Liquid sustained release preparation

Abstract

The invention discloses a liquid sustained release preparation. The preparation comprises an active component, an organic solvent, an amphoteric substance and / or oil, phospholipid and a stabilizer, wherein the active ingredient is selected from the following group: bupivacaine, ropivacaine, lidocaine, or a combination thereof; the organic solvent is selected from the following groups: a ketone organic solvent, a sulfone organic solvent, an amide organic solvent, an ester organic solvent and an alcohol organic solvent; the HLB value of the amphoteric substance is 1-8; the oil is selected from soybean oil, castor oil, corn oil, cottonseed oil, sesame oil or a combination thereof; the stabilizer is sulfur-containing organic acid or organic mercaptan. The preparation disclosed by the invention is simple in process, long in slow release time, mild in preservation condition and convenient for clinical use.

Description

Technical Field

[0001] This invention relates to the field of pharmaceutical preparations, and more specifically to a liquid sustained-release formulation. Background Technology

[0002] Postoperative pain is a complex physiological response of the body to the disease itself and surgical trauma; it is an acute form of pain. Postoperative pain brings about a series of physiological and psychological reactions in patients, leading to abnormalities in gastrointestinal function, cardiopulmonary function, coagulation function, and endocrine metabolism, and causing various complications, seriously affecting the patient's postoperative recovery.

[0003] Local anesthetics are drugs that reversibly block the generation and transmission of sensory nerve impulses at the site of application. Commonly used drugs in clinical practice include lidocaine, procaine, ropivacaine, bupivacaine, levobupivacaine, tetracaine, and benzocaine. Ordinary preparations, such as bupivacaine injection, typically have a duration of action of less than 6–12 hours. A single dose is insufficient for prolonged analgesia, while multiple doses result in poor patient compliance, prolonging hospital stays, increasing treatment costs, and causing significant fluctuations in blood drug concentrations with peak-and-trough effects, leading to a series of toxic side effects.

[0004] Marketed long-acting local anesthetic formulations include liposomes and gels. Liposomes include ropivacaine liposomes and bupivacaine hydrochloride liposomes (trade name: Expareel). These liposomes have complex formulations and manufacturing processes, making industrial production difficult. Long-term storage requires refrigeration at 2-8°C, and vesicles are prone to rupture, sedimentation, and aggregation during storage, which is detrimental to storage and transportation. Gel products include bupivacaine in situ gel (trade name: Posimir) and bupivacaine and meloxicam extended-release solution (trade name: Zynrelef), both approved by the US FDA. Bupivacaine and meloxicam sustained-release solutions (trade name: Zynrelef) are prepared using high-concentration polyorthoester polymers to create sustained-release formulations. Bupivacaine in-situ gel (trade name: Posimir) contains a high concentration of sucrose isobutyrate. Both of these gel products have excessive viscosity and low fluidity, making them inconvenient for clinical use. They require larger needles for local injection or can only be applied topically, and can also negatively impact wound healing and swelling. Furthermore, long-acting bupivacaine hydrochloride formulations under development include PLGA microspheres. However, PLGA microspheres have complex manufacturing processes, low drug loading, and degradation products such as lactic acid and glycolic acid can cause pH changes at the injection site, triggering inflammatory reactions. These shortcomings limit the application of PLGA microspheres in long-acting local anesthetic formulations. In addition, the main excipients of the aforementioned gel products are unconventional, with limited availability and high cost.

[0005] In addition, while long-acting local anesthetics on the market have significant advantages in safety, especially cardiac safety, compared to immediate-release bupivacaine hydrochloride, their efficacy has been questioned. For example, in a registrational phase 3 clinical trial of bupivacaine hydrochloride liposomes (trade name: Expareel), it only achieved clinically significant analgesia within 24 hours post-operation. However, numerous real-world studies have shown that Expareel's analgesic effect is not superior to conventional immediate-release local anesthetics (Anesthesiology 2021; 134:283–344). This means that even though Expareel's analgesic effect mainly occurs within 24 hours of administration, its analgesic effect (within 0-24 hours and 0-72 hours) has not been widely confirmed.

[0006] Therefore, it is necessary to innovate and develop a new type of long-acting local anesthetic formulation to address the problems of existing long-acting local anesthetic formulations. This formulation can exert analgesic effects within 72 hours after surgery, especially within 24 hours after surgery, while maintaining excellent safety. Preferably, the formulation has the characteristics of good stability, easy storage at room temperature, and more convenient and safer clinical use. More preferably, the formulation has better economic efficiency. Summary of the Invention

[0007] To address the aforementioned problems, this invention provides a liquid sustained-release formulation comprising a carrier and a pharmaceutical active ingredient, which can be administered via oral, injection, or topical routes.

[0008] In a first aspect of the present invention, a liquid sustained-release formulation is provided, the formulation comprising: an active ingredient, an organic solvent, an amphoteric substance and / or an oil, a phospholipid, and a stabilizer;

[0009] The active ingredient is an amide-based local anesthetic drug, and optionally a nonsteroidal anti-inflammatory drug;

[0010] The organic solvent is selected from the group consisting of: ketone organic solvents, sulfone organic solvents, amide organic solvents, ester organic solvents, and alcohol organic solvents;

[0011] The HLB value of the amphoteric substance is 1 to 8;

[0012] The oil is selected from the group consisting of soybean oil, castor oil, corn oil, cottonseed oil, sesame oil, or a combination thereof;

[0013] The stabilizer is a sulfur-containing organic acid or organic thiol;

[0014] Preferably, the amide-type local anesthetic is a compound selected from the group consisting of: levobupivacaine, ropivacaine, lidocaine, bupivacaine, or a combination thereof; the nonsteroidal anti-inflammatory drug is selected from the group consisting of: meloxicam, celecoxib, ibuprofen, flurbiprofen, flurbiprofen ester, or a combination thereof.

[0015] In another preferred embodiment, the formulation comprises: an active ingredient, an organic solvent, an oil, and a stabilizer.

[0016] In another preferred embodiment, the formulation comprises an active ingredient, an organic solvent, an amphoteric substance and / or an oil, and a stabilizer.

[0017] In another preferred embodiment, the formulation comprises an active ingredient, an organic solvent, an oil, and a stabilizer.

[0018] In another preferred embodiment, the formulation consists of an active ingredient, an organic solvent, and an oil.

[0019] In another preferred embodiment, the formulation comprises an active ingredient, an organic solvent, an amphoteric substance and / or an oil, phospholipids, and a stabilizer.

[0020] In a preferred embodiment, the ketone organic solvent is methylpyrrolidone;

[0021] The sulfone organic solvent is dimethyl sulfoxide;

[0022] The amide organic solvent is dimethylacetamide;

[0023] The ester organic solvent is selected from the group consisting of benzyl benzoate, triethyl glycerol, or combinations thereof;

[0024] The alcoholic organic solvent is selected from the group consisting of benzyl alcohol, ethanol, propylene glycol, or combinations thereof.

[0025] In a preferred embodiment, the organic solvent is selected from the group consisting of methylpyrrolidone, dimethyl sulfoxide, benzyl benzoate, benzyl alcohol, anhydrous ethanol, ethanol, propylene glycol, or combinations thereof.

[0026] In another preferred embodiment, the HLB value of the amphoteric substance is 1 to 5.

[0027] In a preferred embodiment, the amphoteric substance is selected from the group consisting of glyceryl stearate, glyceryl monooleate, glyceryl caprylate, glyceryl caprylate, propylene glycol laurate, or combinations thereof.

[0028] In a preferred embodiment, the phospholipid is selected from the group consisting of phosphatidylcholine, soybean phospholipids, egg yolk phospholipids, lecithin, or combinations thereof.

[0029] In a preferred embodiment, the stabilizer is selected from the group consisting of: methanesulfonic acid, acetylcysteine, thioglycerol, cysteine, or combinations thereof.

[0030] In a preferred embodiment, the stabilizer accounts for 0.01 to 10 wt% of the total weight of the formulation; preferably 0.01 to 5 wt%; more preferably 0.01 to 2 wt%.

[0031] In a preferred embodiment, the active ingredient accounts for 1 to 10 wt% of the total weight of the formulation; preferably 1 to 8 wt%; more preferably 1 to 5 wt%.

[0032] In a preferred embodiment, the amphoteric substance accounts for 15-80 wt% of the total weight of the formulation; more preferably 30-75 wt%; and more preferably 35-65 wt%.

[0033] In a preferred embodiment, the oil comprises 10–90 wt% of the total weight of the formulation; preferably 30–90 wt%; more preferably 40–85 wt%; and / or

[0034] The phospholipids comprise 0.1–50 wt% of the total weight of the formulation; preferably 1–50 wt%; more preferably 5–50 wt%.

[0035] In another preferred embodiment, the organic solvent accounts for 1 to 40 wt% of the total weight of the formulation; preferably 5 to 35 wt%; more preferably 5 to 30 wt%.

[0036] In another preferred embodiment, the phospholipid accounts for 0.1 to 50 wt% of the total weight of the formulation; preferably 1 to 50 wt%; more preferably 5 to 50 wt%.

[0037] In a second aspect of the invention, a local anesthetic drug is provided, wherein the local anesthetic drug uses the formulation described in the first aspect of the invention as the anesthetic active ingredient.

[0038] In a third aspect of the invention, a method of local anesthesia is provided, the method comprising administering the preparation of the first aspect of the invention to a subject in need.

[0039] In another preferred embodiment, the object is a human or non-human mammal, such as a rat, mouse, cat, dog, rabbit, pig, sheep, or cow.

[0040] It should be understood that, within the scope of this invention, the above-described technical features of this invention and the technical features specifically described below (such as in the embodiments) can be combined with each other to form new or preferred technical solutions. Due to space limitations, they will not be described in detail here. Attached Figure Description

[0042] Figure 1 The 50% mechanical pain threshold of each group of rats after administration of anesthetic drugs is shown. Detailed Implementation

[0043] Through long-term and in-depth research and extensive screening, the inventors have developed for the first time a liquid sustained-release formulation comprising a carrier and a pharmaceutical active ingredient, which can be administered orally, by injection, or topically. Based on this, the inventors have completed this invention.

[0044] abbreviations

[0045] HLB value: Hydrophilic-Lipophile Balance

[0046] SPC: Soybean lecithin

[0047] DMSO: Dimethyl sulfoxide

[0048] 1W: One week

[0049] 1M: One month

[0050] h: hours

[0051] Liquid sustained-release formulation

[0052] This invention provides a liquid sustained-release formulation comprising: an active ingredient, an organic solvent, an amphoteric substance and / or an oil, and / or a stabilizer;

[0053] The active ingredient is an amide-based local anesthetic drug and an optional nonsteroidal anti-inflammatory drug;

[0054] The organic solvent is selected from the group consisting of: ketone organic solvents, sulfone organic solvents, amide organic solvents, ester organic solvents, and alcohol organic solvents;

[0055] The HLB value of the amphoteric substance is 1 to 8;

[0056] The oil is selected from soybean oil, castor oil, corn oil, cottonseed oil, sesame oil, or a combination thereof;

[0057] The stabilizer is a sulfur-containing organic acid or an organic thiol;

[0058] Preferably, the amide-type local anesthetic is a compound selected from the group consisting of: levobupivacaine, bupivacaine, ropivacaine, lidocaine, or a combination thereof; the nonsteroidal anti-inflammatory drug is selected from the group consisting of: meloxicam, celecoxib, ibuprofen, flurbiprofen, flurbiprofen ester, or a combination thereof.

[0059] The formulation of the present invention is a formulation suitable for the slow release of anesthetic active ingredients over a certain period of time. Its storage stability during use is significantly improved compared with the formulations of the prior art, and the formulation can continue to release for up to 72 hours after local administration, especially maintaining release during the period of 24-72 hours.

[0060] The stabilizer can be any component of sulfur-containing organic acids and organothiols. In a preferred embodiment, the stabilizer is selected from the group consisting of: methanesulfonic acid, acetylcysteine, thioglycerol, cysteine, or combinations thereof.

[0061] In a preferred embodiment, the ketone organic solvent is methylpyrrolidone; the sulfone organic solvent is dimethyl sulfoxide; the amide organic solvent is dimethylacetamide; the ester organic solvent is selected from the group consisting of benzyl benzoate, triethyl glycerol, or combinations thereof; and the alcohol organic solvent is selected from the group consisting of benzyl alcohol, ethanol, propylene glycol, or combinations thereof. In the most preferred embodiment, the organic solvent is selected from the group consisting of methylpyrrolidone, dimethyl sulfoxide, benzyl benzoate, benzyl alcohol, anhydrous ethanol, ethanol, propylene glycol, or combinations thereof.

[0062] The amphoteric substance can be any component having the desired HLB value. In a preferred embodiment, the HLB value of the amphoteric substance is 1 to 5. In the best embodiment, the amphoteric substance is selected from the group consisting of glyceryl stearate, glyceryl monooleate, glyceryl caprylate, glyceryl caprylate, propylene glycol laurate, or combinations thereof.

[0063] In some preferred embodiments, the formulation further includes phospholipids, preferably selected from the group consisting of phosphatidylcholine, soybean phospholipids, egg yolk phospholipids, lecithin, or combinations thereof.

[0064] In another preferred embodiment, the formulation comprises: 0.01 to 10 parts by weight of stabilizer; preferably 0.01 to 5 parts by weight; more preferably 0.01 to 2 parts by weight.

[0065] In another preferred embodiment, the active ingredient accounts for 1 to 10 parts by weight of the total weight of the formulation; preferably 1 to 8 parts by weight; more preferably 1 to 5 parts by weight.

[0066] In another preferred embodiment, the amphoteric substance accounts for 15 to 80 parts by weight of the total weight of the formulation; preferably 30 to 75 parts by weight; more preferably 35 to 65 parts by weight.

[0067] In another preferred embodiment, the oil accounts for 10 to 90 parts by weight of the total weight of the preparation; preferably 30 to 90 parts by weight; more preferably 40 to 85 parts by weight.

[0068] In another preferred embodiment, the organic solvent accounts for 1 to 40 parts by weight of the total weight of the formulation; preferably 5 to 35 parts by weight; more preferably 5 to 30 parts by weight.

[0069] In another preferred embodiment, the phospholipid accounts for 0.1 to 50 parts by weight of the total weight of the formulation; preferably 1 to 50 parts by weight; more preferably 5 to 50 parts by weight.

[0070] Pharmaceutical compositions for local anesthesia

[0071] Since the formulations of the present invention are suitable as active ingredients in pharmaceutical compositions for local anesthetics, the formulations of the present invention can be used to prepare local anesthetic drugs, wherein the local anesthetic drugs use the formulations as described in the first aspect of the present invention as the anesthetic active ingredient.

[0072] The pharmaceutical composition can be prepared by adding any amount of other components that do not affect its efficacy and stability to the formulation as described in the first aspect of the invention, or by encapsulating the required amount of the formulation in a single- or multiple-dose delivery device suitable for local anesthetic administration, such as a pre-sealed syringe.

[0073] The main advantages of this invention are:

[0074] 1. The liquid sustained-release formulation of the present invention has the advantages of small dosage, long duration of action, low cost, more convenient clinical use, and high patient compliance.

[0075] 2. Existing bupivacaine liposome and microsphere formulations have complex preparation processes and demanding storage conditions (can only be maintained at 2-8℃ for a long time), while the liquid formulation of the present invention has a simple process, good stability, long sustained-release time (≥72h), and mild storage conditions (can be stored at 25℃ for a long time).

[0076] 3. Existing long-acting bupivacaine injections use unconventional, custom-made excipients (such as polyorthoesters), which are limited in source and costly. The formulation of this invention can achieve the technical effect of a long-acting formulation using conventional excipients, which has significant advantages.

[0077] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, were generally performed under conventional conditions or as recommended by the manufacturer. Unless otherwise stated, percentages and parts are weight percentages and parts by weight.

[0078] Example 1. Investigating the solubility of bupivacaine in different solvents

[0079] The solubility of bupivacaine base in aqueous phase (water, phosphate buffer at pH 7.4), organic phase (anhydrous ethanol, N-methylpyrrolidone, dimethyl sulfoxide, benzyl benzoate, propylene glycol, triethyl glycerol), and oil (castor oil, soybean oil, cottonseed oil, corn oil, sesame oil) at room temperature (0-30℃, preferably 10-30℃) was investigated.

[0080] The experimental results are shown in Table 1 below:

[0081] Table 1. Solubility of bupivacaine in different solvents

[0082]

[0083] Experiments show that bupivacaine has relatively low solubility in aqueous phases but high solubility in organic phases and oils, especially in anhydrous ethanol, N-methylpyrrolidone, benzyl benzoate, propylene glycol, dimethyl sulfoxide, castor oil, and cottonseed oil. Therefore, organic phases or oils are used as solvents in subsequent formulations.

[0084] Example 2. Investigating the effects of different amphoteric substances and oils on the phase transition of the formulation in water.

[0085] Weigh the ingredients according to Formula 1 in Table 2, stir magnetically at room temperature, and dissolve until the solution becomes a transparent liquid to obtain the liquid formulation. Inject the above formulation into water using a syringe to investigate the effects of different amphoteric substances and oils on the phase transition of the formulation in water.

[0086] Among them, the amphoteric substance glyceryl stearate ( ATO 5), glyceryl monooleate (Peceol) TM ), caprylic / capric acid glyceride mono- and diglycerides (Labrafac) TM MC60) and propylene glycol lauroate TM FCC), lauroyl polyoxyethylene-32 glycerol ester ( The HLB values ​​for 44 / 14 are 1, 3.5, 5, 5, and 11, respectively.

[0087] Table 2. Effects of different amphoteric substances and oils on the phase change of the formulation in water

[0088]

[0089]

[0090] As shown in Table 2 above, formulations numbered 1-5 all exhibited good phase transitions and formed reservoirs, with HLB values ​​all less than 8. However, formulation number 5, which uses an amphoteric substance, had an HLB value greater than 8 and could not form a morphologically stable reservoir. Formulations numbered 6-10, being oil-based and not amphoteric substances, also formed good reservoirs.

[0091] This experiment shows that formulations using amphoteric substances (glyceryl stearate, glyceryl monooleate, glyceryl caprylate, caprylic / capric acid mono- and diglycerides, and propylene glycol laurate) and oils (soybean oil, castor oil, cottonseed oil, corn oil, and sesame oil) with HLB in the range of 1-8 can all form significant phase transitions in vitro, forming reservoirs that facilitate sustained release of the formulation.

[0092] Therefore, an amphoteric substance or oil with HLB in the range of 1-8 is added to subsequent formulations.

[0093] Example 3. Investigating the effect of different phospholipids on the phase transition of the formulation in water.

[0094] Weigh the ingredients according to the prescription in the table below, stir magnetically at room temperature, and dissolve until the solution becomes a clear liquid to obtain the liquid formulation. Inject the above formulation into water using a syringe to investigate the effect of different phospholipids on the phase transition of the formulation in water.

[0095] Table 3. Effects of different phospholipids on phase transition of the formulation in water

[0096]

[0097] Table 3 shows that formulations containing hydrogenated soybean lecithin cannot form reservoirs, while egg yolk lecithin and soybean lecithin (SPC) can. Reservoir formation indicates a potential for sustained release, while the absence of a reservoir suggests otherwise. Furthermore, considering the source, egg yolk lecithin is derived from egg yolks, while soybean lecithin is derived from plants and is less likely to cause allergies; from a cost perspective, soybean lecithin is more readily available and cheaper.

[0098] Example 4. Screening of stabilizers

[0099] Weigh the ingredients according to Formula 2 in Table 4, stir magnetically at room temperature until the solution becomes a clear liquid, thus obtaining the liquid formulation. Store at 40°C for one week to investigate the effect of different organic acid stabilizers on the stability of the formulation.

[0100] Table 4. Prescription 2

[0101]

[0102] The experimental results are shown in Table 5 below:

[0103] Table 5. Effects of different organic acids on formulation stability

[0104]

[0105]

[0106] Experimental results showed that the content of organic acid stabilizers varied significantly in formulations without them (Formulation 1). The addition of organic acid stabilizers (Formulations 3-5) significantly improved the stability of the formulations, especially sulfur-containing organic acids such as methanesulfonic acid (Formulation 3) and acetylcysteine ​​(Formulation 5). Furthermore, the addition of glycine did not have a positive effect on stability, suggesting that this improvement was not related to pH adjustment itself, but rather to the addition of sulfur-containing substances.

[0107] Example 5. Screening of solvent and stabilizer combinations

[0108] Weigh the contents of Formula 3 in Table 6 below, stir magnetically at room temperature, and dissolve until the solution becomes a transparent liquid to obtain the liquid preparation.

[0109] Table 6. Prescription 3

[0110]

[0111]

[0112] The above preparations were placed at 40℃ and 25℃, and the total impurities were detected by HPLC at 0 days, 2 weeks, and 1 month. The results are shown in Table 7 below:

[0113] Table 7. Effects of solvent and different stabilizer combinations on formulation stability

[0114]

[0115]

[0116] In summary, formulations containing solvents such as anhydrous ethanol or propylene glycol and stabilizers (formulations 2, 3, and 6) showed significant impurity growth and poor stability. However, combinations containing solvents such as DMSO and stabilizers such as methanesulfonic acid or acetylcysteine ​​(formulations 1, 4, 5, and 8-11) significantly increased formulation stability, with almost zero impurity growth after one month at 40°C and 25°C.

[0117] Example 6. In vitro dissolution experiment

[0118] Weigh the contents of Formula 4 in Table 8 below, stir magnetically at room temperature, and dissolve until the solution becomes a transparent liquid to obtain the liquid preparation.

[0119] Table 8. Prescription 4

[0120]

[0121] Prepare liquid formulations according to the serial numbers in Table 8, take 200 mg and place them in a dialysis bag, shake at 37℃ and 250 rpm, and take samples at 8 h, 24 h, 48 h and 72 h to detect the release amount. The results are shown in Table 9 below:

[0122] Table 9. In vitro dissolution effect of the formulation of the present invention.

[0123]

[0124] Experimental results show that all liquid formulations of the present invention can achieve sustained release for 72 hours, and as can be seen from formulations 4 to 6, the release can be adjusted by different percentages of stabilizer. Furthermore, the results from formulation 6 show that the release rate at 72 hours for each formulation using DMSO as a solvent, without the addition of stabilizer, is slightly lower than that of other formulations. Therefore, it is preferable to add stabilizer to the liquid formulation.

[0125] Example 7. Long-term stability test

[0126] The preparations prepared according to Formula 4 in Table 8 were placed at 40°C, and the total impurities were detected by HPLC at 0 days, 1 month, and 3 months. The results are shown in Table 10 below:

[0127] Table 10. Long-term stability of the formulation of the present invention.

[0128]

[0129] Experimental results show that the liquid formulations of the present invention exhibit excellent stability, especially when containing the solvent DMSO and organic acid stabilizers (formulations 1-5), the resulting liquid formulations demonstrate exceptionally high stability. In contrast, formulation 6, which contains only the solvent DMSO and no organic acid stabilizers, showed a significant increase in impurities during stability testing.

[0130] Therefore, adding organic acid stabilizers to formulations using DMSO as a solvent is beneficial for controlling the growth of impurities and improving the stability of the formulation.

[0131] Example 8. Rat PK Experiment

[0132] The PK experiment was conducted on SD rats using the preparations formulated according to prescription 4 in Table 8 and the marketed long-acting local anesthetic preparation Expalar. Rats were selected at 6-9 weeks of age, and the experimental protocol is shown in Table 11 below:

[0133] Table 11. Animal grouping and administration

[0134]

[0135]

[0136] Rats were administered the formulation via a single subcutaneous injection. Blood samples of 0.15 mL were collected from the jugular vein before administration and at 0.25, 0.5, 1, 2, 4, 8, 10, 24, 48, and 72 hours after administration. The collected whole blood was placed in EDTA-K2 anticoagulant tubes, thoroughly mixed by inverting several times, and stored on moist ice. The tubes were then centrifuged (1500–1600 g) for 10 minutes within 30 minutes to separate the plasma. The plasma samples were stored at -40 to -20°C for biological sample analysis. The results are shown in Table 12 below.

[0137] Table 12. In vivo metabolism of the formulation of the present invention.

[0138]

[0139]

[0140] In animal experiments, if the active drug can be detected in the animal's blood sample at 72 hours, it indicates that the formulation can be continuously released. As shown in the table above, the active drug can be detected in formulations 1-6 of this application at 72 hours, indicating that the formulations of this application can be continuously released in vivo for 72 hours.

[0141] As can be seen from formulations 1-3, different proportions of API and different proportions of amphoteric substances can all enable the formulation to release for 72 hours;

[0142] In formulations 4–6, the proportion of stabilizers was: formulation 5 (2%) > formulation 4 (1%) > formulation 6 (no stabilizer). Their corresponding AUC values ​​at 24h–72h (and AUC values) were as follows: 0-72h With AUC 0-24h The difference was that formulation 5 > formulation 4 > formulation 6, indicating that increasing the proportion of stabilizer helps to increase the release of the formulation after 24 hours.

[0143] Therefore, the formulations of the present invention can significantly prolong release in rats (release duration ≥72h), and the addition of stabilizers can regulate release, significantly increasing the release of bupivacaine after 24h.

[0144] Based on the exposure AUC, the exposure levels of formulations 1-6 of this invention within 0-24h were all higher than those of the marketed bupivacaine liposome Expareel, indicating that the analgesic effect of the formulations of this invention is superior within 0-24h.

[0145] Example 9. Screening of stabilizer types

[0146] This experiment further screened the effects of different types of stabilizers on in vitro dissolution and stability. The contents of Formula 5 in Table 13 were weighed, and the solution was dissolved by magnetic stirring at room temperature until it became a transparent liquid, thus obtaining the liquid formulation.

[0147] Table 13, Prescription 5

[0148]

[0149] When preparing liquid formulations according to the serial numbers of prescription 5 in Table 13, it was found that preparations 2, 6, and 7 containing butylated hydroxytoluene could not be completely dissolved into clear and transparent solutions, while the other preparations could be prepared into solutions.

[0150] 200 mg of each of formulations 1, 3, 4, and 5 were placed in dialysis bags and shaken at 37°C and 250 rpm. Samples were taken at 8 h, 24 h, 48 h, and 72 h to detect the release. The results are shown in Table 14 below:

[0151] Table 14. In vitro dissolution effect of the formulation of the present invention.

[0152]

[0153] Experimental results showed that the stabilizers thioglycerol (formulation 1), cysteine ​​(formulation 3), butylated hydroxyanisole (formulation 4), and vitamin E acetate (formulation 5) had no effect on dissolution.

[0154] The formulations prepared according to Table 13 were placed at 40°C, and the total impurities were detected by HPLC at day 0 and month 1. The results are shown in Table 15 below:

[0155] Table 15. Stability of the formulation of the present invention.

[0156]

[0157] Experimental results showed that the total impurities in the formulations containing the stabilizers cysteine ​​(formulation 3) and thioglycerol (formulation 1) did not increase significantly, indicating that the addition of sulfur-containing organic acids (such as cysteine) or sulfur-containing organic thiols (thioglycerol) can improve the stability of the formulations.

[0158] Example 10. Screening of stabilizer dosage

[0159] Weigh the contents of Formula 6 in Table 16 below, stir magnetically at room temperature, and dissolve until the solution becomes a transparent liquid to obtain the liquid preparation.

[0160] Table 16. Prescription 6

[0161]

[0162] Prepare the liquid formulations according to the serial numbers of Formula 6 in Table 16. Take 200 mg of each formulation and place them in dialysis bags. Shake at 37℃ and 250 rpm. Take samples at 8h, 24h, 48h, and 72h to detect the release. The results are shown in Table 17 below:

[0163] Table 17. In vitro dissolution effect of the formulation of the present invention.

[0164]

[0165]

[0166] Experimental results show that different amounts of stabilizers (such as sulfur-containing organic acid cysteine ​​and sulfur-containing organic thioglycerol) have no effect on dissolution.

[0167] The formulations prepared according to Table 16 were placed at 40°C, and the total impurities were detected by HPLC at day 0 and month 1. The results are shown in Table 18 below:

[0168] Table 18. Stability of the formulation of the present invention.

[0169]

[0170] Experimental results show that different amounts of stabilizers (such as sulfur-containing organic acids cysteine ​​and sulfur-containing organic thioglycerols) have little effect on stability.

[0171] In summary, the results show that different amounts of sulfur-containing alcohols and sulfur-containing organic acids, namely thioglycerol and cysteine, have good stability for different formulations and have no effect on dissolution.

[0172] Example 11. Dissolution and stability of different formulations (including compound preparations containing nonsteroidal anti-inflammatory drugs).

[0173] Weigh the contents of Formula 7 in Table 19 below, stir magnetically at room temperature, and dissolve until the solution becomes a transparent liquid to obtain the liquid preparation.

[0174] Table 19. Prescription 7

[0175]

[0176] During the preparation process, it was unexpectedly discovered that when the amount of bupivacaine was 50 mg / g, mesylic acid (formulation 2) needed to be added to prepare a clear solution, indicating that mesylic acid can increase the solubility of bupivacaine in this formulation.

[0177] Prepare liquid formulations according to the serial numbers in Table 19, take 200 mg and place them in a dialysis bag, shake at 37℃ and 250 rpm, and take samples at 8h, 24h, 48h and 72h to detect the release amount. The results are shown in Table 20 below:

[0178] Table 20. In vitro dissolution effect of the formulation of the present invention.

[0179]

[0180]

[0181] According to the in vitro dissolution (Example 6) and in vivo PK results (Example 8) of the formulation prepared by Formula 4 in Table 8, it can be seen that the formulation that can be continuously released in vitro for 72 hours can also be sustained in vivo for 72 hours, indicating that the formulation of the present invention has good in vitro-in vivo correlation.

[0182] As can be seen from Table 20 of this embodiment, the formulations prepared according to Formula 5 in Table 19 can be continuously released in vitro for 72 hours. Therefore, it can be predicted that the formulations in Formula 5 in Table 19 can be continuously released in vivo for 72 hours, indicating that the formulations of the present invention have excellent sustained-release effect.

[0183] The formulations prepared according to Table 19 were placed at 40°C, and the total impurities were detected by HPLC at day 0 and month 1. The results are shown in Table 21 below:

[0184] Table 21. Stability of the formulation of the present invention.

[0185]

[0186] Experimental results show that the formulations of the present invention have good stability. The total impurities in the compound preparation (formulation 7) containing the nonsteroidal anti-inflammatory drug meloxicam are slightly higher than those in other formulations, but still within the allowable range. Moreover, the growth rate of total impurities is slow, and the overall stability is maintained.

[0187] Example 12. Wistar rat efficacy experiment

[0188] Weigh the contents of Formula 8 in Table 22 below, stir magnetically at room temperature, and dissolve until the solution becomes a transparent liquid to obtain the liquid preparation.

[0189] Table 22. Prescription 8

[0190]

[0191] The efficacy experiment of Wistar rats was conducted using the formulation prepared according to Table 22. The experimental protocol is shown in Table 23 below:

[0192] Table 23. Animal grouping and administration

[0193] Formulation serial number Animal numbers dose route of administration Is fasting necessary? Model group 4 physiological saline subcutaneous injection no Exparel 4 0.04ml / each subcutaneous injection no 1 4 0.04ml / each subcutaneous injection no 2 4 0.04ml / each subcutaneous injection no 3 4 0.04ml / each subcutaneous injection no 4 4 0.04ml / each subcutaneous injection no

[0194] Animal sex: Male;

[0195] Establishment of the incision pain model: Rats were anesthetized with isoflurane. The left foot was disinfected with 75% alcohol. A 1cm longitudinal incision was made anteriorly at 0.5cm on the rat's foot using a No. 11 scalpel blade. The fascia and muscles were separated, the flexor muscles were elevated, and the muscles were longitudinally incised. After gentle pressure to stop bleeding, the wound was closed, and the skin was sutured with 3-0 sutures. The rats were returned to their cages after regaining consciousness.

[0196] Administer antibiotics to prevent infection;

[0197] Subcutaneous administration: After the incision was sutured, two injection points were made on both sides of the incision, 0.02 ml at each point, 0.04 ml per animal; the model group was given an equal volume of physiological saline.

[0198] The rat mechanical hyperalgesia test - Von Frey method: After drug administration, the mid-foot of the hind limb on the operated side of the rat was stimulated with Von Frey monofiber at different time points, and the mechanical claw withdrawal threshold was tested as the pain threshold.

[0199] The "up-and-down" method was used for testing: Nine intensities of Von Frey filaments (equivalent to 1, 1.4, 2, 4, 6, 8, 10, 15, and 26 g) were used. Rats were placed in custom-made organically partitioned glass boxes with metal mesh bottoms. Before testing, rats were allowed to acclimatize to the new environment for at least 15 minutes. During testing, all animals were stimulated with a 6 g filament on the plantar surface of the rat's hind paw (approximately 3 mm from the incision). Uniform pressure was applied to bend the filament (approximately 90°) and held for about 1 second. If the animal exhibited an escape response (defined as X), the above procedure was repeated with the next higher intensity filament until no escape response (defined as O) occurred. After the first occurrence of XO or OX, the next higher or lower intensity filament was used to measure 4 times using the "up-and-down" method. The interval between each filament change was approximately 30 seconds. Detailed test results were recorded, and the minimum intensity of the escape response and the 50% escape threshold (Von Frey test) were calculated. If an animal showed no escape response to a 26g filament stimulus, its pain threshold was considered to be 26g; if an animal showed an escape response to a 1g filament stimulus, its pain threshold was considered to be 1g. Tests were conducted before modeling and at 1, 3, 8, 24, 48, and 72 hours after drug administration. Results are as follows: Figure 1 As shown.

[0200] Based on the efficacy results, the 50% mechanical pain threshold was consistent across all groups before administration, but after modeling and administration, the 50% mechanical pain threshold in the model group decreased rapidly, indicating that the modeling was successful.

[0201] In addition, the 50% mechanical pain threshold in the Expare group was significantly higher than that in the model group within 8 hours, but the 50% mechanical pain threshold in the group after 24 hours was not much different from that in the model group, indicating that the effect of the marketed long-acting local anesthetic Expare can only last for about 8 hours, and the analgesic duration is relatively short.

[0202] Formulations 1, 2, and 4 all had a higher 50% mechanical pain threshold within 24 hours than Expare, indicating that their analgesic effect and duration of analgesia were superior to Expare.

[0203] Formulation 3 had a higher 50% mechanical pain threshold than Expare in the 0-72h range, indicating that its analgesic effect and duration of analgesia were significantly better than Expare.

[0204] All documents mentioned in this invention are incorporated herein by reference as if each document were individually incorporated by reference. Furthermore, it should be understood that after reading the foregoing teachings of this invention, those skilled in the art can make various alterations or modifications to this invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A liquid sustained-release formulation, characterized in that, The formulation includes: active ingredients, organic solvents, amphoteric substances and / or oils, phospholipids, and stabilizers; The active ingredient is an amide-based local anesthetic drug and an optional nonsteroidal anti-inflammatory drug; The organic solvent is selected from the group consisting of: ketone organic solvents, sulfone organic solvents, amide organic solvents, ester organic solvents, and alcohol organic solvents; The HLB value of the amphoteric substance is 1 to 8; The oil is selected from the group consisting of soybean oil, castor oil, corn oil, cottonseed oil, sesame oil, or a combination thereof; The stabilizer is a sulfur-containing organic acid or organic thiol; Preferably, the amide-type local anesthetic is a compound selected from the group consisting of: bupivacaine, ropivacaine, lidocaine, levobupivacaine, or a combination thereof; the nonsteroidal anti-inflammatory drug is selected from the group consisting of: meloxicam, celecoxib, ibuprofen, flurbiprofen, flurbiprofen ester, or a combination thereof.

2. The formulation according to claim 1, characterized in that, The ketone organic solvent is methylpyrrolidone; The sulfone organic solvent is dimethyl sulfoxide; The amide organic solvent is dimethylacetamide; The ester organic solvent is selected from the group consisting of benzyl benzoate, triethyl glycerol, or combinations thereof; The alcoholic organic solvent is selected from the group consisting of benzyl alcohol, ethanol, propylene glycol, or combinations thereof.

3. The formulation according to claim 1, characterized in that, The organic solvent is selected from the group consisting of methylpyrrolidone, dimethyl sulfoxide, benzyl benzoate, benzyl alcohol, anhydrous ethanol, ethanol, propylene glycol, or combinations thereof.

4. The formulation according to claim 1, characterized in that, The amphoteric substance is selected from the group consisting of: glyceryl stearate, glyceryl monooleate, glyceryl caprylate, glyceryl caprylate, propylene glycol laurate, or combinations thereof.

5. The formulation as described in claim 1, characterized in that, The phospholipids are selected from the group consisting of phosphatidylcholine, soybean phospholipids, egg yolk phospholipids, lecithin, or combinations thereof.

6. The formulation according to claim 1, characterized in that, The stabilizer is selected from the group consisting of: methanesulfonic acid, acetylcysteine, thioglycerol, cysteine, or combinations thereof; The stabilizer accounts for 0.01 to 10 wt% of the total weight of the formulation; preferably 0.01 to 5 wt%; more preferably 0.01 to 2 wt%.

7. The formulation according to claim 1, characterized in that, The active ingredient accounts for 1 to 10 wt% of the total weight of the formulation; preferably 1 to 8 wt%; more preferably 1 to 5 wt%.

8. The formulation according to claim 1, characterized in that, The amphoteric substance accounts for 15-80 wt% of the total weight of the formulation; preferably 30-75 wt%; more preferably 35-65 wt%.

9. The formulation according to claim 1, characterized in that, The oil comprises 10–90 wt% of the total weight of the preparation; preferably 30–90 wt%; more preferably 40–85 wt%; and / or The phospholipids comprise 0.1–50 wt% of the total weight of the formulation; preferably 1–50 wt%; more preferably 5–50 wt%.

10. A local anesthetic drug, characterized in that, The local anesthetic drug uses the formulation described in any one of claims 1-9 as the anesthetic active ingredient.

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