CN116196266A - Local anesthetic low molecular weight gel, liposome and preparation method thereof - Google Patents

Abstract

The invention discloses local anesthetic low molecular weight gel, liposome and a preparation method thereof, wherein the local anesthetic low molecular weight gel comprises the following raw materials: local anesthetics, bile salts, aqueous solvents or buffers; the local anesthetic is selected from amide local anesthetics; the bile acid salt is at least one selected from sodium cholate, sodium deoxycholate, sodium chenodeoxycholate, sodium lithocholate, sodium ursodeoxycholate, sodium glycodeoxycholate, sodium taurocholate, sodium glycotaurocholate, sodium glycochenodeoxycholate, sodium phenylpropanecholate, sodium caseinate, sodium white cholate, cholic acid dimer, cholic acid side chain amino acid conjugate, cholic acid side chain PEG conjugate and cholic acid side chain glucose conjugate. The gel and liposome preparation process is simple and controllable, and the purpose of postoperative pain management can be achieved after one-time administration.

Description

Local anesthetic low molecular weight gel, liposome and preparation method thereof

Technical Field

The invention belongs to the field of pharmaceutical preparations, and relates to local anesthetic low-molecular-weight gel and liposome and a preparation method thereof.

Background

Although undesirable, pain is an unavoidable consequence of surgery. Up to 80% of surgical patients are reported to experience acute postoperative pain, and 30% of patients experience severe postoperative pain. Pain is most severe within the first 48 hours after surgery. The research shows that the high postoperative acute pain almost doubles the probability of the development of moderate chronic pain, increases the risk of heart and lung complications and is unfavorable for postoperative recovery. And due to prolonged hospital stay, unscheduled readmission, and the occurrence of subsequent chronic pain syndromes, poor postoperative pain control can lead to high medical costs and increased mortality, an event with significant clinical, social and economic impact. Post-operative pain management market research reports show that post-operative pain management market size is $ 315 billion in 2020, and is expected to reach $ 480 billion in 2028, growing from 2021 to 2028 at a compound annual growth rate of 5.4%.

Chronic pain is defined as any pain that persists for more than 6 months, and although international guidelines for pain recommend treatment, more than 60% of patients with chronic pain do not improve or respond poorly and often experience adverse effects. While the mechanism of chronic pain is complex, it may be challenging or impossible to determine the mechanism behind pain in clinical practice. Therefore, effective management of acute pain after surgery would be one of the best means to prevent chronic pain. Indeed, a single injection of peripheral nerve block lasting less than 1 day may reduce sustained post-mastectomy pain for 3 months and 12 months. Opioids have long been the gold standard for relief of acute postoperative pain, especially in moderate or severe pain. However, they are prone to tolerance, dependence and addiction, further causing significant adverse events including, but not limited to, respiratory and central nervous system depression, constipation, nausea and vomiting.

Opioid minimization strategies include the use of non-opioid anaesthesia, regional anaesthesia techniques, multi-modal non-opioid analgesics, non-drug interventions, etc. (e.g., early administration of physical therapy and needle sticks). Infiltration of the surgical site with Local Anesthetics (LA) is an important element of a multi-mode analgesic regimen. Although local anesthetics have excellent analgesic effects (much less systemic adverse effects than opioids), the duration of action after a single injection is relatively short, up to only 12 hours. If combined with various adjuvants (dexmedetomidine, clonidine, especially dexamethasone) it may be extended to 24 hours. This is due to the direct effect of the adjuvant on local vasoconstriction, on the peripheral nerves or the initiation of systemic anti-inflammatory processes. However, most adjuvants can only be used for an analgesic period of 0-12h, and at most (buprenorphine and dexamethasone) can only be used for less than 24h. The likelihood of adverse reactions increases with increasing administration of drugs, and many adjuvants may increase the incidence of side effects such as itching, nausea/vomiting, hypotension, bradycardia and sedation. Continuous peripheral nerve block is an important means to clinically extend the analgesic efficacy of local anesthetics, and compared to single injection local anesthetics, the pain relief capacity is comparable to epidural analgesia, but the hemodynamic stability is improved. Although the development of ultrasound guidance technology enables catheters to be accurately inserted into the nerve side, the problems of mechanical nerve stimulation, knotting, migration, blockage or shearing, liquid leakage or inflammation at the site of catheter insertion, bacterial colonization, infusion pump failure and the like associated with catheters are inevitably caused after exogenous catheters are inserted into human bodies.

Therefore, the local anesthetic sustained release preparation which can achieve the same analgesic efficacy as the epidural analgesia and the continuous infusion of the nerve conduit by one administration and reduce the fluctuation of the blood concentration is the focus of the current postoperative long-acting analgesic field. It not only reduces the side effects and poor patient compliance associated with invasive techniques such as catheters, dura mater puncture, but also greatly reduces the risk of local drug systemic toxicity by reducing the total dose and number of doses administered, taking a significant role in the control of post-operative acute pain, short but strong "burn" rebound pain with single resistance lag, and prevention of chronic pain longer post-operative. Several studies have been conducted at home and abroad to introduce long-term local anesthetic preparations such as liposomes, suspensions, clathrates, gels, injectable liquid polymers, polymer microparticles, and the like. Certain progress is made in analgesic efficacy, but microsphere burst is serious and muscle toxicity is high; the implant has poor biocompatibility and insufficient mechanical strength; hydrogel has weak encapsulation capability and slow degradation; and the nanoparticle dissolves out too quickly.

The long-acting local anesthetic preparations which are currently marketed in batches comprise bupivacaine polycystic chamber liposome Exparel for injection, collagen matrix Xaracoll containing bupivacaine for implantation, compound bupivacaine/meloxicam polymer solution Zynslef for instillation, sucrose acetate isobutyrate viscous solution Posimir containing bupivacaine for instillation. Exparel has been marketed for decades, but recent studies have emphasized that it can only partially demonstrate the prolongation of postoperative analgesic duration compared to conventional bupivacaine after a single administration. In addition, the Exparel has the defects of limited drug loading, strict temperature control and relatively short shelf life. Xaracoll, zynrelef, posimir on the market in the last two years has few indications in batches, no serious adverse reaction is reported yet, but the comprehensive curative effect and safety are yet to be explored: the Xaracoll implanted foreign body has strong sense and slow degradation; the adverse effects of nausea, vomiting and bruising of Posimir containing very high doses of bupivacaine (660 mg) are not quite small, and the organic solvent benzyl alcohol used in the method has low safety in nerve block and no significant advantage in analgesic effect; the Zynslef curative effect of double-effect anesthesia is optimal among the four, but the cost is high, and meanwhile, the safety of directly dripping meloxicam in the combined medicine into a wound is still to be checked.

Liposomes, which are one of the most widely studied drug carriers in the field of local anesthetics sustained release in recent years, have significant advantages over non-lipid carriers, such as biocompatibility, biodegradability, non-immunogenicity, and relatively low cost. At present, two local anesthetic liposomes in clinical stages exist in China: ropivacaine multivesicular liposomes LY09606 from green leaf pharmaceutical company are being developed in phase I clinical studies, and HR18034 ropivacaine liposomes for injection are being developed in phase ii clinical studies.

However, the following problems are encountered in the development of liposomes encapsulating local anesthetics, except for the inherent poor stability of liposomes, the burst release of drugs, and the like: firstly, local anesthetics have poor water solubility, local anesthetics hydrochloride hydrate is commonly used clinically, but the hydrochloride hydrate is not easy to carry medicine when preparing liposome, and secondly, the local anesthetics single-chamber liposome obtained by directly carrying the liposoluble local anesthetics is often provided with the problems of low medicine carrying amount and low encapsulation efficiency. This is disadvantageous for long-term analgesia on the one hand, and on the other hand, unencapsulated drugs may be at risk of toxicity, the removal of which would also present a cost-increasing problem. The prepared common local anesthetic liposome is difficult to achieve higher drug loading and expected sustained and controlled release effects. One common feature of liposome formulations that have been studied is that LA encapsulation is not as high as that obtained by other DDSs.

The production of expelel, which is already on the market, relies on a complex two-step double emulsification process and requires neutral lipids, which are generally costly. Chinese patent 202110046374.7 discloses a ropivacaine reservoir composition of grease-lecithin-local anesthetic-drug effect enhancer, wherein phospholipid in the composition can be stimulated by receptor liquid to complete self-assembly of liposome after local application, so that local anesthetic liposome with high drug loading capacity is obtained, and pain can be relieved in rats for two to three days. However, the formulation is relatively large in initial diffusion and release after administration, and the organic solvent benzyl alcohol therein is highly irritating after topical application. Chinese patent 202110964079.X discloses near infrared response liposome temperature-sensitive gel for encapsulating local anesthetics, overcomes the defect of insufficient slow release capability of simple liposome, realizes the problems of responsiveness and adjustable release, and achieves slow release for more than 3 days in vitro. The liposome is composed of DLPC, DSPC, eggPC and cholesterol, has an encapsulation rate of 94% on ropivacaine, but has smaller particle size (200 nm) which is unfavorable for slow release, and has low local anesthetic concentration (1 mg/mL) which is unfavorable for long-acting analgesia. Although the additionally introduced gel is beneficial to slow release, the quality index needed to be inspected in the process is more, and the mass production is not facilitated. Ion gradient liposomes providing higher encapsulation efficiency than conventional liposomes, patent US20150250724A1 discloses local anesthetic ion gradient liposomes having an aqueous phase in the inner region of the liposome (pH 6.5 citric acid solution/ammonium sulfate solution) lower than the pH of the external aqueous phase (pH 7.2 PBS), having an average particle diameter of not less than 1 μm and having 10 or more layers of membranes, and having an analgesic time of not less than 3 days after administration. However, the ion gradient liposome has complex process and difficult industrial production, and the stability is still to be further enhanced due to the low pH value of the internal water phase.

Therefore, there is still a need in the art of long-acting local anesthetic formulations to develop more formulations with good biocompatibility, controllable process and stable long-acting anesthetic effect to meet the diverse postoperative analgesic needs of patients.

Disclosure of Invention

The invention provides a low molecular weight hydrogel and liposome containing amide local anesthetics, which have simple and controllable preparation process and a preparation method thereof, and can achieve the purpose of postoperative pain management after one-time administration.

Local Anesthetics (LA) are weak bases, in solution in both charged and uncharged forms. The uncharged form of LA readily diffuses into neurons and then binds to the intracellular portions of voltage-gated sodium channels, thereby blocking the transmission of action potentials. Tissue acidosis typically occurs during inflammation due to injury, infection or surgery and is maintained for a longer period of time due to the presence of inflammatory factors, which reduces penetration of liposoluble LA into nerve cell membranes without utilizing maintenance of analgesic efficacy. The hydrochloride hydrate of the local anesthetic commonly used in clinic has good water solubility, so that the hydrochloride hydrate is easy to rapidly diffuse into blood circulation after local injection administration, and has short half-life.

Exogenous toxicity from crosslinkers, additives, initiators or byproducts, and low gel efficiency due to the use of light and radiation to initiate the crosslinking reaction are unavoidable challenges for many polymer gel applications. While low molecular weight natural substances as good alternatives to polymeric biomaterials have considerable advantages in terms of use in developing hydrogels for use in drug carrier systems. Low Molecular Weight Gels (LMWG) are formed from small molecules through various non-covalent interactions, which have the outstanding advantages of high biodegradability, high biocompatibility and the absence of toxic impurities due to the simplicity of the gelation process, compared to polymer gels. The amphiphilic small molecules forming the low molecular weight gel have the characteristics of accessibility, high purity, known chemical structure, biocompatibility of initial components and easy gelation. The tunable and reversible nature of the non-covalent interactions brings the performance of stimulus responsiveness and self-healing to low molecular weight gels. Various stimuli, such as pH, light, temperature, carbon dioxide, redox reactions, can induce changes in the microstructure and macroscopic properties of the hydrogels. The ease of chemical modification and reversible physical gelation allows the low molecular weight gel to be more readily decomposed or dissolved in body fluids than the polymer gel, thereby allowing the loaded drug to be released in a desired manner.

Natural Bile Acids (BAs) and Bile Salts (BSs) and derivatives thereof, which have high biocompatibility and safety, exhibit valuable gel-forming properties: bile acid salt and its side chain derivative sodium salt have a special bowl-shaped structure with one hydrophobic surface and the other hydrophilic surface, and can form nano fiber, nano band, nano tube and micelle through hydrogen bond and hydrophobic action under proper condition, and further crosslink to form gel and precipitate. BSs and derivatives thereof promote the absorption of paracellular and transcellular drugs by enlarging the tight junctions between cells and promoting the transport of liposoluble drugs in micellar form, have been widely used as absorption enhancers and to increase drug encapsulation.

The inventors have found that the use of a bile acid salt gel system for delivering local anesthetics has unexpected advantages: first bile acid salts are typical surfactants. Early studies by the inventors found that the use of high concentrations of surfactants at higher concentrations in hydrophobic LA greatly enhanced LA solubility through hydrophobic interactions and formation of aggregates such as micelles, consistent with the widely reported surfactants in the literature facilitating wetting of hydrophobic materials by reducing surface tension at the interface of dissolved drug particles. However, when the inventors controlled the concentration of the specific surfactant to be added at the Critical Micelle Concentration (CMC), the addition of the surfactant in the hydrophobic drug rather causes further decrease in the solubility of the drug, and is particularly shown by precipitation of fine crystals to form a suspension after adding a small amount of surfactant to the pharmaceutically acceptable salt solution of LA, which is greatly of interest to the inventors. The inventors believe that below CMC, a more hydrophobic complex is formed between the surfactant and the hydrophobic drug having an amino group due to non-covalent interactions such as electrostatic interactions, hydrophobic interactions, van der waals forces, pi-pi interactions, and the like. The formation of the hydrophobic complex increases the lipophilicity of LA, which significantly increases the ability of LA to penetrate the lipophilic membrane, which is advantageous for local anesthetics with reduced lipid solubility due to protonation in the acidic environment of the surgical site, which promotes its penetration into nerve cells and facilitates maintenance of analgesic efficacy.

Therefore, in the process of compounding bile acid salt with medicine and gradually gelling the bile acid salt under the action of hydrogen bond and hydrophobicity among molecules, on one hand, the hydrophobic domain of local anesthetics also participates in the construction of a gel system, and the gel skeleton and the medicine have the action of surfactant-LA complex, and on the other hand, free gel molecules and the local anesthetics form the surfactant-LA complex so as to increase the hydrophobicity and anchoring on the gel skeleton. The local anesthetic bile acid salt gel obtained by the method has very strong medicine-gel interaction inside, thereby having exceptional stability and slow release capability.

In summary, aiming at the defects existing in the field, the local anesthetic and the bile acid salt are compounded, meanwhile, the bile acid salt is initiated to form low molecular weight hydrogel, and the local anesthetic low molecular weight hydrogel of a slow release mechanism of gel skeleton drug release combined compound corrosion is obtained through a simple preparation process.

The technical scheme of the invention is as follows:

a local anesthetic low molecular weight hydrogel comprises the following raw materials: local anesthetics, bile salts, aqueous solvents or buffers;

the local anesthetic is selected from amide local anesthetics;

the bile acid salt is at least one selected from sodium cholate, sodium deoxycholate, sodium chenodeoxycholate, sodium lithocholate, sodium ursodeoxycholate, sodium glycodeoxycholate, sodium taurocholate, sodium glycotaurocholate, sodium glycochenodeoxycholate, sodium phenylpropanecholate, sodium caseinate, sodium white cholate, cholic acid dimer, cholic acid side chain amino acid conjugate, cholic acid side chain PEG conjugate and cholic acid side chain glucose conjugate.

The local anesthetic used in the invention can be a commercially pure product, and can also be prepared from pharmaceutically acceptable salts of the local anesthetic: adjusting pH of the local anesthetic medicinal salt water solution to be alkaline to separate out local anesthetic alkali, and then directly using the local anesthetic alkali in subsequent preparation or centrifuging and freeze-drying to obtain a sample for subsequent preparation.

Preferably, the local anesthetic is selected from at least one of ropivacaine, bupivacaine, lidocaine, levobupivacaine, mepivacaine, cinchocaine, pyrrole caine, etidocaine, prilocaine and pharmaceutically acceptable salts thereof.

Further preferably, the local anesthetic is ropivacaine or a pharmaceutically acceptable salt thereof.

The local anesthetic is preferably ropivacaine or a pharmaceutically acceptable salt thereof. Bupivacaine and ropivacaine are the most widely used local anesthetics in clinic. Ropivacaine is less fat-soluble than bupivacaine and therefore has a lower potency, but on the other hand also has a higher safety margin. In clinical practice, equal doses of ropivacaine exhibit approximately the same analgesic efficacy as bupivacaine and produce less motor block and exhibit significant sensory/motor block separation, thus ropivacaine is increasingly becoming a more preferred for clinical local analgesia.

Preferably, the bile acid salt is sodium deoxycholate. The process of deoxycholate sodium gel is simple and controllable, can be initiated by an acidic environment, and the obtained gel is composed of a hydrophobic effect and a hydrogen bond effect and has good drug release performance.

The aqueous solvent or buffer solution is at least one selected from water, hydrochloric acid with pH of 6.5, acid aqueous solution with pH of 6.5, histidine buffer with pH of 6.5, PBS buffer, tris-HCl buffer with pH of 6.5, physiological saline, 1wt% of sodium carboxymethyl cellulose solution and 1wt% of sodium hyaluronate solution.

The aqueous acid solution refers to the pH of water adjusted by organic acid such as formic acid, acetic acid, tartaric acid, succinic acid, etc., or the pH of water adjusted by amino acid such as glycine, alanine, aspartic acid, glutamic acid, etc.

In addition to functioning as a gel, bile salts need to form a hydrophobic complex with local anesthetics. Preferably, the molar ratio of bile acid salt to local anesthetic is 1.2-4.5:1, a step of; preferably 2-2.5:1, a step of; most preferably 2:1.

preferably, the local anesthetic low molecular weight gel also contains a gel modifier; the gel modifier is at least one of mannitol, sodium chloride, calcium chloride, glycine, alanine, aspartic acid, glutamic acid, alanine, graphene oxide and carbon nano-sheets.

The gel modifier has the function of making the local anesthetic low molecular weight gel have a stronger structure.

Preferably, the dosage of the gel modifier in the local anesthetic low molecular weight gel is 0.1-1wt%; further preferably 0.2 to 0.7wt%; most preferably 0.5wt%.

The invention also provides a preparation method of the local anesthetic low-molecular-weight hydrogel, which comprises the following steps:

mildly sonicating local anesthetics or pharmaceutically acceptable salts thereof, gel modifier and bile acid salt in an aqueous solvent for 10-30min, and then mildly stirring or incubating at 25 ℃ until phase equilibrium;

or, mildly and ultrasonically treating bile acid salt and a gel modifier in an aqueous solvent for 10-30min, and mildly stirring or incubating at 25 ℃ until blank gel is obtained; adding local anesthetic into the blank gel, mixing by probe ultrasound, and stirring gently for 8-15h.

Preferably, the ultrasonic power of the probe is 35%, the ultrasonic is carried out for 2 times, each time is 3min, and the interval between the two times of ultrasonic is 2min.

Preferably, the gentle ultrasound is performed at room temperature with a gentle ultrasound power of 100-200W; most preferably 100W.

Preferably, the gentle stirring is carried out at room temperature at a stirring speed of 200-400rpm; most preferably 300rpm.

In local anesthetics low molecular weight hydrogels, the local anesthetics are not simply free in the gel cavity, but rather participate in the construction of the bile acid salt gel by hydrophobic interactions and form hydrophobic complexes with the free bile acid salt molecules, which can be demonstrated by the following process: (1) Adding local anesthetics into the bile acid salt aqueous solution, and stirring gently overnight to obtain a bile acid salt-local anesthetics compound micro-nano suspension; (2) Adding alkali into the local anesthetic low molecular weight hydrogel to destroy the gel structure, thus obtaining a suspension similar to the suspension (the structure is highly similar under an electron microscope); (3) The local anesthetic low molecular weight gel has excellent stability, can be stably placed at room temperature for more than four months without obvious change, and a large amount of water can be separated out on the surface after the blank bile acid salt gel without the medicine is placed for several days.

In some embodiments, the local anesthetic low molecular weight gel exhibits analgesic efficacy for at least 12 hours. In some embodiments, the local anesthetic low molecular weight gel exhibits analgesic efficacy for 12-24 hours. In some embodiments, the local anesthetic low molecular weight gel exhibits analgesic efficacy for at least 24 hours. In some embodiments, the local anesthetic low molecular weight gel exhibits analgesic efficacy for one to two weeks.

The local anesthetic low molecular weight hydrogel has a stable structure, and the local anesthetic carried by the local anesthetic low molecular weight hydrogel forms a local anesthetic-bile acid salt compound. The enhanced hydrophobicity of the local anesthetic-bile acid salt complex enables the complex to diffuse into the liposome phospholipid bilayer more easily, thus realizing higher drug loading. The gel and the liposome are combined, so that the defects of sudden release and rapid elimination of metabolism of the liposome in a physiological environment can be overcome, the local drug concentration is increased, and the slow release of the drug is better controlled.

The inventor combines local anesthetic low molecular weight hydrogel with liposome initially, and is different from the traditional pharmacy means of embedding liposome into the prior gel, but uses liposome to wrap the gel containing the drug, thus obtaining unexpected drug release performance and supplementing the prior single-chamber local anesthetic sustained-release preparation field.

The invention provides a local anesthetic low-molecular-weight hydrogel liposome, which comprises the following raw materials: local anesthetics, bile salts, aqueous solvents or buffers, liposomes;

the local anesthetic is selected from amide local anesthetics;

the bile acid salt is at least one of sodium cholate, sodium deoxycholate, sodium chenodeoxycholate, sodium lithocholate, sodium ursodeoxycholate, sodium glycodeoxycholate, sodium taurocholate, sodium glycotaurocholate, sodium glycochenodeoxycholate, sodium phenylpropanecholate, sodium caseinate, sodium white cholate, cholic acid dimer, cholic acid side chain amino acid conjugate, cholic acid side chain PEG conjugate and cholic acid side chain glucose conjugate;

the liposome comprises phospholipid and cholesterol; in the liposome, the mole percentage of cholesterol is 10-80%;

the molar ratio of the phospholipid to the local anesthetic is 0.5-5:1.

preferably, the liposome has a mole percentage of cholesterol of 20-40%.

Preferably, the molar ratio of the phospholipid to the local anesthetic is 1-2:1.

the encapsulation rate of the liposome in the local anesthetic low molecular weight gel liposome to bile acid salt gel can not reach 100%. Preferably, in the local anesthetic low molecular weight gel liposome, the molar dosage ratio of bile acid salt to local anesthetic is 1-5.5:1, a step of; preferably 3.5-4.5:1, a step of; most preferably 4:1.

The phospholipid is one or more of phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylserine, phosphatidic acid and phosphatidylinositol. Including but not limited to lecithin, soybean lecithin, cephalin, sphingomyelin, dipalmitoyl phosphatidylcholine (DPPC), distearoyl phosphatidylcholine (DSPC), dimyristoyl phosphatidylcholine (DMPC), 1-palmitoyl-2-linoleoyl-sn-glycero-3-phosphatidylcholine (PLPC), dioleoyl phosphatidylcholine (DOPC), egg yolk phosphatidylcholine (EPC), sinigyl phosphatidylcholine (DEPC), dilauryl phosphatidylcholine (DLPC), 1, 2-didecanoyl-sn-glycero-3-phosphate choline (DDPC), hydrogenated Soybean Phosphatidylcholine (HSPC), l-myristoyl-2-palmitoyl phosphatidylcholine (MPPC) l-palmitoyl-2-myristoyl phosphatidylcholine (PMPC), l-palmitoyl-2-stearoyl phosphatidylcholine (PSPC), l-stearoyl-2-palmitoyl phosphatidylcholine (SPPC), dipalmitoyl phosphatidylinositol (DPPI), 1, 2-dioleoyl-sn-glycero-3-phosphatidylinositol (DOPI), 1, 2-dioleoyl-sn-glycero-3-phosphocholine (DLOPC), palmitoyl phosphatidylcholine (POPC), lysophosphatidylcholine, dioleoyl phosphatidylcholine, distearoyl phosphatidylethanolamine (DSPE), dimyristoyl phosphatidylethanolamine (DMPE), dipalmitoyl phosphatidylethanolamine (DPPE), di-oleoyl phosphatidylglycerol (DOPG), di-myristoyl phosphatidylglycerol (DPPG), 1-myristoyl-2-stearoyl-sn-glycero-3-phosphocholine (MSPC), 1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine (SOPC), 1-stearoyl-2-myristoyl-sn-glycero-3-phosphocholine (SMPC), distearoyl phosphatidylglycerol (DSPG), dipalmitoyl glycerophosphospherein (DPPG), dipalmitoyl phosphatidylserine (DPPS), 1, 2-dioleoyl-sn-glycero-3-phosphoserine (DOPS), dimyristoyl phosphatidylserine (DMPS), distearoyl phosphatidylserine (DSPS), dipalmitoyl phosphatidic acid (DPPA), 1, 2-dioleoyl-sn-glycero-3-phosphotides (DPPA), dimyristoyl phosphatidic acid (DMPA), distearoyl phosphatidylinositol (DSPA).

Preferably, the phospholipid is soybean lecithin.

The invention also provides a preparation method of the local anesthetic low-molecular-weight gel liposome, which comprises the following steps:

(a) Mildly and ultrasonically treating bile acid salt and a gel modifier in an aqueous solvent for 10-30min, and mildly stirring or incubating at 25 ℃ until blank gel is obtained;

(b) Dissolving the liposome in a volatile organic solvent, and spin-evaporating to obtain a lipid membrane;

(c) Hydrating the lipid membrane prepared in step (b) with the blank gel prepared in step (a), thereby obtaining blank liposome;

(d) The pH value of the blank liposome is adjusted to be neutral, and then the blank liposome is dialyzed for more than 8 hours in deionized water, and the dialysate is changed during the dialysis;

(f) Adding local anesthetic into the blank liposome after dialysis in the step (d), and carrying out active drug loading by probe ultrasound to obtain the local anesthetic low molecular weight gel liposome.

Preferably, the volatile organic solvent in step (b) is at least one selected from chloroform, dichloromethane, methanol, ethanol, diethyl ether and tert-butanol; chloroform is more preferable.

Preferably, step (c) comprises: mixing blank gel with lipid membrane, performing water bath ultrasound at a temperature higher than lipid phase transition temperature in the lipid membrane for 10-30min, and performing probe ultrasound with an ultrasonic cell pulverizer.

Preferably, the ultrasonic power of the probe is 35%, the ultrasonic is carried out for 2 times, each time is 3min, and the interval between the ultrasonic of the probe and the ultrasonic of the probe is 2min.

The dialysis in step (d) is to remove free bile acid salt hydrogel from the blank liposome solution.

The ultrasonic conditions of the probe for actively carrying the medicine in the step (f) are as follows: the power is 35%, the ultrasonic is carried out for 2 times, each time is 3min, and the interval between the ultrasonic probe and the ultrasonic probe is 2min.

The local anesthetic low molecular weight gel and liposome containing the same of the present invention may further comprise conventional excipients and pharmaceutically acceptable carriers disclosed in the art other than the above description, providing suitable pharmaceutical and pharmacological properties for postoperative analgesia in various forms and modes of administration. Any formulation with the local anesthetic low molecular weight gel as a core according to the present invention should be regarded as the scope of the present invention.

The local anesthetic low molecular weight gel and the liposome containing the same of the present invention are injectable and can be administered in various modes such as implantation, intramuscular administration, subcutaneous administration, etc., preferably subcutaneous injection infiltration anesthesia.

Compared with the prior art, the invention has the main advantages that:

(1) The local anesthetic low molecular weight gel and the liposome containing the same have simple and controllable preparation process and are easy for large-scale production.

(2) The auxiliary materials used for the local anesthetic low molecular weight gel and the liposome containing the local anesthetic low molecular weight gel are auxiliary materials with high safety and high biocompatibility, and can be directly injected for infiltration anesthesia locally.

(3) The local anesthetic low molecular weight gel and the liposome containing the same obviously improve the defect of short half-life period of local anesthetic aqueous solution, can be slowly released in vitro for more than 24 hours, and can reach the maximum analgesic time of two weeks in vivo.

(4) The local anesthetic low molecular weight gel and the liposome containing the same overcome the great inconvenience that the clinical local anesthetic aqueous solution needs to be administrated for multiple times, and can greatly improve the compliance of patients.

Drawings

FIG. 1 is a graph showing the particle size distribution of ropivacaine-sodium deoxycholate complex suspensions prepared in example 1;

FIG. 2 is an SEM image of a ropivacaine-sodium deoxycholate complex suspension prepared in example 1;

FIG. 3 is a gel structure diagram of ropivacaine-deoxycholate sodium prepared in example 3: a is gel appearance, B is an image under a gel optical microscope, C is an SEM image of gel, and D is an SEM image of gel lyophilized powder;

FIG. 4 is a graph showing the in vitro release results of ropivacaine-sodium deoxycholate gel prepared in example 3;

FIG. 5 shows ropivacaine-bile acid salt gel liposomes of example 5, prescription 19, 20, 21, 22, respectively, from left to right;

FIG. 6 shows ropivacaine-bile acid salt gel liposomes of example 5, prescription 27, 26, 25, respectively, from left to right;

FIG. 7 is a graph showing the particle size distribution of ropivacaine-sodium deoxycholate gel liposomes prepared in example 6;

FIG. 8 is a TEM image of ropivacaine-sodium deoxycholate gel liposomes prepared in example 6;

FIG. 9 is a graph showing the in vitro release results of ropivacaine-sodium deoxycholate gel liposomes prepared in example 6;

fig. 10 is a graph showing the results of in vivo analgesia experiments in mice of ropivacaine-deoxycholate sodium gel prepared in example 3: the left is mechanical pain analgesic efficacy, the right is thermal pain analgesic efficacy;

FIG. 11 is a graph showing the in vitro cytotoxicity results of ropivacaine-sodium deoxycholate gel prepared in example 3;

FIG. 12 is a graph showing the results of H & E staining of major organs and sciatic nerves after administration of ropivacaine-sodium deoxycholate gel prepared in example 3;

FIG. 13 is a graph showing the results of biochemical indicators of serum blood after administration of ropivacaine-sodium deoxycholate gel prepared in example 3.

Detailed Description

The invention will be further elucidated with reference to the drawings and to specific embodiments. It is to be understood that these examples are illustrative of the present invention and are not intended to limit the scope of the present invention. The experimental methods, in which specific conditions are not noted in the following examples, are generally conducted under conventional conditions or under conditions recommended by the manufacturer.

Terminology:

the term "mixing" refers to the process of uniformly distributing two or more components in a solution using stirring or heating means well known in the pharmaceutical arts.

The term "w/v" refers to the mass concentration expressed in g of solute dissolved in 100mL of water. 1% (w/v) means that the mass concentration of the solute is 1g/100mL.

The term "biocompatibility" is a property of living tissue to react to inactive materials, generally referred to as compatibility between the materials and the host, as defined by the international organization for standardization (International Standards Organization, ISO).

The term "release" refers to the rate and extent of release of a drug from a sustained or controlled release formulation in a defined solvent.

The term "particle size distribution" refers to the number of particles contained in a formulation solution over a range of different particle sizes as measured using a blue wave laser particle size analyzer.

EXAMPLE 1 preparation of ropivacaine-sodium deoxycholate hydrophobic Complex

453.2mg of sodium deoxycholate was weighed out and dissolved in 10mL of ultrapure water, followed by slow addition of 150mg of ropivacaine with continuous stirring, stirring overnight at 300rpm to complete the reaction.

Particle size and distribution of ropivacaine-sodium deoxycholate hydrophobic complex suspension solutions were examined using a blue wave laser particle size analyzer. The particle size distribution is shown in FIG. 1. The results show that the particle size of the ropivacaine-sodium deoxycholate hydrophobic complex is 3668nm and the PDI is 0.29. The larger particle size of the disclosed compound is beneficial to the slow release of local anesthetics. As shown in fig. 2, the structure of the complex was examined by Scanning Electron Microscopy (SEM), and as a result, the formation of ropivacaine-sodium deoxycholate complex was again verified.

EXAMPLE 2 preparation of ropivacaine-sodium deoxycholate gel

Table 1 ropivacaine-sodium deoxycholate gel formulation

Ropivacaine hydrochloride, a gel modifier and bile acid salt are mildly and ultrasonically treated in a solvent for 30min according to the dosage of the table 1, and then stirred at 300rpm for reaction overnight to prepare ropivacaine-deoxycholate sodium gel. Or firstly, the bile acid salt and the gel modifier are mildly and ultrasonically treated in a solvent for 30min, and the mixture is stirred and reacted at 300rpm for overnight until blank gel is obtained. And then ropivacaine is added, the probe is subjected to ultrasonic treatment (the power P=35%, ultrasonic treatment is carried out for 2 times, each time is carried out for 3 minutes, and the interval between the ultrasonic treatment and the ultrasonic treatment is 2 minutes), the mixture is uniformly mixed, and the mixture is stirred and reacted at 300rpm overnight to obtain the ropivacaine-deoxycholate sodium gel.

EXAMPLE 3 Structure of ropivacaine-deoxycholate sodium gel

According to prescription 2, 453.2mg of sodium deoxycholate is weighed and put into 5mL of 1% CMC-Na aqueous solution to be completely dissolved, and 180mg of ropivacaine hydrochloride monohydrate is weighed and put into 5mL of 1% CMC-Na aqueous solution to be completely dissolved, so that transparent solution is obtained. The two were mixed and sonicated in a gentle water bath for 30min, then stirred at 300rpm overnight to give a poorly flowing cream ropivacaine-deoxycholate sodium gel.

The gel structure was examined visually and by optical microscopy, and the structure of ropivacaine-deoxycholate sodium gel and its lyophilized powder was examined by Scanning Electron Microscopy (SEM), as shown in fig. 3, where a is the gel appearance, B is the image under the gel optical microscopy, C is the SEM image of the gel, D is the SEM image of the gel lyophilized powder. It is clear from B, C, D that the gel network is structured by irregular cross-linking of fibers. It can be seen from C, D that the long fibers forming the network skeleton have some particles irregularly dispersed in the network, namely ropivacaine-sodium deoxycholate complex. The size of ropivacaine-sodium deoxycholate complex in the gel is smaller than the size of the complex produced by direct reaction of Yu Luopai-card and sodium deoxycholate (see example 1), due to the participation of ropivacaine in building the gel matrix, thereby reducing the inter-aggregation between ropivacaine-sodium deoxycholate complexes.

Example 4 in vitro Release of ropivacaine-deoxycholate sodium gel

1mL of the ropivacaine-deoxycholate sodium gel prepared in example 3 was taken in a dialysis bag (MWCO: 8000-14000, MD44), and both ends of the dialysis bag were clamped by dialysis clamps, and placed in a beaker containing 150mL of release medium (PBS containing 0.2% Tween 20). The beaker was placed in a constant temperature gas bath at 37℃and 25rpm and 1mL was sampled at the predetermined time point while replenishing 1mL of fresh mobile phase. Ropivacaine concentration was measured by ultraviolet spectrophotometry and the release was calculated as shown in figure 4. The result shows that the ropivacaine-deoxycholate sodium gel has no burst release, can be released for more than 24 hours in vitro continuously, and then the medicine in the rest gel is released slowly.

EXAMPLE 5 preparation of ropivacaine-bile acid salt gel liposomes

Table 2 prescription and preparation of ropivacaine-bile acid salt gel liposomes

Ropivacaine-sodium deoxycholate gel liposomes were prepared according to the amounts prescribed in table 2. Sodium deoxycholate is added to an aqueous solvent or buffer. The solution was sonicated (power 100W) at room temperature for 30min and then reacted overnight with stirring at 300rpm to give a bile salt hydrogel. After the phospholipid and cholesterol were completely dissolved in chloroform, they were completely evaporated to dryness at 40℃using a rotary evaporator. The lipid membrane was gelled with bile salt water, sonicated in a water bath (200W of ultrasound power) at 40 ℃ for 30min, then sonicated with a probe (power p=35%, ultrasound 2 times for 3 min each, 2 min interval between the two) to empty liposomes. The blank liposome was adjusted to neutral pH and then dialyzed against deionized water for more than 8 hours, during which time the dialysate was changed. Finally, ropivacaine is added into the blank liposome solution after dialysis, and the probe is subjected to ultrasonic treatment (power P=35%, ultrasonic treatment for 2 times, each time for 3 minutes, and the interval between the two times is 2 minutes) for actively carrying medicine. The liposomes obtained from formulas 19-22 are shown in FIG. 5, and formulas 19, 20, 21, 22 are shown from left to right. The liposomes obtained from prescriptions 25-27 are shown in figure 6 as prescriptions 27, 26, 25 from left to right.

EXAMPLE 6 preparation of ropivacaine-sodium deoxycholate gel liposomes

Ropivacaine-sodium deoxycholate gel liposomes were prepared in the amounts prescribed in prescription 27 of example 5:

(1) 900mg of sodium deoxycholate is added into 10mL of hydrochloric acid solution with pH of 6.5, the solution is subjected to ultrasonic treatment (power is 100W) for 30min at room temperature, and stirred at 300rpm overnight to obtain sodium deoxycholate gel;

(2) 828.6mg lecithin and 211.3mg cholesterol were dissolved in chloroform, and the mixture was completely spin-dried at 40℃to form a film using a rotary evaporator;

(3) Hydrating the lipid membrane in (2) with the sodium deoxycholate gel in (1), performing water bath ultrasound (the ultrasound power is 200W) at 40 ℃ for 30min, and then performing probe ultrasound (the power P=35%, the ultrasound is performed for 2 times, 3 minutes each time, and 2 minutes are spaced between the two times) to obtain Bai Zhi plastids;

(4) Regulating the pH of the hollow white liposome in the step (3) to be neutral, and dialyzing in deionized water for more than 8 hours, wherein the dialysate is replaced;

(5) 150mg of ropivacaine is added to the blank liposome solution after dialysis in (4), and the probe is subjected to ultrasonic treatment (power P=35%, ultrasonic treatment is carried out for 2 times each for 3 minutes, and the interval between the two times is 2 minutes) for active drug loading.

Particle size and distribution of the liposome solution were examined using a blue wave laser particle size analyzer, as shown in fig. 7. The result shows that the particle size of the ropivacaine-deoxycholate sodium gel liposome is 1755nm and the PDI is 0.23. The structure of the gel liposome was examined by Transmission Electron Microscopy (TEM), as shown in fig. 8, and the result showed that the structure of a liposome-encapsulated black complex gel was formed, and the liposome size of the large vesicle was substantially consistent with the particle size measurement result.

Example 7 in vitro Release of ropivacaine-sodium deoxycholate gel liposomes

In vitro release of ropivacaine-sodium deoxycholate gel liposomes prepared in example 6 was examined in 150mL release medium by taking 1mL of ropivacaine-sodium deoxycholate gel liposome solution prepared in example 6 in dialysis bags as shown in fig. 9. The result shows that the ropivacaine-deoxycholate sodium gel liposome can be released for more than 24 hours in vitro.

Example 8 in vivo analgesic experiments in mice on ropivacaine-sodium deoxycholate gel

To further verify that the ropivacaine-sodium deoxycholate gel disclosed in the invention has a slow release effect, ropivacaine-sodium deoxycholate gel samples were prepared according to the protocol of prescription 2 (example 3, analgesic tests were performed using Von Frey method and hot plate method.

The experimental scheme is as follows: pharmacodynamics evaluation is carried out through a sciatic nerve blocking model, namely, 0.2mL local anesthetic gel solution is injected into the peripheral muscle of the nerve of an animal, and the conduction of action potential and nerve impulse is blocked, so that obvious anesthesia and analgesia effects are generated in the nerve control area.

(1) Baseline pain values for C57BL/6 mice were measured daily three days prior to molding: the Von Frey mice were tested for 50% foot-shrinking threshold and for analgesia by hot plate. Animals with abnormal pain threshold were removed. The 6 male mice were randomly divided into 2 groups, i.e., control group: 7.5mg/mL ropivacaine hydrochloride injection group and test sample group: ropivacaine-deoxycholate sodium gel group. The day before the experiment was shaved on the outside of the right leg of the mice for the next day of the experiment.

(2) A1.25% solution of tribromoethanol was prepared with isopropanol and physiological saline and passed through a 0.22 μm membrane, and the mice were briefly anesthetized by intraperitoneal injection at a dose of 150 mg/kg. After the mice became calm and the eversion was not apparent, the limbs were fixed in a prone position with medical PE tape (care was taken to have the right plantar surface facing upwards). The skin at the femur of the right thigh was gently cut longitudinally, and then the biceps femoris was blunt dissected using hemostat to expose the sciatic nerve. Under direct vision, 0.2mL of local anesthetic solution was injected in parallel into the sciatic nerve roots or muscles surrounding the sciatic nerve, and the skin was then sutured with absorbable sutures. After injection, sensory nerve block tests, von Frey and hotplate, were performed on each group of mice at pre-set time points. The hot plate test should be repeated three times.

(3) Von Frey and hotplate procedures:

von Frey method: mice were placed on a 0.5cm x 0.5cm metal mesh basket and their field of activity was limited with a beaker. After the mice were acclimatized for 10min, von frey filaments (scale of force 0.02, 0.04, 0.07, 0.16, 0.4, 0.6, 1.0, 1.4, 2.0 g) were stimulated vertically from 0.02g scale to right midplantar skin, the filaments were pressurized to "S" or "C" shape for a minimum of 3S after contact with the sole, and the longest stimulation time should not exceed 8S until the mice lifted their feet or escaped, observing their right foot responses. The footshrink or licking was noted as positive response ("X"), and the no footshrink licking or unobvious was noted as negative response ("O"). If the first fiber is in negative reaction after stimulation, the next-stage scale fiber is used for stimulation; and vice versa, fiber filament stimulation is performed using the upper scale. The negative response in which the turn occurs (i.e., the first transition from negative to positive) is recorded as the starting point, and then measured 4 times in succession, adjacent stimuli should be spaced at intervals of not less than 1min. The test should be stopped when a negative response is also obtained from 2.0g of fiber stimulation, and the following PWT value is directly recorded as 4.0g, in order to avoid puncturing the tissues of the mouse foot under anesthetic effect. The resulting "OX" sequence for 5 stimulations and the strength (f) of the filaments for 5 stimulations were recorded and the mechanical paw withdrawal threshold (i.e. 50% mechanical paw withdrawal response stimulation strength, paw withdrawal threshold, PWT) was calculated according to equation 1-1.

Where f is the scale value of the last applied Von Frey filament, xf represents the intensity of the last stimulus, xf=lg (f×10000). The k value, provided by the Dixon statistics, is a constant related to the pain pattern, i.e. the OX sequence. Delta is the average difference in logarithmic units for the scale of 5 stimuli.

Hot plate method: the mice were gently placed on a thermostatically heated platform at 55 ℃ at room temperature, timing was started, and the mice were observed for reactions. Licking foot or obvious foot shrinkage is generally considered as positive reaction, otherwise negative reaction. Once a positive response occurred, the timing was stopped immediately and the mice were removed from the hotplate and the thermal latency time was recorded. The same mice were repeated three times with at least 3 minutes between each hot plate test, and the average of the three results represents the mice' thermal latency. If the hot plate is withdrawn without positive reaction for 30s, the skin of the sole of the mouse is prevented from being scalded under the anesthesia condition, and the thermal latency period of the mouse is recorded as 30s. Mice were analyzed for thermal pain hypersensitivity or analgesia using the maximum ratio effect (MPE) and their calculation formulas are shown in 1-2:

where a is the average thermal latency of the mice at the time point of detection, B is the basal thermal latency of the mice, i.e. the baseline level of pain before dosing, C represents the longest thermal latency allowed (30 s in this disclosure). The effective sensory block time (effective analgesic time) is the duration of time from administration to 50% recovery of MPE.

The in vivo analgesic results of ropivacaine-sodium deoxycholate gel mice are shown in figure 10. The results show that ropivacaine-sodium deoxycholate gel can achieve significant mechanical pain analgesic efficacy above 10d and significant thermal pain analgesic efficacy above 13d in sciatica block.

Example 9 in vitro cytotoxicity of ropivacaine-sodium deoxycholate gel

The cytotoxicity of the ropivacaine-deoxycholate sodium gel prepared in example 3 was evaluated using the CCK-8 method.

To assess neurotoxicity, rat adrenal pheochromocytoma cells (PC 12 cells) were cultured. The cell line is a powerful cell line and has been widely used in neuroscience research. To assess general toxicity, mouse mononuclear macrophages (RAW 264.7 cells) were cultured. The cell line is a normal immune cell, is sensitive to stimulation, and plays a key role in the relief of inflammatory pain. PC12 cells were supplemented with 10% HS, 5% FBS, 1% penicillin-streptomycinStock RPMI-1640 cell culture medium, RAW264.7 cells were cultured in DMEM 1X medium supplemented with 10% FBS, and both were cultured in a humidified incubator at constant temperature of 5% CO2 and 37 ℃. Cytotoxicity assessment was performed on gel formulations and ropivacaine hydrochloride solutions using a conventional cell counting kit-8 assay (CCK-8 method). When the cell growth state is good and the cell proliferation is carried out to a certain number, PC12 cells and RAW264.7 cells are inoculated into a 96-well plate according to the density of 1 multiplied by 104 cells per well, the cell culture solution per well is always controlled at 100 mu L, and the temperature is constant at 37 ℃ and the concentration of CO is 5% ₂ After 24h incubation in the environment, the medium was discarded and 100. Mu.L of gel preparation solutions and ropivacaine hydrochloride solutions (RVC final concentrations 1, 5, 10, 20, 50, 100. Mu.M) of different concentrations prepared with medium were added to each well. After incubation for 24, 48, 72h, the medium was discarded, and after incubation for 1-3h with 9% (v/v) CCK-8 in 100. Mu.L medium, absorbance at 450nm was measured with an ELISA reader. Cell viability = (TE-BK)/(NC-BK) ×100%, TE (test) is experimental group, NC (normal control) is control group, BK (blank) is blank group.

The cytotoxicity results are shown in FIG. 11. After 24, 48 and 72 hours of culture with ropivacaine hydrochloride or gel preparation, the survival rate of RAW264.7 cells is not obviously reduced, and even the survival rate of cells is increased with time to be more than 100 percent, which shows that the ropivacaine hydrochloride and the gel preparation have good biocompatibility. For PC12 cells, which are neuron-like cells, reflecting the safety of local anesthetics when applied to nerve cells, it can be seen in FIG. 11 that the formulation group showed higher cell viability than the ropivacaine hydrochloride-treated group within 3 days, almost all PC12 cells in the formulation group survived over 100%, while almost all ropivacaine hydrochloride-treated cells survived under 100%. This demonstrates that immediate administration of ropivacaine would be more pronounced neurotoxic and at the same time demonstrates that the gel formulation possesses higher neuroprotection.

EXAMPLE 10 biocompatibility of ropivacaine-sodium deoxycholate gel

Histopathological and blood biochemical levels of ropivacaine-deoxycholate sodium gel prepared in example 3 were evaluated after administration.

Histological evaluation was performed 4 days and 14 days after dosing, both time points representing the level of acute and chronic inflammation. Sciatic nerves and surrounding musculature, as well as major organs (heart, liver, spleen, lung and kidney) were dissected and collected on days 4 and 14 post-dosing. All tissue samples were fixed in 4% buffered paraformaldehyde for more than 24H, then paraffin embedded sections, stained with hematoxylin and eosin (H & E), and observed for tissue damage or inflammatory response. The sciatic nerve containing the surrounding muscles should be transected to visualize the cross section. The final results are shown in FIG. 12. In the H & E results, it can be seen that individual tissues of the sample group also have a slight inflammatory infiltrate. And compared with normal saline, the hydrogel preparation and 0.75% ropivacaine hydrochloride can not aggravate the inflammatory reaction of main organs and sciatic nerves on the basis of the existing inflammation, and reflect the good biocompatibility of the gel preparation.

Prior to the histological collection, the blood of the mice was collected through the orbital vein, and after standing at room temperature for 3 hours, the serum was collected by centrifugation at 4,000rpm for 10min, and if the serum was cloudy, it was centrifuged twice. Lactate Dehydrogenase (LDH), urea nitrogen (BUN) and alkaline phosphatase (ALP) levels were analyzed by a biochemical analyzer. LDH may reflect cardiotoxicity, BUN may reflect renal toxicity, and ALP may reflect hepatotoxicity. The final results are shown in FIG. 13. Ropivacaine, when injected or overdosed by an unexpected intravascular, blocks the myocardial cell membrane NaV channels on a large scale, destroys its structure and releases myocardial enzymes, resulting in an increase in LDH. While ALP and BUN can reflect abnormality of liver and kidney functions, respectively. Of the three criteria LDH, ALP, BUN, at day 4 post-administration, both the formulation and ropivacaine hydrochloride showed smaller values than the saline group, although the results were not significant. On day 14 post-dose, the formulation treated mice all showed smaller ALP, BUN levels than the saline group, while LDH levels were similar to the saline group and below day 4. These results all demonstrate that the formulation has good biocompatibility and safety.

The foregoing embodiments have described the technical solutions and advantages of the present invention in detail, and it should be understood that the foregoing embodiments are merely illustrative of the present invention and are not intended to limit the invention, and any modifications, additions, substitutions and the like that fall within the principles of the present invention should be included in the scope of the invention.

Claims (10)

1. The local anesthetic low molecular weight hydrogel is characterized by comprising the following raw materials: local anesthetics, bile salts, aqueous solvents or buffers;

the local anesthetic is selected from amide local anesthetics;

the bile acid salt is at least one selected from sodium cholate, sodium deoxycholate, sodium chenodeoxycholate, sodium lithocholate, sodium ursodeoxycholate, sodium glycodeoxycholate, sodium taurocholate, sodium glycotaurocholate, sodium glycochenodeoxycholate, sodium phenylpropanecholate, sodium caseinate, sodium white cholate, cholic acid dimer, cholic acid side chain amino acid conjugate, cholic acid side chain PEG conjugate and cholic acid side chain glucose conjugate.

2. The local anesthetic low molecular weight hydrogel of claim 1, wherein the local anesthetic is selected from at least one of ropivacaine, bupivacaine, lidocaine, levobupivacaine, mepivacaine, cinchocaine, pyrrole caine, etidocaine, prilocaine, and pharmaceutically acceptable salts thereof.

3. The local anesthetic low molecular weight hydrogel of claim 1, wherein the molar ratio of bile acid salt to local anesthetic is 1.2-4.5:1.

4. the local anesthetic low molecular weight hydrogel of claim 1, further comprising a gel modifier; the gel modifier is at least one of mannitol, sodium chloride, calcium chloride, glycine, alanine, aspartic acid, glutamic acid, alanine, graphene oxide and carbon nano-sheets.

5. The local anesthetic low molecular weight hydrogel of claim 1, wherein the gel modifier is present in the local anesthetic low molecular weight gel in an amount of 0.1 to 1wt%.

6. A method of preparing a local anesthetic low molecular weight hydrogel as set forth in any one of claims 1 to 5, comprising:

mildly sonicating local anesthetics or pharmaceutically acceptable salts thereof, gel modifier and bile acid salt in an aqueous solvent for 10-30min, and then mildly stirring or incubating at 25 ℃ until phase equilibrium;

or, mildly and ultrasonically treating bile acid salt and a gel modifier in an aqueous solvent for 10-30min, and mildly stirring or incubating at 25 ℃ until blank gel is obtained; adding local anesthetic into the blank gel, mixing by probe ultrasound, and stirring gently for 8-15h.

7. The local anesthetic low-molecular-weight hydrogel liposome is characterized by comprising the following raw materials: local anesthetics, bile salts, aqueous solvents or buffers, liposomes;

the local anesthetic is selected from amide local anesthetics;

the bile acid salt is at least one of sodium cholate, sodium deoxycholate, sodium chenodeoxycholate, sodium lithocholate, sodium ursodeoxycholate, sodium glycodeoxycholate, sodium taurocholate, sodium glycotaurocholate, sodium glycochenodeoxycholate, sodium phenylpropanecholate, sodium caseinate, sodium white cholate, cholic acid dimer, cholic acid side chain amino acid conjugate, cholic acid side chain PEG conjugate and cholic acid side chain glucose conjugate;

the liposome comprises phospholipid and cholesterol; in the liposome, the mole percentage of cholesterol is 10-80%;

the molar ratio of the phospholipid to the local anesthetic is 0.5-5:1.

8. the local anesthetic low molecular weight hydrogel liposome according to claim 7, wherein the mole percent of cholesterol in said liposome is 20-40%; the molar dosage ratio of the phospholipid to the local anesthetic is 1-2:1.

9. the local anesthetic low molecular weight hydrogel liposome according to claim 7, wherein the molar ratio of bile acid salt to local anesthetic is 1-5.5:1.

10. A method of preparing a local anesthetic low molecular weight hydrogel liposome as set forth in any one of claims 7 to 9, comprising:

(a) Mildly and ultrasonically treating bile acid salt and a gel modifier in an aqueous solvent for 10-30min, and mildly stirring or incubating at 25 ℃ until blank gel is obtained; the method comprises the steps of carrying out a first treatment on the surface of the

(b) Dissolving the liposome in a volatile organic solvent, and spin-evaporating to obtain a lipid membrane;

(c) Hydrating the lipid membrane prepared in step (b) with the blank gel prepared in step (a), thereby obtaining blank liposome;

(d) The pH value of the blank liposome is adjusted to be neutral, and then the blank liposome is dialyzed for more than 8 hours in deionized water, and the dialysate is changed during the dialysis;

(f) Adding local anesthetic into the blank liposome after dialysis in the step (d), and carrying out active drug loading by probe ultrasound to obtain the local anesthetic low molecular weight gel liposome.

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