Testosterone transdermal patch based on soluble microneedle array and preparation method thereof

Abstract

The application discloses a testosterone transdermal sustained-release patch based on a soluble microneedle array and a preparation method thereof. The microneedle patch comprises a backing layer, a substrate layer, a separable weak connection layer and a microneedle array layer. The backing layer is located on the first side of the microneedle patch. The substrate layer is located between the backing layer and the separable weak connection layer. The microneedle array layer is connected with the substrate layer through the separable weak connection layer and is located on the second side corresponding to the backing layer. After the drug-loaded needle tip of the microneedle patch is inserted into the stratum corneum, the drug-loaded needle tip can be separated from the substrate layer and left in the epidermis or the superficial dermis area. The microneedle patch and the preparation method thereof have the advantages of being capable of forming a local drug depot in the skin, taking into account early release and late sustained release, avoiding the pain of traditional injection and the requirement of professional operation, etc.

Description

Technical Field

[0001] This invention relates to a biomedical materials technology, particularly a transdermal sustained-release testosterone patch based on a soluble microneedle array and its preparation method. Background Technology

[0002] Testosterone is the most important androgen in men. Insufficient testosterone levels can lead to decreased libido, erectile dysfunction, muscle loss, decreased bone density, anemia, metabolic abnormalities, low mood, and a decline in quality of life. Testosterone replacement therapy is commonly used for male hypogonadism and other treatments requiring androgen supplementation. Current testosterone preparations mainly include injectable formulations, gels, transdermal patches, and oral formulations.

[0003] Although the above dosage forms have been used in clinical practice, they still have the following shortcomings: (1) Injections can usually maintain a long dosing interval, but the dosing process is painful, local discomfort, requires professional operation, and has large fluctuations in blood drug concentration peaks and valleys; (2) Gels and ordinary transdermal patches are relatively convenient to use, but transdermal absorption is greatly affected by the skin stratum corneum barrier, and the absorption efficiency and individual differences are difficult to control. In addition, gels have the risk of secondary exposure; (3) Oral testosterone or testosterone ester preparations may be limited by factors such as gastrointestinal absorption, food influence and first-pass metabolism, and the stability of blood drug concentration is still insufficient.

[0004] Based on the above issues, a common soluble testosterone microneedle based on hyaluronic acid (such as...) was developed. Figure 1 As shown), it can be stably shaped and achieve transdermal delivery of testosterone, and shows a more gradual trend of serum testosterone changes in animals compared with injection administration. However, this ordinary soluble testosterone microneedle has the following problems: (1) Hydrophobic testosterone or testosterone ester drugs have problems such as uneven dispersion, easy crystallization, limited drug loading and insufficient content uniformity in hydrophilic microneedle matrix; (2) Ordinary soluble microneedles dissolve rapidly after being inserted into the skin, resulting in insufficient sustained release capacity; (3) Existing testosterone injections have problems such as pain during administration, insufficient compliance and large fluctuations in peak and trough of blood drug concentration; (4) Existing testosterone gels and ordinary patches have problems such as unstable transdermal absorption, skin irritation or risk of secondary exposure; (5) Ordinary microneedles have difficulty simultaneously achieving early onset and later stable maintenance.

[0005] Therefore, there is an urgent need to design a microneedle drug delivery system that can form a local drug reservoir in the skin, take into account both initial onset and subsequent sustained effect, and improve the stability of hydrophobic testosterone ester loading. Summary of the Invention

[0006] To avoid the shortcomings of the existing technology, the present invention provides a transdermal sustained-release testosterone drug delivery patch based on a soluble microneedle array and its preparation method, so that the drug-loaded needle tip forms a local drug reservoir in the skin, realizing transdermal delivery and sustained release of testosterone drugs.

[0007] The present invention adopts the following technical solution to solve the technical problem.

[0008] The transdermal sustained-release testosterone patch based on a soluble microneedle array of the present invention includes a backing layer 1, a base layer 2, a separable weakly connecting layer 3, and a microneedle array layer 4.

[0009] The backing layer 1 is located on the first side of the microneedle patch and is used to provide application support, array fixation and pressure transmission.

[0010] The base layer 2 is located between the backing layer 1 and the separable weak connection layer 3, and is used to transfer the pressure of the backing layer 1 to the separable weak connection layer 3.

[0011] The microneedle array layer 4 is connected to the base layer 2 through a separable weak connection layer 3 and is located on the second side corresponding to the backing layer 1;

[0012] The microneedle array layer 4 includes a plurality of drug-loaded needle tips 41; the plurality of drug-loaded needle tips are arranged in an array to form the microneedle array layer 4.

[0013] The drug-loaded needle tip 41 includes an initial release layer 411 and a long-acting sustained-release core layer 412 located inside the initial release layer; after being inserted into the skin, the drug-loaded needle tip can separate from the basal layer and remain in the intradermal layer to form a local drug reservoir, thereby realizing the initial release and subsequent continuous release of testosterone drugs.

[0014] The structural features of the transdermal sustained-release testosterone patch based on a soluble microneedle array of the present invention are also as follows:

[0015] More preferably, the backing layer 1 is made of a flexible polymer film, a medical tape substrate, an aluminum-plastic composite film, a polyester film, a polyurethane film, a medical pressure-sensitive adhesive support layer, or a combination thereof.

[0016] More preferably, the base layer 2 is made of polyvinylpyrrolidone, polyvinyl alcohol, hyaluronic acid, sodium carboxymethyl cellulose, gelatin, medical pressure-sensitive adhesive layer or a combination thereof.

[0017] More preferably, the initial release layer comprises a hydrophilic polymer matrix, free testosterone, or a testosterone cyclodextrin inclusion complex.

[0018] More preferably, the hydrophilic polymer matrix is ​​one or a combination of two or more of hyaluronic acid, polyvinylpyrrolidone, polyvinyl alcohol, sodium carboxymethyl cellulose, gelatin, alginate, and hydroxypropyl methylcellulose.

[0019] More preferably, the long-acting sustained-release core layer includes a testosterone ester drug sustained-release unit and a matrix material.

[0020] More preferably, the long-acting sustained-release core layer further includes a dispersant, stabilizer, plasticizer, or molding additive.

[0021] More preferably, the material of the separable weak bonding layer 3 is hyaluronic acid, polyvinylpyrrolidone, polyvinyl alcohol, gelatin, sodium carboxymethyl cellulose, alginate, or a combination thereof.

[0022] This invention also provides a method for preparing a transdermal sustained-release testosterone patch based on a soluble microneedle array, comprising the following steps:

[0023] Step 1: Prepare a sustained-release unit for testosterone ester drugs;

[0024] Step 2: Prepare the long-lasting, sustained-release core layer molding solution;

[0025] Step 3: Prepare the initial release layer molding solution;

[0026] Step 4: Add the long-acting sustained-release core layer molding solution to the microneedle mold, so that the long-acting sustained-release core layer molding solution enters the microneedle mold and forms the internal area of ​​the drug-loaded needle tip.

[0027] Step 5: Add initial release layer molding fluid to form the outer or top area of ​​the drug-loaded needle tip.

[0028] Step 6: Form a separable weakly connected layer at the base of the drug-loaded needle tip;

[0029] Step 7: Add the base layer and backing layer materials in sequence;

[0030] Step 8: After drying and demolding, a transdermal sustained-release testosterone patch based on a soluble microneedle array is obtained.

[0031] More preferably, the initial release layer is a hyaluronic acid / polyvinylpyrrolidone matrix containing a testosterone-hydroxypropyl-β-cyclodextrin inclusion complex; the weak linking layer is a hyaluronic acid / polyvinylpyrrolidone matrix with a thickness of 20 μm to 80 μm.

[0032] Compared with existing technologies, the beneficial effects of this invention are reflected in:

[0033] This invention discloses a transdermal sustained-release testosterone patch based on a soluble microneedle array, comprising a backing layer, a base layer, a separable weakly connecting layer, and a microneedle array layer. The backing layer is located on a first side of the microneedle patch and provides support for application, array fixation, and pressure transmission. The base layer is located between the backing layer and the separable weakly connecting layer and transmits pressure from the backing layer to the separable weakly connecting layer. The microneedle array layer is connected to the base layer through the separable weakly connecting layer and is located on a second side corresponding to the backing layer. The microneedle array layer includes multiple drug-loaded needle tips. The multiple drug-loaded needle tips are arranged in an array to form the microneedle array layer. Each drug-loaded needle tip includes an initial release layer and a long-acting sustained-release core layer located inside the initial release layer. After insertion into the skin, the drug-loaded needle tip can separate from the base layer and remain intradermally, forming a local drug reservoir to achieve initial release and subsequent sustained release of testosterone.

[0034] This invention discloses a transdermal sustained-release testosterone patch based on a soluble microneedle array and its preparation method, including:

[0035] Step 1: Prepare a sustained-release unit for testosterone ester drugs;

[0036] Step 2: Prepare the long-lasting, sustained-release core layer molding solution;

[0037] Step 3: Prepare the initial release layer molding solution;

[0038] Step 4: Add the long-acting sustained-release core layer molding solution to the microneedle mold, so that the long-acting sustained-release core layer molding solution enters the microneedle mold and forms the internal area of ​​the drug-loaded needle tip.

[0039] Step 5: Add initial release layer molding fluid to form the outer or top area of ​​the drug-loaded needle tip.

[0040] Step 6: Form a separable weakly connected layer at the base of the drug-loaded needle tip;

[0041] Step 7: Add the base layer and backing layer materials in sequence;

[0042] Step 8: After drying and demolding, a transdermal sustained-release testosterone patch based on a soluble microneedle array is obtained.

[0043] The transdermal sustained-release testosterone patch based on a soluble microneedle array and its preparation method of the present invention have the advantages of forming a local drug reservoir in the skin, taking into account both early release and late sustained release, and avoiding the pain and professional operation requirements of traditional injection drug administration. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the structure of a conventional microneedle and its transdermal action site.

[0045] Figure 2 This is a schematic diagram of the transdermal sustained-release testosterone patch based on a soluble microneedle array according to the present invention.

[0046] Figure 3 This is a schematic diagram of the layered structure of the drug-loaded needle tip of the transdermal sustained-release testosterone patch based on a soluble microneedle array according to the present invention.

[0047] Figure 4 This is a schematic diagram illustrating the process by which the microneedles of the transdermal sustained-release testosterone patch based on a soluble microneedle array of the present invention are inserted into the skin, and the needle tips separate and remain in the skin to form a drug reservoir.

[0048] Figure 5 This is a schematic diagram of the drug delivery process and drug release pathway of the transdermal sustained-release testosterone patch based on a soluble microneedle array according to the present invention.

[0049] Figure 6 This is a schematic flowchart illustrating the preparation process of the transdermal sustained-release testosterone patch based on a soluble microneedle array according to the present invention.

[0050] Figure 7 This is a photograph of the conventional hyaluronic acid testosterone microneedle patch of the present invention.

[0051] Figure 8 These are photographs of microneedle samples with different drug loadings (20 mg and 40 mg) according to the present invention.

[0052] Figure 9 Microscopic images of microneedles as observed by optical microscopes and scanning electron microscopes.

[0053] Figure 10 This is a flowchart for the validation process in animal (rat) experiments.

[0054] Figure 11 This is a schematic diagram illustrating the manifestations and animal verification of low testosterone levels.

[0055] Figure 12 The graph shows the dynamic changes in serum testosterone and the results of biochemical index detection in five groups of experimental subjects (rats).

[0056] Figure 13 This is a stained image of a histopathological section of the penis tissue of the experimental subject (rat).

[0057] Figure 14 This is a stained image of a pathological section of liver tissue from an experimental subject (rat).

[0058] Figure 15 This is a stained image of a pathological section of the heart tissue of the experimental subject (rat).

[0059] The present invention will be further described below through specific embodiments and in conjunction with the accompanying drawings. Detailed Implementation

[0060] See Figures 2-6 The transdermal sustained-release testosterone patch based on a soluble microneedle array of the present invention includes a backing layer 1, a base layer 2, a separable weakly connecting layer 3 and a microneedle array layer 4.

[0061] The backing layer 1 is located on the first side of the microneedle patch and is used to provide application support, array fixation and pressure transmission.

[0062] The base layer 2 is located between the backing layer 1 and the separable weak connection layer 3, and is used to transfer the pressure of the backing layer 1 to the separable weak connection layer 3.

[0063] The microneedle array layer 4 is connected to the base layer 2 through a separable weak connection layer 3 and is located on the second side corresponding to the backing layer 1;

[0064] The microneedle array layer 4 includes a plurality of drug-loaded needle tips 41; the plurality of drug-loaded needle tips are arranged in an array to form the microneedle array layer 4.

[0065] like Figure 2 and Figure 3 As shown, the drug-loaded needle tip 41 includes an initial release layer 411 and a long-acting sustained-release core layer 412 located inside the initial release layer; after being inserted into the skin, the drug-loaded needle tip can separate from the basal layer and remain in the intradermal space to form a local drug reservoir, thereby achieving the initial release and subsequent continuous release of testosterone drugs.

[0066] The present invention relates to a transdermal sustained-release testosterone patch based on a soluble microneedle array. The initial release layer of the drug-loaded needle tip, which can be placed within the skin, contains free testosterone and / or testosterone cyclodextrin inclusion complexes, while the long-acting sustained-release core layer contains nano- or microparticle sustained-release units of testosterone ester drugs. After the drug-loaded needle tip of the microneedle patch is inserted into the stratum corneum, under the action of tissue fluid and / or the external force of removing the backing layer and basal layer, the weakly connecting layer can be separated, softened, swollen, dissolved, or mechanically broken. The drug-loaded needle tip can then separate from the basal layer and remain in the subepidermal or superficial dermal region, thereby forming a local intradermal drug reservoir and achieving transdermal delivery, initial onset, and subsequent sustained release of testosterone drugs.

[0067] In specific implementation, the backing layer 1 is made of flexible polymer film, medical tape substrate, aluminum-plastic composite film, polyester film, polyurethane film, medical pressure-sensitive adhesive support layer or a combination thereof.

[0068] In specific implementation, the base layer 2 is made of polyvinylpyrrolidone, polyvinyl alcohol, hyaluronic acid, sodium carboxymethyl cellulose, gelatin, medical pressure-sensitive adhesive layer or a combination thereof.

[0069] The base layer is used to fix the microneedle array and withstand pressure before drug delivery. In one embodiment, it includes polyvinylpyrrolidone and / or polyvinyl alcohol to improve the mechanical support properties of the patch after drying and molding.

[0070] In specific implementation, the initial release layer 411 includes a hydrophilic polymer matrix, free testosterone, or a testosterone cyclodextrin inclusion complex.

[0071] The initial release layer, located on the outer side, top, outer shell region, or peripheral region near the tip surface of the drug-loaded needle, is used to release a portion of the testosterone drug early in the course of administration, establishing initial drug exposure. For example, Figure 3 The black circular object in the middle is the fast-release drug 4111.

[0072] The testosterone cyclodextrin inclusion complex may be selected from testosterone-hydroxypropyl-β-cyclodextrin inclusion complex, testosterone-sulfobutyl ether-β-cyclodextrin inclusion complex, or other inclusion complexes that can improve the dispersibility and apparent solubility of testosterone. In one embodiment, the testosterone drug contained in the initial release layer accounts for 10% to 30% of the total drug load of the patch, in order to achieve early release during administration.

[0073] In specific implementation, the hydrophilic polymer matrix is ​​one or more of the following: hyaluronic acid, polyvinylpyrrolidone, polyvinyl alcohol, sodium carboxymethyl cellulose, gelatin, alginate, and hydroxypropyl methylcellulose.

[0074] In specific implementation, the hydrophilic polymer matrix is ​​preferably a hyaluronic acid / polyvinylpyrrolidone composite system or a hyaluronic acid / polyvinyl alcohol composite system.

[0075] In practice, the initial release layer may also include plasticizers, film-forming aids, stabilizers, or solubilizing components.

[0076] In specific implementation, the long-acting sustained-release core layer includes a testosterone ester drug sustained-release unit and a matrix material.

[0077] In specific implementation, the initial release layer is a cone or pyramid; the long-acting sustained-release core layer is a cone or pyramid with the same size ratio as the initial release layer, but scaled down proportionally. In one preferred embodiment, the long-acting sustained-release core layer is a cone or pyramid with the exact same shape as the initial release layer; multiple fast-release drugs 4111 are disposed inside the cone or pyramid of the initial release layer; the fast-release drugs 4111 are spherical and uniformly distributed within the cone or pyramid of the initial release layer, such as... Figure 3 As shown.

[0078] The long-acting sustained-release core layer is located within the drug-loaded needle tip, encapsulating the initial release layer. This core layer primarily serves to sustain the release of testosterone esters after needle tip placement, thereby prolonging drug release time and reducing fluctuations in blood drug concentration. The testosterone ester sustained-release unit can be a nano-release unit or a microparticle-release unit. For example, Figure 3 The blank circular object is a slow-release particle 4121.

[0079] like Figure 3 As shown, the long-acting sustained-release core layer is a cone or pyramid with the same shape as the initial release layer but a smaller size, and the center lines and center points of the two overlap, so that the drug-loaded needle tip 41 forms an inner and outer double-layer structure: the inner layer is the long-acting sustained-release core layer, and the outer layer is the initial release layer; wherein the outer initial release layer contains a plurality of uniformly distributed spherical fast-release drugs 4111, and the inner long-acting sustained-release core layer contains a plurality of uniformly distributed sustained-release particles 4121; the bottom of the cone or pyramid is sequentially provided with the separable weak connecting layer 3, the base layer 2 and the backing layer 1.

[0080] When preparing the initial release layer 411 and the long-lasting sustained-release core layer 412, the inner long-lasting sustained-release core layer 412 is first formed using a small mold; then, a large mold is replaced, and the large mold is filled with the initial release layer molding liquid. The long-lasting sustained-release core layer 412 is then placed inside the initial release layer molding liquid, so that the center point and center line of the long-lasting sustained-release core layer 412 overlap with the center point and center line of the large mold, respectively. In this way, the center points and center lines of the initial release layer 411 and the long-lasting sustained-release core layer 412 overlap, forming an inner and outer double-layer structure.

[0081] The testosterone ester drug may be selected from testosterone undecanoate, testosterone heptaate, testosterone cyclopentylpropionate, testosterone propionate, or combinations thereof. In one embodiment, the testosterone ester drug is testosterone undecanoate, or a combination of testosterone undecanoate and testosterone heptaate.

[0082] The nano-release unit or particulate release unit can be selected from the following materials: polylactic acid-glycolic acid copolymer drug-loaded microspheres or microparticles; polylactic acid-glycolic acid copolymer drug-loaded nanoparticles; solid lipid nanoparticles; nanostructured lipid carriers; testosterone ester nanocrystals; polymer-lipid composite nanoparticles. In one embodiment, the particulate release unit is testosterone undecanoate polylactic acid-glycolic acid copolymer drug-loaded microparticles.

[0083] When drug-loaded microspheres or microparticles are used, the particle size is preferably 0.5 μm to 20 μm, more preferably 1 μm to 10 μm, and even more preferably 2 μm to 6 μm. When nanoparticles are used, the particle size is preferably 80 nm to 800 nm, more preferably 100 nm to 400 nm.

[0084] The matrix material in the long-acting sustained-release core layer can be selected from hyaluronic acid, polyvinylpyrrolidone, polyvinyl alcohol, sodium carboxymethyl cellulose, gelatin, alginate, or combinations thereof. Hyaluronic acid or a hyaluronic acid / polyvinylpyrrolidone composite matrix is ​​preferred.

[0085] In a preferred embodiment, the testosterone drug contained in the long-acting sustained-release core layer accounts for 70%-90% of the total drug load of the patch based on testosterone equivalents, and the testosterone drug contained in the initial release layer accounts for 10%-30% of the total drug load of the patch.

[0086] In practice, the long-acting sustained-release core layer may also include dispersants, stabilizers, plasticizers, or molding auxiliaries.

[0087] In specific implementation, the material of the separable weak bonding layer 3 is hyaluronic acid, polyvinylpyrrolidone, polyvinyl alcohol, gelatin, sodium carboxymethyl cellulose, alginate, or a combination thereof.

[0088] A separable weak connecting layer is located between the drug-loaded needle tip and the base layer. Before drug administration, it maintains the overall structural integrity of the microneedle patch and the mechanical strength required for insertion. After the drug-loaded needle tip is inserted into the skin, the separable weak connecting layer absorbs water, softens, swells, or dissolves under the action of tissue fluid, or preferentially breaks down when the base layer is removed, thereby separating the drug-loaded needle tip from the base layer and allowing the drug-loaded needle tip to remain in the skin. The thickness of the weak connecting layer is preferably 10 μm to 150 μm, more preferably 20 μm to 80 μm.

[0089] In a preferred embodiment, the weak bonding layer is a hyaluronic acid / polyvinylpyrrolidone composite layer.

[0090] By setting the weak connection layer, the present invention enables the drug-loaded needle tip to separate from the base layer after insertion into the skin, reducing the retention time of the patch on the outside and allowing the drug to be continuously released intradermally mainly in the form of the indwelling needle tip.

[0091] In specific implementations, the single-piece microneedle array can be 6×6, 8×8, 10×10, 12×12, or other regular or irregular arrays, preferably 8×8 or 10×10 arrays. The microneedle height can be 300–800 μm, preferably 500–700 μm. The microneedle bottom diameter can be 100–400 μm, preferably 150–250 μm. The microneedle density can be 100–200 needles / cm². The patch base side length can be 5–20 mm.

[0092] Experiments have shown that hyaluronic acid microneedles with an 8×8 array, a base side length of approximately 9 mm, a single needle height of approximately 600 μm, and a bottom diameter of approximately 200 μm are preferred for microneedle arrays, as they offer good formability and a basis for percutaneous insertion. The drug loading capacity of a single microneedle patch, based on testosterone equivalents, can be 5–30 mg, preferably 10–20 mg. Higher drug loading capacities can be designed by increasing the area of ​​the microneedle patch, increasing the number of drug-loaded needle tips, or improving the filling density of the drug-loaded needle tips.

[0093] This invention also provides a method for preparing a transdermal sustained-release testosterone patch based on a soluble microneedle array, comprising the following steps:

[0094] Step 1: Prepare a sustained-release unit for testosterone ester drugs;

[0095] The sustained-release unit for testosterone ester drugs is a nano-sustained-release unit or a microparticle sustained-release unit; the drug-loaded microparticles of polylactic acid-glycolic acid copolymer containing testosterone ester drugs can be prepared by emulsification solvent evaporation, nanoprecipitation, spray drying, membrane emulsification or other pharmaceutically acceptable methods;

[0096] Step 2: Prepare the long-lasting, sustained-release core layer molding solution;

[0097] Step 3: Prepare the initial release layer molding solution;

[0098] The formulation of the long-acting sustained-release core layer molding solution is as follows: 12% (w / v) hyaluronic acid (HA), 6% (w / v) polyvinylpyrrolidone K30 (PVPK30), and 5% (w / v) PLGA drug-loaded microparticles containing testosterone undecanoate. If necessary, 0.5%–1.5% (w / v) glycerol may be added, and the solution is prepared with purified water. First, dissolve the PVP in purified water, then slowly add the HA and allow it to swell completely. Next, add the PLGA drug-loaded microparticles and form a homogeneous suspension under low-speed stirring. After vacuum degassing for 10–30 min, the solution is used for molding.

[0099] The initial release layer molding solution formulation is as follows: 12% (w / v) hyaluronic acid (HA), 6% (w / v) PVP K30, and the addition of testosterone-hydroxypropyl-β-cyclodextrin inclusion complex, so that the testosterone equivalent in this layer accounts for 10% to 30% of the total testosterone equivalent of a single patch; if necessary, 0.5% to 1.5% (w / v) glycerol is added. Prepare the solution in the above order, mix thoroughly, degas under vacuum, and then pour it into the mold.

[0100] Step 4: Add the long-acting sustained-release core layer molding solution to the microneedle mold, so that the long-acting sustained-release core layer molding solution enters the microneedle mold and forms the internal area of ​​the drug-loaded needle tip.

[0101] Vacuum, centrifugation, pressurization, scraping or a combination thereof can be used to assist in the molding process, so that the long-acting sustained-release core layer molding solution containing the testosterone ester drug sustained-release unit is added to the needle tip area of ​​the microneedle mold, thereby forming the internal area of ​​the drug-loaded needle tip.

[0102] Step 5: Add initial release layer molding fluid to form the outer or top area of ​​the drug-loaded needle tip.

[0103] The initial release layer filling solution may contain a hyaluronic acid / polyvinylpyrrolidone matrix and / or a testosterone-hydroxypropyl-β-cyclodextrin inclusion complex. Step 5 is performed after the long-acting sustained-release core layer is filled in step 4, thereby forming an outer fast-release structure of the drug-loaded needle tip on the outer surface of the inner region of the needle tip, thus forming an inner and outer two-layer structure: an outer fast-release structure and an inner sustained-release structure, which meets the requirements of both early release and late sustained release.

[0104] Step 6: Form a separable weakly connected layer at the base of the drug-loaded needle tip;

[0105] In one embodiment, a hyaluronic acid / polyvinylpyrrolidone solution is applied to the base of the needle tip to form a weak bonding layer with a thickness of 20 μm to 80 μm.

[0106] Step 7: Add the base layer and backing layer materials in sequence;

[0107] The base layer material is a self-prepared aqueous polymer solution, and the backing layer is a medical polymer film; after the weak bonding layer is dried, the base layer solution is poured in, and then the backing film is attached to the surface of the base layer.

[0108] The mixture consists of 10% (w / v) polyvinyl alcohol (PVA), 15% (w / v) PVP K90, and 1.0%–1.5% (w / v) glycerol. First, PVA is added to purified water and stirred at 80–90 °C until completely dissolved. After cooling to below 40 °C, PVP and glycerol are added, stirred until homogeneous, and degassed before being poured to form the base layer. The backing layer can be a medical-grade polyurethane or polyester film with a thickness of approximately 50–100 μm, bonded to the base layer through self-adhesion or by medical pressure-sensitive adhesive.

[0109] Step 8: After drying and demolding, a transdermal sustained-release testosterone patch based on a soluble microneedle array is obtained.

[0110] The drying method can be room temperature drying, vacuum drying, low temperature drying, freeze drying, or a combination thereof. Vacuum drying or low temperature vacuum drying is preferred to reduce drug migration and crystallization.

[0111] In one embodiment, low-temperature vacuum drying is employed. For example, after completing the molding of each layer, the PDMS mold is placed in a vacuum drying oven at 30±5 ℃, and the vacuum is evacuated to approximately -0.08±0.01 MPa for 12–24 h. Once the sample quality is basically stable and can be completely demolded, the pressure is restored to normal and the mold is demolded. To reduce drug migration, crystallization, and changes in polymer particle properties, the drying temperature is preferably controlled below 35 ℃. After demolding, the mold can be sealed and stored in a desiccator.

[0112] In specific implementation, the initial release layer is a hyaluronic acid / polyvinylpyrrolidone matrix containing a testosterone-hydroxypropyl-β-cyclodextrin inclusion complex; the weak linking layer is a hyaluronic acid / polyvinylpyrrolidone matrix with a thickness of 20 μm to 80 μm.

[0113] The present invention also provides the subject of use of a transdermal sustained-release testosterone patch based on a soluble microneedle array in the course of testosterone replacement therapy.

[0114] like Figure 6 This is a flowchart of the preparation method of the present invention. Wherein, T represents testosterone, HA represents hyaluronic acid, and PVP represents polyvinylpyrrolidone.

[0115] Experiments have shown that the low-dose microneedling group is closer to the physiological supplementation pattern than the high-dose microneedling group. Therefore, this invention preferably uses an adjustable and relatively conservative dosage range to balance efficacy and safety.

[0116] Example 1: Ordinary hyaluronic acid-testosterone soluble microneedle patch

[0117] In Example 1, hyaluronic acid was used as the matrix material. A composite solution of hyaluronic acid and testosterone was injected into a PDMS (Polydimethylsiloxane) microneedle mold, and then vacuum dried to form a conventional soluble testosterone microneedle patch. The resulting patch was an 8×8 regular array with a base side length of approximately 9 mm, a single needle height of approximately 600 μm, and a bottom diameter of approximately 200 μm.

[0118] Example 2: Separable layered microneedle patch containing testosterone undecanoate PLGA microparticles.

[0119] Example 2 is based on the hyaluronic acid microneedle molding process described in Example 1, with the microneedle structure designed as a separable, indwelling needle tip structure. The patch includes a backing layer, a base layer, a separable weakly connecting layer, and a drug-loaded needle tip. The drug-loaded needle tip includes an initial release layer and a long-acting sustained-release core layer.

[0120] The initial release layer contains free testosterone and / or testosterone-hydroxypropyl-β-cyclodextrin inclusion complex, and the matrix is ​​hyaluronic acid / polyvinylpyrrolidone or hyaluronic acid / polyvinyl alcohol.

[0121] The long-acting sustained-release core layer contains testosterone undecanoate PLGA drug-loaded microparticles, supplemented with hyaluronic acid or a hyaluronic acid / polyvinylpyrrolidone matrix. The particle size of the testosterone undecanoate PLGA drug-loaded microparticles is preferably 2-6 μm.

[0122] A separable weak bonding layer is disposed between the needle tip and the substrate layer. The material is hyaluronic acid / polyvinylpyrrolidone, and the thickness is preferably 20-80 μm.

[0123] In the preparation process, the core layer molding solution containing testosterone undecanoate PLGA drug-loaded microparticles is first added to the PDMS microneedle mold, and then the microneedle is introduced into the internal region of the needle tip by vacuum or centrifugation. Next, the initial release layer molding solution containing testosterone inclusion complex is added to form the outer layer or top region of the needle tip. Subsequently, a weak connection layer is formed at the root of the needle tip. Finally, the base layer and backing layer materials are added, and the microneedle patch is obtained after drying and demolding.

[0124] During use, the patch is pressed onto the skin surface, and the microneedles penetrate the stratum corneum to reach the subepidermal or superficial dermal region. Subsequently, with the action of tissue fluid and / or removal of the backing layer and basal layer, the weakly connecting layer can be softened, swollen, dissolved, or broken, allowing the drug-loaded needle tip to separate from the basal layer and remain intradermal. The initial release layer releases a portion of the testosterone-like drug, while the long-acting sustained-release core layer contains testosterone undecanoate PLGA microparticles that further and continuously release the drug, thus achieving early release and subsequent maintenance.

[0125] Example 3: Separable layered microneedle patch containing testosterone undecanoate lipid nanoparticles.

[0126] Example 3 is essentially the same as Example 2, except that the sustained-release unit in the long-acting sustained-release core layer is testosterone undecanoate solid lipid nanoparticles or nanostructured lipid carriers. The lipid nanoparticles are dispersed in hyaluronic acid or a hyaluronic acid / polyvinylpyrrolidone matrix and formed into a drug-loadable needle tip through a stepwise molding process.

[0127] Example 4: Separable layered microneedle patch containing testosterone undecanoate nanocrystals.

[0128] Example 4 is basically the same as Example 2, except that the sustained-release unit in the long-acting sustained-release core layer is testosterone undecanoate nanocrystals. The nanocrystals are prepared by antisolvent precipitation, high-pressure homogenization or wet milling, and then mixed with hyaluronic acid or hyaluronic acid / polyvinylpyrrolidone matrix and poured into the tip area of ​​the microneedle mold.

[0129] Before designing and preparing the transdermal sustained-release testosterone patch based on soluble microneedle array of the present invention, a conventional soluble testosterone microneedle patch (without a separable weak connecting layer) was made using hyaluronic acid as the microneedle matrix material. The specific experimental process is as follows.

[0130] 1. Preparation of ordinary hyaluronic acid-testosterone soluble microneedles

[0131] Soluble hyaluronic acid-testosterone microneedles were prepared according to Example 1 above. Preliminary verifications were conducted on the microneedle morphology, needleability, model drug distribution, in vitro skin insertion and dissolution, in vitro drug release, and in vivo efficacy and safety in animals. Figure 7 This is an actual image of a standard hyaluronic acid-testosterone microneedle patch. Figure 8 Photographs of microneedle samples with different drug loading capacities (20 mg and 40 mg).

[0132] 2. Description of microneedle morphology

[0133] Figure 9 Microscopic images of microneedles as observed by optical and scanning electron microscopes. Optical and scanning electron microscopy observations show that the microneedles have regular structures and intact tips. Figure 9 This indicates that the hyaluronic acid matrix system has good needle-forming properties and can serve as a basis for further constructing layered, separable microneedle structures.

[0134] 3. Distribution of model drugs

[0135] Methylene blue was used as a model drug, and its distribution in the microneedle matrix was observed using laser confocal microscopy. The results showed that the model drug was relatively uniformly dispersed in the microneedles, indicating that the molding and drying process employed had a good foundation for drug dispersion and shaping.

[0136] 4. Skin insertion and dissolution

[0137] In vitro model experiments showed that conventional hyaluronic acid-testosterone microneedles can be inserted into the skin and gradually dissolve in the tissue fluid environment. Specifically, in vitro porcine skin experiments showed that the needle body could dissolve within approximately 7 minutes, demonstrating its rapid response and drug release mechanism.

[0138] 5. In vitro release

[0139] In vitro release experiments showed that testosterone from conventional hyaluronic acid testosterone microneedles could be completely released within 48 hours, exhibiting a certain degree of sustained release. This result indicates that the testosterone-hydrophilic microneedle matrix system possesses the basis for transdermal delivery and release regulation, and also provides a technical foundation for further extending the release duration through indwelling needle tips and sustained-release core layers. Animal experiments showed that this conventional microneedle patch could increase serum testosterone levels in castrated rats, and exhibited a more gradual trend in serum testosterone changes compared to the injection group.

[0140] In summary, in vitro experiments showed that: ordinary hyaluronic acid testosterone microneedles can be stably shaped with a regular conical structure and intact and relatively sharp needle tips; the model drug can be evenly dispersed in the microneedle body; ordinary soluble microneedles can be inserted into pig skin and gradually dissolve in tissue fluid environment, with the needle body dissolving completely within about 7 minutes; in vitro release experiments showed that testosterone in ordinary hyaluronic acid testosterone microneedles can be completely released within 48 hours.

[0141] 6. Animal experiments

[0142] Animal studies were conducted to investigate the efficacy and safety of the treatment for testosterone deficiency. Thirty 7-week-old male SD rats were randomly divided into 5 groups after acclimatization. The animal experimental validation flowchart is shown below. Figure 10 As shown.

[0143] Figure 10 Section A describes the treatment process for rats from week 7 to 20. Week 7 is for acclimatization feeding. Week 8 involves the following procedures: collecting tail vein blood to measure initial testosterone levels; establishing a model (removal of both testes and epididymis; see attached images in Section B); G1 model group; G2 model group + testosterone injection group; G3 model group + low-dose microneedling group; G4 model group + high-dose microneedling group; G5 control group. Week 12 involves the following procedures: second testosterone measurement for each group; G2 testosterone injection; G3 low-dose microneedling; G4 high-dose microneedling. Week 16 involves the following procedures: collecting tail vein blood to measure testosterone levels in each group. Week 20 involves the following procedures: euthanizing rats and collecting relevant samples: heart, liver, and penis from each group; collecting blood for testosterone and biochemical index measurements. Section C shows practical images of the injection and application of low-dose and high-dose microneedles to the rats.

[0144] The animal experiment used 30 seven-week-old male SD rats, which were randomly divided into 5 groups:

[0145] G1 is the castration group;

[0146] G2 was the testosterone injection group, with testosterone undecanoate 100 mg / kg, administered subcutaneously;

[0147] G3 is the low-dose microneedle group, with each microneedle carrying 20 mg of drug.

[0148] G4 is the high-dose microneedle group, with each microneedle carrying 40 mg of drug.

[0149] G5 represents the normal control group.

[0150] Groups G1-G4 established a testosterone deficiency model through castration. After successful modeling, microneedle patch or injection administration was performed, and serum samples were collected at different time points to detect testosterone levels. At the same time, biochemical indicators such as liver function, kidney function, blood glucose, and blood lipids were measured, and histopathological evaluation of major organs was performed. Figure 11 This is a schematic diagram illustrating the manifestations and animal verification of low testosterone levels.

[0151] 7. Dynamic changes in serum testosterone

[0152] Figure 12 The figures show the dynamic changes in serum testosterone and the detection results of biochemical indicators in five groups of experimental subjects (rats); Part A shows the blood test results, and Part B shows the testosterone level results. The results showed that serum testosterone levels in the G1 castration group remained low for a long period, significantly lower than the normal control group, indicating successful modeling. The G2 injection group showed more obvious peak-trough fluctuations. In the G3 low-dose microneedle group, testosterone levels recovered to near the normal range with relatively small overall fluctuations. While the G4 high-dose microneedle group further increased testosterone levels, they were higher than the normal group at some time points, suggesting a potential risk of supraphysiological exposure. The experimental results indicate that percutaneous microneedle delivery of testosterone can increase serum testosterone levels in castrated rats, and shows a more gradual trend compared to injection administration.

[0153] 8. Biochemical indicators and histopathology

[0154] Biochemical results showed that the low-dose microneedling group was generally closer to the normal control group in terms of liver function, kidney function, blood glucose, and blood lipids. The high-dose microneedling group and the injection group showed an increasing trend in some indicators, suggesting that higher doses may increase metabolic burden. Histopathological evaluation showed that the low-dose microneedling group generally exhibited characteristics closer to normal physiological states in tissues such as the penis, liver, and heart, with no obvious adverse pathological damage observed. Figure 13 A stained image of a histopathological section of the penis tissue of the experimental subject (rat); Figure 14 A stained image of a pathological section of liver tissue from an experimental subject (rat); Figure 15 This is a stained image of a pathological section of the heart tissue of the experimental subject (rat). Figures 13-15 In the diagram, HE represents the staining pattern of hematoxylin-eosin staining, Masson represents the staining pattern of Masson trichrome staining, and Oil Red O represents the staining pattern of Oil Red O staining.

[0155] The above experimental results demonstrate that the conventional hyaluronic acid-testosterone microneedle system possesses good needleability, percutaneous delivery feasibility, and preliminary effectiveness and safety.

[0156] Based on the above experiments, this invention further introduces a separable weakly connecting layer, an initial release layer, a long-acting sustained-release core layer, and nano or microparticle sustained-release units to improve the loading stability of hydrophobic testosterone esters and to form a local drug reservoir through an intradermal indwelling needle tip.

[0157] The transdermal sustained-release testosterone patch based on a soluble microneedle array and its preparation method of the present invention have the following technical features.

[0158] 1. Through the separable weak connecting layer, the drug-loaded needle tip can separate from the basal layer after insertion into the skin and remain in the intradermal layer, which is conducive to the formation of a local drug reservoir.

[0159] 2. Through the layered design of the initial release layer and the long-acting sustained-release core layer, both early release and later sustained release can be taken into account.

[0160] 3. By formulating hydrophobic testosterone ester drugs into nano or microparticle sustained-release units, their dispersibility and loading stability in hydrophilic microneedle matrices can be improved.

[0161] 4. By forming a local drug reservoir within the skin, the problem of limited release time caused by the rapid dissolution of ordinary soluble microneedles can be reduced.

[0162] 5. By using microneedles for percutaneous delivery, the pain and professional operation requirements of traditional injection can be avoided, and it is expected to reduce the fluctuation of blood drug concentration peaks and troughs.

[0163] 6. Experiments have demonstrated that the microneedle patch of this invention possesses a clear foundation for preparation and further industrialization development value. Using a conventional hyaluronic acid-testosterone microneedle system, the microneedle's shapeability, skin insertion, drug distribution, in vitro release, and in vivo efficacy in animals were verified. Building upon this foundation, this invention further introduces a separable indwelling needle tip, a layered drug-loading structure, and a nano- or microparticle sustained-release core layer to improve sustained release capability and the stability of hydrophobic testosterone ester loading.

[0164] This invention proposes a combined design of a separable indwelling drug-loaded needle tip, an initial release layer, a long-acting sustained-release core layer, and nano or microparticle sustained-release units, which can improve the loading stability of hydrophobic testosterone esters in the microneedle system and form a local drug reservoir through the intradermal indwelling needle tip, thereby achieving the initial release and subsequent sustained release of testosterone drugs.

[0165] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0166] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A transdermal sustained-release testosterone patch based on a soluble microneedle array, characterized in that, It includes a backing layer (1), a base layer (2), a separable weakly connecting layer (3), and a microneedle array layer (4); the separable weakly connecting layer is a hyaluronic acid / polyvinylpyrrolidone composite layer; the hyaluronic acid / polyvinylpyrrolidone solution is applied to the root of the needle tip; The backing layer (1) is located on the first side of the microneedle patch and is used to provide application support, array fixation and pressure transmission. The base layer (2) is located between the backing layer (1) and the separable weak bonding layer (3) and is used to transfer the pressure of the backing layer (1) to the separable weak bonding layer (3). The microneedle array layer (4) is connected to the base layer (2) through a separable weak connection layer (3) and is located on the second side corresponding to the backing layer (1); The microneedle array layer (4) includes multiple drug-loaded needle tips (41); the multiple drug-loaded needle tips are arranged in an array to form the microneedle array layer (4). The drug-loaded needle tip (41) includes an initial release layer (411) and a long-acting sustained-release core layer (412) located inside the initial release layer. After being inserted into the skin, the drug-loaded needle tip can separate from the basal layer and remain in the skin to form a local drug reservoir, thereby realizing the initial release and subsequent sustained release of testosterone drugs. The initial release layer is located outside the needle tip and contains testosterone-hydroxypropyl-β-cyclodextrin inclusion complex. The long-acting sustained-release core layer is located inside the initial release layer and contains testosterone undecanoate PLGA drug-loaded microparticles.

2. The transdermal sustained-release testosterone patch based on a soluble microneedle array according to claim 1, characterized in that, The backing layer (1) is made of flexible polymer film, medical tape substrate, aluminum-plastic composite film, polyester film, polyurethane film, medical pressure-sensitive adhesive support layer or a combination thereof.

3. The transdermal sustained-release testosterone patch based on a soluble microneedle array according to claim 1, characterized in that, The base layer (2) is made of polyvinylpyrrolidone, polyvinyl alcohol, hyaluronic acid, sodium carboxymethyl cellulose, gelatin, medical pressure-sensitive adhesive layer or a combination thereof.

4. The transdermal sustained-release testosterone patch based on a soluble microneedle array according to claim 1, characterized in that, The initial release layer comprises a hydrophilic polymer matrix, free testosterone, or a testosterone cyclodextrin inclusion complex.

5. The transdermal sustained-release testosterone patch based on a soluble microneedle array according to claim 4, characterized in that, The hydrophilic polymer matrix is ​​one or a combination of two or more of the following: hyaluronic acid, polyvinylpyrrolidone, polyvinyl alcohol, sodium carboxymethyl cellulose, gelatin, alginate, and hydroxypropyl methylcellulose.

6. The transdermal sustained-release testosterone patch based on a soluble microneedle array according to claim 1, characterized in that, The long-acting sustained-release core layer includes a testosterone ester drug sustained-release unit and a matrix material.

7. The transdermal sustained-release testosterone patch based on a soluble microneedle array according to claim 6, characterized in that, The long-acting sustained-release core layer also includes dispersants, stabilizers, plasticizers, or molding additives.

8. The transdermal sustained-release testosterone patch based on a soluble microneedle array according to claim 1, characterized in that, The material of the separable weak bonding layer (3) is hyaluronic acid, polyvinylpyrrolidone, polyvinyl alcohol, gelatin, sodium carboxymethyl cellulose, alginate or a combination thereof.

9. A method for preparing a transdermal sustained-release testosterone patch based on a soluble microneedle array, characterized in that, Includes the following steps: Step 1: Prepare a sustained-release unit for testosterone ester drugs; Step 2: Prepare the long-acting sustained-release core layer filling solution; the long-acting sustained-release core layer is located inside the initial release layer and contains testosterone undecanoate PLGA drug-loaded microparticles; Step 3: Prepare the initial release layer molding solution; the initial release layer is located on the outside of the needle tip and contains a testosterone-hydroxypropyl-β-cyclodextrin inclusion complex; Step 4: Add the long-acting sustained-release core layer molding solution to the microneedle mold, so that the long-acting sustained-release core layer molding solution enters the microneedle mold and forms the internal area of ​​the drug-loaded needle tip; Step 5: Add initial release layer molding fluid to form the outer or top area of ​​the drug-loaded needle tip. Step 6: Apply hyaluronic acid / polyvinylpyrrolidone solution to the base of the needle tip to form a separable weak bonding layer at the base of the drug-loaded needle tip; the separable weak bonding layer is a hyaluronic acid / polyvinylpyrrolidone composite layer; Step 7: Add the base layer and backing layer materials in sequence; Step 8: After drying and demolding, a transdermal sustained-release testosterone patch based on a soluble microneedle array is obtained.

10. The method for preparing a transdermal sustained-release testosterone patch based on a soluble microneedle array according to claim 9, characterized in that, The initial release layer is a hyaluronic acid / polyvinylpyrrolidone matrix containing a testosterone-hydroxypropyl-β-cyclodextrin inclusion complex; the separable weak linking layer is a hyaluronic acid / polyvinylpyrrolidone matrix with a thickness of 20 μm to 80 μm.

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