An ophthalmic nanomicellar composition and a method of making the same
Patent Information
- Application Number
- CN202610930806.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-06-26
- Publication Date
- 2026-08-18
AI Technical Summary
[0007]本发明的目的在于提供一种眼用纳米胶束组合物，以解决现有物理包封胶束在泪液稀释下稳定性差、药物易突释的问题
[0032](1) This invention pre-modifies the drug into a prodrug containing ortho-dihydroxyl groups and allows it to participate in the dynamic covalent cross-linking of phenylboronic acid esters during micelle self-assembly, thus firmly "anchoring" the drug to the micelle core in the form of covalent bonds. This strategy can effectively resist extreme dilution of ocular surface tears. Even under harsh conditions of 100-fold dilution, the cumulative leakage rate of the drug within 1 hour is still less than 30%, and the particle size change is less than 20%, which significantly inhibits burst release and ensures the integrity of the micelles on the ocular surface.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of pharmaceutical formulation technology, specifically relating to an ophthalmic nanomicelle composition and its preparation method. Background Technology
[0002] Ocular drug delivery, especially to the posterior segment of the eye, has always faced multiple challenges, including rapid clearance from the ocular surface, tear dilution, and the corneal barrier. Traditional eye drops lose a large amount of drug through the nasolacrimal duct after administration, resulting in a very short retention time on the ocular surface and a bioavailability that is usually less than 5%. To overcome these shortcomings, nanomicelles, as a nanocarrier that can solubilize hydrophobic drugs and improve corneal permeability, have attracted widespread attention.
[0003] However, traditional nanomicelles that physically encapsulate drugs have a significant weakness in the ocular environment: when eye drops are applied to the ocular surface, the micelles are rapidly diluted by a large amount of tear fluid (the dilution factor can be tens to hundreds of times).
[0004] This extreme dilution can cause rapid disintegration or swelling of the micelle structure, resulting in a large-scale burst release of the encapsulated drug in a short period of time (i.e., "burst release"). This not only reduces the effective dose of the drug to reach the target, but may also cause irritation due to excessively high local drug concentration. At the same time, the disintegrated micelle fragments cannot maintain a suitable particle size, which significantly reduces their ability to penetrate the corneal epithelium.
[0005] In recent years, strategies to enhance the stability of cross-linked micelles under dilution conditions by constructing reversible covalent bonds (dynamic covalent bonds of phenylboronic acid esters) between phenylboronic acid and 1,2- or 1,3-diol have been reported, but these strategies are mainly focused on antitumor drug delivery systems. Such systems usually rely on a mechanism that is stable at physiological pH (7.4) and breaks down in the weakly acidic microenvironment of tumors. However, the ocular environment has its own characteristics: the pH of tears on the healthy ocular surface is maintained at around 7.4, and there is no acidic environment similar to that of tumor tissue. At the same time, commonly used ophthalmic drugs (such as dexamethasone, cyclosporine A, tacrolimus, etc.) differ significantly from antitumor drugs in chemical structure and hydrophilicity / hydrophobicity, making it difficult to directly apply the above strategies to meet the specific requirements of ophthalmic formulations.
[0006] Therefore, developing an ophthalmic micelle composition that can resist extreme tear dilution, significantly inhibit drug burst release, and maintain stable nanoscale to facilitate ocular penetration remains a pressing technical problem to be solved. Summary of the Invention
[0007] The purpose of this invention is to provide an ophthalmic nanomicelle composition to solve the problems of poor stability and easy drug burst release of existing physically encapsulated micelles under tear dilution.
[0008] Another object of the present invention is to provide a method for preparing the above-mentioned ophthalmic nanomicelle composition.
[0009] To achieve the above objectives, the present invention provides the following technical solution:
[0010] An ophthalmic nanomicelle composition comprising:
[0011] (a) An amphiphilic block copolymer composed of methoxy polyethylene glycol (mPEG) segments bonded to hydrophobic copolymer segments;
[0012] The number-average molecular weight of the mPEG segments is 1000 to 5000 Da;
[0013] The hydrophobic copolymer segments are formed by random copolymerization of X and Y units in a molar ratio of 4:1 to 1:1, and their number average molecular weight is 1000 to 5000 Da.
[0014] The X unit is selected from repeating units of lactide, ε-caprolactone, or trimethylene carbonate;
[0015] The Y unit is a cyclic carbonate repeating unit containing phenylboronic acid side groups, and its structure is as follows:
[0016] The main chain of the repeating unit of the cyclic carbonate is a six-membered cyclic carbonate structure. A side group is attached to the ring of the six-membered cyclic carbonate. The side group is a -L-phenylboronic acid group, where L is a straight-chain or branched alkylene group with 1 to 6 carbon atoms. One end of L is connected to the benzene ring of the phenylboronic acid group through an amide bond (-NH-CO-), and the other end is connected to the ring structure of the six-membered cyclic carbonate.
[0017] (b) A drug prodrug containing an ortho-dihydroxy structure, said drug prodrug being formed from a hydrophobic ophthalmic drug selected from dexamethasone, prednisolone, cyclosporine A, tacrolimus or voriconazole, by linking a glycerol group or a catechol group through a linking arm containing an ester bond or a carbonate bond.
[0018] In this process, the ortho-dihydroxy group of the drug prodrug and the phenylboronic acid side group of the Y unit in the amphiphilic block copolymer are cross-linked in the micelle core through dynamic covalent bonds of phenylboronic acid ester, thereby anchoring the drug prodrug in the core of the micelle in a covalent form.
[0019] Furthermore, the ophthalmic nanomicelle composition has the following properties: at 37°C, after diluting the micelle dispersion of the composition 100 times with isotonic phosphate buffer at pH 7.4, the cumulative leakage rate of the drug prodrug is less than 30% within 1 hour, and the average particle size change of the micelles does not exceed 20%.
[0020] In a preferred embodiment, the molar ratio of X to Y in the amphiphilic block copolymer is 3:1 to 2:1.
[0021] In a preferred embodiment, the drug prodrug is a prodrug formed by linking dexamethasone to a glycerol group via a succinate linker arm.
[0022] In a preferred embodiment, the drug prodrug is a prodrug formed by linking cyclosporine A to a catechol group via a carbonate linker arm.
[0023] In a preferred embodiment, the drug prodrug is a tacrolimus prodrug formed by linking a glutarate linker to a glycerol group.
[0024] In a preferred embodiment, the average particle size of the nuclear crosslinked micelles is 20 to 80 nm, and the polydispersity index is less than 0.15.
[0025] In a preferred embodiment, the ophthalmic nanomicelle composition is in the form of eye drops.
[0026] The present invention also provides a method for preparing the above-mentioned ophthalmic nanomicelle composition, comprising the following steps:
[0027] (1) Dissolve the amphiphilic block copolymer and the drug prodrug together in an organic solvent miscible with water to obtain an organic phase solution;
[0028] (2) At 0 to 10 °C and with stirring, the organic phase solution is added to a phosphate buffer solution with pH 7.2 to 7.8 to perform self-assembly and at the same time, the side group of the phenylboronic acid forms a dynamic covalent crosslink of phenylboronic acid ester with the ortho-dihydroxy group to obtain a nuclear crosslinked predrug nanomicelle dispersion.
[0029] (3) Remove the organic solvent and optionally adjust the micelle concentration and / or remove unassembled free molecules to obtain the ophthalmic nanomicelle composition.
[0030] Preferably, the organic solvent in step (1) is acetone or tetrahydrofuran; the phosphate buffer in step (2) is an isotonic phosphate buffer with pH 7.4. After removing the organic solvent in step (3), the process may further include adding an osmotic pressure regulator and a preservative to prepare eye drops.
[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0032] (1) This invention pre-modifies the drug into a prodrug containing ortho-dihydroxyl groups and allows it to participate in the dynamic covalent cross-linking of phenylboronic acid esters during micelle self-assembly, thus firmly "anchoring" the drug to the micelle core in the form of covalent bonds. This strategy can effectively resist extreme dilution of ocular surface tears. Even under harsh conditions of 100-fold dilution, the cumulative leakage rate of the drug within 1 hour is still less than 30%, and the particle size change is less than 20%, which significantly inhibits burst release and ensures the integrity of the micelles on the ocular surface.
[0033] (2) The cross-linking bond of the phenylboronic ester is a dynamic covalent bond, which is stable at physiological pH. After endocytosis into the cell, it can be gradually broken under the action of the intracellular microenvironment (such as weak acidity, high reactive oxygen species or esterases). At the same time, the ester bond or carbonate bond of the prodrug can also be degraded, so as to realize intelligent and controllable release of active drug.
[0034] (3) The micelle composition can maintain a uniform particle size of 20 to 80 nm, which is very suitable for crossing the ocular surface mucus layer and dense corneal epithelium, and is beneficial to improving the intraocular delivery efficiency of drugs. Attached Figure Description
[0035] Figure 1 This is a flowchart illustrating the preparation process of the present invention.
[0036] Figure 2 This is a bar chart comparing the cumulative leakage rate of the embodiment and the comparative example after dilution by 100 times over 1 hour. Detailed Implementation
[0037] The present invention will be further described in detail below with reference to specific embodiments and accompanying drawings, but the present invention is not limited thereto.
[0038] I. Synthesis of Amphiphilic Block Copolymers
[0039] Synthesis Example 1: Synthesis of mPEG-bP(LA-co-MTC-BA) (X = lactide, Y = MTC-BA, X:Y molar ratio 3:1)
[0040] Preparation of monomer Y, MTC-BA: Starting with 5-methyl-5-hydroxymethyl-1,3-dioxane-2-one (MTC-OH), it was deprotected after reaction with pinacol 4-(4-bromobutamido)phenylboronic acid. Its structure is 5-methyl-5-((4-(4-boronic acid benzamido)butyryloxy)methyl)-1,3-dioxane-2-one. L is -(CH2)4-, with one end connected to the benzene ring of the phenylboronic acid group via an amide bond (-CO-NH-), and the other end connected to the methylene group on the cyclic carbonate ring via an ester bond.
[0041] Under anhydrous conditions, DL-lactide (monomer X) and MTC-BA (monomer Y) were added to a reaction flask in a designed molar ratio using mPEG (molecular weight 2000 Da) as the initiator and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as the catalyst, and reacted at room temperature for 24 h using dichloromethane as the solvent. The product was precipitated with ice-cold ether and dried under vacuum to obtain the block copolymer mPEG-bP (LA-co-MTC-BA). Characterization by gel permeation chromatography (GPC) and nuclear magnetic resonance (NMR) showed that the number-average molecular weight of the hydrophobic segment was approximately 3100 Da, the molecular weight of mPEG was 2000 Da, and the actual molar ratio of X to Y was approximately 2.9:1.
[0042] By using a similar method, the monomer types and feed ratios were adjusted to synthesize the polymers required in Examples 2 and 3, respectively (see Table 1 for details).
[0043] II. Synthesis of drug prodrugs containing ortho-dihydroxy structures
[0044] Prodrug A: Dexamethasone-succinate-glycerol. Dexamethasone was reacted with succinic anhydride in anhydrous pyridine to give dexamethasone-21-succinate monoester. This monoester was then esterified with 1,2-O-isopropylglycerol under DCC / DMAP catalysis, and finally the isopropylene protection was removed with 80% aqueous acetic acid to give prodrug A containing an ortho-dihydroxy group.
[0045] Prodrug B: Cyclosporine A-carbonate-catechol. The hydroxyl group of cyclosporine A (CsA) is reacted with p-nitrophenyl chloroformate to generate an activated carbonate intermediate, which is then reacted with catechol under alkaline conditions to obtain prodrug B, which is linked to an ortho-dihydroxyl group via a carbonate bond.
[0046] Prodrug C: Tacrolimus-glutarate-glycerol. Similar to the synthesis of prodrug A, the hydroxyl group of tacrolimus reacts with glutaric anhydride to form a half ester, which is then deprotected by condensation with 1,2-O-isopropylglycerol to obtain prodrug C containing an ortho-dihydroxy group.
[0047] III. Preparation of nuclear cross-linked nanomicelles
[0048] Example 1
[0049] 50 mg of polymer mPEG-bP(LA-co-MTC-BA) (X:Y≈2.9:1) from Synthesis Example 1 and 10 mg of prodrug A (dexamethasone-succinate-glycerol) were co-dissolved in 1 mL of acetone to form a clear organic phase solution. Under ice bath (4°C) and magnetic stirring (500 rpm), the solution was slowly injected dropwise into 10 mL of isotonic phosphate buffer (pH 7.4). After the addition was complete, stirring was continued for 30 minutes to allow the polymer to self-assemble into micelles and simultaneously complete the crosslinking of the phenylboronic ester. Acetone was then removed under reduced pressure at 30°C using a rotary evaporator, and the micelle solution was centrifuged using an ultrafiltration centrifuge tube (MWCO 10 kDa) to remove unassembled free molecules, and concentrated or diluted to the desired concentration. The final result was a core-crosslinked nanomicelle dispersion.
[0050] Example 2
[0051] Referring to Example 1, the difference is that: the polymer mPEG-bP(CL-co-MTC-BA) (X:Y≈2:1, mPEG2000, hydrophobic segment Mn about 3500Da) with monomer X as ε-caprolactone (CL) is used, the prodrug is prodrug B (CsA-carbonate-catechol), and the organic solvent is tetrahydrofuran.
[0052] Example 3
[0053] Referring to Example 1, the difference is that: the polymer mPEG-bP(TMC-co-MTC-BA) (X:Y≈2.5:1, mPEG5000, hydrophobic segment Mn about 2500Da) with monomer X as trimethylene carbonate (TMC) is used, and the prodrug is prodrug C (tacrolimus-glutarate-glycerol).
[0054] Comparative Example 1 (non-crosslinked micelles without phenylboronic acid)
[0055] The polymer is mPEG-b-PLA (mPEG2000, PLA segment Mn about 3000 Da), which is physically encapsulated with the same prodrug A (dexamethasone-succinate-glycerol) as in Example 1. The preparation method is the same as in Example 1, but no cross-linking reaction occurs.
[0056] Comparative Example 2 (Cross-linked micelles loaded with free active ingredient)
[0057] The polymer is the same as in Example 1, but the loaded drug is unmodified dexamethasone technical (without ortho-dihydroxy), physically encapsulated, and prepared using the same method as in Example 1.
[0058] Comparative Example 3 (Cross-linked micelles prepared without low temperature)
[0059] The formulation is the same as in Example 1, but in preparation step (2), the organic phase is injected into phosphate buffer at room temperature (25°C) for self-assembly and cross-linking, while other operations remain unchanged.
[0060] Comparative Example 4 (prodrug cross-linked micelles containing non-degradable linker arms)
[0061] A dexamethasone-glycerol ether prodrug (with a non-degradable ether linker) was used instead of prodrug A, with the polymer and preparation method the same as in Example 1. This prodrug still contains an ortho-dihydroxy group and can be crosslinked with phenylboronic acid.
[0062] IV. Performance Testing and Data Tables
[0063] The following are the characterization and performance test results of the micelles prepared in the above embodiments and comparative examples.
[0064] Test method:
[0065] Average particle size and polydispersity index (PDI): determined by dynamic light scattering (DLS) at 25°C.
[0066] Encapsulation efficiency: The concentration of free drug was determined by ultrafiltration centrifugation and HPLC, and the encapsulation efficiency was calculated.
[0067] Dilution stability test: Each micelle dispersion was precisely diluted 100-fold with isotonic PBS (pH 7.4) and placed in a 37°C constant temperature shaking water bath. Samples were taken at 1 hour, and free drug was separated by low-temperature ultrafiltration centrifugation. The cumulative leakage rate (%) was determined and calculated by HPLC. Simultaneously, the average particle size of the micelles after 1 hour of dilution was determined by DLS, and the percentage change from the initial particle size before dilution was calculated.
[0068] Table 1. Physicochemical parameters and dilution stability of micelles in each example and comparative example.
[0069] Example 1 45.3 0.12 91.2 12.8 +4.6 Example 2 58.7 0.09 88.5 18.2 +7.3 Example 3 72.1 0.14 85.9 22.4 +9.8 Comparative Example 1 48.1 0.13 86.7 62.5 +48.3 Comparative Example 2 50.5 0.15 75.3 71.8 +35.6 Comparative Example 3 52.4 0.19 82.4 38.9 +24.1 Comparative Example 4 46.8 0.11 90.5 10.5 +3.9
[0070] As can be seen from Table 1, the cumulative drug leakage rate of all nuclear cross-linked micelles after 100-fold dilution was less than 30% within 1 hour, and the particle size change did not exceed 10%, demonstrating excellent dilution stability.
[0071] In Comparative Example 1, because the polymer does not contain phenylboronic acid groups, it cannot form covalent cross-linking anchors. The physically encapsulated prodrug leaks rapidly under high dilution, and the particle size also increases sharply due to the swelling of the micelle structure.
[0072] Comparative Example 2, because the original drug does not contain ortho-dihydroxyl groups and relies solely on physical encapsulation, has even worse stability.
[0073] Comparative Example 3 was prepared at room temperature, and its stability was significantly worse than that of Example 1 due to the reduced crosslinking efficiency.
[0074] Although Comparative Example 4 also formed phenylboronic acid ester crosslinks, it exhibited excellent stability, with leakage rate and particle size variation even comparable to Example 1.
[0075] To fully reveal the comprehensive advantages of the present invention, the drug release behavior was further evaluated, with particular attention paid to the degradability of the connecting arm.
[0076] Release experiment: Each group of micelles was dispersed in pH 7.4 PBS containing esterase (10 U / mL), incubated at 37°C, and samples were taken after 24 hours to determine the cumulative drug release rate.
[0077] Table 2. Cumulative drug release rate and drug release mechanism of each composition in esterase-containing medium over 24 hours.
[0078] Example 1 68.3 Esterase degradation of prodrug + ester bond hydrolysis Comparative Example 4 8.2 Dependence solely on the dissociation of phenylboronic esters
[0079] A comprehensive analysis based on the data in Tables 1 and 2 is conducted to draw the following conclusions:
[0080] The cross-linked micelles of Example 1 not only firmly anchor the drug under extremely diluted conditions (extremely low leakage rate), but also have ester-bonded linker arms that can be rapidly degraded by enzymes in vivo, effectively releasing the active drug and achieving the intelligent delivery requirement of "highly stable extracellular and rapid intracellular drug release".
[0081] Although Comparative Example 4 exhibits excellent dilution stability, the drug cannot be effectively released due to the non-degradable ether bond in the connecting arm, resulting in a cumulative release rate of only 8.2% over 24 hours, which has almost no therapeutic value. Comparative Examples 1-3, on the other hand, have significant defects in dilution stability or drug delivery methods.
[0082] The above results fully demonstrate that the present invention synergistically constructs a novel ophthalmic nanomicelle composition by combining a specific "random copolymer containing phenylboronic acid" with an "ortho-dihydroxy drug prodrug containing a biodegradable linker arm" and employing a low-temperature synchronous self-assembly crosslinking process.
[0083] Under conditions simulating extreme dilution of ocular surface tears, the performance parameters of this composition fall entirely within the range described in this invention (leakage rate <30% in 1 hour, particle size change <20%), demonstrating unexpected technical effects and providing a highly promising solution for efficient ocular surface delivery of hydrophobic ophthalmic drugs.
[0084] Preparation of eye drops
[0085] In the micelle dispersion of Example 1 above, an appropriate amount of sodium chloride was added to adjust the osmotic pressure to 300 mOsmol / kg, and 0.01% benzalkonium chloride was added as a preservative. After filtration through a 0.22 μm sterile filter, the solution was filled into an eye drop dosage form.
[0086] The above description is merely a preferred embodiment and comparative example of the present invention, and is not intended to limit the patent scope of the present invention. Any equivalent structural or procedural transformations made using the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.
Claims
1. An ophthalmic nanomicellar composition characterized in that, Include: (a) An amphiphilic block copolymer composed of methoxy polyethylene glycol (mPEG) segments bonded to hydrophobic copolymer segments; The number-average molecular weight of the mPEG segments is 1000 to 5000 Da; The hydrophobic copolymer segments are formed by random copolymerization of X and Y units in a molar ratio of 4:1 to 1:1, and their number average molecular weight is 1000 to 5000 Da. The X unit is selected from repeating units of lactide, ε-caprolactone, or trimethylene carbonate; The Y unit is a cyclic carbonate repeating unit containing phenylboronic acid side groups, and its structure is as follows: The main chain of the repeating unit of the cyclic carbonate is a six-membered cyclic carbonate structure. A side group is attached to the ring of the six-membered cyclic carbonate. The side group is a -L-phenylboronic acid group, where L is a straight-chain or branched alkylene group with 1 to 6 carbon atoms. One end of L is connected to the benzene ring of the phenylboronic acid group through an amide bond (-NH-CO-), and the other end is connected to the ring structure of the six-membered cyclic carbonate. (b) A drug prodrug containing an ortho-dihydroxy structure, said drug prodrug being formed from a hydrophobic ophthalmic drug selected from dexamethasone, prednisolone, cyclosporine A, tacrolimus or voriconazole, by linking a glycerol group or a catechol group through a linking arm containing an ester bond or a carbonate bond. In this process, the ortho-dihydroxy group of the drug prodrug and the phenylboronic acid side group of the Y unit in the amphiphilic block copolymer are cross-linked in the micelle core through dynamic covalent bonds of phenylboronic acid ester, thereby anchoring the drug prodrug in the core of the micelle in a covalent form. Furthermore, the ophthalmic nanomicelle composition has the following properties: at 37°C, after diluting the micelle dispersion of the composition 100 times with isotonic phosphate buffer at pH 7.4, the cumulative leakage rate of the drug prodrug is less than 30% within 1 hour, and the average particle size change of the micelles does not exceed 20%.
2. The ophthalmic nanomicelle composition according to claim 1, wherein, The molar ratio of X to Y in the amphiphilic block copolymer is 3:1 to 2:
1.
3. The ophthalmic nanomicelle composition according to claim 1, wherein, The drug prodrug is a prodrug formed by linking dexamethasone to a glycerol group via a succinate linker arm.
4. The ophthalmic nanomicelle composition according to claim 1, wherein, The drug prodrug is a prodrug formed by linking cyclosporine A to a catechol group via a carbonate linker arm.
5. The ophthalmic nanomicelle composition according to claim 1, wherein, The drug prodrug is a tacrolimus prodrug formed by linking a glutarate linker to a glycerol group.
6. The ophthalmic nanomicelle composition according to claim 1, wherein, The average particle size of the nuclear cross-linked micelles is 20 to 80 nm, and the polydispersity index is less than 0.
15.
7. The ophthalmic nanomicelle composition according to claim 1, wherein the dosage form is an eye drop.
8. A method for preparing the ophthalmic nanomicelle composition according to any one of claims 1-7, comprising the following steps: (1) Dissolve the amphiphilic block copolymer and the drug prodrug together in an organic solvent miscible with water to obtain an organic phase solution; (2) At 0 to 10 °C and with stirring, the organic phase solution is added to a phosphate buffer solution with pH 7.2 to 7.8 to perform self-assembly and at the same time, the side group of the phenylboronic acid forms a dynamic covalent crosslink of phenylboronic acid ester with the ortho-dihydroxy group to obtain a nuclear crosslinked predrug nanomicelle dispersion. (3) Remove the organic solvent and optionally adjust the micelle concentration and / or remove unassembled free molecules to obtain the ophthalmic nanomicelle composition.
9. The method according to claim 8, wherein, The organic solvent mentioned in step (1) is acetone or tetrahydrofuran; the phosphate buffer mentioned in step (2) is an isotonic phosphate buffer with pH 7.
4.
10. The method according to claim 8, wherein, After removing the organic solvent in step (3), osmotic pressure regulators and preservatives are added to prepare eye drops.