A thermosensitive sustained-release gel-type drug delivery system and its application in subcutaneous implants

Abstract

The present invention relates to a temperature-sensitive sustained-release gel-type drug delivery system and its application in subcutaneous implants. The hypoglycemic drug glimepiride (GLM) is prepared into a temperature-sensitive sustained-release gel-type subcutaneous implant for in vivo hypoglycemic research. The present invention loads the third-generation sulfonylurea hypoglycemic drug glimepiride on graphene oxide (GO) and encapsulates it in the temperature-sensitive material hydroxybutyl chitosan (HBC) to form a sustained-release gel-type subcutaneous implant delivery system. Compared with the traditional oral administration of glimepiride, this new drug delivery system can reduce the number of drug administrations, enable the drug to be released continuously and slowly, maintain a stable blood drug concentration, and avoid a series of adverse reactions such as the first-pass effect of the liver and gastrointestinal damage. In addition, it can be directly implanted in a specific location by subcutaneous injection to exert its drug effect, without the need for surgical implantation or removal.

Description

Technical Field

[0001] The invention belongs to the technical field of pharmaceutical preparations, and in particular relates to a temperature-sensitive sustained-release gel-type drug delivery system and application thereof in a temperature-sensitive sustained-release gel-type subcutaneous implant. Background Art

[0002] Diabetes is a metabolic disease characterized by high blood sugar. As of November 14, 2022, the number of diabetes patients in China exceeded 140 million, ranking first in the world. However, the disease control rate of diabetes is only 36.7%, so the situation of disease prevention and control is extremely severe. The third-generation sulfonylurea hypoglycemic drug glimepiride (GLM) is currently marketed in dosage forms for oral administration. It takes about 2.5 hours for oral administration to reach the peak blood drug level, and the blood drug concentration fluctuates greatly. The dissolution rate in the gastrointestinal tract is slow, resulting in low oral bioavailability and poor clinical efficacy. Therefore, it is particularly important to develop a new dosage form for this type of drug.

[0003] As a promising dosage form, subcutaneous implants have broad application prospects in areas such as anti-tumor and pain relief. A prominent advantage of this dosage form is its long-lasting effect, which reduces the need for continuous medication. It provides stable blood drug levels during medication, and the released drug is absorbed directly into the bloodstream to exert a systemic effect. However, traditional implantable drug delivery systems have some shortcomings. For example, implantation requires a small local incision through surgery. If the material is not easily degradable, it can easily cause an inflammatory response, which can affect patient compliance. However, a new in situ gel-type implant currently exists. This is a liquid at room temperature. After subcutaneous injection, it rapidly undergoes a phase transition at body temperature of 37°C to form a semi-solid implant, achieving continuous and slow drug release to exert its therapeutic effect.

[0004] Hydroxybutyl chitosan aqueous solutions can spontaneously cross-link at a certain temperature to form thermosensitive hydrogels with good biocompatibility and excellent biodegradability. However, their poor mechanical properties and stability, as well as their susceptibility to temperature-induced burst release of drugs, limit their application. Summary of the Invention

[0005] To address the above-mentioned technical problems, the present invention provides a temperature-sensitive sustained-release gel-type drug delivery system and its application in subcutaneous implants. This invention loads the hypoglycemic drug GLM onto GO and encapsulates it in the temperature-sensitive material HBC to prepare a sustained-release gel-type subcutaneous implant drug delivery system. Compared to traditional oral GLM dosage forms, this novel drug delivery system can reduce the number of drug administrations, enable sustained and slow drug release, maintain stable blood drug concentrations, and avoid the first-pass effect in the liver and gastrointestinal damage. Furthermore, it can be directly implanted in a specific location via subcutaneous injection, eliminating the need for surgery.

[0006] The technical solution employed in this invention is a temperature-sensitive sustained-release gel-type drug delivery system, comprising a temperature-sensitive HBC-GO drug delivery system made from graphene oxide (GO) and a temperature-sensitive material (HBC). The temperature-sensitive HBC is hydroxybutyl chitosan, obtained using chitosan as a raw material, 1,2-butylene oxide as an etherifying agent, and an isopropyl alcohol solution as a dispersion system.

[0007] The invention provides an application of a thermosensitive sustained-release gel-type drug delivery system in the preparation of a thermosensitive sustained-release gel-type subcutaneous implant.

[0008] A thermosensitive sustained-release gel-type subcutaneous implant is prepared by loading drug X with a temperature-sensitive HBC-GO drug loading system to form an HBC-GO@X hydrogel.

[0009] Preferably, in the above-mentioned thermosensitive sustained-release gel-type subcutaneous implant, the drug X is a hypoglycemic drug.

[0010] Preferably, in the above-mentioned thermosensitive sustained-release gel-type subcutaneous implant, the hypoglycemic drug is a sulfonylurea drug.

[0011] Preferably, in the above-mentioned thermosensitive sustained-release gel-type subcutaneous implant, the sulfonylurea drug is glimepiride.

[0012] A method for preparing a thermosensitive sustained-release gel-type subcutaneous implant comprises the following steps:

[0013] 1) Add the temperature-sensitive material HBC into distilled water and fully dissolve it at 4°C to obtain an HBC aqueous solution.

[0014] 2) GO was added to distilled water, ultrasonically dispersed, and crushed with a cell shear to obtain a GO dispersion.

[0015] 3) Weigh drug X and add it to the GO dispersion containing Tween 80, and stir it by ultrasound and magnetic stirring to obtain a drug-loaded GO@X solution.

[0016] 4) The GO@X solution obtained in step 3) is centrifuged, and the resulting precipitate is mixed with the HBC aqueous solution obtained in step 1), and vortexed to obtain HBC-GO@X hydrogel.

[0017] Preferably, the above-mentioned preparation method, the preparation method of the temperature-sensitive material HBC, comprises the following steps:

[0018] 1) Weigh the purified chitosan and add it to a NaOH solution to fully alkalize the chitosan. Use gauze to squeeze out the excess alkaline solution and collect the flocculent insoluble matter to obtain the alkalized chitosan.

[0019] 2) Alkalized chitosan was dispersed in an aqueous solution of isopropanol and stirred at room temperature for 24 hours. The reaction system was then heated to 60°C and 1,2-butylene oxide was added to the system. The mixture was stirred and reacted for 24 hours. After the reaction was completed, the pH of the solution was adjusted to neutral. The solution was dialyzed for 72 hours and freeze-dried to obtain HBC.

[0020] Preferably, in the above preparation method, the mass ratio of GO:HBC is 1:30-50.

[0021] Preferably, in the above preparation method, the mass ratio of drug X:GO is 1:1-3.

[0022] The beneficial effects of the present invention are:

[0023] 1. The present invention constructs an injectable temperature-sensitive HBC-GO drug delivery system, which can prolong the drug action time and achieve a sustained release effect.

[0024] 2. The injectable temperature-sensitive HBC-GO drug delivery system constructed by the present invention introduces graphene oxide into hydroxybutyl chitosan hydrogel. Graphene oxide has good mechanical properties and can be stably dispersed in water, which can increase the mechanical properties and stability of the hydrogel. It also has good biocompatibility and transmembrane ability. It can load glimepiride through π-π stacking and other effects, increase the drug loading amount, and slowly release the drug.

[0025] 3. The thermosensitive sustained-release gel-type subcutaneous implant provided by the present invention changes the oral administration mode of the hypoglycemic drug GLM. It is injected subcutaneously in the form of a subcutaneous implant to exert its hypoglycemic effect, which can maintain a stable blood drug concentration, improve the bioavailability in the body, and reduce the occurrence of gastrointestinal adverse reactions.

[0026] 4. The present invention prepares glimepiride into an injectable, temperature-sensitive, sustained-release in situ gel-type implant, which can reduce the number of drug administrations, enable the drug to be released continuously and slowly, maintain a stable blood drug concentration, and at the same time avoid the first-pass effect of the liver and gastrointestinal damage, etc., providing a new idea for the treatment of diabetes. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the infrared spectrum (FT-IR) of HBC.

[0028] Figure 2 This is the NMR image of HBC ( 1 1H NMR).

[0029] Figure 3 It is the rheological analysis of HBC.

[0030] Figure 4 This is a scanning electron microscope (SEM) image of HBC.

[0031] Figure 5 are the infrared spectra (FT-IR) of HBC and HBC-GO@GLM.

[0032] Figure 6 This is the swelling ratio test (SR) of HBC-GO@GLM.

[0033] Figure 7 is the scanning electron microscopy (SEM) image of HBC-GO@GLM.

[0034] Figure 8 This is the rheological analysis of HBC-GO@GLM.

[0035] Figure 9 This is a study on the effect of pH on the in vitro release of HBC-GO@GLM.

[0036] Figure 10 This is a study on the effect of temperature on the in vitro release of HBC-GO@GLM.

[0037] Figure 11 This is the in vivo degradation test of HBC-GO@GLM.

[0038] Figure 12 This is the pharmacokinetic analysis of HBC-GO@GLM. DETAILED DESCRIPTION

[0039] The preparation method of the embodiment glimepiride temperature-sensitive sustained-release gel subcutaneous implant (I) is as follows:

[0040] 1. Preparation of hydroxybutyl chitosan (HBC)

[0041] 1) Add 1 g of chitosan (CS) to 10 mL of NaOH solution (50%, w / w), alkalize for 24 h, squeeze out the excess alkaline solution with gauze, and collect the flocculent insoluble matter to obtain the alkaline chitosan CS.

[0042] 2) Disperse the alkalized CS in 20 mL of isopropanol / water (1:1, v / v) and stir at room temperature for 24 hours. Then, heat the reaction system to 60°C in a water bath. Add 20 mL of 1,2-butylene oxide while stirring. Stir for another 24 hours, then adjust the pH to 7.0 using 10% v / v HCl. Finally, dialyze the solution against deionized water for 3 days and freeze-dry for 48 hours to obtain HBC.

[0043] 2. Preparation of HBC aqueous solution

[0044] 500 mg of HBC was placed in a container, 10 mL of distilled water was added, and the HBC was fully dissolved at 4°C to obtain an HBC aqueous solution.

[0045] 3. Preparation of GO dispersion

[0046] Weigh 10 mg of graphene oxide powder, add 10 mL of distilled water, ultrasonically disperse for 2 h, and crush with a cell shearer for 1 h to obtain a GO dispersion.

[0047] 4. Preparation of GO@GLM solution

[0048] 5 mg of glimepiride was weighed and added to the GO dispersion obtained in step 3, and then 0.1 mL of 0.5% Tween 80 solution was added. The mixture was ultrasonicated for 10 min and magnetically stirred for 2 h at room temperature to obtain a drug-loaded GO@GLM solution.

[0049] 5. Preparation of gel-type subcutaneous implant HBC-GO@GLM

[0050] The GO@GLM solution obtained in step 4 was centrifuged, and the precipitate obtained by centrifugation was mixed with the HBC aqueous solution obtained in step 2, and vortexed to mix, thereby obtaining a gel-type subcutaneous implant HBC-GO@GLM.

[0051] (2) Detection and characterization

[0052] 1. Infrared spectroscopy (FT-IR) detection of HBC

[0053] Chitosan and freeze-dried HBC were pressed into pellets containing 200 mg of potassium bromide. The measurement range was 400-4000 cm -1 The results are as follows Figure 1 As shown. Both -OH and -NH2 of chitosan are active groups, which can undergo substitution reactions with C6–OH or C2-NH2. After alkalization, the reaction activity of C6–OH is greater than that of C2-NH2, and the substitution reaction mainly occurs at C6–OH. 2876-2970cm -1 and 1465cm -1 The new absorption peaks appearing at are the stretching vibration of CH and the bending vibration of CH3, indicating that the product has successfully introduced the hydroxybutyl group.

[0054] 2. HBC H NMR spectrum ( 1 H NMR)

[0055] Weigh 3 mg each of chitosan powder and HBC powder. Scanning frequency is 50.32 MHz, magic angle spinning method is used, and spinning speed is 4000 Hz. Figure 2Compared with the hydrogen spectrum of chitosan in the literature, the new signal peaks appearing at 0.84 and 1.33 ppm are attributed to the protons on CH3 and CH2 of the hydroxybutyl part, respectively, and the integrated area ratio of these new peaks is 3:2, indicating that the hydroxybutyl group is successfully bonded to the chitosan chain.

[0056] 3. Rheological determination of HBC

[0057] The elastic modulus (G') and viscous modulus (G") of HBC during gelation were measured using a rheometer. The temperature dependence of G' and G" was recorded at a heating rate of 1°C / min in the temperature range of 4-50°C, and the gelation temperature of the sample was determined at the intersection of G' and G". The angular frequency was 1 rad / s, the strain was 0.5%, the cone-plate diameter was 0.5 mm, and the taper was 2°. Figure 3 As shown in the figure, as the temperature increases from 4°C to 50°C, the G' and G" of the HBC solution continue to increase. When the temperature rises to 19.1°C, the G" and G' of the HBC solution intersect, indicating that gelation has occurred and the HBC aqueous solution has become a gel. Therefore, the critical gelation temperature of the prepared HBC hydrogel is 19.1°C. The main driving force for gel formation is due to the hydrophobic interaction between the HBC molecular chains. As the temperature increases, the hydrogen bonds between the HBC chains and the water molecules are destroyed, and a physical cross-linking network is formed through hydrophobic bonds, which eventually causes the HBC to change from a liquid to a semi-solid preparation.

[0058] 4. Scanning electron microscope image (SEM) of HBC

[0059] The synthesized HBC was prepared into 3wt% and 5wt% HBC hydrogels and then freeze-dried. A clear cross section of the freeze-dried sample was screened for gold sputtering, and the surface and internal morphologies of the gels at different concentrations were analyzed using a scanning electron microscope. Figure 4 As shown. All hydrogels have a porous network structure inside, and the pore walls are smooth and dense. The pore size of the hydrogel decreases with the increase of the hydroxybutyl chitosan content. When the hydroxybutyl chitosan concentration is low (3wt%) (left figure), the network structure of the sample is relatively loose, and the pores are large and uneven. As the hydroxybutyl chitosan concentration increases (5wt%) (right figure), the sample forms a dense, uniform, and ordered gel network structure. Therefore, subsequent experiments used HBC hydrogels with a mass fraction of 5wt%.

[0060] 5. Infrared spectrum (FT-IR) of HBC-GO@GLM

[0061] Fourier transform infrared spectroscopy at 4 cm -1 The resolution is 4000-400cm -1 The results are as follows: Figure 5As shown in the figure, the infrared spectrum of HBC-GO@GLM composite hydrogel after the introduction of GO did not change significantly, and the hydroxybutyl chitosan at 2876-2970 cm -1 and 1462cm -1 There are characteristic peaks at the bottom, but some peaks are enhanced or broadened, which shows that there is no chemical reaction between GO and HBC, and the formation is induced by the physical way, that is, the electrostatic attraction and hydrogen bonding between the two.

[0062] 6. Swelling rate test (SR) of HBC-GO@GLM

[0063] After the HBC-GO@GLM hydrogel was freeze-dried, the dry gel was weighed and recorded as W0. The dry gel was immersed in a certain amount of 37°C distilled water. Samples were taken out at different time intervals and the excess water on the surface was gently wiped off with filter paper. The weight was then weighed as W0. t This process is carried out for three consecutive weighings until the weight of the swollen gel remains unchanged. The swelling degree is calculated according to the formula. The results are as follows Figure 6 As shown in the figure, the hydrogel rapidly swells upon absorbing water, then gradually flattens out, reaching equilibrium swelling after 2 hours, making it a fast-swelling hydrogel. When the dry gel is placed in water, the hydroxybutyl groups and unsubstituted free amino groups on the molecular chains become hydrophilic. The entry of water molecules loosens the internal mesh of the gel, causing the gel to expand and swell. After absorbing a certain amount of water, the diffusion of water molecules into the gel slows, slowing the gel's swelling until the entire gel reaches its maximum swelling and equilibrium. The SRs are approximately 130% and 200%, respectively. Furthermore, the SR of the HBC hydrogel is higher than that of the HBC-GO@GLM composite hydrogel at all time points. This suggests that the addition of carbon material may increase the hydrogel's network density, leading to a decrease in SR. It may also be due to the formation of hydrogen bonds between the -OH groups in HBC and the -COOH groups in GO, resulting in more polymer-polymer interactions than polymer-water interactions, leading to a decrease in SR.

[0064] 7. Scanning electron microscopy (SEM) image of HBC-GO@GLM

[0065] The prepared HBC-GO@GLM was heated to 37°C in a water bath to form a gel and then immediately freeze-dried to preserve the internal structure of the gel. The internal cross-section was sprayed with gold under vacuum conditions and its internal morphology was observed using a scanning electron microscope. The results are as follows Figure 7 As shown in Figure 2, the HBC-GO@GLM composite hydrogel exhibits a dense three-dimensional network structure, with numerous micropores uniformly distributed throughout the hydrogel. The addition of GO to the HBC-GO hydrogel maintains structural stability and a denser structure during the freeze-drying process.

[0066] 8. Rheological determination of HBC-GO@GLM

[0067] The elastic modulus (G') and viscous modulus (G") of HBC-GO@GLM during the gelation process were measured by rheometer. The temperature dependence of G' and G" was recorded at a heating rate of 1°C / min in the temperature range of 4-50°C, and the gelation temperature of the sample was determined at the intersection of G' and G". The angular frequency was 1 rad / s, the strain was 0.5%, the cone-plate diameter was 0.5 mm, and the taper was 2°. The results are shown in Figure 2. Figure 8 As shown, the addition of graphene oxide does not affect the excellent thermosensitive hydrogel properties of hydroxybutyl chitosan itself. The gel phase transition temperature of the HBC-GO@GLM composite hydrogel increases to 27.2°C. Furthermore, the addition of GO increases the hydrogel's storage modulus, which is most pronounced at 40°C. The storage modulus of the HBC hydrogel without GO is only 2626 Pa, while the addition of GO increases the storage modulus of the composite hydrogel to 4165 Pa. This indicates that the addition of GO not only preserves the thermosensitive properties of HBC itself but also improves the hydrogel's mechanical properties, making it more stable.

[0068] 9. Study on the effect of pH on the in vivo release of HBC-GO@GLM

[0069] The in vitro release of HBC@GLM and HBC-GO@GLM thermosensitive gels under different pH conditions was studied using a membraneless release method. Three 2 mL portions of HBC@GLM and HBC-GO@GLM thermosensitive gels were placed in centrifuge tubes and allowed to stand at 37°C for 10 min. After forming a stable gel state, 20 mL of 37°C 0.1% Tween80-PBS (pH 6.0), 0.1% Tween80-PBS (pH 7.4), and 0.1% Tween80-PBS (pH 8.0) were added to each aliquot. The gels were then placed in a thermostat at 25 rpm for release studies. 1 mL of the aliquots were removed with a pipette at 15 min, 30 min, 1 h, 2 h, 4 h, 8 h, 18 h, 24 h, 48 h, 72 h, 96 h, 120 h, and 144 h, and 1 mL of PBS solution of the same pH was added simultaneously. The sample was filtered through a microporous membrane and then fed into HPLC to determine the GLM content and calculate the cumulative release (Q). Figure 9As shown, HBC@GLM exhibited a burst release in a PBS solution at pH 6.0, with the drug completely released within 1 hour. This is likely due to the dissolution of the HBC hydrogel in the acidic release medium, which disrupted the gel system and resulted in complete drug release. Since the drug was loaded onto GO, the HBC-GO@GLM hydrogel continued to release the drug, but the amount of GLM released decreased. This is likely due to the reduced charge on the GO edges under acidic conditions, resulting in poor dispersion in water and a certain impact on drug release. The HBC hydrogel did not dissolve in neutral or alkaline release media; it only swelled. Drug release was primarily controlled by the degree of gel swelling and swelling kinetics, with drug release from the gel primarily occurring through diffusion. Drug release was faster in a release medium at pH 7.4 than in a release medium at pH 8.0. This is likely due to the greater gel swelling at neutral pH, which facilitates drug dissolution. At a pH of 7.4, HBC@GLM released the drug at an excessively rapid rate within the first 12 hours, reaching a cumulative release of approximately 60.84%. After 48 hours, release essentially ceased, reaching a cumulative release of 75.79%. HBC-GO@GLM released the drug more rapidly within the first 6 hours, with a cumulative release of approximately 22.62%. The release rate then slowed significantly, with release essentially ceasing around 96 hours, reaching a cumulative release of 80.48%. This suggests that the introduction of GO increased the drug release rate from the HBC hydrogel, significantly delaying its release time and resulting in a more effective sustained-release effect.

[0070] 10. Study on the effect of temperature on the in vivo release of HBC-GO@GLM

[0071] The effect of temperature on the in vitro release of HBC-GO@GLM thermosensitive gels was investigated using a membrane-based release assay. Two 2mL aliquots of HBC@GLM and HBC-GO@GLM thermosensitive gels were placed in centrifuge tubes and allowed to stand for 10 minutes at 25°C and 37°C, respectively. After forming a stable gel, 20mL of 0.1% Tween 80-PBS (pH 7.4) solution at the same temperature was added to each aliquot. The gels were then placed in a thermostatted oscillator at 25 rpm for release studies. Subsequently, 1mL of the aliquots were removed with a pipette at 15 minutes, 30 minutes, 1 hour, 2 hours, 4 hours, 8 hours, 18 hours, 24 hours, 48 hours, 72 hours, 96 hours, 120 hours, and 144 hours, and 1mL of PBS solution at the same temperature was added simultaneously. The removed samples were centrifuged at 10,000 rpm for 5 minutes, and the supernatant was collected. The concentration was measured by HPLC, and the cumulative release was calculated. HBC hydrogel is temperature sensitive, so the drug release behavior of hydrogel at different temperatures was further investigated. Figure 10As shown in the figure, at 25°C, the initial release rate of GLM from the HBC hydrogel is very fast, exhibiting a "burst release" phenomenon. This is likely because 25°C is near the phase transition temperature of the hydrogel, and the HBC hydrogel is easily affected by temperature, changing from a gel to a liquid state, resulting in rapid drug release. The release rate and amount of HBC@GLM at 37°C are much higher than at 25°C. This is because the swelling degree and swelling rate of the gel at 37°C are greater than those at 25°C, and the larger pore size of the gel mesh at 37°C makes it easier for drug molecules to enter and exit, resulting in a faster drug release rate at 37°C. Observing the curve of HBC-GO@GLM, it can be seen that the introduction of GO prolongs the release time and increases the amount released, indicating that GO can significantly increase drug loading and demonstrate that regulating temperature can control drug release behavior. After analysis, it was found that the reason why HBC hydrogel has a greater swelling degree at higher temperatures is that: when the temperature is low, there is a hydrogen bonding effect in the polymer chains of the gel network, which makes the polymer chains in the entire network entangled with each other and present a contracted state: as the temperature rises, this hydrogen bonding effect is weakened, and the entangled polymer chains gradually untie and disperse into the aqueous solution. At the same time, more water molecules enter the gel, which causes the swelling rate of the entire network to increase, thereby accelerating the expansion process of the drug.

[0072] 11. In vivo degradation test of HBC-GO@GLM

[0073] In order to explore the degradation rate of HBC@GLM and HBC-GO@GLM thermosensitive gels in rats, a gel subcutaneous injection degradation experiment was conducted on the back of male SD rats. The spinal column on the back of the rat was used as the axis of symmetry, and HBC@GLM and HBC-GO@GLM hydrogels were injected on the left and right sides respectively. 30 male SD rats were used, 3 in each group, and the corresponding hydrogels were injected at the corresponding positions, with 200μL injected at each position. The rats were killed 10 minutes after the injection, and then they were killed at the predetermined time point. The skin on the back of the rats was cut open, and the degradation of the gel at each injection site was observed and photographed for record. The results are shown in the figure below. Figure 11As shown in Figure 2, rats were subcutaneously injected with HBC@GLM and HBC-GO@GLM in situ gels, and autopsied immediately 10 minutes later. Observations revealed that both HBC@GLM and HBC-GO@GLM thermosensitive sustained-release gel-type subcutaneous implants rapidly gelled at the injection site and maintained a well-defined spherical morphology, effectively preventing sudden drug release. Within 24 hours, significant gel residue remained in both HBC@GLM and HBC-GO@GLM thermosensitive sustained-release gel-type subcutaneous implants, gradually decreasing in size as their subcutaneous residence time increased. The HBC@GLM in situ gel was nearly completely degraded by 72 hours, and the drug entered the bloodstream as the gel degraded. The GO-incorporated HBC-GO@GLM in situ gel still had a small amount of residue after 96 hours, indicating continued drug release from the GO-loaded gel, demonstrating that the incorporation of GO can prolong the duration of drug action. This is because GO, due to its large particle size, cannot penetrate the subcutaneous tissue. However, due to the small amount of GO added, it can be eliminated from the body through subcutaneous metabolism. Because subcutaneous tissue contains a high concentration of body fluids, the prepared gel-based subcutaneous implant degrades faster in vivo than in vitro. Daily observations revealed that the surrounding capillaries and skin tissue structure remained normal and were not damaged by the HBC-GO@GLM in situ gel implant. This experiment demonstrates that the prepared HBC-GO@GLM thermosensitive sustained-release gel-based subcutaneous implant exhibits good biodegradability and biocompatibility.

[0074] 12. Pharmacokinetic study of HBC-GO@GLM

[0075] Twelve SD male rats were randomly divided into four groups, namely, oral gavage GLM group, subcutaneous injection GLM group, subcutaneous injection HBC@GLM group and subcutaneous injection HBC-GO@GLM group, with 3 rats in each group. They were fasted for 12 hours before administration and had free access to water; 0.2 mL of thermosensitive gel was injected subcutaneously on the back of each rat. After the injection, 0.5 mL of blood was collected from the fundus venous plexus at 0.5 h, 1 h, 2 h, 4 h, 6 h, 8 h, 12 h, 24 h, 48 h, 72 h, 96 h, 120 h, 144 h, 168 h, 192 h, and 216 h, and placed in a centrifuge tube pretreated with sodium heparin. The blood sample was shaken to allow full contact with the anticoagulant, and then the blood sample was centrifuged at 10,000 rpm at 4 ° C in a refrigerated centrifuge for 10 min. The upper layer of plasma was taken and added to the injection bottle, and the GLM content in the plasma was measured by HPLC. Figure 12 It can be seen from the blood drug concentration curve in that after oral administration, the blood drug concentration of GLM reached its peak at 2 hours, and the maximum blood drug concentration C maxThe three subcutaneous GLM injection groups showed reduced fluctuations in blood concentration, prolonged peak time and duration of effect, achieving a good sustained-release effect. Furthermore, after subcutaneous injection, the peak blood concentration was less pronounced, effectively reducing patient discomfort and avoiding adverse reactions such as hypoglycemia caused by a sudden increase in drug concentration.

[0076] This study successfully prepared a glimepiride thermosensitive sustained-release gel-type subcutaneous implant. By loading the oral hypoglycemic drug glimepiride onto graphene oxide, the resulting injectable HBC-GO@GLM thermosensitive sustained-release in-situ gel-type implant controls drug release and prolongs its duration of action. This implant also regulates blood sugar levels, reduces fluctuations, and minimizes adverse reactions, providing a novel approach for the treatment of diabetes.

Claims

1. A thermosensitive sustained-release gel-type subcutaneous implant, characterized in that: The thermosensitive sustained-release gel-type subcutaneous implant is a thermosensitive HBC-GO drug loading system that loads drug X to prepare HBC-GO@X hydrogel; The preparation method of the temperature-sensitive HBC-GO drug delivery system is to cross-link graphene oxide (GO) and a temperature-sensitive material (HBC) at a mass ratio of 1:30-50; the temperature-sensitive material (HBC) is hydroxybutyl chitosan prepared using chitosan as a raw material, 1,2-butylene oxide as an etherifying agent, and an isopropyl alcohol solution as a dispersion system; The drug X is a sulfonylurea hypoglycemic drug.

2. A thermosensitive sustained-release gel-type subcutaneous implant according to claim 1, characterized in that: The sulfonylurea hypoglycemic drug is glimepiride.

3. The method for preparing a thermosensitive sustained-release gel-type subcutaneous implant according to claim 1 or 2, characterized in that: The preparation method comprises the following steps: 1) Add the thermosensitive material HBC into distilled water and fully dissolve it at 4°C to obtain an HBC aqueous solution; 2) GO was added to distilled water, ultrasonically dispersed, and crushed with a cell shear to obtain a GO dispersion; 3) Weigh drug X and add it to the GO dispersion containing Tween 80, then perform ultrasonic and magnetic stirring to obtain a drug-loaded GO@X solution. 4) The GO@X solution obtained in step 3) is centrifuged, and the resulting precipitate is mixed with the HBC aqueous solution obtained in step 1), and vortexed to obtain HBC-GO@X hydrogel.

4. The preparation method according to claim 3, characterized in that The preparation method of the temperature-sensitive material HBC comprises the following steps: 1) Weigh the purified chitosan and add it to a NaOH solution to fully alkalize the chitosan. Use gauze to squeeze out the excess alkaline solution and collect the flocculent insoluble matter to obtain the alkalized chitosan. 2) Alkalized chitosan was dispersed in an aqueous solution of isopropanol and stirred at room temperature for 24 hours. The reaction system was then heated to 60°C and 1,2-butylene oxide was added to the system. The mixture was stirred and reacted for 24 hours. After the reaction, the pH of the solution was adjusted to neutral. The solution was dialyzed for 72 hours and freeze-dried to obtain HBC.

5. The preparation method according to claim 3, characterized in that By mass ratio, drug X:GO=1:1-3.

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