Lidocaine multivesicular liposome as well as preparation method and application thereof

Abstract

The invention relates to lidocaine multivesicular liposome as well as a preparation method and application thereof, belongs to the field of medicines, and solves at least one of the problems of higher toxicity, insufficient safety, short action time, limited clinical application range, higher cost and the like of the existing postoperative analgesic medicine. The lidocaine multi-vesicular liposome is prepared from lidocaine and a lipid, wherein the lidocaine and the lipid are added into the lidocaine multi-vesicular liposome; the lipid comprises amphiphilic lipid, negatively charged phospholipid, neutral lipid and cholesterol. The lidocaine multi-vesicular liposome prepared by the preparation method is high in safety, solves the problems of systemic toxicity, neurotoxicity, cardiotoxicity and the like of the existing postoperative analgesic drugs, has the characteristics of long-acting slow release, remarkable analgesic effect and wide clinical application range, and is suitable for clinical application. And a new solution is provided for effectively relieving postoperative pain.

Description

Technical Field

[0001] The present invention relates to the field of medicine, and particularly to a lidocaine multi-lamellar liposome and its preparation method and application. Background Art

[0002] Postoperative pain is a global health problem. There are approximately 300 million surgical operations performed globally each year. In China, the annual number of surgeries is close to 70 million. The results of multi-center studies from China show that among the entire surgical population, 48.7% of patients report moderate or severe acute pain after surgery, and 32.3% of patients report severe acute pain. Poorly managed acute pain not only increases patient discomfort but may also lead to a series of complications, prolong hospital stays, reduce the quality of life of patients, and increase the risk of patients developing chronic pain. Therefore, providing adequate postoperative acute pain management is crucial.

[0003] The existing methods for postoperative analgesia mainly include subcutaneous, intramuscular, intravenous injection of analgesics or oral analgesics, but these methods have problems such as short action time and imperfect analgesic effect. In order to extend the action time of analgesics, the current clinical practice usually uses an analgesic pump after surgery. The intravenous analgesic pump requires a venous access for systemic drug administration, and the main analgesic drugs are opioid drugs, but there are risks of adverse reactions such as respiratory depression, nausea and vomiting, and constipation. In particular, respiratory depression may endanger the life of the patient. Especially for patients undergoing abdominal surgery, they may also face problems such as visceral pain and delayed recovery of postoperative gastrointestinal function, and intravenous administration of opioid analgesic drugs cannot solve the above problems. The epidural analgesic pump continuously pumps analgesics into the patient's spinal canal through a catheter, but there are many limitations. For example, there are risks such as spinal hematoma, catheter kinking, and detachment. At the same time, the epidural analgesic pump has high requirements for operating techniques, and there are relatively high risks for patients with severe cardio-pulmonary-liver-kidney dysfunction or those with a bleeding tendency or coagulation dysfunction. Local administration of local anesthetics is also one of the analgesic methods, but due to the short action time of existing local anesthetics, increased dosing is likely to result in systemic toxicity, neurotoxicity, or circulatory toxicity, etc. It can only be achieved by continuously pumping a small amount of drug through a porous catheter placed in the patient's body cavity (such as the abdominal cavity, etc.), around the nerve, or subcutaneously. However, due to the small drug loading capacity, a large amount of liquid is often required, which is difficult to implement clinically. Research shows that intraperitoneal administration of local anesthetics can not only relieve postoperative visceral pain in patients undergoing abdominal surgery but also reduce the patient's inflammatory response and promote the recovery of gastrointestinal function. However, there is currently no safe local anesthetic sustained-release preparation suitable for the patient's abdominal cavity.

[0004] Therefore, developing a safe, effective, long-acting and sustained-release postoperative analgesic drug with a wider clinical application range and greater economy is of great significance for improving postoperative acute pain management. Summary of the Invention

[0005] In view of the above analysis, the present invention aims to provide a lidocaine multi-lamellar liposome, its preparation method and application, and provides a new solution for solving at least one of the problems existing in existing postoperative analgesic drugs, such as relatively high toxicity, insufficient safety, short action time, limited clinical application range, high cost, etc.

[0006] The object of the present invention is achieved by the following technical solutions: The present invention provides a lidocaine multi-lamellar liposome, which contains lidocaine and lipids; the lipids include amphiphilic lipids, negatively charged phospholipids, neutral lipids and cholesterol.

[0007] Furthermore, the mass ratio of the lipids to the lidocaine is 0.75 - 1.10; and / or, Among the lipids, the mass percentage content of the amphiphilic lipids is 30 - 70%, the mass percentage content of the negatively charged phospholipids is 3.5 - 11%, the mass percentage content of the neutral lipids is 7 - 20%, and the mass percentage content of the cholesterol is 18 - 46%.

[0008] Furthermore, the lidocaine multi-lamellar liposome contains lidocaine and blank multi-lamellar liposomes; The blank multi-lamellar liposome is composed of a lipid bilayer formed by the lipids. The blank multi-lamellar liposome contains multiple aqueous compartments inside, and the aqueous compartments are separated by the lipid bilayer; wherein, the lidocaine is located between the lipid bilayers and / or inside the aqueous compartments.

[0009] Furthermore, in the lidocaine multi-lamellar liposome, the encapsulation efficiency of the lidocaine is 90.0% - 98.2%.

[0010] Furthermore, the D 50 of the lidocaine multi-lamellar liposome is 22 - 30 μm, the D 90 is 45 - 60 μm, the D 10 is 10 - 15 μm, and the SPAN is 1.0 - 2.0; and / or, The Zeta potential of the lidocaine multi-lamellar liposome is ±10 mV to ±60 mV.

[0011] Furthermore, the sustained release period of the lidocaine multi-lamellar liposome reaches 24 - 72 h.

[0012] Furthermore, the lidocaine includes lidocaine base and / or a salt form of lidocaine, wherein the salt form of lidocaine includes at least one of lidocaine hydrochloride, lidocaine bisulfate, lidocaine mesylate, lidocaine lactate, and lidocaine phosphate.

[0013] Furthermore, the preparation of the stock solution of lidocaine multi-lamellar liposomes is achieved by successively adding an oil phase including lidocaine, amphiphilic lipids, negatively charged phospholipids, cholesterol, neutral lipids, and an organic solvent to a first aqueous phase and a second aqueous phase to form a W / O / W type second emulsion, followed by removing the organic solvent, concentrating the dilute liposome solution to obtain a liposome suspension, and replacing the liquid medium of the suspension with a third aqueous phase.

[0014] The present invention provides a method for preparing lidocaine multi-lamellar liposomes for preparing the lidocaine multi-lamellar liposomes as described above; the preparation method includes the following steps: (1) Preparation of the oil phase: Mix lidocaine base, amphiphilic lipids, negatively charged phospholipids, cholesterol, neutral lipids, and an organic solvent to obtain the oil phase; (2) Preparation of the first aqueous phase: Mix an acidifying agent and water to obtain the first aqueous phase; (3) Preparation of the second aqueous phase: Mix a pH regulator and an osmotic pressure regulator with water to obtain the second aqueous phase; (4) Preparation of the third aqueous phase: Mix an osmotic pressure regulator with water to obtain the third aqueous phase; (5) Add the first aqueous phase to the oil phase and form a W / O type first emulsion through high-shear emulsification; (6) Add the second aqueous phase to the W / O type first emulsion and form a W / O / W type second emulsion through shearing; (7) Remove the organic solvent in the W / O / W type second emulsion to obtain a dilute liposome solution; (8) Concentrate the dilute liposome solution to a target concentration to obtain a liposome suspension; replace the liquid medium in the liposome suspension with a third aqueous phase to obtain the stock solution of lidocaine multi-lamellar liposomes.

[0015] The present invention provides the application of the above-mentioned lidocaine multi-lamellar liposomes and the lidocaine multi-lamellar liposomes obtained by the above-mentioned preparation method in the preparation of safe, long-acting, and low-toxic sustained-release analgesic drugs, and the administration method of the sustained-release analgesic drugs includes coelomic injection.

[0016] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects: Lidocaine has always been used as a short-acting analgesic drug in clinical local analgesia. However, different from the previous short-acting lidocaine preparations, the present invention first proposes to combine lidocaine with multi-lamellar liposomes, and through specific innovative preparation processes, develop lidocaine multi-lamellar liposomes. The lidocaine multi-lamellar liposomes of the present invention have good stability, high drug encapsulation efficiency, large drug loading capacity, good in vitro sustained-release effect, and no burst release phenomenon; under systemic administration, the potential toxicity of the drug is reduced, and the safety of the drug is greatly improved; compared with the existing injection solution, the present invention has significantly improved in terms of maintaining blood drug concentration, drug residence time, and analgesic effect. The lidocaine multi-lamellar liposomes prepared by the present invention can effectively achieve the effects of in vivo sustained release and long-acting analgesia, while expanding the drug application scenarios, and provide a new solution for solving at least one of the problems existing in the existing postoperative analgesic drugs, such as high toxicity, insufficient safety, short action time, limited clinical application scope, and high cost, and has great clinical application value.

[0017] (1) When lidocaine is used as a classic local anesthetic for postoperative analgesia, due to its pharmacokinetic characteristics, there are significant clinical limitations: the conventional dosage form has a short elimination half-life (1.5 - 2 hours), and the effective analgesia only lasts for 4 - 6 hours after a single dose, making it difficult to cover the high-incidence pain window period of 24 hours after surgery. Traditional solutions rely on repeated injections or continuous infusion devices, but frequent drug administration easily leads to fluctuations in blood drug concentration, and there are risks such as myocardial depression and neurotoxicity, which are particularly dangerous for patients with combined cardiovascular diseases or liver function disorders. Through dosage form improvement, the present invention breakthroughly adopts the multi-lamellar liposome delivery technology, and realizes the stepwise release of the drug by constructing a multi-compartment vesicle structure (the outer liposome rapidly releases to achieve immediate analgesia, and the inner core reservoir continuously releases to maintain the effective blood drug concentration), effectively achieving the in vivo and in vitro sustained release of the drug, prolonging the residence time of the drug in the body, and achieving an analgesic effect of up to 24 hours under a single injection, providing a safe and effective new analgesic drug.

[0018] (2) Compared with the current postoperative analgesia mode dominated by opioid drugs, the present invention achieves a breakthrough improvement through a dual safety mechanism: First, an innovation is made in the composition, using lidocaine as the active drug ingredient to replace traditional opioid drugs, avoiding the common toxic and side effects of opioid drugs, such as gastrointestinal adverse reactions such as nausea and vomiting, respiratory depression, and drug dependence, and providing a new analgesic option for people who are not suitable for using opioid drugs; in addition, by using multi-lamellar liposomes as carriers, the present invention reconstructs the pharmacokinetic curve of lidocaine, realizes the long-acting and stable sustained release of lidocaine in vivo, reduces its systemic toxicity as an amide local anesthetic, and effectively improves the safety of lidocaine as an amide local anesthetic, with great clinical application value.

[0019] (3) The currently commonly used postoperative analgesia mode with an analgesic pump as the carrier can provide continuous and stable analgesic effects for patients by continuously injecting analgesic drugs after surgery. However, there are still many limitations in actual clinical applications: Firstly, the application cost of the analgesic pump is relatively high, increasing the medical cost of patients. Secondly, to ensure the stability of the drug delivery channel and prevent catheter detachment, the implantation and maintenance processes of the device require high operating skills of medical staff, and close monitoring by an experienced nursing team is required after surgery. In addition, patients may be restricted by the device during activities, affecting the postoperative rehabilitation process. The lidocaine multi-lamellar liposome preparation in the present invention achieves long-acting analgesia covering 24 hours after surgery without relying on complex equipment for drug delivery. Its clinical operation is simpler and more operable, reducing the high requirements for the operating skills of medical staff. The postoperative nursing process is also simpler, reducing the medical cost and improving the comfort and compliance of patients. In addition, the present invention combines the latest discoveries in the field of anesthesia and analgesia, and innovates the formulation and preparation process of the drug preparation to achieve innovation in the drug delivery method of lidocaine during application. For example, the lidocaine multi-lamellar liposomes of the present invention can be administered intraperitoneally. In this mode, it can effectively relieve visceral pain after abdominal surgery, reduce the postoperative inflammatory response, and promote the recovery of gastrointestinal function, providing a safe, effective and simple new analgesia solution for abdominal surgery patients.

[0020] (4) In some preferred embodiments, the present invention innovates the formulation. By precisely controlling the component ratio of lidocaine and multi-lamellar liposomes and optimizing the structure and characteristic parameters of the preparation (such as particle size distribution, encapsulation efficiency, zeta potential, etc.), efficient and stable encapsulation of lidocaine in multi-lamellar liposomes is achieved. Through the above embodiments, the prepared lidocaine multi-lamellar liposomes have uniform particle size, high encapsulation efficiency and moderate surface potential, thus improving the stability and sustained release performance of the preparation, and ensuring that the preparation can achieve its characteristics of reducing toxicity, safety, long-acting and sustained release.

[0021] (5) In some preferred embodiments, on the basis of the formulation innovation, the present invention optimizes the preparation process, precisely controls the key process parameters related to the production of the preparation, better ensures the efficient and stable encapsulation of lidocaine in multi-lamellar liposomes, thereby improving the stability and sustained release performance of the preparation, and ensuring that the preparation can achieve its characteristics of reducing toxicity, safety, long-acting and sustained release.

[0022] In the present invention, the above technical solutions can also be combined with each other to achieve more preferred combination schemes. Other features and advantages of the present invention will be described in the subsequent specification, and some advantages can be made obvious from the specification, or understood by implementing the present invention. The objectives and other advantages of the present invention can be realized and obtained from the content specifically pointed out in the specification and the drawings. Brief Description of the Drawings

[0023] The accompanying drawings are only for the purpose of showing specific embodiments, and are not considered to be a limitation of the present invention. Throughout the drawings, the same reference signs denote the same components; Figure 1 It is an optical micrograph of lidocaine multi-lamellar liposomes according to an embodiment of the present invention. Among them, (a) is a microscopic image at a scale of 100 μm, (b) is a microscopic image at a scale of 50 μm, and (c) is a microscopic image at a scale of 20 μm; Figure 2 It is an in vitro release curve of lidocaine multi-lamellar liposomes according to an embodiment of the present invention; Figure 3 It is an in vitro release curve of lidocaine multi-lamellar liposomes according to Example 9 of the present invention; Figure 4 It is a change curve of the body weight of rats in groups G1 to G5 over time in Experimental Example 8 of the present invention; Figure 5 It is a statistical chart of the number of writhing times of the experimental group and the blank control group in Experimental Example 9 of the present invention; among them, (a) is the number of writhing times at 1 hour, (b) is the number of writhing times at 6 hours, and (c) is the number of writhing times at 24 hours; Figure 6 It is a curve graph of the change of blood drug concentration over time of rats in Experimental Example 10 of the present invention. Detailed embodiments

[0024] The preferred embodiments of the present invention will be specifically described below with reference to the accompanying drawings. The accompanying drawings form a part of this application and are used together with the embodiments of the present invention to explain the principles of the present invention, and are not used to limit the scope of the present invention.

[0025] Lidocaine is a commonly used amide local anesthetic. Due to its short elimination half-life (1.5 - 2 hours), the effective analgesia after a single dose only lasts for 4 - 6 hours, making it difficult to cover the high-incidence pain window period of 24 hours after surgery; the above pharmacokinetic characteristics greatly limit the application of lidocaine in the field of postoperative analgesia.

[0026] Due to the three-phase release characteristics and its excellent sustained-release properties, the multi-lamellar liposome technology has been attracting increasing attention in the development of sustained-release pharmaceutical preparations. However, in the field of long-acting analgesia, there has been no relevant report on the combination application of lidocaine and multi-lamellar liposomes. The inventors of the present invention innovatively proposed to combine lidocaine with multi-lamellar liposome technology, aiming to achieve low toxicity, high safety, long-acting and sustained-release analgesic effects of lidocaine in vivo. However, achieving efficient encapsulation of lidocaine in multi-lamellar liposomes, while ensuring its drug activity and enabling the encapsulated lidocaine to have a safe and long-acting sustained-release effect in vivo, is a highly challenging technical problem, and the prior art has not provided relevant ingredient formulations and process routes. For this reason, through in-depth research, the inventors proposed the following innovative technical solutions: In a first aspect, the present invention provides a lidocaine multi-lamellar liposome, and the lidocaine multi-lamellar liposome contains lidocaine and lipids; the lipids include amphiphilic lipids, negatively charged phospholipids, neutral lipids and cholesterol.

[0027] In some embodiments, the mass ratio of the lipids to the lidocaine is 0.75 - 1.10. Exemplarily, the mass ratio of the lipids to the lidocaine is 0.75, 0.80, 0.85, 0.87, 0.90, 0.95, 1.0, 1.05, 1.10.

[0028] In some embodiments, among the lipids, the mass percentage content of the amphiphilic lipids is 30 - 70%, the mass percentage content of the negatively charged phospholipids is 3.5 - 11%, the mass percentage content of the neutral lipids is 7 - 20%, and the mass percentage content of the cholesterol is 18 - 46%.

[0029] Exemplarily, among the lipids, the mass percentage content of the amphiphilic lipids is 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%.

[0030] Exemplarily, among the lipids, the mass percentage content of the negatively charged phospholipids is 3.5%, 4.0%, 5.0%, 6.0%, 7.0%, 8.0%, 9.0%, 10.0%, 11.0%.

[0031] Exemplarily, among the lipids, the mass percentage content of the neutral lipids is 7.0%, 8.0%, 10.0%, 12.0%, 14.0%, 15.0%, 16.0%, 18.0%, 20.0%.

[0032] Exemplarily, among the lipids, the mass percentage content of the cholesterol is 18%, 20%, 22%, 25%, 27%, 30%, 32%, 35%, 37%, 40%, 43%, 46%.

[0033] Specifically, the lidocaine multi-lamellar liposomes comprise lidocaine and blank multi-lamellar liposomes; the blank multi-lamellar liposomes are composed of lipid bilayers formed by the lipids, the interior of the blank multi-lamellar liposomes contains multiple aqueous chambers, and the aqueous chambers are separated by the lipid bilayers; wherein, the lidocaine is located between the lipid bilayers and / or within the aqueous chambers.

[0034] In some embodiments, in the lidocaine multi-lamellar liposomes, the encapsulation efficiency of lidocaine is 90.0% - 98.2%. Exemplarily, the encapsulation efficiency is 90.0%, 91.0%, 92.0%, 93.0%, 94.0%, 95.0%, 96.0%, 97.0%, 98.0%, 98.2%.

[0035] In some embodiments, the D 50 of the lidocaine multi-lamellar liposomes is 22 - 30 μm, the D 90 is 45 - 60 μm, the D 10 is 10 - 15 μm, and the SPAN is 1.0 - 2.0.

[0036] Exemplarily, the D 50 of the lidocaine multi-lamellar liposomes is 22 μm, 24 μm, 26 μm, 28 μm, 30 μm.

[0037] Exemplarily, the D 90 of the lidocaine multi-lamellar liposomes is 45 μm, 48 μm, 50 μm, 52 μm, 55 μm, 57 μm, 60 μm.

[0038] Exemplarily, the D 10 of the lidocaine multi-lamellar liposomes is 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm.

[0039] Exemplarily, the SPAN of the lidocaine multi-lamellar liposomes is 1.0, 1.2, 1.4, 1.6, 1.8, 2.0.

[0040] In some embodiments, the Zeta potential of the lidocaine multi-lamellar liposomes is from ±10 mV to ±60 mV.

[0041] Exemplarily, the Zeta potential of the lidocaine multi-lamellar liposomes is [Z1, Z2], where Z1 and Z2 each independently take values such as -60 mV, -50 mV, -40 mV, -30 mV, -20 mV, -10 mV, 10 mV, 20 mV, 30 mV, 40 mV, 50 mV, 60 mV. Z1 ≤ Z2, and Z1 and Z2 are both negative or both positive.

[0042] In some embodiments, the sustained-release period of the lidocaine multi-lamellar liposomes reaches 24 - 72 h.

[0043] In the above embodiments, the present invention realizes the efficient and stable encapsulation of lidocaine in the multi-lamellar liposomes by precisely regulating the composition ratio of lidocaine and the multi-lamellar liposomes and optimizing the structural and characteristic parameters of the preparation (such as particle size distribution, encapsulation efficiency, zeta potential, etc.). For example, in terms of the composition ratio, the mass ratio of lipid to the lidocaine is controlled to be 0.75 - 1.10; in terms of the specific composition of the lipid, the mass percentage content of the amphiphilic lipid is controlled to be 30 - 70%, the mass percentage content of the negatively charged phospholipid is 3.5 - 11%, the mass percentage content of the neutral lipid is 7 - 20%, and the mass percentage content of cholesterol is 18 - 46%, which is beneficial to realizing the structural stability and efficient encapsulation of the lidocaine multi-lamellar liposomes. For example, by controlling the particle size distribution, encapsulation efficiency, zeta potential, etc. of the lidocaine multi-lamellar liposomes, the structural stability, uniform particle size, and moderate surface zeta potential of the lidocaine multi-lamellar liposomes are realized, ensuring stable existence in vitro and long-acting and sustained release of lidocaine after entering the body, avoiding insufficient release or burst release phenomena.

[0044] In some embodiments, the lidocaine includes lidocaine base and / or a salt form of lidocaine, wherein the salt form of lidocaine includes at least one of lidocaine hydrochloride, lidocaine bisulfate, lidocaine mesylate, lidocaine lactate, and lidocaine phosphate. In the embodiments of the present invention, the lidocaine base is located between the lipid bilayers and / or in the aqueous chamber, and the salt form of lidocaine is located in the aqueous chamber.

[0045] It can be understood that lidocaine base refers to the original state of lidocaine, that is, the form without forming a salt. In terms of chemical structure, lidocaine base has a free tertiary amino group , and this amino group shows alkalinity in aqueous solution. The chemical name of lidocaine is 2-(diethylamino)-N-(2,6-dimethylphenyl)acetamide.

[0046] In some embodiments, the preparation of the stock solution of the lidocaine multi-lamellar liposomes is obtained by sequentially adding an oil phase including lidocaine, amphiphilic lipid, negatively charged phospholipid, cholesterol, neutral lipid, and an organic solvent to a first aqueous phase and a second aqueous phase to form a W / O / W type second emulsion, followed by removing the organic solvent, concentrating the dilute liposome solution to obtain a liposome suspension, and replacing the liquid medium of the suspension with a third aqueous phase.

[0047] Exemplarily, in the preparation of the stock solution of the lidocaine multi-lamellar liposomes, the lidocaine is lidocaine base.

[0048] Preferably, in the preparation of the stock solution of lidocaine multilamellar liposomes, the mass ratio of lidocaine, amphiphilic lipid, negatively charged phospholipid, cholesterol, and neutral lipid is (35 - 45):(16 - 20):(1 - 5):(5 - 15):(3 - 5).

[0049] Preferably, the mass ratio of lidocaine, amphiphilic lipid, negatively charged phospholipid, cholesterol, and neutral lipid is (38 - 43):(17 - 19):(2 - 4):(7 - 13):(3.5 - 4.5).

[0050] More preferably, the mass ratio of lidocaine, amphiphilic lipid, negatively charged phospholipid, cholesterol, and neutral lipid is (39 - 41):(17 - 19):(2.5 - 3.5):(9 - 11):(3.8 - 4.2).

[0051] Exemplarily, the amphiphilic lipid is selected from one or a combination of several of dioleoyl phosphatidylcholine, egg yolk lecithin, hydrogenated soy phosphatidylcholine, dioleoyl phosphatidylethanolamine, dipalmitoyl phosphatidylcholine, dioleoyl phosphatidylethanolamine, and distearoyl phosphatidylethanolamine.

[0052] Exemplarily, the negatively charged phospholipid is selected from one or a combination of several of sodium dipalmitoyl phosphatidylglycerol, dipalmitoyl phosphatidylglycerol, dipalmitoyl phosphatidylserine, phosphatidylserine, and distearoyl phosphatidylglycerol.

[0053] Exemplarily, the neutral lipid is selected from one or a combination of several of glyceryl trioctanoate, glyceryl trioleate, soybean oil, tocopherol, and squalene.

[0054] Preferably, the addition amount of the organic solvent is calculated based on cholesterol, and 20 - 30 ml of the organic solvent is added per 1 g of cholesterol. 20 ml, 22 ml, 24 ml, 26 ml, 28 ml, or 30 ml of the organic solvent is added per 1 g of cholesterol. Exemplarily, the organic solvent includes one or a mixture of several of dichloromethane, chloroform, ether, and ethanol.

[0055] Specifically, the first aqueous phase is obtained by mixing an acidifying agent with water, the second aqueous phase is obtained by mixing a pH regulator and an osmotic pressure regulator with water, and the third aqueous phase is obtained by mixing an osmotic pressure regulator with water.

[0056] Preferably, in the first aqueous phase, the concentration of the acidifying agent is 180 - 220 mM, such as 180 mM, 190 mM, 200 mM, 210 mM, 220 mM. More preferably, the concentration of the acidifying agent is 195 - 205 mM. For example, the acidifying agent is orthophosphoric acid.

[0057] Preferably, in the second aqueous phase, the concentration of the pH regulator is 0.15 - 0.25% (w / w), and the concentration of the osmotic pressure regulator is 2 - 4% (w / w). Exemplarily, the concentration of the pH regulator is 0.15% (w / w), 0.17% (w / w), 0.20% (w / w), 0.23% (w / w), 0.25% (w / w), and the concentration of the osmotic pressure regulator is 2.0% (w / w), 2.2% (w / w), 2.4% (w / w), 2.6% (w / w), 2.9% (w / w), 3.2% (w / w), 3.5% (w / w), 3.8% (w / w), 4.0% (w / w).

[0058] More preferably, in the second aqueous phase, the concentration of the pH regulator is 0.19 - 0.21% (w / w), and the concentration of the osmotic pressure regulator is 2.6 - 3.2% (w / w).

[0059] Exemplarily, in the second aqueous phase, the pH regulator is a basic amino acid; preferably a mixture of one or both of lysine and arginine, for example: L-lysine monohydrate.

[0060] Preferably, in the third aqueous phase, the concentration of the osmotic pressure regulator is 0.9% (w / w).

[0061] Exemplarily, in the second and third aqueous phases, the osmotic pressure regulator is selected from one or a mixture of several of glucose, sodium chloride, sucrose, sorbitol, trehalose, and cyclodextrin. Preferably, in the second aqueous phase, the osmotic pressure regulator is anhydrous glucose or sucrose. In the third aqueous phase, the osmotic pressure regulator is sodium chloride.

[0062] In some embodiments, the oil phase is sequentially added to the first aqueous phase and the second aqueous phase to form a W / O / W type second emulsion. The ratio of the volume of the first aqueous phase to the volume of the oil phase is 0.9 - 1.1; the ratio of the volume of the second aqueous phase to the sum of the volumes of the oil phase and the first aqueous phase is 2.5 - 3.5.

[0063] For example, the ratio of the volume of the first aqueous phase to the volume of the oil phase is 0.90, 0.92, 0.95, 0.98, 1.0, 1.02, 1.05, 1.08, 1.10. The ratio of the volume of the second aqueous phase to the sum of the volumes of the oil phase and the first aqueous phase is 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5.

[0064] In some embodiments, in the stock solution of the lidocaine multilamellar liposomes, the concentration of lidocaine is 1.0 mg / mL - 17.5 mg / mL; exemplarily, the concentration of lidocaine is 1 mg / mL, 3 mg / mL, 5 mg / mL, 7 mg / mL, 9 mg / mL, 11 mg / mL, 13 mg / mL, 15 mg / mL, 17.5 mg / mL. In the stock solution of the lidocaine multilamellar liposomes, the lidocaine multilamellar liposomes have an external pH range of 5.8 to 7.4. Exemplarily, the external pH value of the lidocaine multilamellar liposomes is 5.8, 6.0, 6.2, 6.4, 6.6, 6.8, 7.0, 7.3, 7.4.

[0065] In a second aspect, the present invention provides a method for preparing lidocaine multilamellar liposomes for preparing the lidocaine multilamellar liposomes as described above; the preparation method includes the following steps: (1) Preparation of the oil phase: Mix lidocaine base, amphiphilic lipid, negatively charged phospholipid, cholesterol, neutral lipid with an organic solvent to obtain an oil phase; (2) Preparation of the first aqueous phase: Mix an acidifying agent with water to obtain a first aqueous phase; (3) Preparation of the second aqueous phase: Mix a pH regulator and an osmotic pressure regulator with water to obtain a second aqueous phase; (4) Preparation of the third aqueous phase: Mix an osmotic pressure regulator with water to obtain a third aqueous phase; (5) Add the first aqueous phase to the oil phase and form a W / O type first emulsion through high-shear emulsification; (6) Add the second aqueous phase to the W / O type first emulsion and form a W / O / W type second emulsion through shearing; (7) Remove the organic solvent in the W / O / W type second emulsion to obtain a dilute liposome solution; (8) Concentrate the dilute liposome solution to a target concentration to obtain a liposome suspension; replace the liquid medium in the liposome suspension with the third aqueous phase to obtain the stock solution (also called the original medicinal solution) of the lidocaine multilamellar liposomes.

[0066] In some embodiments, in step (1), the mass ratio of lidocaine base, amphiphilic lipid, negatively charged phospholipid, cholesterol, neutral lipid is (35 - 45):(16 - 20):(1 - 5):(5 - 15):(3 - 5).

[0067] In some embodiments, in step (5), the ratio of the volume of the first aqueous phase to the volume of the oil phase is 0.9 - 1.1. The volume of the oil phase refers to the total volume of all components in the oil phase.

[0068] In some embodiments, in step (6), the ratio of the volume of the second aqueous phase to the volume of the W / O type first emulsion is 2.5 - 3.5. The volume of the first emulsion refers to the total volume of all components in the first emulsion.

[0069] Compared with the prior art, through the ingredient formulation design and step coordination in the preparation method, the present invention successfully prepares lidocaine multi-lamellar liposomes, providing an innovative and feasible solution for achieving stable, safe, and long-acting release in vivo. For example, placing the lipophilic lidocaine base in the oil phase and further mixing it with the first aqueous phase, the second aqueous phase, etc. is beneficial to obtaining a higher encapsulation efficiency, improving the structural stability of lidocaine multi-lamellar liposomes, the uniformity of lidocaine distribution, and the consistency of particle size, providing a strong guarantee for achieving low toxicity, safety, long-acting, and sustained release of lidocaine.

[0070] Specifically, the preparation method design and optimization of the present invention are mainly based on the following mechanisms: 1. Optimization of drug release kinetics: (1) Regulation of oil-water partition coefficient: Lidocaine base, as a lipophilic drug, has higher solubility in the oil phase (such as lipids). By controlling the proportion of each component in the oil phase and the oil phase / water phase ratio, the diffusion path of lidocaine from the liposome to the body cavity fluid (such as peritoneal fluid) is effectively extended, forming a concentration gradient-dependent sustained release. (2) Structure barrier of multi-lamellar liposomes: The multi-lamellar structure wraps lidocaine through multiple phospholipid bilayers. Compared with single-lamellar liposomes, the release rate of lidocaine is significantly slowed down. The oil phase serves as a drug storage depot, further reducing the risk of sudden release of lidocaine.

[0071] 2. Enhancement of in vivo environment adaptability; anti-dilution and retention: The body cavity fluid (such as peritoneal fluid) is rich in proteases and lipases. The oil-phase liposomes can resist enzymatic hydrolysis due to the hydrophobicity of the phospholipid structure, and at the same time reduce the influence of the dilution effect of the body cavity fluid (such as peritoneal fluid) on lidocaine, maintaining the local effective concentration.

[0072] 3. Improvement of biocompatibility: The components of the oil phase (such as phospholipids, cholesterol) are similar to the cell membrane structure, which can reduce the risk of inflammatory reactions when lidocaine multi-lamellar liposomes enter the body cavity (such as intraperitoneal), and at the same time reduce the irritation of lidocaine to the body cavity inner membrane (such as peritoneum), meeting the microenvironment physiological characteristics of the body cavity inner membrane.

[0073] Preferably, the mass ratio of lidocaine base, amphiphilic lipid, negatively charged phospholipid, cholesterol, and neutral lipid is (38 - 43):(17 - 19):(2 - 4):(7 - 13):(3.5 - 4.5).

[0074] More preferably, the mass ratio of lidocaine base, amphiphilic lipid, negatively charged phospholipid, cholesterol, and neutral lipid is (39 - 41):(17 - 19):(2.5 - 3.5):(9 - 11):(3.8 - 4.2).

[0075] In the preparation of multilamellar vesicles (MVLs), the preparation of the oil phase is the crucial first step. Among them, the mass ratio of lidocaine base, amphiphilic lipid, negatively charged phospholipid, cholesterol, and neutral lipid not only determines the physicochemical properties of lidocaine multilamellar vesicles, but also directly affects their sustained-release characteristics, drug loading rate, particle size uniformity, and structural stability, etc.

[0076] (a) Lidocaine base: As the main active ingredient, it is responsible for providing analgesic effects. An appropriate ratio ensures sufficient drug loading while avoiding the instability or rupture of vesicles caused by too high a concentration. A high drug loading rate helps to extend the drug efficacy time, reduce the dosing frequency, reduce the dosage, and further reduce toxicity.

[0077] (b) Amphiphilic lipid (amphiphilic phospholipid molecule): The main component forming the lipid bilayer (i.e., phospholipid bilayer), providing structural support and barrier functions. An appropriate amount of amphiphilic lipid can enhance the stability and flexibility of the membrane, prevent vesicle fusion or rupture, thus ensuring the continuous release of the drug and improving clinical safety.

[0078] (c) Negatively charged phospholipid: Imparts a negative charge to the surface of the liposome membrane formed by the lipid bilayer, increasing its stability in the in vivo environment. An appropriate ratio of negatively charged phospholipid can prevent the aggregation between vesicles, maintain the consistency of vesicle particle size, help lidocaine to be continuously released at the expected rate, avoid sudden drug release or large differences in release rate caused by vesicle rupture or fusion, and improve the safety and effectiveness of lidocaine multilamellar vesicles.

[0079] (d) Cholesterol: Regulates the fluidity of the liposome membrane, enhancing the mechanical strength and stability of the membrane. An appropriate amount of cholesterol can improve the physicochemical stability of the liposome, prevent excessive fluidity or hardening of the membrane, and ensure the long-acting sustained release of lidocaine within an appropriate time.

[0080] (e) Neutral lipid: Assists in forming a stable multilamellar structure, fills the internal space of the liposome, and helps maintain the vesicle morphology. The presence of an appropriate amount of neutral lipid helps to construct a more complex internal structure of the multilamellar liposome vesicles, increase the encapsulation rate of lidocaine, and support the long-term sustained-release characteristics at the same time.

[0081] It can be seen that the synergistic effect among lidocaine base, amphiphilic lipids, negatively charged phospholipids, cholesterol and neutral lipids is crucial for the preparation of lidocaine multilamellar liposomes with low toxicity, safety, long-acting and sustained-release properties. By precisely controlling the proportion of each component, their synergistic effect can be maximized, significantly improving the drug loading rate, particle size uniformity and structural stability of lidocaine multilamellar liposomes, further strengthening the advantages of the lidocaine multilamellar liposomes of the present invention in terms of toxicity reduction, safety, long-acting and sustained-release.

[0082] As an alternative embodiment, the lidocaine base described in the present invention can be replaced by its salt form, for example: lidocaine hydrochloride.

[0083] Exemplarily, the amphiphilic lipid is selected from one or a combination of several of dioleoyl phosphatidylcholine, egg yolk lecithin, hydrogenated soy phosphatidylcholine, dioleoyl phosphatidylcholine, dipalmitoyl phosphatidylcholine, dioleoyl phosphatidylethanolamine, distearoyl phosphatidylethanolamine.

[0084] Exemplarily, the negatively charged phospholipid is selected from one or a combination of several of sodium dipalmitoyl phosphatidylglycerol, dipalmitoyl phosphatidylglycerol, dipalmitoyl phosphatidylserine, phosphatidylserine and distearoyl phosphatidylglycerol.

[0085] Exemplarily, the neutral lipid is selected from one or a combination of several of glyceryl trioctanoate, glyceryl trioleate, soybean oil, tocopherol, squalene.

[0086] In some preferred embodiments, in step (1), the addition amount of the organic solvent is calculated based on cholesterol, and 20 - 30 ml of the organic solvent is added per 1 g of cholesterol.

[0087] Exemplarily, 20 ml, 22 ml, 24 ml, 26 ml, 28 ml, 30 ml of the organic solvent is added per 1 g of cholesterol.

[0088] Exemplarily, the organic solvent includes one or a mixture of several of dichloromethane, chloroform, ether, ethanol.

[0089] Compared with other components, the chemical properties of cholesterol are relatively stable. Therefore, taking cholesterol as the benchmark can better ensure the consistency and repeatability of the performance of the prepared lidocaine multilamellar liposomes among different batches, avoiding the influence on the particle size uniformity, structural stability, safety and sustained-release characteristics of lidocaine multilamellar liposomes due to insufficient or excessive amount of the organic solvent.

[0090] In some embodiments, in step (1), lidocaine base, amphiphilic lipids, negatively charged phospholipids, cholesterol, neutral lipids and an organic solvent are mixed and heated to promote uniform mixing of the components. Preferably, the heating time is 2 to 5 h and the heating temperature is 30-50 °C, which is beneficial to improving the stability, drug encapsulation efficiency, particle size uniformity, etc. of lidocaine multilamellar liposomes. If the heating temperature is too high or the time is too long, on the one hand, lipid oxidation and structural damage are likely to occur: the unsaturated fatty acid chains in the phospholipid bilayer are prone to oxidative degradation, resulting in damage to the integrity of the liposome membrane and reducing the drug encapsulation efficiency; on the other hand, cholesterol phase transition failure is likely to occur: cholesterol may detach from the phospholipid bilayer at high temperatures, weakening its role in stabilizing the membrane structure and resulting in a wider particle size distribution of lidocaine multilamellar liposomes.

[0091] If the heating temperature is too low or the time is too short, insufficient mixing is likely to occur: the solubility of lipid components decreases at low temperatures, making it difficult to form a uniform organic phase, resulting in different sizes of multilamellar liposome vesicles and even layering; uneven drug distribution is also likely to occur: lipophilic drugs such as lidocaine cannot be fully dispersed in the lipid phase, resulting in a reduced subsequent encapsulation efficiency.

[0092] Preferably, in step (1), the mixing is carried out by magnetic stirring, the stirring speed is 50-150 rpm, and the time is 2-5 h. Exemplarily, the stirring speeds are 50 rpm, 60 rpm, 80 rpm, 100 rpm, 120 rpm, 140 rpm, 150 rpm. Preferably, it is 80-120 rpm.

[0093] In some preferred embodiments, in step (2), in the preparation of the first aqueous phase, the concentration of the acidifying agent is 180-220 mM.

[0094] Exemplarily, the concentration of the acidifying agent is 180 mM, 190 mM, 200 mM, 210 mM, 220 mM. More preferably, the concentration of the acidifying agent is 195-205 mM.

[0095] Preferably, orthophosphoric acid is used as the acidifying agent to prepare the first aqueous phase. In the actual preparation process, the volume of orthophosphoric acid required is calculated according to the purity of orthophosphoric acid to ensure that the concentration of the acidifying agent in the final solution falls within the specified range. Exemplarily, the purity of orthophosphoric acid is 85%.

[0096] In the preparation process of multilamellar vesicles (MVLs), controlling the concentration of the acidifying agent in the first aqueous phase is also one of the key steps. By adjusting the concentration of the acidifying agent and coordinating it with the composition ratio in step (1) and the added volume of the first aqueous phase in step (5), the amount of the acidifying agent added can be ensured to be within an appropriate range, which has a significant positive impact on the performance of lidocaine multilamellar vesicles, especially its sustained-release effect and safety. An appropriate amount of the acidifying agent can adjust the surface charge of the bilayer lipid membrane, enhance the mechanical strength and stability of the membrane structure, reduce the aggregation or rupture between vesicles, optimize the emulsification process, and ensure the uniform distribution of the inner aqueous phase in the oil phase, thereby preparing lidocaine multilamellar vesicles with consistent particle sizes and more regular morphologies. This stable structure and uniform particle size are crucial for improving the sustained-release effect of lidocaine multilamellar vesicles and ensuring safety.

[0097] In some preferred embodiments, in step (3), in the preparation of the second aqueous phase, the concentration of the pH regulator is 0.15 - 0.25% (w / w), and the concentration of the osmotic pressure regulator is 2 - 4% (w / w).

[0098] Exemplarily, in the preparation of the second aqueous phase, the concentration of the pH regulator is 0.15% (w / w), 0.17% (w / w), 0.20% (w / w), 0.23% (w / w), 0.25% (w / w), and the concentration of the osmotic pressure regulator is 2.0% (w / w), 2.3% (w / w), 2.5% (w / w), 2.9% (w / w), 3.2% (w / w), 3.5% (w / w), 3.8% (w / w), 4.0% (w / w).

[0099] More preferably, in the preparation of the second aqueous phase, the concentration of the pH regulator is 0.19 - 0.21% (w / w), and the concentration of the osmotic pressure regulator is 2.6 - 3.2% (w / w).

[0100] Exemplarily, in the preparation of the third aqueous phase, the concentration of the osmotic pressure regulator is 0.9% (w / w).

[0101] Exemplarily, in the preparation of the second aqueous phase, the pH regulator is a basic amino acid; preferably a mixture of one or both of lysine and arginine, for example: L-lysine monohydrate.

[0102] Exemplarily, in the preparation of the second aqueous phase and the third aqueous phase, the osmotic pressure regulator is selected from one or a mixture of several of glucose, sodium chloride, sucrose, sorbitol, trehalose, and cyclodextrin. Preferably, in the preparation of the second aqueous phase, the osmotic pressure regulator is anhydrous glucose or sucrose. In the preparation of the third aqueous phase, the osmotic pressure regulator is sodium chloride.

[0103] It can be understood that the second aqueous phase mainly contains pH regulators and osmotic pressure regulators, which are used to provide a suitable microenvironment for the internal aqueous phase, which is particularly important for encapsulating drugs. The pH regulator is used to adjust the pH of the internal aqueous phase to ensure the stability and optimal encapsulation efficiency of lidocaine. The osmotic pressure regulator helps to balance the osmotic pressure between the internal and external aqueous phases, prevent excessive water from entering and exiting the internal aqueous phase, and thus maintain the stability of the internal structure of lidocaine multivesicular liposomes and the uniformity of particle size.

[0104] It can be understood that the third aqueous phase mainly contains only an osmotic pressure regulator, which is used as a part of the external aqueous phase after the W / O / W emulsion is formed. Its main function is to maintain an osmotic pressure similar to that of the biological environment (such as blood or tissue fluid in the peritoneal cavity) into which it is finally released, so as to avoid the expansion, contraction or rupture of the lidocaine multivesicular liposomes due to the difference in osmotic pressure, and ensure the stability and safety of the lidocaine multivesicular liposomes during in vivo delivery and sustained release.

[0105] It can be seen that the effects of the osmotic pressure regulators in the second aqueous phase and the third aqueous phase are different, and therefore the controlled concentration ranges are also different.

[0106] In some preferred embodiments, in step (5), the high shearing process has a shearing speed of 5000-25000 rpm and a shearing time of 5-60 min. For example, the shearing speed is 5000 rpm, 8000 rpm, 10000 rpm, 12000 rpm, 15000 rpm, 18000 rpm, 20000 rpm, 22000 rpm, 25000 rpm. The shearing time is 5 min, 8 min, 10 min, 15 min, 20 min, 25 min, 30 min, 40 min, 50 min.

[0107] More preferably, in step (5), during the high shearing, the shearing speed is 10000-20000 rpm, and the shearing time is 10-30 min.

[0108] In the preparation process of multivesicular liposomes (MVLs), in step (5), the reasonable control of shear rate and time is one of the keys to form the W / O type first emulsion (colostrum). Appropriately increasing the shear rate and extending the shear time to the above-mentioned suitable range can effectively reduce the colostrum particle size, which helps to form small MVLs with uniform particle size, which can not only improve the encapsulation rate of lidocaine and optimize the lipid-drug ratio, but also help to reduce the release rate of lidocaine and improve its sustained release effect. However, too high a shear rate or too long a shear time will lead to excessive energy input, which may cause thermal effects and mechanical stress damage, destroy the phospholipid bilayer structure, reduce the encapsulation efficiency, and may lead to uneven particle size distribution and introduce impurities.

[0109] In some preferred embodiments, in step (6), during the shearing, the shearing speed is 500 - 2500 rpm and the shearing time is 30 - 180 s. Exemplarily, the shearing speed is 500 rpm, 800 rpm, 1000 rpm, 1200 rpm, 1500 rpm, 1800 rpm, 2000 rpm, 2200 rpm, 2500 rpm. The shearing time is 30 s, 45 s, 60 s, 75 s, 90 s, 105 s, 120 s, 135 s, 150 s, 165 s, 180 s.

[0110] More preferably, in step (6), during the shearing, the shearing speed is 1000 - 2000 rpm and the shearing time is 45 - 120 s.

[0111] During the preparation of multi - vesicular liposomes (MVLs), in step (6), reasonably controlling the shearing speed and time is one of the keys to forming the W / O / W type secondary emulsion (multiple emulsion). Appropriately reducing the shearing speed and shortening the shearing time to the above - mentioned appropriate range can increase the particle size of the multiple emulsion, which helps to improve the drug - loading rate of lidocaine - loaded multi - vesicular liposomes and optimize the lipid - drug ratio. A larger particle size not only enables each multi - vesicular liposome to encapsulate more lidocaine, improving the lipid - drug ratio, but also helps to maintain the structural stability and reduce the risk of rupture or fusion. In addition, a stable structure and moderate particle size contribute to achieving the expected sustained - release effect, ensuring that lidocaine is slowly released at a predetermined rate and prolonging the action time. However, too low a shearing speed or too short a shearing time is not conducive to sufficient emulsification, but will instead reduce the encapsulation efficiency and affect the sustained - release effect, and may lead to non - uniform particle size distribution.

[0112] In some preferred embodiments, in step (7), the organic solvent in the W / O / W type secondary emulsion is removed by nitrogen bubbling. During the nitrogen bubbling, the nitrogen - blowing temperature is 15 - 30 °C, the nitrogen - blowing time is 10 - 60 min, and the nitrogen - blowing flow rate is 0.25 - 10 L / min. Exemplarily, the nitrogen - blowing temperature is 15 °C, 18 °C, 20 °C, 22 °C, 25 °C, 28 °C, 30 °C. The nitrogen - blowing time is 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min. The nitrogen - blowing flow rate is 0.25 L / min, 0.5 L / min, 1.0 L / min, 2.0 L / min, 3.0 L / min, 4.0 L / min, 5.0 L / min, 6.0 L / min, 7.0 L / min, 8.0 L / min, 9.0 L / min, 10.0 L / min.

[0113] More preferably, in step (7), the organic solvent in the W / O / W type second emulsion is removed by nitrogen bubbling. During the nitrogen bubbling, the nitrogen blowing temperature is 20 - 25 °C, the nitrogen blowing time is 20 - 50 min, and the nitrogen blowing flow rate is 0.5 - 5.0 L / min.

[0114] During the preparation of multilamellar vesicles (MVLs), appropriately increasing the nitrogen blowing temperature and extending the nitrogen blowing time to the above appropriate range in step (7) can more thoroughly remove the organic solvent and ensure that the residual amount is reduced to the lowest level. Although this process may lead to a decrease in the concentration of the active pharmaceutical ingredient, i.e., lidocaine, in the multilamellar vesicles and a slight reduction in the encapsulation efficiency, it helps to form a higher lipid-drug ratio and can reduce the release rate of lidocaine, thereby achieving a more stable sustained-release effect and prolonging the action time of lidocaine. However, if the nitrogen blowing temperature is too high or the time is too long, it will have an adverse impact on the stability of lidocaine and the lipid membrane structure in the multilamellar vesicles.

[0115] In one embodiment, in step (8), a tangential flow filtration device is used to concentrate the dilute liposome solution obtained in step (7) to the target concentration to obtain a liposome suspension; the liquid medium in the liposome suspension is replaced with a third aqueous phase to obtain a stock solution of lidocaine multilamellar vesicles.

[0116] Preferably, during the concentration to the target concentration, the inlet flow rate is 100 - 2000 ml / min, and the concentration multiple is 3 - 9. Exemplarily, the inlet flow rates are 100 ml / min, 200 ml / min, 500 ml / min, 800 ml / min, 1000 ml / min, 1200 ml / min, 1500 ml / min, 1800 ml / min, 2000 ml / min. The concentration multiples are 3, 4, 5, 6, 7, 8, 9. More preferably, the inlet flow rate is 200 - 1500 ml / min, and the concentration multiple is 3 - 7.

[0117] In some embodiments, during the concentration to the target concentration, optionally, the filtration pore size is 500 - 5000 kDa. Exemplarily, the filtration pore sizes are 500 kDa, 600 kDa, 700 kDa, 750 kDa, 800 kDa, 900 kDa, 1000 kDa, 1500 kDa, 2000 kDa, 3000 kDa, 4000 kDa, 5000 kDa.

[0118] Preferably, the filtration pore size is 500 - 2000 kDa. Further, the filtration pore size is 600 - 900 kDa.

[0119] It can be understood that the filtration pore size refers to the pore size of the filtration module (or filter membrane) used in the tangential flow filtration device.

[0120] By regulating the filtration pore size, the particle size distribution, drug encapsulation efficiency, and release kinetic characteristics of the lidocaine multi-lamellar liposome stock solution can be optimized. On the basis of ensuring a long-acting and sustained release effect (the sustained release period reaches 24 - 72 hours), the release rate of the lidocaine multi-lamellar liposome of the present invention can also be flexibly adjusted at different time points according to different requirements, so as to meet specific sustained release requirements.

[0121] Preferably, during the process of replacing the liquid medium with the third aqueous phase, the inlet flow rate is 100 - 2000 ml / min, and the washing and filtration multiple is 3 - 9. Exemplarily, the inlet flow rate is 100 ml / min, 200 ml / min, 500 ml / min, 800 ml / min, 1000 ml / min, 1200 ml / min, 1500 ml / min, 1800 ml / min, 2000 ml / min. The washing and filtration multiple is 3, 4, 5, 6, 7, 8, 9. More preferably, the inlet flow rate is 200 - 1500 ml / min, and the washing and filtration multiple is 3 - 7.

[0122] In some embodiments, the target concentration is 5 - 20 mg / ml. Exemplarily, the target concentration is 5 mg / ml, 8 mg / ml, 10 mg / ml, 12 mg / ml, 15 mg / ml, 18 mg / ml, 20 mg / ml.

[0123] The stock solution of lidocaine multi-lamellar liposome obtained by the preparation method according to the second aspect has at least one of the following characteristics: (a) Structure: The lidocaine multi-lamellar liposome contains lidocaine and blank multi-lamellar liposomes; the blank multi-lamellar liposomes are composed of lipid bilayers formed by the lipids, and the interior of the blank multi-lamellar liposomes contains multiple aqueous compartments, and the aqueous compartments are separated by the lipid bilayers; wherein, the lidocaine is located between the lipid bilayers or in the aqueous compartments.

[0124] (b) Drug content: In the stock solution of the lidocaine multi-lamellar liposome, the concentration of lidocaine is 1.0 mg / mL - 17.5 mg / mL; Exemplarily, the concentration of lidocaine is 1 mg / mL, 3 mg / mL, 5 mg / mL, 7 mg / mL, 9 mg / mL, 11 mg / mL, 13 mg / mL, 15 mg / mL, 17.5 mg / mL.

[0125] (c) Drug encapsulation efficiency: In the stock solution of the lidocaine multi-lamellar liposome, the encapsulation efficiency of lidocaine is 90.0% - 98.2%. Exemplarily, the encapsulation efficiency is 90.0%, 91.0%, 92.0%, 93.0%, 94.0%, 95.0%, 96.0%, 97.0%, 98.0%, 98.2%.

[0126] (d) Particle size distribution: In the stock solution of the lidocaine multi-lamellar liposomes, the D 50 of the lidocaine multi-lamellar liposomes is 22 - 30 μm, D 90 is 45 - 60 μm, D 10 is 10 - 15 μm, and the SPAN is 1.0 - 2.0. Exemplarily, the D 50 of the lidocaine multi-lamellar liposomes is 22 μm, 24 μm, 26 μm, 28 μm, 30 μm. Exemplarily, the D 90 of the lidocaine multi-lamellar liposomes is 45 μm, 48 μm, 50 μm, 52 μm, 55 μm, 57 μm, 60 μm. Exemplarily, the D 10 of the lidocaine multi-lamellar liposomes is 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm. Exemplarily, the SPAN of the lidocaine multi-lamellar liposomes is 1.0, 1.2, 1.4, 1.6, 1.8, 2.0.

[0127] (e) pH: In the stock solution of the lidocaine multi-lamellar liposomes, the lidocaine multi-lamellar liposomes have an external pH range of 5.8 to 7.4. Exemplarily, the external pH value of the lidocaine multi-lamellar liposomes is 5.8, 6.0, 6.2, 6.4, 6.6, 6.8, 7.0, 7.3, 7.4.

[0128] (f) Drug release rate: The in vitro sustained release period of the lidocaine multi-lamellar liposomes reaches 24 - 72 h; specifically, 10 - 35% is released in 2 h, 25 - 70% is released in 8 h, 35 - 96% is released in 24 h, ≥85% is released in 48 h, and ≥94% is released in 72 h. The above drug release rates indicate that the lidocaine multi-lamellar liposomes have no burst release phenomenon and can provide the drug smoothly to ensure that patients can smoothly pass through the peak period of postoperative pain.

[0129] The drug release rate is usually measured in vitro. Specifically, the lidocaine multi-lamellar liposomes are placed in an artificial medium that simulates the in vivo environment (such as specific pH value, temperature, etc.), and samples are taken at different time points for analysis to determine the change in drug concentration. The above percentages represent the cumulative release ratio relative to the total amount of loaded drug.

[0130] (g) Zeta potential: The Zeta potential of the lidocaine multi-lamellar liposomes is ±10 mV to ±60 mV.

[0131] Exemplarily, under low-temperature storage conditions (such as 2 - 8°C), the investigation time is from 10 days to 30 days, and the Zeta potential is from ±30 mV to ±60 mV (the upper and lower limits of the potential have the same sign, either positive or negative); for example, -60 mV to -30 mV. This shows that the stability at 2 - 8°C exceeds 20 days, and this high stability is particularly important for long-term storage and meets the transportation requirements.

[0132] Exemplarily, under room-temperature storage conditions (such as 25°C), the investigation time is from 10 days to 30 days, and the Zeta potential is from ±10 mV to ±40 mV (the upper and lower limits of the potential have the same sign, either positive or negative); for example, -40 mV to -10 mV. At a higher temperature, the Zeta potential decreases but still remains within a reasonable range. Such a Zeta potential can still provide sufficient stability to ensure that the lidocaine multilamellar liposomes do not undergo significant physical changes or performance degradation in the short term, meeting the requirements of clinical applications.

[0133] (h) Lipid-drug ratio: In the lidocaine multilamellar liposomes, the mass ratio of lipid to lidocaine is 0.75 - 1.10. A suitable lipid-drug ratio is beneficial to achieving an optimized balance among the encapsulation efficiency of the lidocaine drug, the long-acting and sustained-release effect, physicochemical stability, biocompatibility, and safety.

[0134] (i) Lipid components: In the lipid (existing in the form of a lipid bilayer), the ranges of each component are as follows: the mass percentage content of the amphiphilic lipid is 30 - 70%, the mass percentage content of the negatively charged phospholipid is 3.5 - 11%, the mass percentage content of the neutral lipid is 7 - 20%, and the mass percentage content of cholesterol is 18 - 46%.

[0135] Exemplarily, in the lipid, the content of the amphiphilic lipid is 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%.

[0136] Exemplarily, in the lipid, the content of the negatively charged phospholipid is 3.5%, 4.0%, 5.0%, 6.0%, 7.0%, 8.0%, 9.0%, 10.0%, 11.0%.

[0137] Exemplarily, in the lipid, the content of the neutral lipid is 7.0%, 8.0%, 10.0%, 12.0%, 14.0%, 15.0%, 16.0%, 18.0%, 20.0%.

[0138] Exemplarily, in the lipid, the content of cholesterol is 18%, 20%, 22%, 25%, 27%, 30%, 32%, 35%, 37%, 40%, 43%, 46%.

[0139] In some embodiments, in the lipid, the ranges of the components are as follows: the mass percentage of the amphiphilic lipid is 45-55%, the mass percentage of the negatively charged phospholipid is 6.0-8.0%, the mass percentage of the neutral lipid is 10-15%, and the mass percentage of the cholesterol is 25-35%.

[0140] In a third aspect, the present invention provides the use of the above-mentioned lidocaine multi-lamellar liposomes and the lidocaine multi-lamellar liposomes obtained by the above-mentioned preparation method in the preparation of a safe, long-acting, and low-toxicity sustained-release analgesic drug, and the administration method of the sustained-release analgesic drug includes coelomic injection.

[0141] Coelomic injection is a method of directly injecting a drug (lidocaine multi-lamellar liposomes) into the coelom. The coelom includes but is not limited to the abdominal cavity. When performing coelomic injection, it also includes compounding the lidocaine multi-lamellar liposomes with a pharmaceutically acceptable carrier for injection.

[0142] It can be understood that abdominal surgery is a common type of surgery in the surgical field. Due to factors such as its large trauma, inflammatory response, mucosal ischemia and hypoxia, and traction of the viscera and peritoneum, incision pain, visceral pain, and trauma stress response will inevitably occur after the surgery. Therefore, postoperative analgesia is particularly important. The lidocaine multi-lamellar liposomes and their preparation method provided by the present invention provide a new solution for safe and effective analgesia after abdominal surgery. The lidocaine multi-lamellar liposomes are injected into the body by coelomic injection, and a single injection can enable patients to safely and effectively pass through the high-incidence period of postoperative pain.

[0143] The technical solutions of the present invention will be further described in detail below with reference to specific examples, preparation examples, and comparative examples.

[0144] Preparation Example 1: This preparation example provides a method for preparing lidocaine multi-lamellar liposomes, which includes the following steps: (1) Preparation of the oil phase: Weigh 75 g of lidocaine base, dioleoyl phosphatidylcholine (DEPC), sodium dipalmitoyl phosphatidylglycerol (DPPG), cholesterol, and glyceryl trioctanoate according to the weight ratio of 40:18:3:10:4 and dissolve them in 250 ml of dichloromethane by heating for 3 h at a heating temperature of 40°C. During the dissolution process, magnetic stirring is used at a rotation speed of 100 rpm to promote uniform mixing; (2) Preparation of the first aqueous phase: Dissolve 85% orthophosphoric acid in purified water to a concentration of 200 mM to obtain the first aqueous phase; (3) Preparation of the second aqueous phase: Dissolve L-lysine monohydrate and anhydrous glucose in purified water to concentrations of 0.2% (w / w) and 2.9% (w / w) respectively to obtain the second aqueous phase; (4) Preparation of the third aqueous phase: Dissolve sodium chloride in purified water at a concentration of 0.9% (w / w) to obtain the third aqueous phase; (5) Add 1.0 times the volume of the first aqueous phase to the oil phase and form a W / O type first emulsion through high-shear emulsification; during high-shear emulsification, the shear rate is 15,000 rpm and the time is 20 min; (6) Add 3.0 times the volume of the second aqueous phase to the W / O type first emulsion and form a W / O / W type second emulsion through shearing; during shearing, the shear rate is 1,500 rpm and the time is 60 s; (7) Remove dichloromethane in the W / O / W type second emulsion by nitrogen bubbling to obtain a dilute liposome solution; during nitrogen bubbling, the nitrogen-blowing temperature is 22 °C, the nitrogen-blowing time is 30 min, and the nitrogen-blowing flow rate is 1.5 L / min; (8) Use a tangential flow filtration device with an inlet flow rate of 800 ml / min, a concentration factor of 5, and a filtration pore size of 2,000 kDa to obtain a liposome suspension; then, at an inlet flow rate of 800 ml / min and a washing and filtration multiple of 5, replace the liquid medium in the liposome suspension with the third aqueous phase to obtain a stock solution of lidocaine multilamellar liposomes; divide the stock solution into vials and seal them with rubber stoppers and aluminum caps.

[0145] Preparation Example 2: The steps and parameters of this preparation example are basically the same as those of Preparation Example 1, except that: in the preparation of the oil phase in step (1), the mass ratio of each component is different from that of Preparation Example 1. In this preparation example, the weight ratio of lidocaine base, dierucoyl phosphatidylcholine (DEPC), sodium salt of dipalmitoyl phosphatidylglycerol (DPPG), cholesterol, and glyceryl trioctanoate is 35:18:3:10:4.

[0146] Preparation Example 3: The steps and parameters of this preparation example are basically the same as those of Preparation Example 1, except that: in the preparation of the oil phase in step (1), the mass ratio of each component is different from that of Preparation Example 1. In this preparation example, the weight ratio of lidocaine base, dierucoyl phosphatidylcholine (DEPC), sodium salt of dipalmitoyl phosphatidylglycerol (DPPG), cholesterol, and glyceryl trioctanoate is 45:18:3:10:4.

[0147] Preparation Example 4: The steps and parameters of this preparation example are basically the same as those of Preparation Example 1, except that: in the preparation of the oil phase in step (1), the mass ratio of each component is different from that of Preparation Example 1. In this preparation example, the weight ratio of lidocaine base, dierucoyl phosphatidylcholine (DEPC), sodium salt of dipalmitoyl phosphatidylglycerol (DPPG), cholesterol, and glyceryl trioctanoate is 40:16:1:5:3.

[0148] Preparation Example 5: This preparation example is basically the same as Preparation Example 1 in terms of steps and parameters, except that: in the preparation of the oil phase in step (1), the mass ratio of each component is different from that in Preparation Example 1. In this preparation example, the weight ratio of lidocaine base, dierucoyl phosphatidylcholine (DEPC), sodium salt of dipalmitoyl phosphatidylglycerol (DPPG), cholesterol, and glyceryl trioctanoate is 40:20:5:15:5.

[0149] Preparation Example 6: This preparation example is basically the same as Preparation Example 1 in terms of steps and parameters, except that: in the preparation of the oil phase in step (1), the addition amount of dichloromethane is different from that in Preparation Example 1. In this preparation example, the addition amount of dichloromethane is 200 ml.

[0150] Preparation Example 7: This preparation example is basically the same as Preparation Example 1 in terms of steps and parameters, except that: in the preparation of the first aqueous phase in step (2) and the second aqueous phase in step (3), the concentrations of orthophosphoric acid, L-lysine monohydrate, and anhydrous glucose are different from those in Preparation Example 1. In this preparation example, in the first aqueous phase, the concentration of orthophosphoric acid is 180 mM; in the second aqueous phase, the concentration of L-lysine monohydrate is 0.25% (w / w), and the concentration of anhydrous glucose is 2.0% (w / w).

[0151] Preparation Example 8: This preparation example is basically the same as Preparation Example 1 in terms of steps and parameters, except that: in steps (5) and (6), the shearing process parameters are different from those in Preparation Example 1. In this preparation example, in step (5), in the high-shear process, the shear speed is 5000 rpm and the time is 60 min.

[0152] Preparation Example 9: This preparation example is basically the same as Preparation Example 1 in terms of steps and parameters, except that: in step (6), in the shearing process, the shear speed is 2500 rpm and the time is 30 s.

[0153] Preparation Example 10: This preparation example is basically the same as Preparation Example 1 in terms of steps and parameters, except that: in step (7), the nitrogen purging process parameters are different from those in Preparation Example 1. In this preparation example, the nitrogen purging temperature is 30 °C and the nitrogen purging time is 60 min.

[0154] Preparation Example 11: This preparation example is basically the same as Preparation Example 1 in terms of steps and parameters, except that: in step (1), the analgesic is different from that in Preparation Example 1. In this preparation example, lidocaine is lidocaine hydrochloride.

[0155] Preparation Example 12: This preparation example is basically the same as Preparation Example 1 in terms of steps and parameters, except that: in step (8), the filtration pore size is different from that in Preparation Example 1. In this preparation example, the filtration pore size is 750 kDa.

[0156] The stock solutions of lidocaine multilamellar liposomes obtained from the above Preparation Example 1 to Preparation Example 12 respectively correspond to Examples 1 to 12 (that is, Preparation Example 1 corresponds to Example 1, Preparation Example 2 corresponds to Example 2, and so on).

[0157] Comparative Example 1: This comparative example is basically the same as Preparation Example 1 in terms of steps and parameters, except that: in the preparation of the oil phase in step (1), the mass ratio of each component is different from that in Preparation Example 1. In this comparative example, the weight ratio of lidocaine base, dierucoyl phosphatidylcholine (DEPC), sodium dipalmitoyl phosphatidylglycerol (DPPG), cholesterol, and glyceryl trioctanoate is 30:25:8:4:8.

[0158] Comparative Example 2: This comparative example is basically the same as Preparation Example 1 in terms of steps and parameters, except that: in the preparation of the oil phase in step (1), the mass ratio of each component is different from that in Preparation Example 1. In this comparative example, the weight ratio of lidocaine base, dierucoyl phosphatidylcholine (DEPC), sodium dipalmitoyl phosphatidylglycerol (DPPG), cholesterol, and glyceryl trioctanoate is 50:15:1:3:6.

[0159] Comparative Example 3: This comparative example is basically the same as Preparation Example 1 in terms of steps and parameters, except that: in step (5), the addition amount of the first aqueous phase is different from that in Preparation Example 1. In this comparative example, 1.2 times the volume of the first aqueous phase is added to the oil phase.

[0160] Comparative Example 4: This comparative example is basically the same as Preparation Example 1 in terms of steps and parameters, except that: in step (6), the addition amount of the second aqueous phase is different from that in Preparation Example 1. In this comparative example, 3.8 times the volume of the second aqueous phase is added to the W / O type first emulsion.

[0161] Experimental Example 1: Drug Content Test 1.1. Experimental Steps: ① Chromatographic Conditions: Octadecylsilane chemically bonded silica gel is used as the filler; phosphate buffer - acetonitrile (35:65) is used as the mobile phase; the column temperature is 30 °C; the detection wavelength is 254 nm; the injection volume is 10 µl.

[0162] ② Solution Preparation: Reference solution: Weigh an appropriate amount of lidocaine or lidocaine hydrochloride reference substance accurately, dissolve it in methanol and dilute to a solution containing 0.53 mg per 1 ml (calculated as lidocaine base).

[0163] Test solution: Measure an appropriate amount of the original medicinal liquid prepared in the examples and comparative examples, dissolve it in methanol and dilute to a solution containing 0.53 mg per 1 ml (calculated as lidocaine base).

[0164] ③ Injection for detection: After the system is stable, inject the blank solvent, reference solution and test solution in sequence, and calculate according to the peak area by the external standard method.

[0165] 1.2. Experimental results: The drug content test results of the examples and comparative examples are shown in Table 1.

[0166] Experimental Example 2: Determination of encapsulation efficiency 2.1. Experimental procedure: ① Chromatographic conditions: The chromatographic conditions for detecting the encapsulation efficiency are the same as those for the content determination.

[0167] ② Solution preparation: Reference solution: Weigh an appropriate amount of lidocaine base or lidocaine hydrochloride reference substance accurately, dissolve it in methanol and dilute to a solution containing 0.053 mg per 1 ml (calculated as lidocaine base).

[0168] Test solution: Disperse the sample evenly, first dilute it 5 times with normal saline, centrifuge, and take the supernatant and dilute it 1 time with methanol.

[0169] ③ Injection for detection After the system is stable, inject the blank solvent, reference solution and test solution in sequence, calculate the content of lidocaine base or lidocaine hydrochloride in the test sample by the external standard method, which is the free lidocaine base or lidocaine hydrochloride; then calculate the encapsulation efficiency according to the content result under the content item.

[0170] 2.2. Experimental results: The encapsulation efficiency test results of the examples and comparative examples are shown in Table 1.

[0171] Experimental Example 3: Determination of pH After the medicinal liquid stands still, it will be stratified. Before measurement, shake the medicinal liquid well until it is evenly dispersed, and then measure the pH value. The test results are shown in Table 1.

[0172] The results in Table 1 show that compared with the comparative examples, the examples of the present invention can improve the drug loading efficiency through the optimization of the components and processes, which is specifically reflected in the improvement of the encapsulation efficiency. A higher encapsulation efficiency means that more drugs can be effectively loaded into the lipid carrier, which not only helps to improve the analgesic effect of the drug per unit dose, but also can reduce the amount of free drug that is not encapsulated, thereby reducing side effects and improving safety.

[0173] Table 1: Drug content, encapsulation efficiency and pH results of examples and comparative examples ;

[0174] Experimental Example 4: Determination of particle size distribution 4.1 Experimental procedure: The particle size distribution was determined using a Malvern MS 3000 (Malvern Panalytical). After an appropriate amount of this product (i.e., the liquid medicines prepared in the examples and comparative examples) was dispersed evenly, 0.9% sodium chloride solution was used as the dispersant with a refractive index of 1.33. The wet method was adopted for determination, and it was stirred at 2000 rpm, and the sample was added drop by drop until the obscuration reached 12% for detection.

[0175] 4.2 Experimental results: The particle size distribution test results of the examples and comparative examples are shown in Table 2.

[0176] The expected target of the examples of the present invention for the particle size distribution is: D 10 ≥10 μm, D 50 is 17 - 30 μm (preferably 20 - 30 μm), D 90 <65 μm (preferably ≤60 μm), which can ensure the safe and long - acting sustained release of lidocaine multilamellar liposomes in the body cavity and avoid the phenomena of insufficient release or burst release. According to the results in Table 2, the examples of the present invention achieved a uniform particle size distribution that meets the expected target through the optimization of components and processes.

[0177] Table 2: Particle size distribution test results of examples and comparative examples ;

[0178] Experimental Example 5: Determination of drug release 5.1 Experimental procedure: ① Chromatographic conditions: The chromatographic conditions are the same as those for the determination of encapsulation efficiency.

[0179] ② Solution preparation Release medium preparation: 0.8% bovine serum albumin and 50 mM phosphate buffer solution (PBS); Reference substance solution: An appropriate amount of lidocaine reference substance was accurately weighed, dissolved in methanol and quantitatively diluted to prepare a solution containing 0.053 mg of lidocaine per 1 ml; ③ In vitro release After the liquid medicines prepared in the examples and comparative examples were dispersed evenly, they were diluted 17 times with the release medium and placed on a shaker at 37 °C and 30 revolutions per minute for in vitro release experiments. Samples were taken and detected at 2, 8, 24, 48, and 72 hours respectively.

[0180] 5.2. Experimental results: The test results of the in vitro release experiments of the examples and comparative examples are shown in Table 3 and Figure 2 and Figure 3 .

[0181] The expected goals for the sustained-release effect of the examples of the present invention are as follows: the release rate at 2 hours is 10 - 35% (preferably 14 - 35%), the release rate at 8 hours is 25 - 70% (preferably 33 - 53%), the release rate at 24 hours is 35 - 96% (preferably 35 - 85%), and the release rate at 72 hours is ≥90% (preferably ≥99%).

[0182] According to the results in Table 3, compared with the comparative examples, the lidocaine multilamellar liposomes obtained in the examples of the present invention achieved the above-mentioned expected goals for the sustained-release effect by controlling the formulation and preparation process of the lidocaine multilamellar liposomes. Compared with other examples, Examples 1 and 12 achieved better sustained-release effects through further optimization of the ingredients and processes. The in vitro release experiment results show that the lidocaine multilamellar liposomes prepared in the examples of the present invention have good sustained-release performance, no burst release phenomenon occurs, and can continuously and stably release the drug. This enables patients to obtain continuous and effective analgesic effects during the critical pain peak period from 0 to 48 hours after surgery, providing an innovative solution for relieving postoperative pain.

[0183] Table 3: In vitro release results of examples and comparative examples (%) ;

[0184] Experimental Example 6: Determination of Zeta potential 6.1. Experimental steps: Use a Zetasizer Ultra nanoparticle size and Zeta potential analyzer for determination. The instrument setting parameters are shown in Table 4. Take the liquid medicine obtained in Example 9, dilute it 10 times with physiological saline to obtain the sample to be tested, and detect the Zeta potential of the diluted sample. The test results are shown in Table 5.

[0185] Table 4: Parameters of the Zeta potential test instrument ; 6.2. Experimental results: The results of the changes in parameters such as the Zeta potential of the lidocaine multilamellar liposomes obtained in the examples of the present invention under different investigation conditions over time are shown in Table 5.

[0186] According to the results in Table 5, under the low-temperature storage condition (2 - 8°C), the investigation time was from 10 days to 30 days, and the Zeta potential was from -50 mV to -30 mV. In addition, parameters such as particle size distribution, pH, osmotic pressure, content, and encapsulation efficiency did not change significantly within 30 days. This indicates that the stability at 2 - 8°C exceeded 20 days, and this high stability is particularly important for long-term storage and meets the transportation requirements. Under the room-temperature storage condition (25°C), the investigation time was from 10 days to 30 days, and the Zeta potential was from -40 mV to -10 mV. At a higher temperature, the Zeta potential decreased but still remained within a reasonable range. Such a Zeta potential can still provide sufficient stability to ensure that the obtained lidocaine multilamellar liposomes do not undergo significant physical changes or performance degradation in the short term, meeting the requirements of clinical applications.

[0187] Table 5: Variation results of Zeta potential, etc. with time under different conditions ;

[0188] Experimental Example 7: Characterization of the structural morphology 7.1 Experimental procedure: After uniformly dispersing the solution of lidocaine multilamellar liposomes obtained in Example 1, it was diluted with 0.9% sodium chloride and observed for the morphological structure under a Morphologi 4 particle size and shape analyzer, as Figure 1 shown.

[0189] 7.2 Experimental results: From Figure 1 it can be seen that in the solution of lidocaine multilamellar liposomes obtained in the examples of the present invention, there are multiple small vesicles. Inside each small vesicle, there are multiple internal aqueous compartments, and each aqueous compartment is composed of a liposome membrane, and lidocaine is encapsulated inside the multilamellar liposomes. The complex multilamellar structure and the encapsulation effect of the liposome membrane can achieve the sustained release and controlled release of lidocaine. This property helps to maintain the effective concentration of lidocaine in the body cavity, extend the action time of the lidocaine drug, reduce the number of drug administrations, and further reduce the toxic and side effects of the lidocaine drug. The structure of multiple small vesicles and internal aqueous compartments provides a rich drug storage space, enabling the multilamellar liposomes to carry more lidocaine, increasing the drug loading capacity, meeting the requirements of clinical treatment, and making the structure of lidocaine multilamellar liposomes more stable and less susceptible to the influence of the external environment (such as temperature, pH value, enzymes, etc.), thereby extending the shelf life of lidocaine multilamellar liposomes.

[0190] Experimental Example 8: In vivo safety experiment of intraperitoneal administration 8.1. Experimental purpose: Through intraperitoneal injection, systematically observe and evaluate the acute toxicity and safety of the lidocaine multi-lamellar liposomes prepared in the examples of the present invention in male Sprague-Dawley rats.

[0191] 8.2. Experimental overview:

[0192] 8.3. Experimental results Six rats were taken from each group. After receiving a single injection of the test article intraperitoneally, the behavior and physiological activities of the animals were closely observed within 0 - 24 hours after injection. The body weights were recorded and observed from 1 to 14 days after injection. Fourteen days later, the rat cages were changed and food was withheld 12 hours before sacrifice for blood biochemical tests. At the time of sacrifice, the rats were anesthetized with gas to enter a state of unconsciousness and loss of reflexes, and whole blood was taken from the rats by cardiac puncture for blood biochemical and blood routine tests. After blood collection, the rats were decapitated and samples of major organs and tissues were taken (such as heart, liver, kidney, brain, peritoneum).

[0193] (a) Body weight: The change curves of the body weights of the rats in experimental groups G1 to G5 over time are as Figure 4 .

[0194] (b) Blood biochemistry and blood routine: The blood biochemistry and blood routine results of the rats in experimental groups G1 to G5 are shown in Tables 6 and 7 respectively.

[0195] (c) Weights of major organs: The results of the weight changes of the major organs of the rats in experimental groups G1 to G5 are shown in Table 8.

[0196] The data in Tables 6 - 8 are expressed as mean ± standard error (n = 6). "ns" means that when compared pairwise with the blank control group, based on the t-test, after the results were corrected by Bonferroni multiple correction, the results were not statistically significant. The experimental results show that after intraperitoneal injection of the lidocaine multi-lamellar liposomes prepared in the examples of the present invention, there were no significant abnormal changes in the body weights, blood biochemical indices, blood routine parameters, and weights of major organs of the animals. This result fully demonstrates that the lidocaine multi-lamellar liposomes obtained in the examples of the present invention have good biosafety.

[0197] Table 6: Serum biochemical test results in the acute toxicity test of rats in groups G1 - G5 ; Table 7: Blood routine test results in the acute toxicity test of rats in groups G1 - G5 ; Table 8: Major organ weight test results in the acute toxicity test of rats in groups G1 - G5 ;

[0198] Experimental Example 9: Pharmacodynamic Experiment of Intraperitoneal Administration - for Evaluating Analgesic Effect 9.1. Experimental Purpose: To determine the analgesic effect of the lidocaine multilamellar liposomes prepared in Example 1 on the acetic acid-induced writhing abdominal pain model in rats by intraperitoneal injection at a dose of 10 mg / Kg (calculated as free lidocaine base).

[0199] The acetic acid-induced writhing model is a visceral pain / abdominal pain model. By intraperitoneally injecting acetic acid into animals (rats, mice, rabbits), it can cause a writhing response, that is, abdominal muscle contraction, arching of the back, and extension of the hind limbs. The degree of pain is mainly judged by the number of writhing. After intraperitoneal injection of acetic acid, the writhing latency is 3 - 5 min, and the frequency of writhing response increases during 15 - 20 min. The acetic acid-induced writhing model has the advantages of convenient operation, no need to anesthetize animals, and obvious changes. It is one of the widely used visceral pain / abdominal pain models and also a classic preclinical peripheral analgesic drug evaluation model. Visceral pain / abdominal pain can well represent the pain during the postoperative recovery period of abdominal surgery patients. This experiment is based on the rat acetic acid-induced writhing experiment to evaluate the effect of the lidocaine multilamellar liposomes obtained in Example 1 on visceral pain / abdominal pain.

[0200] 9.2. Experimental Overview Thirty-six male Sprague-Dawley rats (6 weeks old, 250 g - 300 g) were randomly divided into a drug administration experimental group and a blank control group (N = 18 in each group), and were respectively injected with the lidocaine multilamellar liposomes prepared in Example 1 (10 mg / Kg, calculated as the encapsulated lidocaine base) or normal saline; at 1 h, 6 h, and 24 h after the injection of the test article, 6 rats were taken from each group respectively, and 1% acetic acid solution at a dose of 10 mL / Kg was intraperitoneally injected. After the injection of acetic acid, the writhing behavior of the animals was observed within 20 minutes, the number of writhing was recorded, and the writhing inhibition rate was statistically analyzed. Writhing was defined as abdominal muscle contraction accompanied by elongation of the body and hind limbs. The formula for the writhing inhibition rate is: Writhing inhibition rate = 100×(average number of writhing in the blank control group - average number of writhing in the experimental group) / average number of writhing in the blank control group.

[0201] 9.3. Experimental Results: The number of writhing and the writhing inhibition rate of the animals with acetic acid-induced modeling at 1 h, 6 h, and 24 h after drug administration were statistically analyzed. As Figure 5And the results in Table 9 showed that after 1 h of drug administration, the writhing times of the animals in the experimental group (p < 0.001, t-test) were significantly lower than those in the blank control group, and the writhing inhibition rate reached 78.37%; after 6 h of drug administration, the writhing times of the animals in the experimental group (p < 0.05, t-test) were significantly lower than those in the blank control group, and the writhing inhibition rate reached 34.47%; after 24 h of drug administration, the writhing times of the animals in the experimental group were significantly lower than those in the blank control group (p < 0.0001, t-test), and the writhing inhibition rate reached 51.20%. The experimental results indicated that after intraperitoneal injection in animals, the lidocaine multi-lamellar liposomes prepared in the embodiments of the present invention could not only significantly relieve pain within 1 hour, but also continuously exert an analgesic effect for up to 24 hours, fully demonstrating that the lidocaine multi-lamellar liposomes obtained in the embodiments of the present invention had excellent long-acting and sustained-release analgesic effects. Figure 5 Data are expressed as mean ± standard error (n = 6). Compared pairwise with the blank control group (t-test), p < 0.05 was considered to be statistically significantly different. , , .

[0202] Table 9: Effects of the experimental group on acetic acid-induced writhing behavior in rats

[0203] Experimental Example 10: Intraperitoneal administration - in vivo sustained-release determination experiment 10.1. Experimental purpose:

[0204] By intraperitoneal injection of drugs, the drug release of the sustained-release preparation (lidocaine multi-lamellar liposomes) prepared in the embodiments of the present invention in male Sprague-Dawley rats was systematically observed and evaluated in comparison with non-sustained-release preparations.

[0205] 10.2. Experimental overview: Fifty-four male Sprague-Dawley rats (6 weeks old, 250 g - 300 g) were randomly divided into a multi-lamellar liposome administration group, a non-sustained-release preparation control group, and a blank control group (N = 18 in each group), and were respectively injected with the lidocaine multi-lamellar liposomes prepared in Example 1 (10 mg / Kg, calculated as the encapsulated lidocaine base) or (lidocaine hydrochloride containing 10 mg / Kg lidocaine base) or normal saline; at 1 h, 6 h, and 24 h after injection of the test article, 6 rats were sacrificed from each group respectively and blood was taken, and after obtaining plasma, lidocaine drug concentration detection was carried out. The detection results are shown in Table 10 and Figure 6 , and the experimental results are expressed as mean ± standard error.

[0206] 10.3. Experimental results: The lidocaine blood drug concentrations in animals of each group were detected at 1 h, 6 h, and 24 h after drug administration, respectively. As shown in Table 10, lidocaine was not detected in the blood of animals in the blank control group at all time points. Compared with the non-sustained release preparation control group (lidocaine hydrochloride), lidocaine multi-lamellar liposomes had a longer residence time in animals. After 6 h of drug administration, the blood drug concentration of the non-sustained release preparation control group (lidocaine hydrochloride) was lower than the limit of quantification (0.2 ng / mL); however, in the lidocaine multi-lamellar liposome drug group, at 6 h, the blood drug concentration was significantly higher than that of the blank and non-sustained release preparation control groups, being 32.99 ± 10.27 ng / mL; even after 24 h, the blood drug concentration of the lidocaine multi-lamellar liposome drug group was still 20.87 ± 12.53 ng / mL.

[0207] Compared with the non-sustained release preparation (lidocaine hydrochloride), at the same drug administration dose (both 10 mg / Kg in terms of free base of lidocaine), the residence time of lidocaine multi-lamellar liposomes in the present invention's examples in vivo increased significantly. This means that in in vivo experiments, the lidocaine multi-lamellar liposomes provided by the present invention also exhibited significant sustained release characteristics, and could maintain lidocaine within the effective concentration range in vivo for a longer time, rather than being rapidly metabolized or excreted from the body like ordinary non-sustained release preparations.

[0208] Based on the significant sustained release characteristics of the lidocaine multi-lamellar liposomes of the present invention shown in in vivo experiments, the present invention successfully achieved the reduction of toxicity and enhancement of efficacy of local anesthetics, and improved safety; by slowly releasing lidocaine, the present invention could achieve the required analgesic effect at a lower drug dose, or provide a more persistent and effective analgesic effect than non-sustained release preparations at the same drug administration concentration. At the same time, by avoiding the high concentration peak of lidocaine within a short time, the present invention further reduced local and systemic toxic reactions, thus significantly improving the safety of the drug.

[0209] The lidocaine multi-lamellar liposomes of the present invention provide an innovative and efficient option for postoperative analgesia (such as postoperative analgesia for abdominal surgery). Currently, before the end of abdominal surgery, 0.5% lidocaine is usually injected intraperitoneally, or after surgery, lidocaine is intermittently or continuously infused through a multi-porous catheter to relieve postoperative pain. However, compared with these traditional methods, the lidocaine multi-lamellar liposomes of the present invention have significant advantages: compared with the non-sustained release preparation (0.5% lidocaine): the lidocaine multi-lamellar liposomes of the present invention have the characteristics of lower toxicity and longer action time. Compared with multi-porous catheter drug administration: the drug administration method of the present invention is more convenient, and a single drug administration can achieve long-acting and safe analgesic effects, without the need for complex catheter placement and continuous infusion equipment, significantly improving patient compliance.

[0210] Table 10: Blood drug concentration data in animals at different time points 。

[0211] As described above, it is only the preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A lidocaine multi-lamellar liposome, characterized in that, The lidocaine multi-lamellar liposomes contain lidocaine and lipids; the lipids contain amphiphilic lipids, negatively charged phospholipids, neutral lipids and cholesterol; the lidocaine multi-lamellar liposomes contain lidocaine and blank multi-lamellar liposomes; The blank multi-lamellar liposomes are composed of lipid bilayers formed by the lipids. The interior of the blank multi-lamellar liposomes contains multiple aqueous chambers, and the aqueous chambers are separated by the lipid bilayers; wherein, the lidocaine is located between the lipid bilayers and / or within the aqueous chambers; In the preparation of the stock solution of the lidocaine multi-lamellar liposomes, the mass ratio of lidocaine to amphiphilic lipids, negatively charged phospholipids, cholesterol, and neutral lipids is (35 - 45):(16 - 20):(1 - 5):(5 - 15):(3 - 5).

2. The lidocaine multi-lamellar liposome according to claim 1, wherein The mass ratio of the lipids to the lidocaine is 0.75 - 1.

10.

3. The lidocaine multi-lamellar liposome according to claim 1, wherein Among the lipids, the mass percentage of the amphiphilic lipids is 30 - 70%, the mass percentage of the negatively charged phospholipids is 3.5 - 11%, the mass percentage of the neutral lipids is 7 - 20%, and the mass percentage of the cholesterol is 18 - 46%.

4. The lidocaine multi-lamellar liposome according to claim 1, characterized in that, In the lidocaine multi-lamellar liposomes, the encapsulation efficiency of lidocaine is 90.0% - 98.2%.

5. The lidocaine multi-lamellar liposome according to claim 1, characterized in that, The D of the lidocaine multilamellar liposomes 50 is 22 - 30 μm, the D 90 is 45 - 60 μm, the D 10 is 10 - 15 μm, the SPAN is 1.0 - 2.0; and / or, The Zeta potential of the lidocaine multi-lamellar liposomes is ±10 mV to ±60 mV.

6. The lidocaine multi-lamellar liposome according to claim 1, wherein, The sustained-release period of the lidocaine multi-lamellar liposomes reaches 24 - 72 h.

7. The lidocaine multi-lamellar liposome according to claim 1, wherein The lidocaine includes lidocaine base and / or its salt forms, wherein the salt forms of lidocaine include at least one of lidocaine hydrochloride, lidocaine bisulfate, lidocaine mesylate, lidocaine lactate, and lidocaine phosphate.

8. The lidocaine multi-lamellar liposome according to claim 7, wherein The preparation of the stock solution of the lidocaine multi-lamellar liposomes is obtained by sequentially adding an oil phase including lidocaine, amphiphilic lipids, negatively charged phospholipids, cholesterol, neutral lipids and an organic solvent to a first aqueous phase and a second aqueous phase to form a W / O / W type second emulsion, followed by removal of the organic solvent, concentration of the dilute liposome solution to obtain a liposome suspension, and replacement of the liquid medium of the suspension with a third aqueous phase.

9. A preparation method of lidocaine multi-lamellar liposomes, characterized in that, For the preparation of the lidocaine multi-lamellar liposomes as described in any one of claims 1 - 8; the preparation method includes the following steps: (1) Preparation of the oil phase: Mix lidocaine base, amphiphilic lipids, negatively charged phospholipids, cholesterol, neutral lipids and an organic solvent to obtain an oil phase; the mass ratio of lidocaine to amphiphilic lipids, negatively charged phospholipids, cholesterol, and neutral lipids is (35 - 45):(16 - 20):(1 - 5):(5 - 15):(3 - 5); (2) Preparation of the first aqueous phase: Mix an acidifying agent and water to obtain a first aqueous phase; (3) Preparation of the second aqueous phase: Mix a pH regulator and an osmotic pressure regulator with water to obtain a second aqueous phase; (4) Preparation of the third aqueous phase: Mix an osmotic pressure regulator and water to obtain a third aqueous phase; (5) Add the first aqueous phase to the oil phase and form a W / O type first emulsion through high-shear emulsification; the ratio of the volume of the first aqueous phase to the volume of the oil phase is 0.9 - 1.1; (6) Add a second aqueous phase to the W / O first emulsion and shear it to form a W / O / W second emulsion; the ratio of the volume of the second aqueous phase to the volume of the W / O first emulsion is 2.5 - 3.5; (7) Remove the organic solvent in the W / O / W second emulsion to obtain a dilute liposome solution; (8) Concentrate the dilute liposome solution to a target concentration to obtain a liposome suspension; replace the liquid medium in the liposome suspension with a third aqueous phase to obtain a stock solution of lidocaine multilamellar liposomes. (10) Use of the lidocaine multilamellar liposomes according to any one of claims 1 - 8 and the lidocaine multilamellar liposomes obtained by the preparation method according to claim 9 in the preparation of a sustained-release analgesic drug.

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