg / mL, drying temperature of 105℃, and centrifugation time of 10 min. Furthermore, the sustained-release performance of HFM with different amounts of tartaric acid was evaluated using a Franz diffusion cell to screen the optimal tartaric acid dosage. Finally, the optimal chemical cross-linking agent, tartaric acid, was determined to be 2.0%, at which point the in vitro drug release performance of HFM was optimal. Attached Figure Description

[0038] Figure 1 Microneedle images prepared with different hydrogel materials (where a represents G / SA / ASG-HFM; b represents PVA / CP-HFM).

[0039] Figure 2 Infrared spectra of PVA / CP hydrogel, carbomer, polyvinyl alcohol, and tartaric acid

[0040] Figure 3 SEM images of the cross-section of the PVA / CP composite hydrogel (left side: 20 μm; right side: 10 μm).

[0041] Figure 4 Swelling curves at different matrix formulation ratios (a. Swelling curves of different CP ratios at 10% PVA; b. Swelling curves of different CP ratios at 15% PVA; c. Swelling curves of different CP ratios at 20% PVA (n=3))

[0042] Figure 5 Appearance of HFM prepared at different temperatures after swelling for 120 min

[0043] Figure 6 HFM swelling curves prepared under different temperature conditions

[0044] Figure 7 Optical micrographs of HFM arrays prepared under various orthogonal process experimental conditions.

[0045] Figure 8 Transdermal diffusion pool

[0046] Figure 9 Bru-specific HPLC chromatograms (a. reference solution; b. blank HFM solution; c. Bru-HFM solution)

[0047] Figure 10 Bru standard curve

[0048] Figure 11 Bru-HFM cumulative release curve (n≥3)

[0049] Figure 12 Images of the Bru-HFM (a. High-definition video taken with a mobile phone; b. High-definition video taken with a mobile phone; c. Optical microscopic side view; d. Optical microscopic microarray image; e. SEM microneedle single needle top view; f. SEM microneedle array image)

[0050] Figure 13 Images show the mechanical properties of Bru-HFM (left: rat ex vivo skin puncture; middle: rat in vivo skin puncture; right: optical micrograph after removal of the patch 5 days after application).

[0051] Figure 14 Trend of HFM in vivo swelling substrate width

[0052] Figure 15 Trend of base diameter variation in HFM ex vivo swelling

[0053] Figure 16 In vivo drug release curve of fully drug-loaded microneedles

[0054] Figure 17 Bru-HFM backing partial drug release curves (n≥3)

[0055] Figure 18 Optical micrograph of a microneedle array after in vivo swelling and needle removal using HFM.

[0056] Figure 19 In vivo drug release curves of Bru-HFM loaded only in needles (n≥3)

[0057] Figure 20 Release curve of Bru-HFM drug-loaded needle in ex vivo Franz diffusion cell

[0058] Figure 21 Organ index in acute toxicity test of female rats ( n=6)

[0059] Figure 22 Organ index in acute toxicity test of male rats ( n=6) Detailed Implementation

[0060] Example 1: A Strychnos nux-vomica hydrogel microneedle drug delivery system

[0061] Formula: Polyvinyl alcohol 1.5g, Carbomer 934P 0.15g, Strychnine 0.05g, Tartaric acid 0.2g, 40% ethanol 10mL.

[0062] Example 2: A Strychnos nux-vomica hydrogel microneedle drug delivery system

[0063] Formula: Polyvinyl alcohol 1.0g, Carbomer 934P 0.10g, Strychnine 0.03g, Tartaric acid 0.1g, 40% ethanol 10mL.

[0064] Example 3: A Strychnos nux-vomica hydrogel microneedle drug delivery system

[0065] Formula: Polyvinyl alcohol 1.0g, Carbomer 934P 0.15g, Strychnine 0.05g, Tartaric acid 0.2g, 40% ethanol 10mL.

[0066] Example 4: A Strychnos nux-vomica hydrogel microneedle drug delivery system

[0067] Formula: Polyvinyl alcohol 1.0g, Carbomer 934P 0.20g, Strychnine 0.05g, Tartaric acid 0.2g, 40% ethanol 10mL.

[0068] Example 5: A Strychnos nux-vomica hydrogel microneedle drug delivery system

[0069] Formula: Polyvinyl alcohol 1.5g, Carbomer 934P 0.10g, Strychnine 0.05g, Tartaric acid 0.15g, 40% ethanol 10mL.

[0070] Example 6: A Strychnos nux-vomica hydrogel microneedle drug delivery system

[0071] Formula: Polyvinyl alcohol 1.5g, Carbomer 934P 0.20g, Strychnine 0.05g, Tartaric acid 0.2g, 40% ethanol 10mL.

[0072] Example 7: A Strychnos nux-vomica hydrogel microneedle drug delivery system

[0073] Formula: Polyvinyl alcohol 2.0g, Carbomer 934P 0.10g, Strychnine 0.05g, Tartaric acid 0.2g, 40% ethanol 10mL.

[0074] Example 8: A Strychnos nux-vomica hydrogel microneedle drug delivery system

[0075] Formula: Polyvinyl alcohol 2.0g, Carbomer 934P 0.15g, Strychnine 0.05g, Tartaric acid 0.2g, 40% ethanol 10mL.

[0076] Example 9: A Strychnos nux-vomica hydrogel microneedle drug delivery system

[0077] Formula: Polyvinyl alcohol 2.0g, Carbomer 934P 0.20g, Strychnine 0.07g, Tartaric acid 0.2g, 40% ethanol 10mL. The formulations of the Strychnine hydrogel microneedle drug delivery system in Examples 1 to 9 are used in the preparation methods of the following examples.

[0078] Example 10: Preparation method of strychnine hydrogel microneedle drug delivery system

[0079] (1) Place strychnine in a beaker, add 10 mL of 40% ethanol solution to dissolve it, and use the strychnine solution as a drug loading solvent for later use.

[0080] (2) Place Carbomer 934P in a beaker, add 2 mL of the drug loading solvent obtained in step (1), stir evenly and let it stand to swell for 30 min; then add 6 mL of polyvinyl alcohol and drug loading solvent in small amounts several times, stirring while adding until the mixed matrix solution is uniform and free of small lumps, and let it stand overnight in a 4°C refrigerator to fully swell, to obtain the mixed matrix solution.

[0081] (3) Add tartaric acid to the remaining drug-carrying solvent. After it is completely dissolved, mix it with the mixed matrix solution obtained in step (2). Place it in a 4°C refrigerator overnight for full cross-linking. Take it out and let it cool to room temperature to obtain a hydrogel solution with a certain fluidity.

[0082] (4) Inject the hydrogel solution obtained in step (3) into the microneedle mold, centrifuge at 4000 r / min for 10 min, place it in a desiccator for 24 h until the moisture is basically completely dried, then place it in an oven to dry for 2 h at a drying temperature of 105℃, take it out and cool it to room temperature, and demold to obtain the strychnine hydrogel microneedle drug delivery system.

[0083] Example 11: Preparation method of strychnine hydrogel microneedle drug delivery system

[0084] (1) Place strychnine in a beaker, add 10 mL of 40% ethanol solution to dissolve it, and use the strychnine solution as a drug loading solvent for later use.

[0085] (2) Place Carbomer 934P in a beaker, add 2 mL of the drug loading solvent obtained in step (1), stir evenly and let it stand to swell for 30 min; then add 5 mL of polyvinyl alcohol and drug loading solvent in small amounts several times, stirring while adding until the mixed matrix solution is uniform and free of small lumps, and let it stand overnight in a 4°C refrigerator to fully swell, to obtain the mixed matrix solution.

[0086] (3) Add tartaric acid to the remaining drug-carrying solvent. After it is completely dissolved, mix it with the mixed matrix solution obtained in step (2). Place it in a 4°C refrigerator overnight for full cross-linking. Take it out and let it cool to room temperature to obtain a hydrogel solution with a certain fluidity.

[0087] (4) Inject the hydrogel solution obtained in step (3) into the microneedle mold, centrifuge at 4000 r / min for 20 min, place it in a desiccator for 24 h until the moisture is basically completely dried, then place it in an oven to dry for 2 h at a drying temperature of 115℃, take it out and cool it to room temperature, and demold to obtain the strychnine hydrogel microneedle drug delivery system.

[0088] Example 12: Preparation method of strychnine hydrogel microneedle drug delivery system

[0089] (1) Place strychnine in a beaker, add 10 mL of 40% ethanol solution to dissolve it, and use the strychnine solution as a drug loading solvent for later use.

[0090] (2) Place Carbomer 934P in a beaker, add 2 mL of the drug loading solvent obtained in step (1), stir evenly and let it stand to swell for 30 min; then add 6 mL of polyvinyl alcohol and drug loading solvent in small amounts several times, stirring while adding until the mixed matrix solution is uniform and free of small lumps, and let it stand overnight in a 4°C refrigerator to fully swell, to obtain the mixed matrix solution.

[0091] (3) Add tartaric acid to the remaining drug-carrying solvent. After it is completely dissolved, mix it with the mixed matrix solution obtained in step (2). Place it in a 4°C refrigerator overnight for full cross-linking. Take it out and let it cool to room temperature to obtain a hydrogel solution with a certain fluidity.

[0092] (4) Inject the hydrogel solution obtained in step (3) into the microneedle mold, centrifuge at 4000 r / min for 15 min, place it in a desiccator for 24 h until the moisture is basically completely dried, then place it in an oven to dry for 2 h at a drying temperature of 95℃, take it out and cool it to room temperature, and demold to obtain the strychnine hydrogel microneedle drug delivery system.

[0093] Example 13: Preparation method of strychnine hydrogel microneedle drug delivery system

[0094] (1) Place strychnine in a beaker, add 10 mL of 40% ethanol solution to dissolve it, and use the strychnine solution as a drug loading solvent for later use.

[0095] (2) Place Carbomer 934P in a beaker, add 1 mL of the drug loading solvent obtained in step (1), stir evenly and let it stand to swell for 30 min; then add 7 mL of polyvinyl alcohol and drug loading solvent in small amounts several times, stirring while adding until the mixed matrix solution is uniform and free of small lumps, and let it stand overnight in a 4°C refrigerator to fully swell, to obtain the mixed matrix solution.

[0096] (3) Add tartaric acid to the remaining drug-carrying solvent. After it is completely dissolved, mix it with the mixed matrix solution obtained in step (2). Place it in a 4°C refrigerator overnight for full cross-linking. Take it out and let it cool to room temperature to obtain a hydrogel solution with a certain fluidity.

[0097] (4) Inject the hydrogel solution obtained in step (3) into the microneedle mold, centrifuge at 3000 r / min for 10 min, place it in a desiccator for 20 h until the moisture is basically completely dried, then place it in an oven to dry for 1.5 h at a drying temperature of 95℃, take it out and cool it to room temperature, and demold to obtain the strychnine hydrogel microneedle drug delivery system.

[0098] Example 14: Preparation method of strychnine hydrogel microneedle drug delivery system

[0099] (1) Place strychnine in a beaker, add 10 mL of 40% ethanol solution to dissolve it, and use the strychnine solution as a drug loading solvent for later use.

[0100] (2) Place Carbomer 934P in a beaker, add 3 mL of the drug loading solvent obtained in step (1), stir evenly and let it stand to swell for 20 min; then add 5 mL of polyvinyl alcohol and drug loading solvent in small amounts several times, stirring while adding until the mixed matrix solution is uniform and free of small lumps, and let it stand overnight in a 4°C refrigerator to fully swell, to obtain the mixed matrix solution.

[0101] (3) Add tartaric acid to the remaining drug-carrying solvent. After it is completely dissolved, mix it with the mixed matrix solution obtained in step (2). Place it in a 4°C refrigerator overnight for full cross-linking. Take it out and let it cool to room temperature to obtain a hydrogel solution with a certain fluidity.

[0102] (4) Inject the hydrogel solution obtained in step (3) into the microneedle mold, centrifuge at 4000 r / min for 10 min, place it in a desiccator for 24 h until the moisture is basically completely dried, then place it in an oven to dry for 2 h at a drying temperature of 105℃, take it out and cool it to room temperature, and demold to obtain the strychnine hydrogel microneedle drug delivery system.

[0103] Example 15: Preparation method of strychnine hydrogel microneedle drug delivery system

[0104] (1) Place strychnine in a beaker, add 10 mL of 40% ethanol solution to dissolve it, and use the strychnine solution as a drug loading solvent for later use.

[0105] (2) Place Carbomer 934P in a beaker, add 2 mL of the drug loading solvent obtained in step (1), stir evenly and let it stand to swell for 40 min; then add 6 mL of polyvinyl alcohol and drug loading solvent in small amounts several times, stirring while adding until the mixed matrix solution is uniform and free of small lumps, and let it stand overnight in a 4°C refrigerator to fully swell, to obtain the mixed matrix solution.

[0106] (3) Add tartaric acid to the remaining drug-carrying solvent. After it is completely dissolved, mix it with the mixed matrix solution obtained in step (2). Place it in a 4°C refrigerator overnight for full cross-linking. Take it out and let it cool to room temperature to obtain a hydrogel solution with a certain fluidity.

[0107] (4) Inject the hydrogel solution obtained in step (3) into the microneedle mold, centrifuge at 4000 r / min for 30 min, place it in a desiccator for 24 h until the moisture is basically completely dried, then place it in an oven to dry for 2 h at a drying temperature of 125℃, take it out and cool it to room temperature, and demold to obtain the strychnine hydrogel microneedle drug delivery system.

[0108] To demonstrate the scientific validity and rationality of the detection method of this invention, the following methodological experimental studies were conducted:

[0109] Part 1: Study on the Preparation Process of Strychnos nux-vomica Hydrogel Microneedles

[0110] To prepare strychnine hydrogel microneedles (Bru-HFM) with satisfactory performance across various parameters, this study used array integrity, bubble quantity, swelling properties, and mechanical properties as evaluation indicators. First, three common polymeric hydrogel materials were optimized. Based on this, single-factor experiments were conducted to screen the matrix material ratio, drying temperature, drug concentration, and centrifugation time. Further optimization was achieved using orthogonal processing to determine the optimal HFM preparation parameters. Using rat skin as a biosimulator, the sustained-release performance of Bru-HFM in the Franz transdermal diffusion cell was used as an evaluation indicator to optimize the dosage of the chemical cross-linking agent tartaric acid.

[0111] 1. Experimental Materials

[0112] 1.1 Main Instruments and Equipment

[0113] Microneedle mold, Taizhou Weikai, needle length 550μm; AE / 240 0.0001 g electronic balance, Shanghai Mettler; AUY220 0.0001 g electronic balance, Shimadzu, Japan; micropipette, Eppendorf, Germany; TD5A-120 centrifuge, Changzhou Jintan Liangyou; 101-3AB electric drying oven, Tianjin Tester; SIPTOP optical microscope, Ningbo Sunny Optical; KQ-500DE CNC ultrasonic cleaner, Kunshan Ultrasonic Instruments; Fourier transform infrared spectrometer, Thermo Scientific Nicoleti S20, USA; JSM-IT700HR scanning electron microscope, NEC Corporation, Japan; RYJ-12B transdermal drug diffusion assay instrument, Shanghai Huanghai Drug Inspection; LC2030C3D high performance liquid chromatograph, Shimadzu, Japan.

[0114] 1.2 Main Reagents and Tests

[0115] Reagents: Polyvinyl alcohol (PVA), Shanghai Yuanye Biotechnology, batch number N07HS200180; Sodium hyaluronate (HA), Shandong Yinhe Biotechnology, HA180422-3; Carbomer 934P (CP), Shanghai Yuanye Biotechnology, Y17O7C22897; Gelatin (G), Tianjin Kemio, 20160611; Sodium alginate (SA), Beijing Solarbio, 1118X051; Anhydrous calcium chloride, Shanghai Yuanye Biotechnology, D10GS170933; Tartaric acid (TA), Tianjin Zhiyuan , 2019110199; 1,4-Butanediol diglycidyl ether (BDDE), Shanghai Yuanye Biotechnology, R09J7P8823; Artemisia argyi gum (ASG), Shanghai Yuanye Biotechnology, X12S11T124420; Sodium hydroxide, Chongqing Chuandong Chemical, 20200301; Ethanol, Tianjin Fengchuan, 20221008; Glacial acetic acid, Shanghai Aladdin, D1918059; Triethylamine, Tianjin Kemio, 20190301; Methanol, Shanghai Maclean, C15280410.

[0116] Test reagent: Strychnine reference standard, Beijing Zhongke Quality Inspection Biotechnology Co., Ltd., purity 99.83%, batch number 21110417.

[0117] 2. Methods and Results

[0118] 2.1 Basic Preparation Process of Strychnos nux-vomica Hydrogel Microneedles

[0119] Bru-HFM is prepared using a fully drug-loaded method. First, an appropriate amount of polymer material is placed in a beaker and mixed evenly with a solvent to allow it to swell fully. Then, a chemical cross-linking agent solution is added. After stirring evenly and allowing it to stand to allow for full cross-linking, a hydrogel solution with a certain degree of fluidity is prepared. This solution is injected into a microneedle mold, centrifuged, and placed in a desiccator for 24 hours until the moisture is basically completely dried. Then, it is placed in an oven to dry, removed, cooled to room temperature, and demolded to obtain the final product.

[0120] 2.2 Screening and Characterization of Strychnos nux-vomica Hydrogel Microneedle Matrix Material

[0121] 2.2.1 Optimal Selection Method for Matrix Materials

[0122] To optimize the selection of different hydrogel materials, three groups of hydrogel materials were selected based on the evaluation indicators of matrix fluidity, microneedle array integrity, bubble amount, and microneedle mechanical properties. The optimization method adopted a two-step screening method, and the details are shown in Table 1.

[0123] Table 1. Preferred Indicators for Hydrogel Materials

[0124]

[0125] 2.2.2 Preparation and Optimization of Hydrogel Matrix Materials

[0126] 2.2.2.1 Preparation of different matrix materials

[0127] This study investigated the feasibility of preparing HFM using three groups of hydrogel composite materials: cross-linked hyaluronic acid hydrogel, cross-linked polyvinyl alcohol / carbomer hydrogel, and cross-linked gelatin / sodium alginate / Artemisia argyi hydrogel. The preparation methods are as follows:

[0128] Preparation of hyaluronic acid hydrogel (HA)

[17] Add 10 mL of 0.25 mol / L NaOH solution to a beaker, add 200 μL of BDDE and mix thoroughly to prepare a chemical crosslinking agent. Add 1 g of HA powder to the crosslinking agent solution, place in a 40℃ water bath for 2 hours with constant stirring to allow the crosslinking reaction to occur. Adjust the pH to 7 using 0.1 mol / L HCl solution. Remove the crosslinked HA material and wash it in purified water to remove residual crosslinking agent. Centrifuge at 4000 r / min for 10 min to remove air bubbles, then let it stand for later use.

[0129] Preparation of polyvinyl alcohol / carbomer hydrogel (PVA / CP)

[18] A hydrogel matrix solution was prepared by mixing PVA (15%, by mass ratio to solvent), carbomer (1%, by mass ratio to solvent), and tartaric acid (1.5%, by mass ratio to solvent). First, 0.1 g of carbomer 934P was placed in a beaker, and an appropriate amount of solvent was added and stirred until homogeneous. The mixture was allowed to swell for 1 hour. Then, 1.5 g of PVA powder and an appropriate amount of solvent were added while stirring until the matrix solution in the beaker became translucent and free of white lumps. The stirred matrix solution was then placed in a refrigerator at 4°C overnight to allow for complete swelling. Next, 0.15 g of tartaric acid was dissolved in the remaining solvent, sonicated for 10 minutes, and allowed to stand at room temperature. The tartaric acid aqueous solution was then added dropwise to the PVA and carbomer mixture. The mixture was then placed in a refrigerator at 4°C overnight to remove air bubbles. A total of 10 mL of solvent was used in the above methods.

[0130] Preparation of gelatin / sodium alginate / Artemisia argyi gum hydrogel (G / SA / ASG)

[19] Weigh 2.5% (by mass of solvent) of gelatin and place it in purified water. Stir for 40 minutes in a 50°C water bath. Add 0.7% (by mass of solvent) of Artemisia argyi and stir well. Then weigh 1.5% (by mass of solvent) of sodium alginate and place it in purified water. Stir until homogeneous in a 50°C water bath and let stand to room temperature. Mix the two matrix materials and let stand overnight to remove air bubbles. Then add an equal volume of 2% calcium chloride solution dropwise while stirring. Let stand overnight to allow for full cross-linking. Finally, wash with purified water to remove any remaining cross-linking agent solution and store at 4°C.

[0131] 2.2.2.2 Optimal Selection of Different Matrix Materials

[0132] Results of the first screening of matrix materials:

[0133] The results of the three groups of HFM materials are shown in Table 2. The HA hydrogel matrix material is too viscous and is not suitable for preparing HFM, while the PVA / CP and G / SA / ASG materials have good fluidity and can be used as backup materials for preparing HFM for further optimization and screening.

[0134] Table 2 Evaluation results of HFM matrix materials

[0135]

[0136] Results of the second step screening of matrix materials:

[0137] HFM was prepared using PVA / CP hydrogel and G / SA / ASG hydrogel matrix solutions with good flowability according to section "2.1". The optimal HFM preparation material was screened based on the integrity of the microneedle array, appearance, mechanical properties, and the amount of air bubbles in the needle body and backing. The screening results are shown in Table 3 below. Figure 1 As shown:

[0138] Table 3 Evaluation of PVA / CP-HFM and G / SA / ASG-HFM

[0139]

[0140] From Table 3 and Figure 1 It is known that G / SA / ASG hydrogel materials are not suitable for preparing HFM, while HFM prepared from PVA / CP hydrogel materials meet all the requirements. Therefore, PVA / CP is the best material for preparing HFM.

[0141] 2.2.3 Characterization of hydrogel materials

[0142] 2.2.3.1 Fourier Transform Infrared Spectroscopy (FITR)

[0143] If the original materials of HFM can be successfully mixed to prepare cross-linked hydrogels, the infrared spectrum of the mixture will differ from that of the pure components. The interactions between the pure components will change the band intensity or wavelength of the infrared spectrum. Infrared spectroscopy can also be used to analyze bond formation in hydrogels. [20-21] Therefore, in this study, the hydrogel materials selected under section "2.2.2" were freeze-dried for 4 days and characterized by infrared spectroscopy using the ATR method. Simultaneously, the infrared spectra of PVA, CP, and TA were detected using the potassium bromide pellet method. The infrared spectral recording range was 4000–400 cm⁻¹. -1 The resolution is 4cm. -1 The result is as follows Figure 2 As shown.

[0144] Depend on Figure 2 We can see that in the PVA spectrum, there is a range of 3660–3010 cm⁻¹. -1 The wide band around the left and right is due to the stretching vibration of the hydroxyl group (OH), 1740 cm. -1 The characteristic peak at this point is due to the vibration of the carbonyl C=O group in the PVA powder; the infrared spectrum of CP is in the range of 3500–2760 cm⁻¹. -1 A broad and strong band belonging to OH was observed within the range, at 1720 cm⁻¹. -1 The characteristic peak at 3300 cm⁻¹ is due to the C=O vibration; the infrared spectrum of TA at 3300 cm⁻¹... -1 and 3210cm -1 There are two overlapping peaks of OH at this point, and a broadband spectrum of 3230–2730 cm⁻¹ is also observed in the TA infrared spectrum. -1 The characteristic peak of OH vibration at 1750 cm⁻¹ -1 The characteristic peak of strong C=O vibration at that location.

[0145] In the spectrum of PVA / CP hydrogel materials, 1710 cm⁻¹ -1The peak at this location shifts significantly towards lower vibrations compared to PVA, indicating the possible presence of unsaturated double bonds near C=O. The crosslinking agent TA in the hydrogel may form covalent ester bonds connecting the two polymers (PVA and CP) through dehydration, thereby creating a crosslinked hydrogel material. [6] .

[0146] 2.2.3.2 Scanning Electron Microscopy (SEM)

[0147] The prepared PVA / CP composite hydrogel was freeze-dried for 4 days, then cut with scissors, and the cross-sectional structure of the hydrogel was observed using scanning electron microscopy (SEM). The results are as follows: Figure 3 As shown.

[0148] Depend on Figure 3 It is known that due to chemical cross-linking and the interaction between macromolecules, the cross-section of hydrogel materials forms a clearly interconnected network structure, which may enable it to have an internal microporous structure for drug storage and to form continuous microporous channels for drug release during swelling.

[0149] 2.3 Single-factor analysis and orthogonal experiment to optimize the Bru-HFM preparation process

[0150] Based on the hydrogel materials selected under section "2.2", single-factor experiments were conducted to optimize the microneedle matrix material formulation ratio, drying temperature, Bru drug loading concentration, and centrifugation time. Based on the results of the single-factor experiments, an L9(3)240 ... 4 Orthogonal arrays were used to conduct process experiments to further optimize the microneedle preparation parameters. The basic conditions were: 15% PVA, 1.0% CP, drying temperature 95℃, drying time 2h, Bru solvent concentration 5mg / mL, centrifugation time 15min, and 10mL of 40% ethanol.

[0151] 2.3.1 Optimization of the preparation process of strychnine hydrogel microneedles through single-factor experiments

[0152] 2.3.1.1 Optimal Selection of Matrix Material Formulation Ratio

[0153] Evaluation indicators: microneedle properties, time-swelling curve, and matrix flowability.

[0154] Evaluation Methods: PVA / CP hydrogels with different formulations were prepared into HFM according to the contents of section "2.1". The microneedle properties were evaluated based on array integrity and bubble amount, and the swelling performance was expressed as the degree of swelling (p) and the swelling curve. The degree of swelling was calculated according to formula (1), where m1 represents the mass of the microneedles after they were dissolved in PBS solution at 37℃, swollen for a certain period of time, and the excess PBS solution on the surface was removed; m2 represents the mass of the dried microneedles before swelling. The swelling curve was plotted with time (min) as the abscissa and swelling degree as the ordinate. The results are as follows: Figure 4 As shown.

[0155]

[0156] Different prescription contents: as shown in Table 4.

[0157] Table 4 Different formulations of PVA / CP hydrogel matrix materials

[0158]

[0159] Table 5. Flowability and microneedle properties of different formulation materials in PVA / CP hydrogel

[0160]

[0161] Observation results: The results are as follows Figure 4 As shown in Table 5, among the different matrix material formulations, F5 exhibits the best swelling performance and good matrix fluidity. Furthermore, the HFM array prepared with this formulation remains intact and bubble-free, maintaining its complete structure even after swelling in PBS solution for 120 min without dissolution. Therefore, formulation F5, i.e., 15% PVA and 1.5% CP, was selected as the optimal matrix formulation for single-factor analysis.

[0162] 2.3.1.2 Optimal Drying Temperature

[0163] Evaluation indicators: HFM physical properties and swelling curve.

[0164] Evaluation method: The performance evaluation of HFM properties is the same as in section "2.3.1.1". The swelling degree curve is evaluated by dissolving HFM prepared at different temperatures in 37℃ PBS solution, calculating the swelling degree at specific time points, and then plotting a curve with swelling time as the x-axis and swelling degree as the y-axis.

[0165] The temperatures tested were 65℃, 75℃, 85℃, 95℃, 105℃, 115℃, and 125℃.

[0166] Observation results: such as Figure 5 As shown. When the drying temperature of HFM is below 105℃, HFM exhibits varying degrees of dissolution after 120 minutes of swelling, with the dissolution becoming more pronounced at lower drying temperatures. When the drying temperature is greater than or equal to 105℃, the microneedles do not dissolve with prolonged swelling time (within 160 hours), maintaining their intact appearance. Figure 6 As shown, the swelling degree of HFM prepared at a drying temperature of 105℃ is significantly higher than that of other HFMs. Therefore, 105℃ is considered the optimal temperature for preparing HFM.

[0167] 2.3.1.3 Optimal Drug Concentration

[0168] Evaluation indicators: drug solubility, matrix flowability, and microneedle properties.

[0169] Methodology: Based on previous research results, 40% ethanol was used as the solvent for dissolving Bru. Bru solutions of different concentrations were prepared, and then HFM was prepared according to section "2.1". The solubility of the drug in the solvent, the flowability of the matrix at different drug loading concentrations, and the appearance of the microneedles were investigated.

[0170] Drug concentrations examined: 1 mg / mL, 5 mg / mL, 10 mg / mL, 15 mg / mL, 20 mg / mL.

[0171] Results: As shown in Table 6, when the drug loading concentration was less than 5 mg / mL, the drug dissolved completely without precipitation, the matrix had good fluidity, and the microneedles remained intact without bubbles. Furthermore, to improve drug loading, the optimal Bru drug loading concentration was selected as 5 mg / mL.

[0172] Table 6 Results of drug solvent concentration screening

[0173]

[0174] 2.3.1.4 Optimal Centrifugation Time

[0175] Evaluation indicators: amount of matrix bubbles and microneedle properties after centrifugation.

[0176] Evaluation Method: The prepared PVA / CP hydrogel solution was filled into a microneedle mold, placed in a horizontal centrifuge, and centrifuged at 4000 r / min. After drying and shaping, the microneedles were removed. The optimal centrifugation time was selected based on the amount of residual air bubbles in the hydrogel solution after centrifugation and the microneedle morphology.

[0177] Centrifugation times were examined: 5 min, 10 min, 15 min, 20 min, 25 min, and 30 min.

[0178] Results: As shown in Table 7, when the centrifugation time is greater than 15 min, the amount of residual bubbles in the matrix and the microneedle properties meet the requirements. To reduce the process time, 15 min is the optimal centrifugation time.

[0179] Table 7 Selection of Centrifugation Time

[0180]

[0181] 2.3.2 Orthogonal Experiment Optimization of Strychnos nux-vomica Hydrogel Microneedle Preparation Process

[0182] 2.3.2.1 Factor level table and scoring criteria for orthogonal experiment

[0183] Based on the single-factor experiments, a factor level table and L9(3) were designed with the matrix formulation (formulation details as shown in Table 5), drying temperature, drying time, and centrifugation time as factors. 4 The orthogonal arrays are shown in Tables 8 and 10. The scoring criteria for the orthogonal experiment are: swelling degree of hydrogel microneedles (swelling degree at 120 min as the scoring standard), skin penetration rate and array integrity, with scoring weights of 60%, 20%, and 20%, respectively, as shown in Table 9. The skin puncture rate is calculated using formula (2), where p2 represents the skin puncture rate, N represents the number of microneedle array needles, and n represents the number of microneedle punctures in the skin. The needle breakage rate is calculated using formula (3), where p3 represents the needle breakage rate, n1 represents the number of broken needles, and N represents the number of microneedle array needles.

[0184]

[0185]

[0186] Table 8 Factor Level Table

[0187]

[0188] Table 9. Orthogonal Experiment Scoring Table

[0189]

[0190] 2.3.2.2 Visual representation of orthogonal experiment results and analysis of variance

[0191] The results of the orthogonal experiment are shown in the orthogonal experiment visual table (Table 10) and the analysis of variance table (Table 11). The range shows that among the factors, drying temperature has a greater impact on the comprehensive score of microneedles, while centrifugation time has the least impact. The order of influence of each factor is as follows: R C >R A >R B >R D Analysis of variance showed that drying temperature had a highly significant effect on the overall microneedle score (p<0.01), while the matrix material ratio and drug loading solvent concentration had significant effects on the overall microneedle score (p<0.05). In summary, the optimal HFM formulation is A2B2C2D1, i.e., 15% PVA, 1.5% CP, Bru solvent concentration of 5 mg / mL, drying temperature of 105℃, and centrifugation time of 10 min.

[0192] Table 10. Visual Representation of Orthogonal Experiments

[0193]

[0194]

[0195] Table 11 Analysis of Variance Table

[0196]

[0197] Note: *P < 0.05; **P < 0.01; F 0.05 (2, 2) = 19; F 0.01 (2,2)=99

[0198] Optical micrographs of HFM arrays prepared under various conditions in orthogonal process experiments 1-9 are shown below. Figure 7 As shown.

[0199] 2.4 In vitro transdermal assay to investigate different amounts of cross-linking agent (tartaric acid)

[0200] The basic preparation process for HFM was determined through the above single-factor and orthogonal experiments. Based on this process, the effect of different amounts of cross-linking agents on the sustained-release performance of HFM was further investigated to enable the microneedles to have long-term transdermal sustained-release properties. Using the drug release performance of Bru-HFM in an in vitro Franz diffusion cell as an indicator, the optimal amount of tartaric acid, the chemical cross-linking agent for HFM, was selected.

[0201] 2.4.1 In vitro transdermal diffusion test method

[0202] To vertical transdermal diffusion cell (e.g.) Figure 8 (7 mL) Inject 20% ethanol aqueous solution as the receiving solution. Place microneedles with different amounts of tartaric acid (0.075%, 0.1%, 0.15%, 0.2%, by mass ratio to solvent) on isolated rat skin (stratum corneum facing up), press for about 30 seconds to allow the needle to pierce the stratum corneum, and fix with medical tape to prevent it from falling off. Place the fixed microneedles and rat skin on the diffusion pool (stratum corneum facing the supply pool). Set the rotation speed to 300 r / min and the temperature to 37℃. Take 1 mL samples at 0.5, 1, 2, 4, 8, 10, 24, 48, 72, and 96 h respectively, filter through a 0.22 μm microporous membrane, and place the filtrate in a high performance liquid chromatography injection bottle for later use. Replenish the blank receiving solution after each sampling. HPLC determine the mass concentration of Bru in each sample, and calculate the cumulative permeability (Q) of Bru according to formula (4):

[0203]

[0204] In the formula, Q is the cumulative permeability at the nth sampling point, and C... n Vn represents the Bru mass concentration (μg / mL) of the receiving solution at the nth sampling point, V0 represents the volume of the receiving cell (mL), and Vn represents the mass concentration of Bru at the nth sampling point. i C represents the sampling volume (mL) at the i-th sampling. i Let represent the concentration of Bru in the receiving solution (μg / mL) during the i-th (i≤n-1) sampling, and W represent the drug content in Bru-HFM.

[0205] 2.4.2 Establishment of HPLC method for strychnine content determination and determination of Bru-HFM drug loading

[0206] 2.4.2.1 Chromatographic conditions

[0207] Column: Agilent C 18 Column (4.6 mm × 250 mm, 5 μm); Mobile phase A: 1.20% glacial acetic acid and 0.13% triethylamine aqueous solution, Mobile phase B: chromatographic methanol; Column temperature 30℃; Flow rate 1.0 mL / min; Wavelength 365 nm; Injection volume 10 μL.

[0208] 2.4.2.2 Solution Preparation

[0209] Reference solution: Accurately weigh 2.5 mg of strychnine reference standard and dilute to the mark with methanol in a 25 mL volumetric flask to obtain a 100 μg / mL Bru reference solution.

[0210] Test solution: Take one Bru-HFM tablet into a 25 mL volumetric flask, dilute to the mark with 40% ethanol, let stand overnight, shake several times, filter through a 0.22 μm microporous membrane, and collect the filtrate to obtain the test solution.

[0211] Blank microneedle solution: Take one blank microneedle and follow the same method as the test sample solution preparation method.

[0212] 2.4.2.3 Specificity Test

[0213] Take Bru reference solution, Bru-HFM test solution, and blank HFM solution, and inject and analyze them according to the HPLC chromatographic conditions in section "2.4.2.1".

[0214] like Figure 9 The retention times of the main peak in the Bru-HFM sample solution and the Bru absorption peak in the Bru reference solution were basically consistent, while no absorption peak appeared at the same time point in the negative control blank HFM solution, indicating that the excipients had no effect on the absorption of Bru. The method specificity met the requirements.

[0215] 2.4.2.4 Plotting the Standard Curve

[0216] Using the reference solution prepared under section "2.4.2.2" as the base solution, a series of reference solutions with concentrations of 100, 80, 40, 20, 10, 4, and 1 μg / mL were prepared by dilution at different ratios. The Bru peak area of ​​each reference solution was detected according to the HPLC chromatographic conditions under section "2.4.2.1". A standard curve was plotted with the Bru peak area on the ordinate and the corresponding reference solution concentration on the abscissa.

[0217] like Figure 10The linear relationship of the standard curve meets the requirements, R 2 =0.9998, and the linear equation is y = 18792x - 5677.4, indicating that Bru has a good linear relationship with the chromatographic peak area in the concentration range of 1 to 100 μg / mL.

[0218] 2.4.2.5 Precision Test

[0219] Take Bru reference standard solutions at concentrations of 80, 40, and 20 μg / mL, and inject them six times consecutively under the HPLC chromatographic conditions described in section "2.4.2.1". Calculate the RSD value based on the peak area to assess precision. See Table 12.

[0220] Table 12 Precision test results (n=6)

[0221]

[0222] According to Table 12, the precision of the Bru peak area in the high, medium, and low concentration Bru solutions is less than 3%, indicating that the instrument has good precision.

[0223] 2.4.2.6 Recovery Test

[0224] Accurately weigh 0.50 mg, 0.99 mg, and 1.97 mg of Bru reference standard into 25 mL volumetric flasks. Add the excipients for a single HFM tablet (calculated as 30 tablets based on the orthogonal experimental optimization in "2.3.2") according to the microneedle preparation process, mix well, add an appropriate amount of 40% ethanol, stir evenly, and let stand overnight to allow full swelling. Then, dilute to 25 mL with methanol, shake several times, let stand overnight, and filter through a 0.22 μm microporous membrane. Analyze the filtrate according to the HPLC chromatographic conditions in "2.4.2.1" to determine the Bru content, and calculate the recovery rate and RSD value. Recovery rate (%) = Actual Bru measurement (mg) / Bru added amount (mg) × 100%. See Table 13.

[0225] Table 13 Results of the spiking recovery test (n=3)

[0226]

[0227]

[0228] The results in Table 13 show that the average recovery rate of the spiking was 98.43%, and the RSD was 1.77%, which meets the requirements.

[0229] 2.4.2.7 Repeatability Test

[0230] Six batches of microneedles were prepared, with three microneedles randomly selected from each batch. Test solutions were prepared according to method “2.4.2.2”, and HPLC chromatographic analysis was performed under the conditions described in “2.4.2.1”. The Bru content and RSD of the microneedles were calculated. See Table 14.

[0231] Table 14 Results of Repeatability Tests (n=3)

[0232]

[0233] The repeatability test results are shown in Table 14. The average RSD of strychnine content among different batches of Bru-HFM was 1.91% < 3%, indicating that the microneedle preparation process has good repeatability.

[0234] 2.4.2.8 Stability Test

[0235] Take the same Bru-HFM test solution and filter it through a microporous membrane at 0, 2, 4, 8, 12, 24, and 48 h. Take the filtrate and determine the Bru peak area under the HPLC chromatographic conditions in section "2.4.2.1". Calculate the sample content and RSD at each time point. See Table 15.

[0236] Table 15 Stability Test Results

[0237]

[0238] Stability test results showed that the RSD of the Bru-HFM test solution at different times was 0.17% < 3%, indicating that the Bru-HFM test solution remained stable within 48 hours.

[0239] 2.4.2.9 Determination of drug loading in Bru-HFM

[0240] Six Bru-HFM tablets were randomly selected and placed in a 25 mL volumetric flask. The flask was diluted to volume with 40% ethanol, shaken repeatedly, and left overnight. The solution was filtered through a 0.22 μm microporous membrane. The filtrate was analyzed under the HPLC chromatographic conditions described in section “2.4.2.1”, and the average drug loading per tablet was calculated. See Table 16.

[0241] Table 16 Results of Bru-HFM Drug Loading Measurement

[0242]

[0243] The results of the drug loading determination of Bru-HFM are shown in Table 16. The average drug loading of HFM is 1002.82±19.45μg / tablet.

[0244] 2.4.3 Optimal Use of Crosslinking Agent

[0245] Bru-HFM was prepared with different TA dosages (0.75%, 1.0%, 1.5%, and 2.0%). Three tablets of each microneedle were randomly selected, and the drug concentration and cumulative permeation rate of the microneedles in the Franz diffusion cell at each time point were detected according to the methods in sections "2.2.1" and "2.4.2.1". The in vitro percutaneous cumulative permeation curve of Bru-HFM was plotted with cumulative permeation rate on the ordinate and time (t / h) on the abscissa. The results are as follows. Figure 11 As shown.

[0246] The results of in vitro transdermal experiments of Bru-HFM prepared with different amounts of cross-linking agent (TA) are as follows: Figure 1-11 As shown, the drug release rates of each microneedle in the 0–24 h range were relatively high. The cumulative release rates of 0.075%, 1.0%, 1.5%, and 2.0% TA-HFM in 24 h were 25.00%, 44.36%, 38.54%, and 50.12%, respectively; and the cumulative release amounts were 252.64 μg, 436.05 μg, 391.97 μg, and 496.13 μg, respectively.

[0247] The drug release rate of microneedles was relatively slow between 24 and 144 hours. At 144 hours, the cumulative release rates of the 0.075%, 1.0%, and 1.5% TA-HFM microneedles were comparable, all around 68%, with cumulative release amounts of 688.99 μg, 662.83 μg, and 688.74 μg, respectively. The 2.0% TA-HFM microneedle had a cumulative release rate of 78.15% at 144 hours, with a cumulative release amount of 773.60 μg. Overall, the release rate of 0.075% TA-HFM was lower than other microneedles between 24 and 144 hours, while the release rates of 1.0% and 1.5% TA-HFM were comparable. The release rate of 2.0% TA-HFM was consistently higher than other microneedles. After 144 hours, the cumulative drug release of all microneedles reached a near-equilibrium.

[0248] The time to reach drug release equilibrium was basically the same for microneedles with different TA contents, all around 144 hours. However, under 2.0% TA conditions, the cumulative drug permeability of Bru-HFM was consistently higher than that of other types of microneedles. Therefore, HFM exhibited the best in vitro drug release performance when the TA content was 2.0%, and this was determined to be the optimal amount of crosslinking agent for preparing Bru-HFM.

[0249] 3. Chapter Summary

[0250] (1) Three groups of polymeric mixtures (HA, PVA / CP, G / SA / ASG) for preparing hydrogel microneedles were screened, and the hydrogel materials were characterized by infrared spectroscopy and scanning electron microscopy. The results showed that PVA / CP was the best material for preparing HFM.

[0251] (2) The optimal Bru-HFM preparation process was selected through single-factor experiments and orthogonal experiments as follows: 15% PVA, 1.5% CP, Bru solvent concentration of 5 mg / mL, drying temperature of 105℃, and centrifugation time of 10 min.

[0252] (3) An in vitro HPLC method for the determination of Bru was established and its methodology was validated. The drug loading of Bru-HFM was also determined. All methodological test results met the requirements, with RSD values ​​all less than 3%. The linearity of the standard curve met the requirements. 2 =0.9998, and the linear equation is y = 18792x - 5677.4. The sustained-release performance of Bru-HFM under different TA dosages was investigated using an in vitro Franz diffusion cell to optimize the optimal TA dosage. It was finally found that the in vitro drug release performance of HFM was optimal when the TA dosage was 2.0%, and 2.0% TA was determined as the preparation process condition for Bru-HFM.

[0253] Part Two: Evaluation of the Strychnine Hydrogel Microneedle Drug Delivery System

[0254] The results of the first part of the study show that the prepared Bru-HFM has good sustained-release properties. However, further quality assessment is needed to meet the requirements for transdermal drug delivery of Bru-HFM. Based on the optimized Bru-HFM preparation process, Bru-HFM was prepared. General quality evaluation was conducted by examining its appearance, mechanical properties, drug loading, and in vivo swelling properties. Drug release performance was evaluated by examining the in vivo and Franz in vitro drug release rates in rats. Safety performance was evaluated through acute toxicity tests.

[0255] 1. Experimental Instruments and Materials

[0256] 1.1 Main Instruments

[0257] 550μm microneedle mold, Taizhou Weikai; AE / 240 0.0001 g electronic balance, Shanghai Mettler; AUY220 0.0001 g electronic balance, Shimadzu, Japan; micropipette, Eppendorf, Germany; TD5A-120 centrifuge, Changzhou Jintan Liangyou; 101-3AB electric drying oven, Tianjin Tester; SIPTOP optical microscope, Ningbo Sunny Optical; KQ-500DE CNC ultrasonic cleaner, Kunshan Ultrasonic Instruments; JSM-IT700HR scanning electron microscope, NEC Corporation; RYJ-12B transdermal drug diffusion assay instrument, Shanghai Huanghai Pharmaceutical Inspection; LC2030C 3D high performance liquid chromatograph, Shimadzu, Japan.

[0258] 1.2 Main Reagents and Tests

[0259] Reagents: Polyvinyl alcohol (PVA), Yuanye Bio-Technology Co., Ltd., Shanghai, N07HS200180; Sodium hyaluronate (HA), Galaxy Biotech Co., Ltd., Shandong, HA180422-3; Carbomer 934P (CP), Yuanye Bio-Technology Co., Ltd., Shanghai, Y17O7C22897; Tartaric acid (TA), Zhiyuan Chemical Reagent Co., Ltd., Tianjin, 2019110199; Ethanol, Fengchuan Chemical Reagent Co., Ltd., Tianjin, 20221008; Glacial acetic acid, Aladdin Industrial Corporation, Shanghai, D1918059; Triethylamine, Kermel Chemical Reagent Co., Ltd., Tianjin, 20190301; Methanol, Macklin Biochemical Co., Ltd., Shanghai, C15280410.

[0260] Test drug: Brucine reference substance, Beijing Zhongke Quality Inspection Biotechnology Co., Ltd., purity 99.83%, batch number 21110417.

[0261] 1.3 Animals

[0262] Female Wister rats, body weight 190 - 220 g, SPF grade. The animals were sourced from Beijing Sibefu Biotechnology Co., Ltd., production license number: SCXK (Jing) 2019 - 0010. After purchase, they were conventionally raised in the school animal house. The raising environment had sufficient sunlight and good ventilation. All animals were adaptively fed for one week before the animal experiments. The animal experiments complied with the requirements of the Ethics Committee of Guizhou University of Traditional Chinese Medicine regarding animal care and use, ethical review number: 20230179.

[0263] 2 Methods and Results

[0264] 2.1 Preparation process flow of Bru-HFM

[0265] According to the screening results of the Bru-HFM preparation process in the first part, prepare with a solvent volume of 10 mL: First, accurately weigh 50 mg of Bru reference substance and place it in a beaker, add 10 mL of 40% ethanol to dissolve to obtain a Bru solution, which is used as the solvent for preparing HFM. Weigh 0.15 g of CP and place it in a beaker, evenly spread it on the bottom of the cup, drop 2 mL of the above drug-loading solvent, stir evenly and let it swell for 30 min. Then add PVA and the drug-loading solvent in small amounts multiple times, stirring continuously until the mixed matrix solution is uniform without small lumps (finally, the total added amount of PVA is 1.5 g, and the total added amount of the drug-loading solvent is 6 mL). Let it stand in a 4℃ refrigerator overnight for sufficient swelling. Weigh 0.2 g of TA and dissolve it in the remaining drug-loading solvent. After complete dissolution, mix it with the above mixed matrix solution, and then place it in a 4℃ refrigerator overnight for sufficient cross-linking. Take it out and let it stand at room temperature to obtain the Bru-HFM drug-loading matrix solution. Fill the drug-loading matrix solution into a microneedle mold, centrifuge at 4000 r / min for 10 min, take it out after drying in a dryer for 24 h, dry it in an electric drying oven at 105℃ for 2 h, take it out and cool it to room temperature, and demold to obtain Bru-HFM.

[0266] 2.2 Evaluation of appearance properties

[0267] The integrity of the microneedle array was observed using a mobile phone high-definition camera, optical microscope, and scanning electron microscope (SEM). The results are as follows: Figure 12 As shown.

[0268] like Figure 12 As shown, the Bru-HFM array is complete, neat, bubble-free, and transparent overall. Figure 12 -ab); The needle body is conical, with layered annular patterns on the surface, uniform array spacing, and no broken needles or other defects. Figure 12 -cdef).

[0269] 2.3 Mechanical Performance Evaluation

[0270] The mechanical performance evaluation of Bru-HFM involved pressing the microneedles into the rat's ex vivo and in vivo skin for 30 seconds with a finger, then removing them to observe the microneedle insertion. This was to evaluate the ex vivo skin puncture performance in the rat (abdomen) and the in vivo skin puncture performance in the rat (thigh knee joint). The HFM was then applied to the rat's skin for 5 days before being removed to observe for any breakage. Results are as follows: Figure 13 As shown.

[0271] Bru-HFM successfully pierced the detached abdominal skin and the in vivo skin of the knee joint of rats, forming distinct and neatly arranged micropores on the skin. After 5 days of in vivo application, optical microscopy revealed significant swelling of the HFM within the skin. Upon removal, the needle became bent and elongated, but no needle breakage, missing pieces, or dissolution occurred. In summary, the prepared dried HFM exhibits good hardness and mechanical toughness after in vivo swelling.

[0272] 2.4 Drug Loading Determination

[0273] Prepare HFM according to the procedure in section 2.1, randomly select 6 tablets, and determine the drug loading of each microneedle and the average drug loading according to the method in section 2.4.2.1 of Part 1. See Table 17.

[0274] Table 17 Results of Drug Loading Measurement

[0275]

[0276]

[0277] As shown in Table 17, the average drug loading per Bru-HFM tablet is 1022.51 ± 2.20 μg / tablet.

[0278] 2.5 Evaluation of swelling performance

[0279] The swelling performance of HFM is an important factor affecting its drug release rate. The evaluation of the swelling performance of HFM in this study is mainly divided into two parts: in vivo swelling performance in rats and in vitro swelling performance in PBS solution.

[0280] 2.5.1 In vivo swelling

[0281] Bru-HFM was applied to the knee joint of rats, with finger pressure applied for 30 seconds to ensure needle penetration. It was then secured with white medical tape. The patch was removed at 0, 2, 4, 8, 24, 48, 72, and 94 hours. Images were taken using an optical microscope, and the actual change in the base width of the HFM needle was measured using MvImage vt software. Results are as follows: Figure 14 As shown.

[0282] like Figure 14 During the swelling of rat in vivo skin, the base width of HFM continuously increased over time, swelling from an initial 278.43 μm to 552.03 μm (1.98 times the initial width). The swelling reached equilibrium at approximately 72 hours.

[0283] 2.5.2 In vitro swelling

[0284] Bru-HFM needles were immersed in PBS solution at 37℃. The changes in the width of the HFM needle base at 0, 0.5, 1, 2, and 3 hours of swelling were measured using an optical microscope and MvImage vt software. The results are as follows: Figure 15 As shown.

[0285] like Figure 15 HFM swells in PBS solution, and the width of the microneedle substrate can be increased from the initial 278.43 μm to a maximum equilibrium value of 612.15 μm after about 2 hours.

[0286] Combining the in vivo and in vitro swelling results of HFM, it can be concluded that the in vitro swelling performance of PBS solution is significantly better than that of in vivo swelling, which may be due to the presence of lipid-soluble components in the interdermal fluid. Furthermore, neither solution exhibits dissolution, which meets the requirements for transdermal drug delivery via HFM.

[0287] 2.6 Drug release rate study

[0288] Hydrogel materials swell after absorbing water, creating micropores that release the loaded substance. Therefore, to investigate the drug release rate of Bru-HFM after swelling and whether the drug loaded in the backing portion can be continuously released through the needle, Bru-HFM was divided into three groups for drug release rate investigation: the full microneedle drug release rate investigation group, the backing drug release rate investigation group, and the needle drug release rate investigation group.

[0289] 2.6.1 HFM in vivo drug release rate

[0290] Take the same batch of Bru-HFM and test the drug loading according to Section 1, “2.4.2.1”. Apply microneedles to the knee joint of rats (after shaving the fur in this area), press with your finger for 30 seconds, and secure with white medical tape to prevent detachment. Remove the microneedles at 24, 48, 72, 96, 120, and 144 hours after application (n≥3). Test the remaining amount of Bru after release according to Section 1, “2.4.2.1”, calculate the release rate, and plot the release curve. Release rate = (microneedle drug loading - remaining drug in the microneedle after release) / microneedle drug loading * 100%. See Tables 18-19.

[0291] Table 18 Drug Loading of Bru-HFM

[0292]

[0293] Table 19 In vivo drug release rate of fully drug-loaded microneedles ( n≥3)

[0294]

[0295]

[0296] From Tables 18-19 and Figure 16 It can be seen that almost no drug is released from Bru-HFM within 24 hours. This may be because the HFM has not fully swelled and the hydrogel material is still in a state of water absorption and swelling. The drug release rate increases continuously over time from 24 to 144 hours. After 144 hours of in vivo drug release, the drug release rate reaches 51.85%, and the amount of drug released at this time is about 526.89 μg.

[0297] 2.6.2 HFM backing in vivo drug release rate

[0298] Take 6 Bru-HFM tablets, scrape off the needle body with a scalpel, and determine the drug content of the remaining backing material by HPLC. Then, take an appropriate amount of Bru-HFM and apply it to the skin of rats (n≥3) as described in section "2.6.1" for drug release. Remove the HFM, scrape off the needle body with a scalpel, and determine the drug content of the remaining backing material by HPLC. Calculate the release rate and plot the release curve. Release rate = (Drug loading on backing material - Remaining drug on backing material after release) / Drug loading on backing material * 100%. See Tables 20-21.

[0299] Table 20 Drug Loading in Backing Section Only of Bru-HFM

[0300]

[0301] Table 21 In vivo drug release rate of Bru-HFM backing portion ( n≥3)

[0302]

[0303] Experimental results show (see) Figures 17 to 18 The drug-loaded portion of the Bru-HFM backing swells and can release the drug sustainably, with the release rate increasing over time within 144 hours, reaching 57.39% at 144 hours. It is worth mentioning that... Figure 17 It can be seen that the drug release rate of the microneedle backing part is less than 0 before 48 hours of in vivo drug release. This may be because before the swelling equilibrium of HFM, the hydrogel material of the microneedle backing part will continuously absorb water through the channels formed by the needle, causing the drug loaded in the needle to transfer to the backing along with the water, thus resulting in a drug release rate of less than 0.

[0304] 2.6.3 In vivo drug release rate of HFM needle

[0305] Referring to the preparation process in previous studies, a two-step centrifugation method was used to prepare Bru-HFM with only the needle body loaded with drug (the needle body was prepared using a drug-loaded solvent) and the backing not loaded with drug (the backing was prepared using a drug-free solvent). [22-23] Six tablets were taken and their drug loading was calculated using HPLC. Following the method described in section "2.6.1", the tablets were applied to the skin of rats for drug release at 24, 48, 72, and 96 hours (n≥3), and then removed. The drug loading and release rate were calculated using HPLC. Release rate = (microneedle drug loading - remaining drug in the microneedle after release) / microneedle drug loading * 100%. See Tables 22-23.

[0306] Table 22 Bru-HFM drug loading in needles only

[0307]

[0308]

[0309] Table 23 In vivo drug release rate of Bru-HFM loaded only in needles ( n≥3)

[0310]

[0311] As shown in Table 23 and Figure 19As shown, Bru-HFM releases almost no drug within 24 hours. This is likely because HFM does not fully swell during this period, and the hydrogel material remains in a state of water absorption and swelling. The drug release rate of Bru-HFM loaded only in the needle increases over time from 24 to 96 hours, reaching 67.43% at 96 hours. It should be noted that, as shown in Tables 22, 20, and 18, the drug loading of drug-loaded HFM in the needle only (36.15 μg) differs significantly from the drug content of the needle with full drug loading (1016.81 - 885.65 = 131.16 μg). This may be because, during the centrifugation process after filling the mold with the drug-loaded matrix solution, the drug loaded in the backing portion settles towards the needle tip due to gravity and centrifugal force.

[0312] 2.6.4 HFM needle in vitro drug release rate

[0313] Bru-HFM, prepared in the same batch with only needle-loaded drug as described in section "2.6.3", was used to investigate its in vitro Franz cell drug release rate according to the method described in section "2.4.1" of Part 1, and release curves were plotted. The results are shown in Table 24 and... Figure 20 As shown. The method for calculating the drug release rate is the same as formula (4) in Part 1.

[0314] Table 24. In vitro drug release rate of Bru-HFM loaded only in needles ( n≥3)

[0315]

[0316] As shown in Table 24 and Figure 20 The experimental results showed that only the needle-loaded drug Bru-HFM had a relatively fast release rate in the Franz in vitro diffusion cell from 0 to 10 h, a slow release rate from 10 to 48 h, and reached equilibrium at around 48 h with an equilibrium value of about 78.81%. At this time, the cumulative Bru permeation amount was 28.74 ± 1.38 μg.

[0317] 2.7 Acute toxicity study

[0318] Sixty-four SPF-grade Wistar rats (half male, half female, weighing 190–220 g) were randomly divided into a blank control group and high-, medium-, and low-dose strychnine solution groups (prepared by dissolving 30, 20, and 10 times the average drug loading of 1 mg in microneedles in 1 mL of 40% ethanol). Each group consisted of 16 rats (half male, half female). Except for the blank control group, which received no treatment, each group of rats underwent a single skin puncture with a blank HFM (hypothecaryin fluoride filtrate) followed by application of the corresponding concentration of Bru solution, repeated multiple times throughout the day. The rats were observed for mortality, hair loss, and activity levels over 14 days. On day 14 post-administration, the rats were euthanized by cervical dislocation. The appearance of the liver, heart, spleen, lungs, kidneys, thymus, adrenal glands, testes, and epididymis was observed to differentiate them from the control group, and the organ index was calculated. Organ index = organ mass (mg) / body mass (g).

[0319] After microneedling the skin of the rat knee joint and then applying the drug-containing solution, redness and swelling appeared at the treatment site in all dosage groups, but the swelling had largely returned to normal by the second day after the last administration. All rats survived 14 days after administration, with normal diet and water intake, and their coat luster and activity level were not significantly different from the control group, with no other abnormalities observed.

[0320] Dissecting rats and examining their organs, no lesions were observed in the organs of the high, medium, and low dose groups. The organ coefficients were not significantly different from the control group (P > 0.05). Figure 21 (Female) and 22 (male) are shown. In summary, this indicates that even with increased dosage (up to 30 times the normal dose) after administration via microneedle skin puncture, rats do not exhibit toxic reactions, demonstrating that transdermal administration of Bru-HFM at a dose of 1 mg / tablet has high safety.

[0321] 2.8 Summary

[0322] Bru-HFM was prepared according to the optimal preparation process, and the appearance, drug loading, mechanical properties, in vivo swelling properties, in vitro swelling properties, drug release properties, and safety of the microneedles were investigated.

[0323] General quality evaluation results show that the prepared HFM has good appearance; the needle has sufficient mechanical strength to penetrate the stratum corneum of the skin and toughness to be completely removed after in vivo swelling; the drug loading of HFM was 1022.51±2.20 μg / tablet as determined by HPLC; HFM reaches swelling equilibrium in vivo after about 72 hours, at which time the microneedle base width can swell from the initial 278.43 μm to 552.03 μm; and it reaches swelling equilibrium in vitro in PBS solution after about 2 hours, at which time the microneedle base width can swell from the initial 278.43 μm to 612.15 μm.

[0324] The in vivo drug release rate study results showed that Bru-HFM has a significant sustained-release effect and a Bru-enhancing effect. The Bru in the microneedles can achieve sustained release for more than 144 hours in vivo, with a release rate of 51.85±11.96% at 144 hours. The Bru-HFM prepared under the optimal process conditions as determined in Section 1 "2.4.3" for crosslinking agent selection has a release rate of 78.15% in vitro after 144 hours. The release rate of the Bru-HFM backing part in vivo after 144 hours is 57.39±16.65%. The release rate of the microneedles in vivo after 96 hours is 67.43±14.93%, and the release equilibrium is reached after 48 hours in vitro, at which point the release rate is 78.81%.

[0325] Acute toxicity test results showed that transdermal administration of Bru-HFM has a high safety profile, and no toxic reactions occurred even when the dosage was increased (up to 30 times).

[0326] Summarize

[0327] In this invention, PVA / CP hydrogel was selected as the optimal material for preparing HFM. After loading Bru onto the hydrogel, the preparation process of Bru-HFM was optimized through single-factor and orthogonal experiments. The optimal preparation parameters for HFM were determined to be: 15% PVA, 1.5% CP, Bru solvent concentration of 5 mg / mL, drying temperature of 105℃, and centrifugation time of 10 min. The sustained-release performance of HFM with different amounts of tartaric acid was evaluated using a Franz diffusion cell to screen the optimal tartaric acid dosage, which was ultimately determined to be 2.0%.

[0328] The HFM quality evaluation results show that the prepared HFM has good appearance, mechanical strength, and swelling properties, and does not dissolve during the swelling process. The drug loading is approximately 1 mg per tablet. It has a significant drug sustained-release effect and permeation-enhancing effect. It also has high safety.

[0329] The embodiments described herein are merely preferred embodiments of the invention and are not intended to limit the concept and scope of the invention. Any modifications and improvements made by those skilled in the art to the technical solutions of the invention without departing from the design concept of the invention should fall within the protection scope of the invention.

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Claims

1. A method for preparing a strychnine hydrogel microneedle drug delivery system, characterized in that, Comprising the following steps: (1) Take 0.05g strychnine in a beaker, add 10 mL of 40% ethanol solution to dissolve, get strychnine solution as drug-loaded solvent, ready for use; (2) Take 0.15g carbomer 934P in a beaker, add 2 mL of drug-loaded solvent obtained in step (1), stir evenly and stand for 20-40 min for swelling; then add 1.5g polyvinyl alcohol and 6 mL of drug-loaded solvent in small amounts, stir until the mixed matrix solution is uniform without small lumps, stand in the 4℃ refrigerator overnight for full swelling, get the mixed matrix solution; (3) Take 0.2g tartaric acid into the remaining drug-loaded solvent, after complete dissolution, mix with the mixed matrix solution obtained in step (2), then stand in the 4℃ refrigerator overnight for crosslinking, take out and place at room temperature to get a hydrogel solution with certain flowability; (4) Inject the hydrogel solution obtained in step (3) into the microneedle mold, centrifuge at 4000 r / min for 10 min, stand in the dryer for 24 h until the moisture is basically completely dried, then place in the oven for drying for 2h, the drying temperature is 105℃, take out and cool to room temperature, demold to get the strychnine hydrogel microneedle drug delivery system.

2. The use of the strychnine hydrogel microneedle drug delivery system prepared by the method of claim 1 in the preparation of a drug product for treating rheumatoid arthritis.

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