Hyaluronic acid-cyclosporine A conjugate and its ophthalmic suspension preparation

Abstract

The present invention provides a hyaluronic acid-cyclosporine A conjugate and a preparation method thereof, as well as an ophthalmic suspension prepared from the conjugate and a preparation method thereof. The suspension can solve the problem of poor solubility of cyclosporine A, quickly relieve the symptoms of dry eye by virtue of the moisturizing and lubricating effect of hyaluronic acid on the eyeball, and cyclosporine A is slowly released through the hydrolysis of carbonate bonds, so that the suspension has a sustained release function, can reduce the frequency of medication, and can play a role in the eye to inhibit inflammatory response.

Description

Technical Field

[0001] The invention relates to the synthesis of a hyaluronic acid-cyclosporine A conjugate and the preparation of its suspension, as well as a suspension eye drop prepared from the conjugate suspension. Background Art

[0002] Due to its excellent biocompatibility, hyaluronic acid is widely used in the fields of drug controlled release, tissue engineering, and regenerative medicine. In the field of ophthalmology, hyaluronic acid is widely used. Hyaluronic acid can not only be used as an ophthalmic drug to lubricate and nourish the eyeball, but also as a vitreous filler. Cyclosporine A is the first-line drug for the treatment of dry eye. However, cyclosporine A has poor water solubility, and most of the cyclosporine A eye drops on the market are microemulsion preparations. In 2018, the FDA approved the world's first micellar eye drops of cyclosporine A. Surfactants and medium-chain fatty acid glycerides, castor oil, corn oil and other oil-soluble solvents are used in cyclosporine A microemulsion preparations. These excipients increase irritation to the eyes, and dry eye requires long-term medication. There are certain risks in the long-term use of microemulsion preparations. Even Tween 80, a surfactant with certain irritation, is used. Currently, most of the patents for cyclosporine A eye drops are

[0003] In this study, hyaluronic acid, a macromolecular drug for the treatment of dry eye, and cyclosporine A, a small molecule drug for the treatment of dry eye, were coupled together, and a hyaluronic acid-cyclosporine A conjugate suspension was prepared by dialysis technology. The suspension can quickly relieve the symptoms of dry eye by virtue of the moisturizing and lubricating effect of hyaluronic acid on the eyeball. Then, as the drug enters the eye, cyclosporine A is hydrolyzed and exerts its effect in the eye to inhibit inflammatory response. Through the hydrolysis of the carbonate bond, cyclosporine A is slowly released, giving the suspension a sustained-release function, which can reduce the frequency of medication. Summary of the invention

[0004] The purpose of the present invention is to provide a method for synthesizing a hyaluronic acid-cyclosporine A conjugate, a method for preparing a suspension of the hyaluronic acid-cyclosporine A conjugate using a dialysis technique, and a method for preparing an ophthalmic suspension of the hyaluronic acid-cyclosporine A conjugate.

[0005] The present invention synthesizes a hyaluronic acid-cyclosporine A conjugate: a hyaluronic acid-cyclosporine A conjugate having a structure of formula I:

[0006]

[0007] The present invention discloses a method for preparing the above-mentioned hyaluronic acid-cyclosporin A conjugate, comprising the following steps: firstly reacting cyclosporin A with carbonyldiimidazole to obtain an intermediate of cyclosporin A activated by carbonyldiimidazole. Then, hyaluronic acid and a catalyst dimethylaminopyridine are added thereto, and the reaction is carried out at 40° C. for 24 hours to obtain the hyaluronic acid-cyclosporin A conjugate. The synthesis method is simple and direct, the reaction conditions are mild and controllable, and cyclosporin A and hyaluronic acid are coupled together without using a connecting arm. The synthesis method is proposed for the first time in this patent and has not been reported elsewhere.

[0008] In the above technical scheme, the molar ratio of carbonyldiimidazole to cyclosporin A is 1:1-1.5, the molecular weight of hyaluronic acid is 10000Da-100000Da, the activation temperature is 30°C, the activation time is 24 hours, the molar ratio of cyclosporin A to hyaluronic acid is 4:1-1:1, and the reaction temperature is 30-70°C.

[0009] Preferably, the molar ratio of hyaluronic acid, cyclosporine A and carbonyldiimidazole is 2:1:1.2, and the molecular weight of hyaluronic acid is 40000 Da.

[0010] In the above technical solution, the specific reaction process is as follows:

[0011] Cyclosporine A and carbonyldiimidazole are added to dimethyl sulfoxide and / or N,N-dimethylformamide, stirred to dissolve, reacted at 30°C for 12 hours, then hyaluronic acid and N,N-dimethyl-4-pyridinamine are added thereto, reacted at 40°C for 12 hours, then dialyzed in dimethyl sulfoxide for 12 hours using a dialysis bag with a molecular weight cutoff of 7K; then dialyzed with purified water for 24 hours, the white turbid liquid was centrifuged and dried at 40°C to obtain a white powdery solid, which is the hyaluronic acid-cyclosporine A conjugate.

[0012] A suspension is a liquid preparation obtained by dispersing insoluble drug particles in a certain medium. Common suspension preparation methods are mainly divided into Bottom up technology and Top down technology. Bottom up technology mainly includes microprecipitation method and supercritical fluid method, which has many control points and complex process routes. Topdown technology mainly includes medium grinding method and high-pressure homogenization method, which are not convenient for scale-up production and have high energy consumption. The present invention also discloses a method for preparing a hyaluronic acid-cyclosporine A conjugate ophthalmic suspension, comprising the following steps: first dissolving the hyaluronic acid-cyclosporine A conjugate using dimethyl sulfoxide and / or N,N-dimethylformamide, then placing it in purified water, dialyzing to remove the solvent, adding common excipients for ophthalmic preparations, and obtaining a hyaluronic acid-cyclosporine A conjugate ophthalmic suspension.

[0013] In the above suspension preparation method, the concentration of hyaluronic acid-cyclosporin A conjugate in the organic solvent is 1%-5%. The volume ratio of purified water to organic solvent in a single dialysis is 20:1 to 50:1, the single dialysis time is 2-6 hours, and the number of dialysis is 2-6 times. The preferred dialysis scheme is: the concentration of hyaluronic acid-cyclosporin A conjugate is 2%, the ratio of purified water to organic solvent in dialysis is 40:1, the single dialysis time is 4 hours, and the number of dialysis is 3 times.

[0014] The present invention also discloses a prescription and preparation method of a hyaluronic acid-cyclosporine A conjugate suspension eye drops. The preparation method is simple and convenient, and does not require the use of high-end equipment such as high-pressure homogenization, membrane emulsification, microfluidization, and complex preparation processes. The method includes mixing the above-mentioned hyaluronic acid-cyclosporine A conjugate suspension with a dispersion medium. The osmotic pressure regulator, pH regulator, thickener, and suspending agent are dissolved and clarified to obtain a medium. Hyaluronic acid and cyclosporine A are coupled through easily hydrolyzed carbonates, so the pH of the medium is about 7; considering the particle size of the hyaluronic acid-cyclosporine A conjugate suspension and the viscosity of the eye drops, the concentration of the thickener and suspending agent is used, and sodium chloride is added according to the osmotic pressure of the final medium to adjust the osmotic pressure to be isotonic with tears. After obtaining the hyaluronic acid-cyclosporine A suspension, it is mixed with the medium to obtain the hyaluronic acid-cyclosporine A conjugate suspension eye drops.

[0015] The hyaluronic acid-cyclosporin A conjugate of the present invention has a suitable hydrophilic-hydrophobic ratio, so a hyaluronic acid-cyclosporin A conjugate suspension with uniform particle size distribution can be prepared by a solvent replacement method. The specific preparation method can be:

[0016] The hyaluronic acid-cyclosporine A conjugate is dissolved in N,N-dimethylformamide (DMF) or dimethyl sulfoxide (DMSO), and then the conjugate solution is placed in a dialysis bag, and the organic solvent is removed by dialysis using a dialysis bag with a molecular weight cutoff of 7k to obtain a hyaluronic acid-cyclosporine A conjugate suspension.

[0017] The present invention has the following advantages:

[0018] The hyaluronic acid-cyclosporin A conjugate prepared by the present invention has a simple synthesis method, a controllable amount of coupled cyclosporin A, and can couple the macromolecular drug hyaluronic acid and the small molecule drug cyclosporin A for treating dry eye without introducing other bridging molecules. The conjugate combines these two molecules with different action mechanisms, the macromolecular hyaluronic acid plays a role in moisturizing and lubricating the eyeball, and the small molecule cyclosporin A can be slowly released from the hyaluronic acid-cyclosporin A conjugate after hydrolysis in the eye, thereby playing a role of long-term sustained release, and the function of synergistically treating dry eye is achieved by means of these two effects.

[0019] The conjugate disclosed in the present invention has excellent biocompatibility. Compared with the cyclosporine A eye drops on the market, the drug does not contain irritating excipients such as surfactants and cosolvents, which can improve medication compliance.

[0020] The preparation method of the invention is simple, the raw materials used are from a wide range of sources, and the invention has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figures 1-4 are H-NMR spectra and C-NMR spectra of the cyclosporine A hyaluronic acid conjugate in Example 1;

[0022] Figure 5 is a microscope photo of the cyclosporine A hyaluronic acid conjugate ophthalmic suspension preparations in Examples 5, 6, 7 and 8;

[0023] FIG6 is a graph showing the particle size distribution of the cyclosporine A hyaluronic acid conjugate ophthalmic suspension preparations in Examples 5, 6, 7 and 8.

[0024] The invention discloses a preparation method of a cyclosporin A hyaluronic acid conjugate, a cyclosporin A hyaluronic acid conjugate suspension and a suspension eye drop thereof, which is more direct than the coupling method disclosed in the literature and does not require an extra bridging molecule. The cyclosporin A hyaluronic acid conjugate of the invention can be prepared into a suspension or a suspension eye drop, which can solve the problem of poor solubility of cyclosporin A, and no emulsifier irritating to the eyes is used in the suspension, so the eye tolerance is better. DETAILED DESCRIPTION

[0025] The present invention is further described below in conjunction with the accompanying drawings and embodiments, which do not limit the present invention:

[0026] Example 1 Synthesis of Hyaluronic Acid-Cyclosporin A Conjugate

[0027] Accurately weighed carbonyldiimidazole (0.32 g, 1.85 mmol) was placed in a two-necked round-bottom flask that had been treated with anhydrous solution, anhydrous DMSO (100 mL) was added, and the reaction system was placed in an oil bath at 30°C and stirred evenly, and then cyclosporine A (2.22 g, 1.85 mmol) was dissolved in anhydrous DMSO (100 mL) and added dropwise to carbonyldiimidazole; react for 24 hours. Hyaluronic acid (2.81 g, 7.40 mmol) with a molecular weight of 10000 Da was dissolved in anhydrous DMSO (100 mL) and added to the above reaction solution, and reacted at 30°C for 24 hours. After the reaction, the reaction solution was dialyzed with DMSO in a dialysis bag (molecular weight cutoff of 7K) for 12 h, and then dialyzed with purified water for 24 h. After the dialysis, the dialyzate was lyophilized to obtain the product (1.02 g, yield 37.8%). The content of cyclosporine A was detected by liquid phase, and the grafting rate of cyclosporine A was calculated to be 22.6%. The product can be dispersed in water to form a suspension.

[0028] The NMR characterization (400 MHz, DMSO-d6) of the hyaluronic acid-cyclosporine A conjugate is shown in FIG1 .

[0029] Example 2 Synthesis of Hyaluronic Acid-Cyclosporin A Conjugate

[0030] Accurately weighed carbonyldiimidazole (0.32 g, 1.85 mmol) was placed in a two-necked round-bottom flask that had been treated with anhydrous solution, anhydrous DMSO (100 mL) was added, and the reaction system was placed in an oil bath at 30°C and stirred evenly, and then cyclosporine A (2.22 g, 1.85 mmol) was dissolved in anhydrous DMSO (100 mL) and added dropwise to carbonyldiimidazole; react for 24 hours. Hyaluronic acid (2.81 g, 7.40 mmol) with a molecular weight of 1000000Da was dissolved in anhydrous DMSO (100 mL) and added to the above reaction solution, and reacted at 30°C for 24 hours. After the reaction, the reaction solution was dialyzed with DMSO in a dialysis bag (molecular weight cutoff of 7K) for 12 h, and then dialyzed with purified water for 24 h. After the dialysis, the dialyzate was lyophilized to obtain the product (2.26 g, yield 44.2%). The content of cyclosporine A was detected by liquid phase, and the grafting rate of cyclosporine A was calculated to be 26.4%. The product can be dispersed in water to form a suspension.

[0031] The NMR characterization (400 MHz, DMSO-d6) of the hyaluronic acid-cyclosporine A conjugate is shown in FIG2 .

[0032] Example 3 Synthesis of Hyaluronic Acid-Cyclosporin A Conjugate

[0033] Accurately weighed carbonyldiimidazole (0.32 g, 1.85 mmol) was placed in a two-necked round-bottom flask that had been treated with anhydrous solution, anhydrous DMSO (100 mL) was added, and the reaction system was placed in an oil bath at 30°C and stirred evenly, and then cyclosporine A (2.22 g, 1.85 mmol) was dissolved in anhydrous DMSO (100 mL) and added dropwise to carbonyldiimidazole; react for 24 hours. Hyaluronic acid with a molecular weight of 10000 Da (0.70 g, 1.85 mmol) was dissolved in anhydrous DMSO (100 mL) and added to the above reaction solution, and reacted at 30°C for 24 hours. After the reaction, the reaction solution was dialyzed with DMSO in a dialysis bag (molecular weight cutoff of 7K) for 12 h, and then dialyzed with purified water for 24 h. After the dialysis, the dialyzate was lyophilized to obtain the product (0.67 g, yield 13.6%). The content of cyclosporine A was detected by liquid phase, and the grafting rate of cyclosporine A was calculated to be 8.1%, and the product could be dissolved in water.

[0034] The NMR characterization (400 MHz, DMSO-d6) of the hyaluronic acid-cyclosporine A conjugate is shown in FIG3 .

[0035] Example 4 Synthesis of Hyaluronic Acid-Cyclosporin A Conjugate

[0036] Accurately weighed carbonyldiimidazole (0.32 g, 1.85 mmol) was placed in a two-necked round-bottom flask that had been treated with anhydrous solution, anhydrous DMSO (100 mL) was added, and the reaction system was placed in an oil bath at 30°C and stirred evenly, and then cyclosporine A (1.50 g, 1.23 mmol) was dissolved in anhydrous DMSO (100 mL) and added dropwise to carbonyldiimidazole; react for 24 hours. Hyaluronic acid (0.70 g, 1.85 mmol) was dissolved in anhydrous DMSO (100 mL) and added to the above reaction solution, and reacted at 70°C for 24 hours. After the reaction, the reaction solution was dialyzed with DMSO in a dialysis bag (molecular weight cutoff of 7K) for 12 h, and then dialyzed with purified water for 24 h. After the dialysis, the dialyzate was lyophilized to obtain the product (2.79 g, yield 56.7%). The content of cyclosporine A was detected by liquid phase, and the grafting rate of cyclosporine A was calculated to be 32.6%. The product can be dispersed in water to form a suspension.

[0037] The NMR characterization (400 MHz, DMSO-d6) of the hyaluronic acid-cyclosporine A conjugate is shown in FIG4 .

[0038] Example 5 Preparation of Hyaluronic Acid-Cyclosporin A Conjugate Ophthalmic Suspension

[0039] The prescription of hyaluronic acid-cyclosporine A conjugate ophthalmic suspension preparation is shown in the following table:

[0040]

[0041]

[0042] Weigh 0.1g of the hyaluronic acid-cyclosporin A conjugate synthesized in Example 1, dissolve in 10mL of DMSO, place the above solution in a dialysis bag (molecular weight cutoff is 7K), dialyze with 200mL of purified water at room temperature, dialyze 3 times in total, each dialysis time is 4h, and after the dialysis, a hyaluronic acid-cyclosporin A conjugate suspension is obtained. The size of the hyaluronic acid-cyclosporin A conjugate suspension measured by a microscope is about 1 μm, spherical, and has a narrow particle size distribution. The dynamic laser light scattering particle size analyzer tests the particle size to be 1026.63nm. 0.2 g of polyvinyl pyrrolidone, 1.62 g of anhydrous disodium hydrogen phosphate, 0.24 g of sodium dihydrogen phosphate monohydrate, 0.8 g of sodium chloride, and 0.02 g of chlorhexidine acetate were dissolved in 100 mL of purified water to obtain a medium, and the obtained hyaluronic acid-cyclosporin A conjugate solution was mixed with the medium, and the volume was fixed to 200 mL with purified water to obtain a 0.05% hyaluronic acid-cyclosporin A conjugate ophthalmic suspension. The osmotic pressure of the hyaluronic acid-cyclosporin A conjugate ophthalmic suspension was measured to be 282 mOsmol / kg, and the pH value was 6.82.

[0043] Example 6 Preparation of Hyaluronic Acid-Cyclosporin A Conjugate Ophthalmic Suspension

[0044] The present invention prepares a hyaluronic acid-cyclosporine A conjugate suspension. Take the preparation of a hyaluronic acid-cyclosporine A conjugate ophthalmic suspension as an example: weigh 0.25g of the hyaluronic acid-cyclosporine A conjugate synthesized in Example 1, dissolve it in 10mL of DMSO, place the above solution in a dialysis bag (molecular weight cutoff is 7K), dialyze with 300mL of purified water at room temperature, dialyze twice in total, each dialysis time is 4h, and after the dialysis, a hyaluronic acid-cyclosporine A conjugate suspension is obtained. The size of the hyaluronic acid-cyclosporine A conjugate suspension measured by a microscope is about 1μm, spherical, and has a narrow particle size distribution. The dynamic laser light scattering particle size analyzer tests the particle size to be 1125.37nm. 0.1 g of polyvinyl pyrrolidone, 0.81 g of anhydrous disodium hydrogen phosphate, 0.12 g of sodium dihydrogen phosphate monohydrate, 0.26 g of sodium chloride, and 0.01 g of chlorhexidine acetate were dissolved in 50 mL of purified water to obtain a medium, and the obtained hyaluronic acid-cyclosporin A conjugate solution was mixed with the medium, and the volume was adjusted to 100 mL with purified water to obtain a 0.25% hyaluronic acid-cyclosporin A conjugate ophthalmic suspension. The osmotic pressure of the hyaluronic acid-cyclosporin A conjugate suspension eye drops was measured to be 291 mOsmol / kg, and the pH value was 6.86.

[0045] Example 7 Preparation of Hyaluronic Acid-Cyclosporin A Conjugate Ophthalmic Suspension

[0046] The present invention prepares a hyaluronic acid-cyclosporine A conjugate suspension. Take the preparation of a hyaluronic acid-cyclosporine A conjugate ophthalmic suspension as an example: weigh 0.5g of the hyaluronic acid-cyclosporine A conjugate synthesized in Example 1, dissolve it in 10mL of DMSO, place the above solution in a dialysis bag (molecular weight cutoff is 7K), dialyze with 500mL of purified water at room temperature, dialyze 4 times in total, each dialysis time is 5h, and after the dialysis, a hyaluronic acid-cyclosporine A conjugate suspension is obtained. The size of the hyaluronic acid-cyclosporine A conjugate suspension measured by a microscope is about 1μm, spherical, and has a narrow particle size distribution. The dynamic laser light scattering particle size analyzer tests the particle size to be 1306.75nm. 0.1 g of polyvinyl pyrrolidone, 0.81 g of anhydrous disodium hydrogen phosphate, 0.12 g of sodium dihydrogen phosphate monohydrate, 0.26 g of sodium chloride, and 0.01 g of chlorhexidine acetate were dissolved in 50 mL of purified water to obtain a medium, and the obtained hyaluronic acid-cyclosporin A conjugate solution was mixed with the medium, and the volume was adjusted to 100 mL with purified water to obtain a 0.5% hyaluronic acid-cyclosporin A conjugate ophthalmic suspension. The osmotic pressure of the hyaluronic acid-cyclosporin A conjugate suspension eye drops was measured to be 286 mOsmol / kg, and the pH value was 6.78.

[0047] Example 8 Preparation of Hyaluronic Acid-Cyclosporin A Conjugate Ophthalmic Suspension

[0048] The present invention prepares hyaluronic acid-cyclosporine A conjugate. In order to prepare hyaluronic acid-cyclosporine A conjugate ophthalmic suspension, the specific experiment is as follows: weigh 0.1g of the hyaluronic acid-cyclosporine A conjugate synthesized in Example 1, dissolve it in 10mL of DM SO, place the above solution in a dialysis bag (molecular weight cutoff is 7K), dialyze with 200mL of purified water at room temperature, dialyze 3 times in total, each dialysis time is 4h, and after the dialysis, a hyaluronic acid-cyclosporine A conjugate suspension is obtained. The size of the hyaluronic acid-cyclosporine A conjugate suspension measured by a microscope is about 1μm, spherical, and the particle size distribution is narrow. The dynamic laser light scattering particle size analyzer tests the particle size to be 968.58nm. 0.1 g of polyvinyl pyrrolidone, 0.81 g of anhydrous disodium hydrogen phosphate, 0.12 g of sodium dihydrogen phosphate monohydrate, 0.4 g of sodium chloride, and 0.01 g of chlorhexidine acetate were dissolved in 50 mL of purified water to obtain a medium, and the obtained hyaluronic acid-cyclosporin A conjugate solution was mixed with the medium, and the volume was adjusted to 100 mL with purified water to obtain a 0.05% hyaluronic acid-cyclosporin A conjugate ophthalmic suspension. The osmotic pressure of the hyaluronic acid-cyclosporin A conjugate suspension eye drops was measured to be 281 mOsmol / kg, and the pH value was 6.83.

[0049] A microscope photograph of the hyaluronic acid-cyclosporine A conjugate ophthalmic suspension is shown in FIG5 , and a particle size distribution diagram of the hyaluronic acid-cyclosporine A conjugate ophthalmic suspension is shown in FIG6 .

Claims

1. A hyaluronic acid-cyclosporine A conjugate, whose chemical structure is shown in Formula I:

2. The method for preparing the hyaluronic acid-cyclosporine A conjugate according to claim 1, characterized in that: The steps include: I. adding cyclosporin A and carbonyldiimidazole to dimethyl sulfoxide and / or N,N-dimethylformamide, and reacting at 30° C. for 12 hours to obtain an intermediate of cyclosporin A activated by carbonyldiimidazole; II. Add hyaluronic acid and dimethylaminopyridine to the reaction bottle of step I, react at 40°C for 12 hours, and then dialyze in dimethyl sulfoxide for 12 hours using a dialysis bag with a molecular weight cutoff of 7,000Da; then dialyze with purified water for 24 hours, centrifuge the obtained white turbid liquid, collect the solid, and dry it under reduced pressure at 40°C to obtain a white powdery solid, which is the hyaluronic acid-cyclosporin A conjugate.

3. The method for preparing the hyaluronic acid-cyclosporine A conjugate according to claim 2, characterized in that: The molar ratio of carbonyldiimidazole to cyclosporine A is 1:1 to 1:1.5; the molecular weight of the selected hyaluronic acid is 10,000Da to 100,000Da; and the molar ratio of cyclosporine A to hyaluronic acid is 4:1 to 1:

1.

4. The method for preparing the hyaluronic acid-cyclosporine A conjugate according to claim 3, characterized in that: The molar ratio of the hyaluronic acid, cyclosporine A and carbonyldiimidazole is 2:1:1.2, and the molecular weight of the hyaluronic acid is 40,000 Da.

5. An ophthalmic suspension of a hyaluronic acid-cyclosporine A conjugate, characterized in that: The invention is composed of the hyaluronic acid-cyclosporine A conjugate according to claim 1 and an osmotic pressure regulator, a pH regulator, a suspending agent, a thickener and an antibacterial agent; wherein the concentration of the hyaluronic acid-cyclosporine A conjugate is 0.05% W / V to 0.5% W / V.

6. The ophthalmic suspension of hyaluronic acid-cyclosporine A conjugate according to claim 5, characterized in that: Hyaluronic acid-cyclosporine A conjugate 0.1-0.5%, anhydrous disodium hydrogen phosphate 0.81%, sodium dihydrogen phosphate monohydrate 0.12%, sodium chloride 0.12-0.4%, chlorhexidine acetate 0.01%, polyvinyl pyrrolidone 0.1%; the above percentages are by mass.

7. A method for preparing an ophthalmic suspension as claimed in claim 5, characterized in that: The hyaluronic acid-cyclosporine A conjugate according to claim 1 is dissolved in DMSO or DMF, placed in a dialysis bag with a molecular weight cutoff of 7 kDa, and dialyzed with purified water to remove the organic solvent. After the solvent residue test is qualified, an osmotic pressure regulator, a pH regulator, a suspending agent, a thickener and an antibacterial agent are added, and the total amount is supplemented with purified water. After the whole process is sterile, the ophthalmic suspension is obtained after subpackaging.

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