Long-acting analgesic compound as well as preparation method and application thereof

Abstract

The invention discloses a long-acting analgesic compound as well as a preparation method and application thereof. The preparation method comprises the following steps: preparing a mixed solution containing a polymer, a local anesthetic, a non-steroidal anti-inflammatory drug and a solvent into drug-loaded microspheres through an electrostatic spraying technology; the preparation method comprises the following steps: dissolving poloxamer and a natural polymer material in water to obtain a hydrogel solution; and uniformly mixing the drug-loaded microspheres and a hydrogel solution to prepare the long-acting analgesic compound. The long-acting analgesic compound comprises drug-loaded microspheres and hydrogel, the long-acting analgesic compound and the hydrogel are both of a three-dimensional porous network structure, the drug-loaded microspheres are evenly dispersed in the hydrogel, and the drug-loaded microspheres are of a solid spherical structure. The advantages of electrostatic spraying microspheres and hydrogel are combined, the preparation method is mild in condition and simple in process, and the preparation process is non-toxic and harmless; the long-acting analgesic compound has the advantages of thermosensitivity, injectability, high drug loading rate and the like, and can be effectively applied to preparation of analgesic products.

Description

Technical Field

[0001] The present invention belongs to the technical field of biomedicine, and particularly relates to a long-acting analgesic complex, a preparation method thereof and an application thereof. Background Art

[0002] Acute postoperative pain is a common complaint symptom of patients after invasive surgery, usually occurring within 48 hours after surgery. It is reported that these surgeries can cause persistent neuropathic pain, and more than 50% of patients will experience this pain after surgery. Poor control of acute postoperative pain will seriously affect the quality of life and functional recovery of patients, increase the probability of postoperative complications, and prolong the hospitalization time of patients. Clinically, the drugs for pain management mainly include opioid drugs for systemic use and local anesthetics for regional block. Due to the many adverse reactions and addiction of opioid drugs, their application is limited. Compared with systemic medication, the local analgesic administration method is more targeted and safer.

[0003] Currently, the local anesthetic drugs commonly used for postoperative analgesia mainly include ropivacaine hydrochloride, bupivacaine hydrochloride, lidocaine hydrochloride, etc. Their disadvantage is that the action time is only 5-10 hours, which cannot meet the clinical needs. The ideal requirement for a local anesthetic is more than 72 hours. Therefore, the development of long-acting local anesthetics has become a hot topic, and a variety of sustained-release systems loaded with local anesthetic drugs have been developed for postoperative pain management, and most of them are in the experimental stage. Developing an injectable, high drug-loading, and safer sustained-release system loaded with local anesthetic drugs is of great significance.

[0004] The selective inhibitory effect of celecoxib on COX-2 can reduce the level of inflammatory factors in the body, increase the pain threshold, and help intervene in pain perception or conduction at multiple levels, so as to achieve the superposition of analgesic effects and reduce the dosage and side effects of bupivacaine. The analgesic effect of this type of drug is not obvious, and it needs to be combined with other types of analgesics (opioid or local anesthetic) to achieve the effect.

[0005] Compared with many drug sustained-release systems, hydrogel microspheres, as a sustained-release carrier, have many advantages. For example: (1) The drug release rate and duration can be customized by changing the material and manufacturing process; (2) Microspheres are more stable and have a higher drug-loading capacity than other controlled drug delivery technologies such as liposomes; (3) Due to the shorter dosing frequency, microspheres have a long drug release cycle, and the compliance of patients is improved. However, the microspheres prepared by traditional methods have uneven particle size distribution, low drug-loading rate, and rapid drug metabolism, resulting in waste of drugs and materials. Moreover, microspheres also have the disadvantage of poor in-situ retention, and it is difficult to release drugs at the nerve site for a long time. Therefore, how to improve the drug-loading level of anesthetic drugs, improve the retention of microspheres in the body, and enhance the long-term drug release ability is a technical difficulty faced by this field. Summary of the Invention

[0006] The main object of the present invention is to provide a long-acting analgesic complex, a preparation method thereof and an application thereof, so as to overcome the deficiencies of the prior art.

[0007] To achieve the foregoing invention object, the technical solution adopted by the present invention includes:

[0008] One aspect of the present invention provides a preparation method of a long-acting analgesic complex, which includes: preparing drug-loaded microspheres by electrostatic spraying technology from a mixed solution containing a polymer, a local anesthetic, a non-steroidal anti-inflammatory drug, and a solvent;

[0009] Dissolving poloxamer and a natural polymer material in water to obtain a hydrogel solution;

[0010] Mixing the drug-loaded microspheres and the hydrogel solution evenly to prepare a long-acting analgesic complex.

[0011] Another aspect of the present invention provides a long-acting analgesic complex prepared by the preparation method, which includes drug-loaded microspheres and a hydrogel. Both the long-acting analgesic complex and the hydrogel are three-dimensional porous network structures. The drug-loaded microspheres are evenly dispersed in the hydrogel, and the drug-loaded microspheres are solid spherical structures.

[0012] Another aspect of the present invention also provides an application of the long-acting analgesic complex in the preparation of analgesic products.

[0013] Another aspect of the present invention also provides a local anesthetic biomaterial preparation, which includes the long-acting analgesic complex.

[0014] Compared with the prior art, the present invention has at least the following beneficial effects:

[0015] (1) The electrostatic spray microspheres prepared by the present invention have the advantages of small size, uniform particle size, high encapsulation rate, etc. Combining the advantages of electrostatic spray microspheres and hydrogels, the preparation method of the long-acting analgesic complex has mild conditions, simple process, and is non-toxic and harmless during the production process;

[0016] (2) The electrostatic spray microsphere-hydrogel composite material loaded with the long-acting analgesic complex of the present invention has the advantages of thermosensitivity, injectability, high drug loading rate, etc., and has good biocompatibility and biodegradability; this composite material can overcome the defects in the prior art such as limited drug administration methods, difficult control of drug release, and easy occurrence of toxic and side effects due to difficult slow release of drugs;

[0017] (3) After the combination of the local anesthetic and the non-steroidal anti-inflammatory drug in the present invention, the administration doses of both the local anesthetic and the non-steroidal anti-inflammatory drug can be reduced, effectively reducing the toxic and side effects of both; and by combining the advantages of electrostatic spray microspheres and hydrogels, the prepared long-acting analgesic complex successfully overcomes the defects in the prior art such as limited drug administration methods, insufficient drug release time, and easy occurrence of toxic and side effects caused by drug burst release, and has the advantages of wide applicability, safety, injectability, and long-acting nerve block. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments recorded in the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0019] Figure 1 is a schematic diagram of the preparation of bupivacaine-celecoxib electrostatic spray microspheres (MS) of the present invention;

[0020] Figure 2 is the thermosensitive property of the hydrogel (Gel), electrostatic spray microsphere / hydrogel complex (MS / Gel) loaded with bupivacaine and celecoxib of the present invention;

[0021] Figure 3 is a morphological diagram of the hydrogel (Gel);

[0022] Figure 4 is a morphological diagram of the bupivacaine-celecoxib / hydrogel complex (Bup-Cel / Gel);

[0023] Figure 5 is a morphological diagram of the bupivacaine-celecoxib electrostatic spray microspheres (MS);

[0024] Figure 6 is a partially enlarged morphological diagram of the bupivacaine-celecoxib electrostatic spray microspheres (MS);

[0025] Figure 7 is a morphological diagram of the electrostatic spray microsphere / hydrogel complex (MS / Gel) loaded with bupivacaine and celecoxib;

[0026] Figure 8 is a particle size distribution diagram of the bupivacaine-celecoxib electrostatic spray microspheres (MS);

[0027] Figure 9 is a rheological property diagram of the hydrogel (Gel);

[0028] Figure 10It is the rheological property diagram of bupivacaine-celecoxib / hydrogel complex (Bup-Cel / Gel);

[0029] Figure 11 It is the rheological property diagram of electrostatic spray microsphere hydrogel complex (MS / Gel) loaded with bupivacaine and celecoxib;

[0030] Figure 12 It is the drug release rate diagram of bupivacaine (Bup), bupivacaine in bupivacaine-celecoxib electrostatic spray microspheres (MS-Bup), bupivacaine in bupivacaine-celecoxib / hydrogel complex (Bup-Cel / Gel-Bup), and bupivacaine in electrostatic spray microsphere / hydrogel complex loaded with bupivacaine and celecoxib (MS / Gel-Bup);

[0031] Figure 13 It is the drug release rate diagram of celecoxib (Cel), celecoxib in bupivacaine-celecoxib electrostatic spray microspheres (MS-Cel), celecoxib in bupivacaine-celecoxib / hydrogel complex ((Bup-Cel / Gel-Cel), and celecoxib in electrostatic spray microsphere / hydrogel complex loaded with bupivacaine and celecoxib ((MS / Gel-Cel);

[0032] Figure 14 It is the sciatic nerve block effect diagram of mechanical pain of bupivacaine hydrochloride (Bup HCl), bupivacaine liposome (Lip), bupivacaine-celecoxib electrostatic spray microspheres (MS), bupivacaine-celecoxib / hydrogel complex (Bup-Cel / Gel), and electrostatic spray microsphere / hydrogel complex loaded with bupivacaine and celecoxib (MS / Gel);

[0033] Figure 15 It is the sciatic nerve block effect diagram of thermal pain of bupivacaine hydrochloride (Bup HCl), bupivacaine liposome (Lip), bupivacaine-celecoxib electrostatic spray microspheres (MS), bupivacaine-celecoxib / hydrogel complex (Bup-Cel / Gel), and electrostatic spray microsphere / hydrogel complex loaded with bupivacaine and celecoxib (MS / Gel);

[0034] Figure 16 It is the in vivo degradability of bupivacaine hydrochloride (Bup HCl), bupivacaine liposome (Lip), bupivacaine-celecoxib electrostatic spray microspheres (MS), bupivacaine-celecoxib / hydrogel complex (Bup-Cel / Gel), and electrostatic spray microsphere / hydrogel complex loaded with bupivacaine and celecoxib (MS / Gel) at the nerve site;

[0035] Figure 17In vivo safety (H&E staining, scale bar: 400 μm) at the nerve site of bupivacaine hydrochloride (Bup HCl), liposomal bupivacaine (Lip), electrostatic spray microspheres of bupivacaine-celecoxib (MS), bupivacaine-celecoxib / hydrogel complex (Bup-Cel / Gel), and electrostatic spray microspheres / hydrogel complex loaded with bupivacaine and celecoxib (MS / Gel). Detailed implementation mode

[0036] In view of the problems existing in the above-mentioned prior art, through extensive and in-depth research by the inventors of the present invention, a long-acting analgesic complex and its preparation method and application are provided. It mainly combines the advantages of electrostatic spray microspheres and hydrogels, and the obtained long-acting analgesic complex has effects such as injectability, safety, and local long-acting and sustained-release analgesia.

[0037] The following will further explain the technical solution, its implementation process, principle, etc.

[0038] As an aspect of the technical solution of the present invention, a preparation method of a long-acting analgesic complex provided includes:

[0039] Preparing drug-loaded microspheres by electrostatic spray technology from a mixed solution containing a polymer, a local anesthetic, a non-steroidal anti-inflammatory drug, and a solvent;

[0040] Dissolving poloxamer and a natural polymer material in water to obtain a hydrogel solution;

[0041] Mixing the drug-loaded microspheres and the hydrogel solution evenly to prepare a long-acting analgesic complex.

[0042] In some embodiments, the preparation method of the long-acting analgesic complex specifically includes: dissolving the polymer, the local anesthetic, and the non-steroidal anti-inflammatory drug in a solvent, stirring evenly to obtain a mixed solution, and then preparing the drug-loaded microspheres from the mixed solution by electrostatic spray technology.

[0043] In some embodiments, the preparation method of the long-acting analgesic complex specifically includes: adding 60 - 80 mg of drug-loaded microspheres to every 0.6 mL of hydrogel solution, and vortex oscillating for 2 - 4 h to prepare the long-acting analgesic complex.

[0044] Further, the electrostatic spray technology specifically includes: transferring the mixed solution to a syringe, forming a spray-like jet under an electrostatic field, and collecting it with a collector to obtain the drug-loaded microspheres; wherein, the flow rate of the mixed solution input in the electrostatic spray technology is 0.90 - 1.00 mL / h, the voltage is 9 - 11 kV, the ambient temperature is 15 - 30 °C, and the distance between the needle of the syringe and the collector is 10 - 15 cm.

[0045] Further, the syringe is a 10 mL syringe and is equipped with a 20G needle.

[0046] In some embodiments, the polymer includes at least any one of poly (lactic-co-glycolic acid), polycaprolactone, polylactic acid, polyhydroxybutyrate, etc., but is not limited thereto.

[0047] In some embodiments, the local anesthetic includes bupivacaine.

[0048] In some embodiments, the non-steroidal anti-inflammatory drug includes celecoxib.

[0049] In some embodiments, the solvent includes dichloromethane.

[0050] In some embodiments, the mass ratio of the local anesthetic, non-steroidal anti-inflammatory drug to the polymer is 1:1:1 to 2.

[0051] In some embodiments, the mass fraction of the polymer in the mixed solution is 10 to 18%.

[0052] In some embodiments, the natural polymer material includes any one or a combination of two or more of hyaluronic acid, chitosan, carboxymethyl chitosan, sodium alginate, etc., but is not limited thereto.

[0053] In some embodiments, the poloxamer includes poloxamer F127.

[0054] In some embodiments, the mass fraction of the poloxamer in the hydrogel solution is 18 to 25%, and the mass fraction of the natural polymer material in the hydrogel solution is 0.1 to 1%.

[0055] In some more specific embodiments, the preparation method of the long-acting analgesic complex specifically includes the following steps:

[0056] S1: Dissolve the polymer, local anesthetic, and non-steroidal anti-inflammatory drug in a solvent, stir evenly to obtain a mixed solution, and then prepare the drug-loaded microspheres from the mixed solution by electrospray technology;

[0057] S2: Dissolve poloxamer and natural polymer material in water to obtain a hydrogel solution;

[0058] S3: Add 60 - 80 mg of the drug-loaded microspheres to every 0.6 mL of the hydrogel solution, and vortex for 2 - 4 h to prepare the long-acting analgesic complex.

[0059] As an aspect of the technical solution of the present invention, the long-acting analgesic complex prepared by the preparation method includes drug-loaded microspheres and hydrogel. Both the long-acting analgesic complex and the hydrogel have a three-dimensional porous network structure. The drug-loaded microspheres are uniformly dispersed in the hydrogel, and the drug-loaded microspheres are solid spherical structures.

[0060] Further, the drug-loaded microspheres are sustained-release micron particles.

[0061] Further, the drug-loaded microspheres include a polymer, a local anesthetic, and a non-steroidal anti-inflammatory drug.

[0062] Further, the diameter of the drug-loaded microspheres is 1 to 10 μm.

[0063] Further, the mass fraction of the drug-loaded microspheres in the long-acting analgesic complex is 10 to 13.3%.

[0064] Further, the hydrogel is a temperature-sensitive gel.

[0065] Still further, the polymer includes poly(lactic-co-glycolic acid).

[0066] Still further, the local anesthetic includes bupivacaine, the non-steroidal anti-inflammatory drug includes celecoxib, the mass fraction of bupivacaine is 3 to 4%, and the mass fraction of celecoxib is 3 to 4%.

[0067] As an aspect of the technical solution of the present invention, it provides the application of the long-acting analgesic complex in the preparation of analgesic products.

[0068] As an aspect of the technical solution of the present invention, a local anesthetic biomaterial preparation provided by it includes the long-acting analgesic complex.

[0069] In summary, the long-acting analgesic complex of the present invention has good biocompatibility and degradability, and has good flexibility and mechanical strength, and can achieve the effect of long-acting local analgesia in vivo. It is a long-acting sustained-release and selectively pain-blocking local anesthetic biomaterial preparation with the potential for clinical transformation.

[0070] In order to make the objectives, technical solutions and advantages of the present invention clearer, the following further describes the present invention in detail with reference to embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Those skilled in the art make modifications or equivalent replacements on the basis of understanding the technical solutions of the present invention, and without departing from the spirit and scope of the technical solutions of the present invention, they should all be covered within the protection scope of the present invention.

[0071] For those without specific experimental procedures or conditions noted in the examples, the operations or conditions of the conventional experimental procedures described in the literature in this field can be followed. For reagents or instruments without noted manufacturers, they can all be obtained through commercial purchases. The commercial purchases of the remaining raw materials and instruments not mentioned are all conventional choices and do not involve the core technical means of the present invention.

[0072] Raw materials and equipment used in the examples of the present invention

[0073] Raw materials: Poly (lactic-co-glycolic acid) (PLGA, 73:27, Mw = 12333), bupivacaine (Bup, Mw = 288.43), celecoxib (Cel, Mw = 381.37), poloxamer F127 ( P 407 Geismar), hyaluronic acid (HA, Mw = 200,000 - 400,000), carboxymethyl chitosan (CMCTS, degree of substitution ≥ 80%).

[0074] Equipment: Electrostatic sprayer, high-voltage power supply, magnetic stirrer, constant temperature shaker, nitrogen blower.

[0075] Example 1

[0076] (1) Preparation of drug-loaded microspheres encapsulating bupivacaine and celecoxib

[0077] First, PLGA (10 wt%), bupivacaine (10 wt%) and celecoxib (10 wt%) were dissolved in dichloromethane in proportion and magnetically stirred at room temperature for 2 h to obtain a mixed solution; then the mixed solution was transferred to a 10 mL syringe (20G needle) for electrostatic spraying.

[0078] Electrostatic spraying parameters: The solution was pumped at a speed of 1.00 mL / h to form a stable spray jet under a 10 kV electrostatic field. The distance between the needle and the collector was 10 cm.

[0079] The bupivacaine-celecoxib electrostatic spray microspheres (MS) were obtained and stored in a -20 °C refrigerator for later use. The preparation schematic diagram is as Figure 1 shown.

[0080] (2) Preparation of hydrogel solution (Gel)

[0081] Poloxamer F127 (18 wt%) and hyaluronic acid (0.5 wt%) were dissolved in double-distilled water, and the solution was stirred and dissolved in a 5 °C refrigerator to prepare the Gel solution, which was stored in a 4 °C refrigerator for later use. The hydrogel prepared in this example has thermosensitive properties and injectability.

[0082] (3) Preparation of electrostatic spray microsphere / hydrogel composite (MS / Gel)

[0083] Based on (1) and (2), the electrostatic spray microspheres loaded with bupivacaine - celecoxib with a mass ratio of PLGA, bupivacaine, and celecoxib of 1:1:1 and 18% F127 - 0.5% HA hydrogel were selected. According to the calculated drug loading rate of the microspheres, 60 mg of microspheres were added to 0.6 mL of the gel solution and vortex - shaken at 4 °C for 2 h to obtain a uniform suspension. At 37 °C, this suspension can form a gel - state MS / Gel complex, as Figure 2 shown, indicating that this complex has thermosensitive properties.

[0084] Example 2

[0085] The long - acting analgesic complex was prepared using the same operating procedure as in Example 1. However, in this example, when preparing the microspheres by electrospray, the mass ratio of PLGA, bupivacaine, and celecoxib was 2:1:1, and the total mass ratio of PLGA in the mixed solution was 15%. 18% F127 - 0.5% HA was used as the gel solution, and 80 mg of microspheres were added to 0.6 mL of the gel solution. Based on this condition, following the same operation as in Example 1, the MS / Gel complex was prepared. The complex in this example can form a gel at 37 °C, has thermosensitive properties, and has good injectability.

[0086] Example 3

[0087] The long - acting analgesic complex was prepared using the same operating procedure as in Example 1. However, in this example, the effect of the PLGA concentration in the microspheres on the release was investigated. The mass ratio of PLGA, bupivacaine, and celecoxib was 2:1:1, and the total mass ratio of PLGA in the mixed solution was 18%. 18% F127 - 0.5% HA was used as the gel solution, and 80 mg of microspheres were added to 0.6 mL of the gel solution. Based on this condition, following the same operation as in Example 1, the MS / Gel complex was prepared. The thermosensitivity and injectability of the complex prepared in this example are similar to those in Example 2.

[0088] Example 4

[0089] The long - acting analgesic complex was prepared using the same operating procedure as in Example 1. However, in this example, 18% F127 - 0.5% HA - 0.5% CMCTS was used as the gel solution. Based on this condition, following the same operation as in Example 1, the MS / Gel complex was prepared. The complex in this example can form a gel at 37 °C, has thermosensitive properties, and has good injectability.

[0090] Example 5

[0091] The long-acting analgesic complex was prepared using the same operating steps as in Example 1. However, in this example, a gel solution of 18% F127 - 0.1% HA was used. Based on this condition, following the same operation as in Example 1, the MS / Gel complex was prepared. The complex of this example can form a gel at 37°C, has thermosensitive properties, and has good injectability.

[0092] Comparative Example 1

[0093] A hydrogel solution (Gel) was prepared using the same operating steps as in Example 1. However, in this comparative example, a physical mixture of bupivacaine and celecoxib was used instead of the electrosprayed microspheres, and a gel solution of 18% F127 - 0.5% HA was used. 40 mg of the physical mixture of bupivacaine and celecoxib (where the mass ratio of bupivacaine to celecoxib is 1:1) was added to 0.6 mL of the gel solution. Based on this condition, following the same operation as in Example 1, the Bup-Cel / Gel complex was prepared. The complex of this comparative example also has thermosensitive properties, but the drug release rate is lower than that of the MS / Gel complex.

[0094] Comparative Example 2

[0095] A drug-loaded complex encapsulating bupivacaine and celecoxib was prepared using the same operating steps as in Example 1. However, in this comparative example, the effect of a high PLGA concentration on the preparation of the complex was investigated. The mass ratio of PLGA to bupivacaine and celecoxib is 1:1:1, and the total mass ratio of PLGA in the mixed solution is 30%. The complex prepared in this comparative example is not in the form of microspheres, but presents electrospun nanofibers. The dispersibility of this structure in the gel solution is lower than that of microspheres, so the injectability is lower than that of the MS / Gel complex.

[0096] Comparative Example 3

[0097] The long-acting analgesic complex was prepared using the same operating steps as in Example 1. However, in this comparative example, phosphate buffered saline (PBS) was used instead of the gel solution to disperse the microspheres. Based on this condition, following the same operation as in Example 1, the MS / PBS complex was prepared. The complex of this example does not have thermosensitive properties, has poor in-situ performance, and does not have a dual sustained-release effect. The drug release rate is lower than that of Example 1.

[0098] Comparative Example 4

[0099] The long-acting analgesic complex was prepared using the same operating steps as in Example 1. However, in this comparative example, the effect of different drug loadings in the microspheres on the release was investigated. The mass ratio of PLGA to bupivacaine and celecoxib was 10:1:1, and the total mass ratio of PLGA in the mixed solution was 20%. An 18% F127 - 0.5% HA gel solution was used. Based on this condition, following the same operations as in Example 1, the MS / Gel complex was prepared. Although the complex prepared in this comparative example had thermosensitive properties, the increase in the PLGA content in the microspheres resulted in a lower drug release rate than that in Example 1.

[0100] Comparative Example 5

[0101] The long-acting analgesic complex was prepared using the same operating steps as in Example 1. However, in this comparative example, an 18% F127 - 2% HA gel solution was used. Based on this condition, following the same operations as in Example 1, the MS / Gel complex was prepared. The complex prepared in this comparative example also had thermosensitive properties, but the gel viscosity was too high, which was not conducive to injection.

[0102] Comparative Example 6

[0103] The long-acting analgesic complex was prepared using the same operating steps as in Example 1. However, in this comparative example, a 30% F127 - 0.5% HA gel solution was used. Based on this condition, following the same operations as in Example 1, the MS / Gel complex was prepared. The complex prepared in this comparative example also had thermosensitive properties, but the gel viscosity was too high, which was not conducive to injection.

[0104] Test Example 1

[0105] Characterization of the electrosprayed microspheres / hydrogel complex (MS / Gel)

[0106] As Figures 3 - 7 shown, a scanning electron microscope (SEM) was used to observe the surface morphologies of the electrosprayed microspheres, the gel, and the electrosprayed microsphere-gel complex in Example 1, as well as the Bup-Cel / Gel complex in Comparative Example 1; as Figure 8 shown, the SEM showed that the electrosprayed microspheres exhibited a smooth surface and spherical shape, with a uniform particle size distribution and an average particle size of 1.8 μm; both the Gel and the Bup-Cel / Gel complex exhibited an interconnected three-dimensional (3D) porous network structure; in the MS / Gel complex, the microspheres were dispersed throughout the gel matrix.

[0107] Test Example 2

[0108] The present inventors further studied the rheological behaviors of the Gel group, MS / Gel group of Example 1, and Bup-Cel / Gel group of Comparative Example 1 using an HR-2 rheometer (WATERS). The temperature was set at 5 - 45 °C with a temperature increment of 1 °C / min. The premixed sample (2 mL) was added to a 60 mm parallel plate. The sample was allowed to stand for 5 minutes to restore its structure, and then an appropriate amount of silicone oil was added to the edge of the parallel plate to cover its surface and prevent gel dehydration. The changes in storage modulus (G′) and loss modulus (G″) with temperature were measured at 1% strain and 1 Hz frequency respectively, and the results are as Figures 9 - 11 shown. As the temperature increased, G′ gradually increased and exceeded G″ after a certain temperature, indicating a gel transition after heating. The transition temperatures of Gel, Bup-Cel / Gel, and MS / Gel were 26.8 °C, 23.4 °C, and 21.6 °C respectively.

[0109] Test Example 3

[0110] In vitro sustained-release performance test of electrostatic spray microspheres / hydrogel composites (MS / Gel)

[0111] 1. Chromatographic parameters and conditions

[0112] Using an Agilent ZORBAX-C18 (5 μm, 250 mm * 4.6 mm) chromatographic column, with phosphate buffer solution (0.015 mol / L NaH2PO4 solution (pH adjusted to 7.2 with 1 M NaOH)) as the mobile phase, the column temperature was 35 °C, the detection wavelengths were 215 nm for bupivacaine and 250 nm for celecoxib, the flow rate was 1.0 mL / min, and the injection volume was 10 μL.

[0113] 2. Determination of drug loading and encapsulation efficiency

[0114] The present inventors further determined the drug loading and encapsulation efficiency of the electrostatic spray microspheres of Example 1: 10 mg of microspheres were precisely weighed into a 50 mL volumetric flask, 2 mL of dichloromethane was added and sonicated for 30 min to disrupt the microsphere structure, the solvent was removed by nitrogen blowing, methanol was added to dissolve the precipitate, and then sonicated for another 30 min. The solution was filtered through a 0.22 μm filter membrane and analyzed by HPLC injection. The drug loading and encapsulation efficiency were calculated by the following formulas:

[0115] Drug loading (%) = weight of Bup or Cel in microsphere sample / total weight of microspheres × 100%

[0116] Encapsulation efficiency (%) = actual drug loading percentage / theoretical drug loading percentage (percentage of Bup or Cel in the total solid weight of raw materials) × 100%

[0117] Table 1 Drug loading rate and encapsulation efficiency of bupivacaine-celecoxib electrostatic spray microspheres

[0118]

[0119] 3. In vitro release experiment

[0120] The inventor further determined the in vitro release of the MS / Gel complex of Example 1

[0121] Using phosphate buffer solution at pH 7.4, which was added with 0.5% sodium dodecyl sulfate (SDS) as the dissolution medium

[0122] Accurately weigh the following four groups: Bup-Cel group (Bup 3 mg + Cel 3 mg); MS group (microspheres 9 mg), Bup-Cel / Gel group (Bup 3 mg + Cel 3 mg + 0.6 mL Gel), MS / Gel group (microspheres 9 mg + 0.6 mL Gel) into 50 mL centrifuge tubes, add 50 mL of dissolution medium, and perform constant temperature oscillation at 37.0 ± 0.5 °C and a rotation speed of 100 ± 1 r / min. Take 0.5 mL of samples at regular intervals, and at the same time supplement an equal volume of fresh medium. According to the "chromatographic parameters and conditions", inject the samples for determination, and calculate the cumulative drug release percentage according to the following formula, and draw the release curves of Bup and Cel in each group

[0123] Cumulative drug release rate (%) = mass of Bup or Cel released / actual content of Bup or Cel in the microspheres × 100%

[0124] Figures 12 - 13 The drug release curves of Bup, Cel, MS of Example 1, MS / Gel and Bup-Cel / Gel of Comparative Example 1 are as follows: It can be seen from the figure that the Bup raw material drug releases more than 62% within 4 hours, and the Cel raw material drug releases more than 51% within 4 hours; Bup in MS reaches the release plateau within 4 days, Bup in the Bup-Cel / Gel complex reaches the release plateau within 6 days, while Bup in MS / Gel can be slowly released for 10 days, and Cel in all experimental groups is slowly released, and the release amount in 10 days is much lower than that of the raw material drug, which may be related to the relatively strong liposolubility of celecoxib

[0125] Test Example 4

[0126] Based on the rat sciatic nerve block model, evaluate the in vivo nerve block effect of the electrosprayed microspheres / hydrogel complex (MS / Gel)

[0127] Rat sciatic nerve block model: The rats were anesthetized by inhalation of 2% isoflurane, placed on their sides, and kept with the femur perpendicular to the trunk. The ischial tuberosity and greater trochanter were identified by palpation. Subsequently, a 1.2-mm-diameter injection needle was inserted from the posteromedial side of the greater trochanter and advanced anteromedially. Once the needle touched the sciatic bone surface, it was withdrawn 1 mm backward, and then the drug was injected. There were 5 rats in each group, and the injection dose was 0.6 mL per rat. In this experimental example, the complex of Example 1 was used as the experimental group, and bupivacaine hydrochloride (0.5%) and liposomal bupivacaine were used as the control groups for the experiment.

[0128] Evaluation of drug block effect: Twenty-five male SD rats weighing 200 - 350 g were randomly divided into 5 groups (n = 5). 0.6 mL of drug was injected around the left sciatic nerve of each rat: ① Bupivacaine hydrochloride group (Bup HCl 0.5%); ② Liposomal bupivacaine group (Lip, Jiangsu Hengrui); ③ MS group (MS 60 mg + 0.6 mL normal saline); ④ Bup-Cel / Gel group (Bup 20 mg + Cel 20 mg + 0.6 mL Gel); ⑤ MS / Gel group (MS 60 mg + 0.6 mL Gel). A rat sciatic nerve block model was constructed, and mechanical pain sensitivity was evaluated by von Frey filaments before and after injection. Before each test, the rats were placed in a separate compartment on a metal mesh and allowed to acclimatize to the environment for 30 minutes. The mechanical paw withdrawal threshold (PWT) was determined by applying ascending forces (2 g, 4 g, 6 g, 8 g, 10 g, 15 g, 26 g, 60 g) to the von Frey filaments. A response was considered positive if the animal exhibited any adverse behavior during or immediately after removal of the filament, including rapid paw withdrawal, licking, or shaking of the paw. Five repeated stimuli were performed on each rat every 60 seconds. The thermal sensitivity of the hind paw was measured using the Hargreaves test. The rats were placed in a separate compartment on a glass platform and allowed to acclimatize to the environment for 30 minutes. A thermal stimulus was applied from the bottom to the middle of the plantar surface using a radiant heat source, and the latency of paw withdrawal or licking in response to the stimulus was recorded. Each rat was tested three times every 5 minutes. The maximum heating time was 30 seconds to prevent tissue damage. As shown in Table 2, compared with the Bup HCl group, the sciatic nerve block time of the rats in the MS / Gel complex injection group was the longest (mechanical pain 6 h vs 48 h, thermal pain 12 h vs 48 h). The results are as Figure 14 and 15 shown, indicating that the complex has good long-acting block and analgesic effects.

[0129] Table 2 Evaluation of the in vivo sciatic nerve block effect of the MS / Gel complex

[0130]

[0131] Experimental Example 5

[0132] In vivo biosafety of electrostatic spray microsphere / hydrogel complex (MS / Gel)

[0133] To further evaluate the degradability and safety of the drug-loaded material in vivo, this experimental example used the long-acting analgesic complex of Example 1 for the experiment. After perfusing the rats through the heart on the 7th and 21st days after injection, the nerve integrity at the injection site and the material degradation were observed. As Figure 16 shown, local anatomical observation showed that the sciatic nerves of all material groups remained intact without signs of sciatic nerve lesions. A small amount of white residue was observed in the Lip group on the 7th day and was completely degraded by the 21st day. Obvious white residues were observed in the MS group, Bup-Cel / Gel group, and MS / Gel group on the 7th day and were almost completely degraded by the 21st day. HE pathological staining also showed no obvious tissue damage or necrosis in all materials. As Figure 17 shown, indicating that the composite material has good biocompatibility and degradability.

[0134] All aspects, embodiments, features, and examples of the present invention should be considered illustrative in all respects and are not intended to limit the present invention. The scope of the present invention is only defined by the claims. Without departing from the spirit and scope of the claimed present invention, those skilled in the art will appreciate other embodiments, modifications, and uses.

[0135] In addition, the inventors of this case also referred to the foregoing embodiments and conducted experiments with other raw materials, process operations, and process conditions described in this specification, and all obtained relatively ideal results.

[0136] Although the present invention has been described with reference to illustrative embodiments, those skilled in the art will understand that various other changes, omissions, and / or additions can be made without departing from the spirit and scope of the present invention and that elements of the embodiments can be replaced with substantially equivalent ones. Additionally, many modifications can be made without departing from the scope of the present invention to adapt a particular situation or material to the teachings of the present invention. Therefore, the present invention is not intended to be limited to the specific embodiments disclosed for carrying out the present invention, but is intended to include all embodiments falling within the scope of the appended claims. Furthermore, unless specifically stated, any use of the terms first, second, etc. does not denote any order or importance, but the terms first, second, etc. are used to distinguish one element from another.

Claims

1. A method for preparing a long-acting analgesic complex, characterized in that, Comprising: Preparing drug-loaded microspheres by electrostatic spraying technology from a mixed solution containing a polymer, a local anesthetic, a non-steroidal anti-inflammatory drug, and a solvent; Dissolving poloxamer and a natural polymer material in water to obtain a hydrogel solution; Mixing the drug-loaded microspheres and the hydrogel solution evenly to prepare a long-acting analgesic complex.

2. The preparation method according to claim 1, wherein, Specifically comprising: Dissolving the polymer, the local anesthetic, and the non-steroidal anti-inflammatory drug in the solvent, stirring evenly to obtain a mixed solution, and then preparing the drug-loaded microspheres from the mixed solution by electrostatic spraying technology; And / or, the preparation method of the long-acting analgesic complex specifically further comprises: adding 60 - 80 mg of drug-loaded microspheres to every 0.6 mL of hydrogel solution, and vortex shaking for 2 - 4 h to prepare the long-acting analgesic complex.

3. The preparation method according to claim 2, characterized in that, The electrostatic spraying technology specifically comprises: transferring the mixed solution to a syringe, forming a spray-like jet under an electrostatic field, and collecting it by a collector to obtain the drug-loaded microspheres; wherein, the flow rate of the input mixed solution in the electrostatic spraying technology is 0.90 - 1.00 mL / h, the voltage is 9 - 11 kV, the ambient temperature is 15 - 30 °C, and the distance between the needle of the syringe and the collector is 10 - 15 cm.

4. The preparation method according to claim 1, characterized in that: The polymer comprises at least any one of poly(lactic-co-glycolic acid), polycaprolactone, polylactic acid, and polyhydroxybutyrate; And / or, the local anesthetic comprises bupivacaine; And / or, the non-steroidal anti-inflammatory drug comprises celecoxib; And / or, the solvent comprises dichloromethane; And / or, the mass ratio of the local anesthetic, the non-steroidal anti-inflammatory drug to the polymer is 1:1:1 - 2; And / or, the mass fraction of the polymer in the mixed solution is 10 - 18%.

5. The preparation method according to claim 1, characterized in that: The natural polymer material comprises any one or a combination of two or more of hyaluronic acid, chitosan, carboxymethyl chitosan, and sodium alginate; And / or, the poloxamer comprises poloxamer F127; And / or, the mass fraction of the poloxamer in the hydrogel solution is 18 - 25%, and the mass fraction of the natural polymer material in the hydrogel solution is 0.1 - 1%.

6. The long-acting analgesic complex prepared by the preparation method according to any one of claims 1-5, characterized in that: The long-acting analgesic complex comprises drug-loaded microspheres and a hydrogel. Both the long-acting analgesic complex and the hydrogel are three-dimensional porous network structures. The drug-loaded microspheres are evenly dispersed in the hydrogel, and the drug-loaded microspheres are solid spherical structures.

7. The long-acting analgesic complex according to claim 6, wherein: The drug-loaded microspheres are sustained-release micron particles; And / or, the drug-loaded microspheres comprise a polymer, a local anesthetic, and a non-steroidal anti-inflammatory drug; And / or, the diameter of the drug-loaded microspheres is 1 - 10 μm; And / or, the mass fraction of the drug-loaded microspheres in the long-acting analgesic complex is 10 - 13.3%; And / or, the hydrogel is a temperature-sensitive gel.

8. The long-acting analgesic complex according to claim 7, wherein: The polymer comprises poly(lactic-co-glycolic acid); And / or, the local anesthetic comprises bupivacaine, the non-steroidal anti-inflammatory drug comprises celecoxib, the mass fraction of bupivacaine is 3 - 4%, and the mass fraction of celecoxib is 3 - 4%.

9. Use of the long-acting analgesic complex according to any one of claims 6 - 8 in the preparation of an analgesic product.

10. A local anesthetic biomaterial preparation, characterized in that, Comprising the long-acting analgesic complex according to any one of claims 6 - 8.

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