Bupivacaine sustained-release injection as well as preparation method and application thereof

Abstract

The invention relates to the technical field of biological medicines, in particular to a bupivacaine sustained-release injection as well as a preparation method and application thereof. The invention provides a bupivacaine drug compound. The bupivacaine drug compound contains an amide local anesthetic bupivacaine as an active component and a plurality of pharmaceutically acceptable slow-release carrier materials. The drug compound disclosed by the invention adopts a supramolecular synthesis strategy and is prepared into nano-particles through a self-assembly method of a molecular recognition mechanism between Ad and Cd. The novel bupivacaine nano-particles provided by the invention solve the problem of too fast release of the bupivacaine hydrochloride, the preparation method is simple, flexible and modularized, the nano-preparation with controllable carrier size, stable surface chemical property and high drug loading capacity is prepared, the slow release time in vivo can be prolonged, and the analgesic effect can be continuously exerted.

Description

Technical Field

[0001] This invention relates to the field of biomedical technology, and in particular to a bupivacaine sustained-release injection, its preparation method, and its application. Background Technology

[0002] Dental surgeries (such as tooth extractions, dental restorations, and root canal treatments) can cause varying degrees of damage to the alveolar bone and soft tissues surrounding the teeth, often accompanied by severe postoperative pain. The pain typically peaks 6-8 hours after surgery, reaching moderate to severe levels within 24 hours, and can last for 24-72 hours. The peak period is generally 24-48 hours post-surgery, and the duration usually does not exceed 7 days. However, if the pain is not effectively controlled in its early stages, it can develop into chronic postoperative pain, severely impacting the patient's daily diet, sleep, and quality of life. Therefore, effectively alleviating postoperative dental pain is a pressing issue in clinical oral care.

[0003] Currently, common post-dental analgesics include opioids, nonsteroidal anti-inflammatory drugs (NSAIDs), and local anesthetics. Opioids are highly addictive, posing risks of dependence and central nervous system depression, and are not recommended for long-term use. NSAIDs such as ibuprofen and acetaminophen are antipyretic analgesics that only temporarily relieve toothache, have a short duration of action, and ibuprofen can cause side effects on liver and kidney function, as well as gastrointestinal bleeding and cardiovascular adverse reactions. Local anesthetics are drugs that reversibly block the generation and conduction of sensory nerve impulses at the application site. Bupivacaine (BUP) is a commonly used amide-type local anesthetic that blocks nerve excitation and conduction by inhibiting sodium ion channels in nerve cells. Its anesthetic potency is 16 times that of procaine, its duration of action is 8 times that of procaine, and its local anesthetic effect is stronger than lidocaine (about 4 times stronger). It has the characteristics of strong anesthetic efficacy, long duration of action, and obvious separation of sensory and motor blockade. Because of its low concentration in the blood, little accumulation in the body, and long duration of action, it is a relatively safe local anesthetic and is widely used in the treatment of postoperative anesthesia pain, brachial plexus block, epidural anesthesia and spinal anesthesia, as well as some long-term severe cancer pain.

[0004] Although local anesthetics like bupivacaine and lidocaine have strong local anesthetic effects, their duration of action after conventional injection is limited, their half-life is still relatively short, and the analgesic effect lasts for only about 2-4 hours. Therefore, the development of sustained-release bupivacaine injections has become a research hotspot in recent years. Currently, research on various novel modified bupivacaine formulations, such as liposomes, microspheres, and implants, has been reported. The now mature bupivacaine liposome injection suspension (Exparel from Pacira, USA) was the first liposome local anesthetic approved for clinical use. Utilizing DepoFoam multi-capsule liposome technology, it achieves sustained release of the encapsulated drug through a stepwise release mechanism based on the "pomegranate-like" structure of multi-capsule liposomes. It was approved by the FDA in October 2011. However, Expareel suffers from drawbacks such as easy vesicle rupture, limited encapsulation and drug loading rates, and poor stability. Durect, an American company, developed a bupivacaine gel solution (trade name Posimir). The core of this technology is that sucrose isobutyrate (SAIB), benzyl alcohol, and bupivacaine are mixed into a liquid and injected to form a drug reservoir that can be released sustainably. Currently, it can only be administered intra-articularly, and clinical data show that its sustained release can only last for 12-24 hours, which is not significantly different from placebo.

[0005] Currently, there are sustained-release bupivacaine formulations such as liposomes and gels, but they still have problems such as complex preparation, low drug loading, limited release time, and obvious burst release. Therefore, developing a novel bupivacaine sustained-release injection with high encapsulation efficiency and drug loading, stable sustained-release performance, and simple preparation method has important research significance and clinical application value. Summary of the Invention

[0006] Therefore, the technical problem to be solved by this invention is to overcome the problems of complex preparation, low drug loading, and limited release time in existing technologies, thereby providing a method for preparing bupivacaine sustained-release formulations and their application in post-dental analgesia. The bupivacaine sustained-release injection preparation method provided by this invention is simple, flexible, and modular, and can efficiently prepare supramolecular nanoparticles with high drug loading, uniform particle size dispersion, and stable sustained-release performance. This dosage form is convenient for local administration, has a rapid onset of action, and can release bupivacaine within 2-3 days, providing sustained analgesia.

[0007] To address the aforementioned technical problems, this invention provides a method for preparing a bupivacaine sustained-release injection, comprising the following steps: S11: Add β-cyclodextrin-grafted polyethyleneimine (CD-PEI), adamantane-grafted polyethylene glycol (Ad-PEG), and water to an organic solvent containing adamantane-grafted polyamide-amine dendrimer (Ad-PAMAM) and bupivacaine, and mix to obtain a nanoparticle suspension. S12: Perform solid-liquid separation on the nanoparticle suspension to remove impurities and obtain the bupivacaine sustained-release injection.

[0008] Preferably, the mass ratio of the adamantane-grafted polyamide-amine dendritic macromolecule to bupivacaine is 1-12:10-30.

[0009] Preferably, the mass ratio of the adamantane-grafted polyamide-amine dendritic macromolecule, the β-cyclodextrin-grafted polyethyleneimine, and the adamantane-grafted polyethylene glycol is 5-87.5:25:27-108.

[0010] The bupivacaine supramolecular nanoparticles (Bup@SMNPs) constructed in this invention achieve structural self-assembly through specific recognition between Ad and CD. Ad (adamantyl) acts as a guest group, embedding itself into the hydrophobic cavity of CD (β-cyclodextrin) to form a stable host-guest composite structure. This inclusion interaction is highly selective and reversible, forming the basis for the formation of hydrogel networks.

[0011] In the self-assembly system, Ad-PAMAM provides Ad groups to provide skeletal structural support for the cross-linking network, CD-PEI molecules serve as cross-linking nodes, and β-cyclodextrin cavities encapsulate Ad groups to form stable Ad / CD complex bonds, enabling the system to spontaneously aggregate into nanoscale particles at the molecular level.

[0012] The bupivacaine sustained-release injection provided by this invention includes bupivacaine and three polymer building blocks: Ad-PAMAM, Ad-PEG, and CD-PEI. By adjusting the mixing ratio of bupivacaine and the three functional molecular building blocks, the size, surface chemical properties, and drug loading of nanoparticles can be precisely controlled.

[0013] Specifically, the synthesis method of Ad-PAMAM is as follows: PAMAM is dissolved in N,N-dimethylformamide to form a PAMAM solution; then 1-adamantane isocyanate in N,N-dimethylformamide is added to the PAMAM solution, and the mixture is stirred and reacted at room temperature to obtain the final product.

[0014] Specifically, the synthesis method of Ad-PEG is as follows: 1-adamantaneamine hydrochloride is dissolved in CH2Cl2, triethylamine and mPEG-NHS are added sequentially, the solvent is removed after stirring at room temperature, water is added, dialyzed overnight and lyophilized to obtain Ad-PEG.

[0015] Specifically, the synthesis method of CD-PEI is as follows: branched polyethyleneimine is dissolved in dimethyl sulfoxide, 6-p-toluenesulfonyl-β-cyclodextrin (6-OTs-β-CD) is added, and the mixture is reacted at 60-80℃ for 2-4 days, followed by dialyzing with water for 5-7 days. After filtration, CD-PEI is obtained by freeze-drying.

[0016] Preferably, the organic solvent is dichloromethane, acetone, ethyl acetate, N,N-dimethylformamide (DMF), or dimethyl sulfoxide (DMSO).

[0017] Preferably, the concentration of the adamantane-grafted polyamide-amine dendritic macromolecule in the organic solvent is 8-24 mg / mL, and the concentration of bupivacaine is 45-55 mg / mL.

[0018] Preferably, the concentration of the β-cyclodextrin-grafted polyethyleneimine in water is 1-1.5 mg / mL, and the concentration of the adamantane-grafted polyethylene glycol in water is 5.2-5.6 mg / mL.

[0019] Ad-PEG plays a crucial "competitive regulation" role in the system. Its terminal Ad groups can competitively bind to the CD cavities of CD-PEI, thereby inhibiting excessive cross-linking between Ad-PAMAM and CD-PEI. Through this competitive action, the degree of network expansion and particle growth rate can be effectively controlled, thus precisely regulating the size and structural density of nanoparticles.

[0020] This invention introduces an end-capped / solvated group, Ad-PEG, which, on the one hand, competitively binds to the dendritic molecule Ad-PAMAM, inhibiting the continuous expansion of the cross-linked network, and on the other hand, endows the supramolecular nanoparticles (Bup@SMNPs) with good water solubility and dispersibility.

[0021] Preferably, in step S11, the mixing method is ultrasonication 1-3 times, each lasting 10-20 seconds, followed by standing for 0.5-1.5 hours. By combining short-duration, multiple ultrasonications with subsequent standing, the material can be efficiently mixed and dispersed, while avoiding structural damage caused by excessive ultrasonication, and ensuring the stability and uniformity of the dispersion system.

[0022] Preferably, in step S12, the solid-liquid separation method is centrifugation to collect solid particles, and the impurity removal method is water washing followed by freeze drying. Using centrifugation to collect solid particles achieves efficient solid-liquid separation, and water washing removes impurities followed by freeze drying, which preserves the product structure and purity under mild conditions, resulting in a dry and clean solid sample.

[0023] The present invention also provides a bupivacaine sustained-release injection prepared by the above preparation method.

[0024] The above formulation is in the form of bupivacaine nanoparticles, composed of the amide-based local anesthetic bupivacaine or a pharmaceutically acceptable polymeric carrier material.

[0025] This invention is a novel nanoparticle delivery technology that utilizes the molecular recognition mechanism between Ad / CD to achieve self-assembly of nanoparticles loaded with bupivacaine. These nanoparticles, which are encapsulated in polymer materials, undergo slow hydrolysis upon contact with water to release the drug, thus achieving a sustained-release effect.

[0026] The present invention also provides a post-dental analgesic drug, comprising the above-mentioned bupivacaine sustained-release injection.

[0027] This analgesic is used for post-dental surgery analgesia to relieve chronic pain in patients, and a single dose can achieve a slow release over 24-72 hours.

[0028] Compared with the prior art, the above-described technical solution of the present invention has the following advantages: The sustained-release formulation of bupivacaine loaded in this invention is prepared using a simple, flexible, and modular supramolecular synthesis method, which effectively delays the burst release of the drug, reduces the frequency of administration and toxic side effects, and has a rapid onset of action in vivo, providing good postoperative analgesia.

[0029] Furthermore, compared with traditional chemical synthesis or polymer systems, the supramolecular synthesis method used in this invention is controllable, convenient, and flexible. It does not involve strong acids, strong bases, or organic solvent residues, and can complete the self-assembly reaction at room temperature. The process is simple and safe. Attached Figure Description

[0030] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0031] Figure 1 This is the high-performance liquid chromatography (HPLC) chromatogram of bupivacaine, the reference standard of this invention. Figure 2 This is an in vitro release curve of the bupivacaine nanoparticles (formulas 3, 4, 8 and bupivacaine) of the present invention; Figure 3 This is a scanning electron microscope (SEM) image of the bupivacaine nanoparticles of this invention. Detailed Implementation

[0032] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0033] Materials used in the experiment of this invention and their sources Bupivacaine (Bup): CAS No. 38398-39-3, Molecular Formula C 18 H 28 N 2OThe molecular weight is 288.428, and it was purchased from MedChemExpress.

[0034] PAMAM: A dendritic polymer with an ethylenediamine core, CAS No. 142986-44-5, molecular weight 1429.85000, molecular formula C 62 H 128 N 26 O 12 Purchased from McLean.

[0035] 1-Adamantane isocyanates, CAS No. 4411-25-0, molecular weight 177.24300, molecular formula C 11 H 15 No, purchased from McLean.

[0036] 1-Adamaneamine hydrochloride was purchased from Shanghai Mairui Biochemical Technology Co., Ltd., product number A1260; β-Cyclodextrin (CD), CAS No. 7585-39-9, molecular weight 1134.984, molecular formula C 42 H 70 O 35 Purchased from McLean.

[0037] p-toluenesμLfonyl chloride: p-Toluenesulfonyl chloride, CAS No. 98-59-9, molecular weight 190.647, molecular formula C7H7ClO2S, purchased from Maclean's.

[0038] Branched polyethylenimine (PEI, MW=10 kD, 30% in water), CAS No. 9002-98-6, molecular weight 43.06780, molecular formula C2H5N, purchased from Sigma-Aldrich.

[0039] N-hydroxysuccinimide (NHS) functionalized methoxyl polyethyleneglycol (mPEG-NHS, MW=5 kD), CAS No. 756525-94-7, mPEG-NHS was purchased from Shanghai Maclean Biochemical Technology Co., Ltd., product number MKL-P968648.

[0040] 6-p-Toluenesulfonyl-β-cyclodextrin was purchased from Shanghai Maclean Biochemical Technology Co., Ltd. under the code M830137-5g.

[0041] 1-adamantanamine hydrochloride, CAS No. 665-66-7, molecular weight 187.710, molecular formula C 10 H 18 CIN, purchased from McLean.

[0042] Referring to the preparation method of patent CN120242074A, the synthesis methods of CD-PEI, Ad-PEG, and Ad-PAMAM used in the embodiments of this invention are as follows: (1) Synthesis of Ad-PAMAM A methanol solution containing PAMAM (20 wt%, 0.07 mmol) was added to a round-bottom flask. The methanol was evaporated under vacuum and dissolved in 10 mL of dry N,N-dimethylformamide (DMF) to form a PAMAM solution. 1-Adamane isocyanate (1.4 mmol) from 10 mL of dry DMF was added to the PAMAM solution. The mixture was stirred at room temperature for 2 h, and then the solvent was removed under vacuum.

[0043] Add 100 mL of diethyl ether to the reaction residue to produce a white precipitate. Collect the precipitate by filtration, wash the white precipitate with 100 mL × 3 of diethyl ether and dry it to obtain a white solid Ad-PAMAM.

[0044] (2) Synthesis of Ad-PEG To a solution of 1-adamantaneamine hydrochloride (1.0 mmol) dissolved in 10 mL of CH₂Cl₂, triethylamine (1.0 mmol) and mPEG-NHS (0.2 mmol) were added sequentially. The mixture was stirred at room temperature for 2 h, followed by removal of the solvent under vacuum, and water was added to the reaction residue. The solution was transferred to a centrifuge tube and centrifuged at 10,000 rpm for 10 min to remove unreacted 1-adamantaneamine. The solution was filtered through a 0.45 μm filter, dialyzed overnight using a dialysis chamber (MWCO, 2 kD), and lyophilized to obtain a white powder, Ad-PEG.

[0045] (3) Synthesis of CD-PEI Branched polyethyleneimine (10.0 μmol) was dissolved in 100 mL of dimethyl sulfoxide, and 6-p-toluenesulfonyl-β-cyclodextrin (6-OTs-β-CD) (1.0 mmol) was added. The mixture was reacted at 70 °C for 3 days, then transferred to a dialysis chamber (MWCO, 10 kDa) and dialyzed against deionized water for 6 days. After dialysis, the reaction mixture was filtered to remove unreacted 6-OTs-β-CD (white precipitate), and the filtrate was freeze-dried overnight to obtain a white, soft solid product, CD-PEI.

[0046] Example 1: Preparation of bupivacaine nanoparticles Formulations were screened by adjusting the mixing ratio of the drug bupivacaine with the three building blocks. The specific formulations are as follows: Table 1. Ingredient list and test results of the three formulations in Example 1

[0047] The preparation method of Example 1 is as follows: Pre-prepared Ad-PAMAM and Bup solutions (DMSO solvent) were weighed and mixed according to the formulations in Table 1. Then, aqueous solutions containing CD-PEI and Ad-PEG were added sequentially according to the formulations while stirring. The mixture was ultrasonically cleaned twice using an ultrasonic cleaner (Shanghai Titan Technology Co., Ltd.), each time for 15 seconds, and then allowed to stand for 1 hour to obtain a stable nanoparticle suspension. The suspension was centrifuged at 10,000 rpm to collect the nanoparticles, and the nanoparticles were resuspended in 1 mL of ultrapure water. This step was repeated twice to wash the nanoparticles. The supernatant obtained from centrifugation was collected in a new centrifuge tube for quantitative determination of the free drug Bup content by high-performance liquid chromatography to calculate the encapsulation efficiency and drug loading. 3 mL of ultrapure water was added to the collected nanoparticles for re-suspending and washing. The washed nanoparticles were freeze-dried and stored at -20°C for in vitro release assays.

[0048] In Example 1, the concentration of 8-Ad-PAMAM solution prepared with DMSO solvent was 8 mg / mL, the concentration of Bup solution prepared with DMSO solvent was 50 mg / mL, the concentration of CD-PEI prepared with pure water was 1.25 mg / mL, and the concentration of Ad-PEG prepared with pure water solvent was 5.4 mg / mL.

[0049] The only difference between Formula 2 and Formula 1 is that the amount of bupivacaine added is increased from 4 μL to 6 μL; The only difference between Formula 3 and Formula 2 is that the amount of bupivacaine added is increased from 6 to 12 μL; Comparing the average particle size, encapsulation efficiency, and drug loading of formulations 1, 2, and 3 (Table 1), formulation 3, which has a higher encapsulation efficiency and drug loading, was selected as the superior formulation for in vitro release experiments.

[0050] Example 2: Preparation of Bupivacaine Nanoparticles Formulations were screened by adjusting the mixing ratio of the drug bupivacaine with the three building blocks. The specific formulations are as follows: Table 2. Ingredient list and test results of the three formulations in Example 2

[0051] The preparation method is as follows: Pre-prepared Ad-PAMAM and Bup solutions (DMSO solvent) were weighed and mixed according to the formula. Then, while stirring, aqueous solutions containing CD-PEI and Ad-PEG were added sequentially according to the formula. The resulting mixture was ultrasonically cleaned twice, each time for 15 seconds, and then allowed to stand for 1 hour to obtain a stable nanoparticle suspension. The suspension was centrifuged at 10,000 rpm to collect the nanoparticles, and the nanoparticles were resuspended in 1 mL of ultrapure water. This step was repeated twice to wash the nanoparticles. The supernatant obtained from centrifugation was collected in a new centrifuge tube for the quantitative determination of the free drug Bup content by high-performance liquid chromatography to calculate the encapsulation efficiency and drug loading. 3 mL of ultrapure water was added to the collected nanoparticles for re-suspending and washing. The washed nanoparticles were freeze-dried and stored at -20°C for in vitro release assays.

[0052] In Example 2, the concentration of 8-Ad-PAMAM solution prepared with DMSO solvent was 24 mg / mL, the concentration of Bup solution prepared with DMSO solvent was 50 mg / mL, the concentration of CD-PEI prepared with pure water was 1.25 mg / mL, and the concentration of Ad-PEG prepared with pure water was 5.4 mg / mL.

[0053] The only difference between Formulation 5 and Formulation 4 is that the amount of 8-Ad-PAMAM added is increased from 5 μL to 7.5 μL; The only difference between Formulation 6 and Formulation 5 is that the amount of 8-Ad-PAMAM added is increased from 7.5 μL to 10 μL; Comparing the average particle size, encapsulation efficiency, and drug loading of formulations 4, 5, and 6 (Table 2), formulation 4 was selected as the superior formulation for in vitro release testing.

[0054] Example 3: Preparation of Bupivacaine Nanoparticles Formulations were screened by adjusting the mixing ratio of the drug bupivacaine with the three building blocks. The specific formulations are as follows: Table 3. Ingredient list and test results of the three formulations in Example 3

[0055] The preparation method is as follows: Pre-prepared Ad-PAMAM and Bup solutions (DMSO solvent) were weighed and mixed according to the formula. Then, while stirring, aqueous solutions containing CD-PEI and Ad-PEG were added sequentially according to the formula. The resulting mixture was ultrasonically cleaned twice, each time for 15 seconds, and then allowed to stand for 1 hour to obtain a stable nanoparticle suspension. The suspension was centrifuged at 10,000 rpm to collect the nanoparticles, and the nanoparticles were resuspended in 1 mL of ultrapure water. This step was repeated twice to wash the nanoparticles. The supernatant obtained from centrifugation was collected in a new centrifuge tube for the quantitative determination of the free drug Bup content by high-performance liquid chromatography to calculate the encapsulation efficiency and drug loading. 3 mL of ultrapure water was added to the collected nanoparticles for re-suspending and washing. The washed nanoparticles were freeze-dried and stored at -20°C for in vitro release assays.

[0056] In Example 2, the concentration of Ad-PAMAM solution prepared with DMSO solvent was 24 mg / mL, the concentration of Bup solution prepared with DMSO solvent was 50 mg / mL, the concentration of CD-PEI prepared with pure water was 1.25 mg / mL, and the concentration of Ad-PEG prepared with pure water was 5.4 mg / mL.

[0057] The only difference between Formulation 8 and Formulation 7 is that the amount of Ad-PEG added is increased from 40 to 60 μL; The only difference between Formulation 9 and Formulation 8 is that the amount of Ad-PEG added is increased from 60 to 80 μL; Comparing the average particle size, encapsulation efficiency, and drug loading of formulations 7, 8, and 9, formulation 8 was selected as the superior formulation for in vitro release testing. This example is to investigate the effect of changing the amount of Ad-PEG added on drug release behavior.

[0058] Comparative Example: Preparation of Bupivacaine In vitro release experiments were conducted by directly dissolving the drug bupivacaine in phosphate buffer at pH 7.4.

[0059] Experimental Example 1: Determination of the in vitro release performance of the bupivacaine nanoparticles of the present invention by high performance liquid chromatography The bupivacaine nanoparticles prepared according to formula 3 in Example 1 were used for an in vitro release experiment. The specific operation process is as follows: 1. Chromatographic parameters and conditions An Agilent ZORBAX-C18 column (250 mm * 4.6 mm, 5 μm) was used as the chromatographic column, with octadecylsilane-bonded silica gel as the packing material (pH range greater than 8.0); the mobile phase was 0.02 mol / phosphate buffer (2.72 g potassium dihydrogen phosphate and 0.75 g sodium hydroxide were dissolved in 1000 mL of water and the pH was adjusted to 8.0) - acetonitrile (35:65); the detection wavelength was 210 nm; the injection volume was 20 μL, the flow rate was 1.0 mL / min, and the column temperature was 30 °C.

[0060] 2. Determination of drug loading and encapsulation efficiency 10 mg of the prepared nanoparticle powder was accurately measured into a 50 mL volumetric flask, and a certain amount of methanol was added to dissolve it for one day to dissociate Bup@SMNPs and obtain the total amount of drug Bup encapsulated in the nanoparticles. The solution was then sonicated for 30 min. After filtering through a 0.22 μm filter membrane, the solution was analyzed by HPLC.

[0061] The drug loading (LC) and encapsulation efficiency (EE) are calculated using the following formulas: Encapsulation efficiency (%) = (total Bup measured - free Bup collected by centrifugation) / total Bup measured; Drug loading (%) = weight of Bup in the sample / total weight of Bup@SMNPs; 3. In vitro release test Prepare a pH 7.4 phosphate buffer solution in advance (take 1.36 g of potassium dihydrogen phosphate (KH2PO4), 79 mL of 0.1 mol / L NaOH solution, and dilute with water to 200 mL). Accurately weigh the nanoparticle powder stored at -20℃ and add it to the dialysis bag (MW; 3000). Preheat the dialysis bag to 100℃ in a water bath for 10 minutes, and add pure water to half the height of the dialysis bag to check for sealing. Tie both ends of the dialysis bag tightly, and add 1 mL of water to dissolve the nanoparticle powder. Place the dialysis bag containing the nanoparticle suspension in a centrifuge tube containing 20 mL of phosphate buffer solution. Shake at 100 rpm under constant temperature (37℃ ± 0.5). Take the release medium at 0.5, 1, 2, 4, 6, 8, 12, 24, 36, 48, and 72 h. mL of fresh release medium (phosphate buffer) at the same temperature and pH was added. The sample was injected and analyzed according to the "Chromatographic Parameters and Conditions". The cumulative drug release percentage was calculated using the following formula, and the release curve of bupivacaine nanoparticles was plotted. Q n =C n ×V0+(C1+C2+…+C n-1 )×V; where Q n C represents the cumulative release amount at the nth sampling. nLet V be the drug concentration in the nth sample, V0 be the initial volume of the release medium, and V be the volume of each sample. Drug Bup cumulative release rate = drug cumulative release amount Qn / theoretical Bup content in nano-formulation; Figure 2 In the study, the in vitro release time of formulations 3, 4, and 8 was longer than that of the control group with empty bupivacaine. However, the release time of formulation 3 was too fast compared to formulations 4 and 8. This was attributed to the excessive drug loading, which led to a burst release phenomenon. In contrast, the increased addition of Ad-PEG to formulation 8 helped to delay the drug release time.

[0062] Experimental Example 2: Observations using scanning electron microscopy and transmission electron microscopy revealed that the bupivacaine nanoparticles of this invention have reached the nanoscale, and the nanoparticles exhibit regular morphology, good dispersion, and smooth surface.

[0063] 10 mg of bupivacaine nanoparticles prepared in this invention were precisely measured, dissolved in PBS, sonicated in a water bath for 5 min, and then added to a clean and smooth tin foil. The sample was obtained after freeze-drying and dehydration.

[0064] The sample was examined using a scanning electron microscope, and the images showed that most of the nanoparticles had a particle size between 200-300 nm, which meets the requirements of this invention. Figure 3 As shown.

[0065] This invention employs a novel nanodelivery technology, utilizing the host-guest (Ad / Cd) recognition mechanism in supramolecular chemical synthesis to achieve precise control over the size and dynamic surface chemical properties of the Bup@SMNPs carrier. It exhibits significant sustained-release and analgesic effects, providing a local delivery method for post-dental analgesia and showing important clinical application prospects.

[0066] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a bupivacaine sustained-release injection, characterized in that, Includes the following steps: S11: Add β-cyclodextrin-grafted polyethyleneimine, adamantane-grafted polyethylene glycol, and water to an organic solvent containing adamantane-grafted polyamide-amine dendritic macromolecules and bupivacaine, and mix to obtain a nanoparticle suspension. S12: Perform solid-liquid separation on the nanoparticle suspension to remove impurities and obtain the bupivacaine sustained-release injection.

2. The preparation method according to claim 1, characterized in that: The mass ratio of the adamantane-grafted polyamide-amine dendritic macromolecule to bupivacaine is 1-12:10-30.

3. The preparation method according to claim 1, characterized in that: The mass ratio of the adamantane-grafted polyamide-amine dendritic macromolecule, the β-cyclodextrin-grafted polyethyleneimine, and the adamantane-grafted polyethylene glycol is 5-87.5:25:27-108.

4. The preparation method according to claim 1, characterized in that: The organic solvent is dichloromethane, acetone, ethyl acetate, N,N-dimethylformamide, or dimethyl sulfoxide.

5. The preparation method according to claim 1, characterized in that: The organic solvent contains a concentration of 8-24 mg / mL of adamantane-grafted polyamide-amine dendritic macromolecules and a concentration of 45-55 mg / mL of bupivacaine.

6. The preparation method according to claim 1, characterized in that: The concentration of the β-cyclodextrin-grafted polyethyleneimine in water is 1-1.5 mg / mL, and the concentration of the adamantane-grafted polyethylene glycol in water is 5.2-5.6 mg / mL.

7. The preparation method according to claim 1, characterized in that: In step S11, the mixing method is to use ultrasound 1-3 times, each lasting 10-20 seconds, and then let it stand for 0.5-1.5 hours after ultrasound.

8. The preparation method according to claim 1, characterized in that: In step S12, the solid-liquid separation method is to collect solid particles by centrifugation, and the impurity removal method is to wash with water and then freeze-dry.

9. A bupivacaine sustained-release injection prepared by any one of claims 1-8.

10. A post-dental analgesic drug, characterized in that: Includes the bupivacaine sustained-release injection of claim 9.

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