SUSTAINED-RELEASE LIPID COMPOSITION AND PREPARATION METHOD THEREFOR

Abstract

Disclosed are a sustained-release lipid composition and a preparation method therefore. Specifically, the present invention relates to a solid composition containing lipids and a liposome composition obtained therefrom, wherein the liposomes have improved release properties.

Claims

1. A solid composition, comprising: (1) a lipid, wherein the lipid comprises at least one phospholipid; and (2) a free acid or a free base of a drug; and (3) a pharmaceutically acceptable salt, a complex or a chelate of the drug.

2. The solid composition according to claim 1, wherein the phospholipid comprises one or more of phosphatidylcholine, phosphatidylerhanolamine, phosphatidylglycerol, phosphatidylserine, phosphatidic acid, and phosphatidylinositol.

3. The solid composition according to claim 1, wherein the lipid further comprises a steroid.

4. The solid composition according to claim 3, wherein relative to a total molar amount of the lipid, a molar percentage of the cholesterol is 0.1%-90%.

5. The solid composition according to claim 1, wherein based on a total molar amount of the solid composition, a total content of the free acid or the free base of the drug and the pharmaceutically acceptable salt, the complex or the chelate of the drug is 1%-90%.

6. The solid composition according to claim 1, wherein a molar ratio of the free acid or the free base of the drug to the pharmaceutically acceptable salt, the complex or the chelate of the drug is (0.01:1)-(100:1).

7. The solid composition according to claim 1, wherein the drug is selected from the group consisting of an anesthetic, an anti-bleeding agent, an analgesic, and a non-steroidal anti-inflammatory agent.

8. The solid composition according to claim 1 wherein the solid composition comprises: (1) a lipid comprising at least one phospholipid; and (2) a ropivacaine free base; and (3) a pharmaceutically acceptable salt of ropivacaine.

9. A solid composition, comprising: (1) a lipid, wherein the lipid comprises at least one phosphatidylcholine and cholesterol; and (2) a ropivacaine free base; and (3) a pharmaceutically acceptable salt of ropivacaine; wherein a molar ratio of the phosphatidylcholine to the cholesterol is (4:1)-(1:4); a molar ratio of the free base to the pharmaceutically acceptable salt of ropivacaine is (9:1)-(1:9).

10. The solid composition according to claim 1, wherein the solid composition substantially does not comprise a lipid vesicle structure.

11. The solid composition according to claim 1, wherein the solid composition is subjected to a hydration to form a liposome composition.

12. The solid composition according to claim 11, wherein an operation of the hydration is achieved by mixing the solid composition with water or an aqueous solution.

13. The solid composition according to claim 11, wherein the liposome composition reaches a peak concentration of the drug within about 3 hours after being administered to an individual.

14. The solid composition according to claim 11, wherein the liposome composition provides a sustained release of the drug for not less than 12 hours in an individual.

15. A method for preparing the solid composition according to claim 1, comprising a step of mixing the lipid, the free acid or the free base of the drug, the pharmaceutically acceptable salt, the complex or the chelate of the drug, and a liquid medium; and a step of removing the liquid medium.

16. A method for preparing the solid composition according to claim 1, comprising a step of mixing the lipid, the free acid or the free base of the drug, a salt-forming agent, and a liquid medium; and a step of removing the liquid medium, and wherein the salt-forming agent is selected from one or more of the group consisting of an inorganic acid, an organic acid, an inorganic base, an organic base, an inorganic salt, and an organic salt.

17. (canceled)

18. The method according to claim 15, wherein the liquid medium is selected from the group consisting of water, an organic solvent, and a water/organic solvent co-solvent system.

19. The method according to claim 15, wherein a method for removing the liquid medium is evaporation, freeze drying or spray drying.

20. A liposome composition obtained by the solid composition according to claim 1 to a hydration.

21-27. (canceled)

28. A method for preparing a liposome composition, comprising a step of preparing a solid composition, and a step of hydrating the solid composition, wherein: the step of preparing the solid composition comprises (1) a step of mixing a lipid, a free acid or a free base of a drug, a pharmaceutically acceptable salt, a complex or a chelate of the drug, and a liquid medium; and a step of removing the liquid medium, or (2) a step of mixing the lipid, the free acid or the free base of the drug, a salt-forming agent, and the liquid medium; and the step of removing the liquid medium.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0111] FIG. 1 is the image of the ropivacaine liposome prepared in Embodiment 1 under cryo-transmission electron microscope;

[0112] FIG. 2 is the plasma PK curve of the ropivacaine preparation prepared in Embodiment 1;

[0113] FIG. 3 is the in vitro release curve of the ropivacaine liposome prepared in Embodiment 1;

[0114] FIG. 4 is the in vitro release curve of the butorphanol liposome prepared in Embodiment 5;

[0115] FIG. 5 is the plasma PK curve of the butorphanol preparation prepared in Embodiment 5;

[0116] FIG. 6 is the image of the ropivacaine liposome prepared in Embodiment 1 under scanning electron microscope;

[0117] FIG. 7 is the image of the ropivacaine liposome prepared in Embodiment 1 under cryo-scanning electron microscope;

[0118] FIG. 8 is the effect of the subcutaneous injection of the ropivacaine liposome prepared in Embodiment 1 on the pain threshold at the administrated site in cavies;

[0119] FIG. 9 is the effect of the intracutaneous injection of the ropivacaine liposome prepared in Embodiment 1 on the pain threshold at the administrated site in cavies;

[0120] FIG. 10 is the effect of the ropivacaine liposome prepared in Embodiment 1 on the local pain threshold after plantar operation in rats.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Embodiment 1: Preparation of a Ropivacaine Liposome

[0121]

TABLE-US-00001 TABLE 1 Name of Material Mass (g) Molar Mass Molar Ratio Ropivacaine Free Base 2.40 274.41 2.3 Ropivacaine Hydrochloride 0.68 310.88 0.6 Dimyristoylphosphatidylcholine 5.10 677.93 1.9 (DMPC) Cholesterol 1.50 386.65 1.0 Tert-butanol 100 mL / /

[0122] Preparation of a solid composition: 5.10 g of DMPC, 1.50 g of cholesterol, 2.40 g of ropivacaine free base, and 0.68 g of ropivacaine hydrochloride were weighed and dissolved in 100 mL of tert-butanol, and then distributed into 50 penicillin bottles of 10 mL, with 2.0 mL per bottle. The samples were placed in a freeze dryer for freeze drying to prepare the ropivacaine solid composition.

[0123] Preparation of a liposome: The freeze dried product was redissolved in the previous stem in an appropriate amount of saline to mix it uniformly. The content and the encapuslation rate of the liposome were determined by HPLC, the content was 17.989 mg/mL (calculated by the ropivacaine free base, the same below), and the encapuslation rate was 79.34%. It could be known from the manifestations under cryo-transmission electron microscope that it included a multilamellar vesicle (MLU). The particle diameter of the liposome was determined to obtain that D [4,3] was 15.959 μm, d (0.1) was 3.325 μm, d (0.5) was 12.964 μm and d (0.9) was 31.674 μm.

Embodiment 2: Pharmacokinetic Test of the Ropivacaine Liposome in Rats

[0124] 1. Tested Drug

[0125] Ropivacaine liposome prepared in Embodiment 1, with a specification of 17.99 mg/ml;

[0126] Ropivacaine hydrochloride injection available commercially, with a specification of 10 ml:100 mg (calculated by ropivacaine hydrochloride).

[0127] 2. Experimental Animal

[0128] Sprague Dawley rats (SPF grade), male, aging about 6-8 weeks, weighing 180-250 g. Original source: Shanghai Sippr-BK Laboratory Animal Co., Ltd. Certification No.: 20180006003423, Production License No.: SCXK (Shanghai) 2018-0006.

[0129] 3. Test Steps

[0130] The details of grouping and test design are shown in the table below:

TABLE-US-00002 TABLE 2 Administration Concentration of Tested Tested Animal Drug Drug Administration Quantity Dosage Solution Volume Administration Collected Group Gender Quantity Tested Drug (mg/kg) (mg/mL) (mg/kg) Manner Sample 1 Male 5 Ropivacaine 19 10.0 1.9 Subcutaneous Plasma Hydrochioride injection Injection 2 Male 5 Ropivacaine 114 18.7 6.1 Subcutaneous Plasma Liposome injection

[0131] Time and volume for sample collection:

[0132] Group 1: 6 min, 18 min, 30 min, 45 min, 1 h, 1.5 h, 2 h, 3 h, 4 h, 8 h, 12 h and 24 h after administration. There were a total of 12 time points.

[0133] Group 2: Before administration, and 30 min, 1 h, 2 h, 4 h, 8 h, 24 h, 48 h, 72 h, 96 h, 120 h, 144 h and 168 h after administration. There were a total of 12 time points.

[0134] A tolerance of 2 min was allowed for each time point of blood collection within 30 min after administration, a tolerance of 5 min was allowed for each time point of blood collection within 30 min-8 h after administration, a tolerance of 10 min was allowed for each time point of blood collection within 8 h-48 h after administration, and a tolerance of 20 min was allowed for each time point of blood collection within 48 h-168 after administration.

[0135] The collected blood samples were placed in heparin anticoagulant blood collection tubes, and centrifuged to separate blood plasma (centrifuge with a centrifugal force of 6800 g for 6 min, at 2-8° C.). The plasma samples were stored in a −80° C. refrigerator before sending to the entrusting party. The drug concentration was determined in the plasma by HPLS-MS/MS. The test results are shown in FIG. 2 and the table below.

TABLE-US-00003 TABLE 3 PK Parameter of Ropivacaine in Plasma of Rats Ropivacaine Hydrochloride Injection Ropivacaine Liposome Dosage mg/kg 19 114 PK Parameter Mean SD Mean SD t.sub.1/2 h 0.851 0.08 15.1 4.84 t.sub.max h 1.15 0.49 0.60 0.22 C.sub.max ng .Math. mL.sup.−1 1078 187 975 259 AUC.sub.0-t h .Math. ng .Math. mL.sup.−1 3967 696 19825 2635 AUC.sub.0-inf h .Math. ng .Math. mL.sup.−1 3968 695 19955 2663

[0136] After the rats were given the subcutaneous injection of ropivacaine liposome, the time to peak (t.sub.max) is 0.6 h, which is similar to the time to peak (t.sub.max=1.15 h) of commercially available ropivacaine hydrochloride injections, indicating that the ropivacaine liposome can take effect quickly in vivo, and its onset time in vivo is close to that of the commercially available ropivacaine injections. The half life (t.sub.1/2) of ropivacaine liposome is about 18 times of that of the commercially available ropivacaine injections, which proves that the ropivacaine liposome has an ideal sustained-release effect. The administration dosage of the ropivacaine liposome is about 6 times of that of the commercially available preparations, but their peak concentrations (C.sub.max) are similar, which proves that the ropivacaine liposome has a better safety, and its clinically administration dosage can reach at least 6 times of that of the commercially available preparations. In summary, the PK data of the ropivacaine liposome in rats show that this species can not only take effect quickly, but also maintain a longer effect of sustained release, and the higher tolerable dosage is conducive to improving the compliance of patients.

Embodiment 3: Preparation of a Liposome without Ropivacaine Hydrochloride Added Initially

[0137]

TABLE-US-00004 TABLE 4 Name of Material Mass (g) Molar Mass Molar Ratio Ropivacaine Free Base 3.00 274.40 2.9 Dimyristoylphosphatidylcholine 5.10 677.93 1.9 (DMPC) Cholesterol 1.50 386.65 1.0 Tert-butanol 100 mL / /

[0138] According to the method described in Embodiment 1, a liposome was prepared without ropivacaine hydrochloride added initially. The content and the encapuslation rate of the liposome were determined by HPLC; the content was 18.558 mg/mL, and the encapuslation rate was 97.24%.

Embodiment 4: In Vitro Release of the Ropivacaine Liposome

[0139] 1. Cleaning of Dialysis Bags:

[0140] 10 g of sodium bicarbonate and 0.168 g of EDTA.2Na were weighed and added in 500 ml of water, and mixed evenly. A dialysis bag was cut into sections of 10 cm, and the dialysis bags were washed with 200 ml of purified water for 10 times after being boiled with a lotion in a 1 L beaker for 10 min; then 500 ml of purified water was added to boil for 10 min. The dialysis bags that would be suspended for a long time could be stored in 10% ethanol, and should be washed with 200 ml of purified water for 10 times every time before use.

[0141] 2. Preparation of a Release Medium:

[0142] 2.3 g of potassium dihydrogen phosphate, 7.6 g of dipotassium hydrogen phosphate trihydrate, 5.6 g of sodium chloride, and 132 mg of ammonium sulfate were weighed and placed in a 1000 ml volumetric flask, water was added to a constant volume, and then it was mixed evenly.

[0143] 3. Placement and Sampling Determination of Released Samples:

[0144] 1.0 ml of the liposome solution to be tested was accurately measured using a pipette and added into a 10 cm dialysis bag, 1 ml of the release medium was added, both ends of the dialysis bag were clamped with clamps, and then it was placed in a 150 ml tall beaker containing 99 ml of the release medium. The samples were placed on a shaker at 37° C. and 10 rpm for incubation, and 1 ml was sampled each time at the set time points for testing by HPLC.

[0145] The test results are shown in FIG. 3 and the table below.

TABLE-US-00005 TABLE 5 Name of In Vitro Release Degree Sample 1 h 2 h 4 h 24 h 48 h 72 h Embodiment 1 21.22% 28.65% 35.46% 61.40% 76.48% 82.53% Embodiment 3 11.31% 18.48% 23.95% 58.68% 79.83% 93.65%

[0146] It can be seen that because of the higher encapsulation rate, the liposome described in Embodiment 3 has a slower release in vitro within 0-4 h, and the release degree at 4 h is similar to that of the liposome described in Embodiment 1 at 1 h. The above results prove that the higher encapsulation rate will affect the release of the drug at the initial stage, and it is not conducive to the rapid analgesic effect of local analgesics.

Embodiment 5: Preparation of a Butorphanol Liposome

[0147]

TABLE-US-00006 TABLE 6 Mass (g) Name of Material Prescription 1 Prescription 2 Butorphanol Free Base 3.125 3.50 Butorphanol Tartrate 0.815 / Dimyristoylphosphatidylcholine 5.10 5.10 (DMPC) Cholesterol 1.50 1.50 Tert-butanol 100 mL 100 mL Content 16.247 mg/mL 16.939 mg/mL Encapsulation Rate 70.35% 97.76%

[0148] The butorphanol liposome was prepared according to the methods in Embodiment 1 and Embodiment 3.

Embodiment 6: In Vitro Release of the Butorphanol Liposome

[0149] The in vitro release of the butorphanol liposome was determined according to the methods in Embodiment 4. The test results are shown in FIG. 4 and the table below.

TABLE-US-00007 TABLE 7 Name of In Vitro Release Degree Sample 0.5 h 4 h 24 h 48 h 72 h 96 h 120 h Prescription 1 12.74% 22.53% 70.65% 91.57% 93.11% 98.06% 100.90% Prescription 2 9.45% 14.93% 55.40% 72.10% 81.68% 88.19% 93.28%

[0150] The liposome of Prescription 2 has a slower release in vitro within 0-4 h, and its release degree at 4 h is similar to that of the liposome described in Prescription 1 at 0.5 h. It is was proved that the higher encapsulation rate will affect the release of the drug at the initial stage, and it is not conducive to the rapid analgesic effect of butorphanol.

Embodiment 7: Pharmacokinetic Test of the Ropivacaine Liposome in Rats

[0151] 1. Tested Drug

[0152] Prescription 1 of the ropivacaine liposome prepared in Embodiment 5, with a specification of 14.96 mg/ml;

[0153] Commercially available butorphanol tartrate injection, with a specification of 2 mL: 4 mg.

[0154] 2. The experimental animals and the test methods are the same as those described in Embodiment 2.

[0155] 3. Test results: The test results are shown in FIG. 5 and the table below.

TABLE-US-00008 TABLE 8 PK Parameter of Butorphanol in Plasma of Rats Butorphanol Tartrate Injection Butorphanol Liposome Dosage mg/kg 0.5 2 PK Parameter Mean SD Mean SD t.sub.1/2 h 1.04 0.08 15.70 3.91 t.sub.max h 0.26 0.09 0.50 0.00 C.sub.max ng .Math. mL−1 64.65 3.56 28.59 3.11 AUC.sub.0-t h .Math. ng .Math. mL−1 80.40 10.20 340.39 21.72 AUC.sub.0-inf h .Math. ng .Math. mL−1 81.68 10.55 368.63 37.45

[0156] After the rats were given the subcutaneous injection of butorphanol liposome and butorphanol tartrate injection, the times to peak (t.sub.max) are all within 0.5 h, indicating that the butorphanol liposome can take effect quickly in vivo. The half life (t.sub.1/2) of butorphanol liposome is about 15 times of that of the commercially available butorphanol tartrate injection, which proves that the butorphanol liposome has an ideal sustained-release effect. The administration dosage of the butorphanol liposome is about 4 times of that of the commercially available preparations, but peak concentration (C.sub.max) of the butorphanol liposome is lower than the concentration (C.sub.max) of the commercially available butorphanol tartrate injection, which proves that the butorphanol liposome has a better safety, and its clinically administration dosage can reach at least 4 times of that of the commercially available preparations. In summary, the PK data of the butorphanol liposome in rats show that this species can not only take effect quickly, but also maintain a longer effect of sustained release, and the higher tolerable dosage is conducive to improving the compliance of patients.

Embodiment 8: Analgesic Test of the Subcutaneous Injection of the Ropivacaine Liposome in Cavies

[0157] 1. Tested Drug

[0158] Ropivacaine liposome prepared in Embodiment 1;

[0159] Commercially available ropivacaine hydrochloride injection.

[0160] 2. Test Methods

[0161] Cavies were divided into the ropivacaine liposome low, middle and high-dosage groups and the ropivacaine hydrochloride injection group, with 10 cavies in each group, including 5 males and 5 females. The cavies in each group were given the subcutaneous injection of the ropivacaine liposome at a dosage of 0.4, 0.885 and 1.9 mg/cavy (approximately equivalent to 1.3, 2.9 and 6.3 mg/kg, calculated by the ropivacaine free base, the same below) and ropivacaine hydrochloride injection at a dosage of 0.885 mg/cavy (approximately equivalent to 2.9 mg/kg) at the upper part of the left rear leg, respectively; the pain threshold at the injected site was determined using the method of acupuncture at 0.5 h, 1 h, 2 h, 4 h, 6 h, 8 h, 10 h and 24 h after administration.

[0162] The results are shown in FIG. 8. The pain threshold at the injected site at the first detection point (0.5 h) after administration is significantly higher than that before administration (P<0.001); the peak pain threshold is reached at about 1 h after administration, and the ascending percentages of the peak pain threshold are 875.70%, 863.35% and 964.28%, respectively; then the pain threshold slowly decreases, but the pain threshold at 24 h is still higher than that before administration (P<0.05 or P<0.01), and the drug effect lasts for about 24 h. For the cavies given the subcutaneous injection of ropivacaine hydrochloride injection at a dosage of 0.885 mg/cavy, the pain thresholds after administration are significantly higher than that before administration (P<0.001), the peak pain threshold is reached at the first detection point (0.5 h) after administration, and the ascending percentage of the peak pain threshold is 961.23%; the pain threshold rapidly decreases from 4 h after administration, the pain threshold at 4 h after administration is about 45% of the peak pain threshold, the pain threshold at 24 h is not obviously different (P>0.05) from that before administration, and the analgesic effect lasts for about 10 h. At 4-10 h after administration, the pain threshold rapidly decreases in the cavies of the ropivacaine hydrochloride injection group, and the ascending percentage of the peak pain threshold in the cavies of the ropivacaine liposome 0.885 mg/cavy group is significantly higher than that in the ropivacaine hydrochloride injection 0.885 mg/cavy group (P<0.01 or P<0.001).

Embodiment 9: Analgesic Test of the Subcutaneous Injection of the Ropivacaine Liposome in Cavies

[0163] 1. Tested Drug

[0164] Ropivacaine liposome prepared in Embodiment 1;

[0165] Commercially available ropivacaine hydrochloride injection.

[0166] 2. Test Methods

[0167] The cavies which completed the administration of subcutaneous injection described in Embodiment 8 were subjected to a 7-day washout period, and then were used for the analgesic test of intracutaneous injection. The animals in each administration group (10 cavies in each group, including 5 males and 5 females) were given the intracutaneous injection of the ropivacaine liposome at a dosage of 0.2, 0.443 and 0.95 mg/cavy (approximately equivalent to 0.7, 1.5 and 3.1 mg/kg, calculated by the ropivacaine free base, the same below) and ropivacaine hydrochloride injection at a dosage of 0.443 mg/cavy (approximately equivalent to 1.5 mg/kg) at the upper part of the left rear leg, respectively; the pain threshold at the injected site was determined using the method of acupuncture at 0.5 h, 1 h, 2 h, 4 h, 6 h, 8 h, 10 h and 24 h after administration.

[0168] The results are shown in FIG. 9. The pain threshold at the injected site at the first detection point (0.5 h) after administration is significantly higher than that before administration (P<0.001); the peak pain threshold is reached at about 1 h-2 h after administration, and the ascending percentages of the peak pain threshold are 1006.41%, 922.63% and 1266.74%, respectively; then the pain threshold slowly decreases, but the pain thresholds in the cavies of the ropivacaine liposome groups at a dosage of 0.2 and 0.443 mg/cavy at 10 h after administration are still higher than that before administration (P<0.001), and the pain threshold in the cavies of the ropivacaine liposome group at a dosage of 0.95 mg/cavy at 24 h after administration is still higher than that before administration (P<0.001). The analgesic drug effect lasts for about 10 h in the cavies given the intracutaneous injection of ropivacaine liposome at a dosage of 0.2 and 0.443 mg/cavy, and the drug effect lasts for about 24 h in the cavies given the intracutaneous injection of ropivacaine liposome at a dosage of 0.95 mg/cavy. For the cavies given the intracutaneous injection of ropivacaine hydrochloride injection at a dosage of 0.443 mg/cavy, the pain threshold at the first detection point (0.5 h) after administration is significantly higher than that before administration (P<0.001), the peak pain threshold is reached at 1 h after administration, and the ascending percentage of the peak pain threshold is 1100.20%; the pain threshold rapidly decreases at 8 h after administration, by about 23% of the peak pain threshold; the peak pain threshold at 10 h is obviously higher than that before administration, but the pain threshold at 24 h is not obviously different from that before administration, and the analgesic effect lasts for about 10 h. At 6-10 h after administration, the ascending percentages of the peak pain threshold in the cavies of the group given the intracutaneous injection of ropivacaine lipid (0.443 mg/cavy) are significantly higher than those in the ropivacaine hydrochloride injection group (0.443 mg/cavy) (P<0.01 or P<0.001). At 2-24 h after administration, the ascending percentages of the peak pain threshold in the cavies of ropivacaine lipid group (0.95 mg/cavy) are significantly higher than those in the ropivacaine hydrochloride injection group (0.443 mg/cavy) (P<0.05, P<0.01 or P<0.001).

Embodiment 10: Analgesic Test at the Plantar Operative Incision in Rats

[0169] 1. Tested Drugs

[0170] Ropivacaine liposome prepared in Embodiment 1;

[0171] Commercially available ropivacaine hydrochloride injection.

[0172] 2. Test Methods

[0173] Rats were randomly divided by weights into the operation group, the ropivacaine liposome low, middle and high-dosage groups and the ropivacaine hydrochloride injection group, with 10 cavies in each group, including 5 males and 5 females, respectively. The right rear plantar skin was longitudinally incised with a scalpel for the animals of each group, the incisions were about 0.5 cm long and about 0.2 cm deep, and then the incisions were sutured. On Day 2 postoperatively, the animals in each group were given the plantar injection of ropivacaine liposome blank preparation, ropivacaine liposome (0.2, 0.443 and 0.95 mg/rat, approximately equivalent to 0.9, 1.9 and 4.2 mg/kg) and ropivacaine hydrochloride injection at a dosage of 0.443 mg/rat (approximately equivalent to 1.9 mg/kg), respectively; the pain threshold at the injected site was determined using the method of acupuncture at 0.5 h, 1 h, 2 h, 4 h, 6 h, 8 h, 10 h and 24 h after administration.

[0174] The results are shown in FIG. 10. After the plantar operation, the plantar pain threshold in the rats decreases obviously, and the descending percentages of the pain threshold are about 60%. At 0.5-10 h after the plantar injection, the pain thresholds in the rats of the ropivacaine liposome low, middle and high-dosage groups (0.2, 0.443 and 0.95 mg/rat) are significantly higher than that in the operation control group (P<0.05, P<0.01 or P<0.001), representing a dosage-independent at each time point; the analgesic effect of ropivacaine liposome lasts for about 10 h. For the rats given the plantar injection of ropivacaine hydrochloride injection at a dosage of 0.443 mg/rat, the pain thresholds at 0.5 h-2 h after administration are significantly higher than those in the operative control group (P<0.01 or P<0.001), and the analgesic drug effect lasts for about 2 h. For the rats given the plantar injection of ropivacaine liposome at a dosage of 0.443 mg/rat, the ascending percentages of the pain threshold at 6 h-8 h after administration are significantly higher than those in the ropivacaine hydrochloride injection group (0.443 mg/rat) (P<0.05 or P<0.01). For the rats given the plantar injection of ropivacaine liposome at a dosage of 0.95 mg/rat, the ascending percentages of the peak pain threshold at 1 h-10 h are significantly higher than those in the ropivacaine hydrochloride injection group (0.443 mg/rat) (P<0.05, P<0.01 or P<0.001).

Embodiment 11: A Ropivacaine Liposome

[0175]

TABLE-US-00009 TABLE 9 Mass Name of Material L2 L3 L4 Ropivacaine Free Base 3.23 g 3.23 g 3.23 g Ropivacaine 0.65 g 0.65 g 0.65 g Hydrochloride DMPC 1.62 g DEPC 8.58 g DLPC 5.94 g Cholesterol 0.92 g 1.85 g 1.85 g Tert-butanol 80 ml 80 ml 80 ml Water 20 ml 20 ml 20 ml Content of Active 18.335 mg/ml 19.095 mg/ml 19.798 mg/ml Substance Encapsulation Rate 83% 83% 84%

[0176] Phospholipid, cholesterol, ropivacaine free base, and ropivacaine hydrochloride were weighed and dissolved in 100 ml of tert-butanol-water mixed solvent, and then distributed into 20 ml vials, 5 ml per bottle. The samples were placed in a freeze dryer for freeze drying. The freeze dried product was redissolved in an appropriate amount of saline, and mixed uniformly to obtain the target liposome. The content of active substance and the encapsulation rate were determined.

Embodiment 12

[0177] The in vitro release of the ropivacaine liposome L2-L4 was determined using the test methods described in Embodiment 4. The test results are shown in the table below.

TABLE-US-00010 TABLE 10 Name of In Vitro Release Degree Sample 2 h 4 h 24 h 48 h 72 h 96 h L2 24.00% 29.55% 58.17% 74.77% 84.69% 90.42% L3 / 22.92% 56.72% 75.32% 83.50% 91.84% L4 18.91% 25.66% 50.28% 66.95% 77.65% 84.77%

[0178] Although the preferred embodiments of the present disclosure are described above, those of skill in the art should be understood that, these are illustrations only, and under the premise of not deviating from the principle and essence of the present invention, various changes or modifications can be achieved to these embodiments. Therefore, the protective scope of the present invention is defined by the claims attached.