A preparation process of rebamipide tablets

Abstract

The invention discloses a preparation process of rebamipide tablets, and relates to the technical field of pharmaceutical preparations. When preparing rebamipide tablets, the present invention first reacts BOC-lysine tert-butyl ester hydrochloride with isocyanoethyl methacrylate to obtain lysine monomer; lysine monomer is reacted with terminal 2-bromoisobutyrate polylactic acid to obtain an amino acid amphiphilic block copolymer; amino acid amphiphilic block copolymer is used to load rebamipide to obtain a loaded rebamipide amphiphilic copolymer; dopa is reacted with chitosan to obtain dopa-modified chitosan; dopa-modified chitosan and bismuth salt are film-coated on the surface of the loaded rebamipide amphiphilic copolymer to obtain dopa-modified chitosan-coated rebamipide, and then dopa-modified chitosan-coated rebamipide is made into tablets to obtain rebamipide tablets. The rebamipide tablets prepared by the present invention have the advantages of mucosal adhesion, long in vivo retention time, and high cellular uptake.

Description

Technical Field

[0001] The invention relates to the technical field of pharmaceutical preparations, and in particular to a preparation process of rebamipide tablets. Background Art

[0002] Rebamipide, whose chemical name is 2-(4-chlorobenzamido)-3-(1,2-dihydro-2-oxo-4-quinolyl)propionic acid, is an amide derivative, a water-insoluble amphoteric electrolyte, weakly acidic, and appears as a white crystalline powder. It is odorless, bitter, and hygroscopic. It is soluble in dimethyl sulfoxide and dimethylformamide, slightly soluble in alkaline solutions, very slightly soluble in methanol or ethanol, and almost insoluble in water or dilute hydrochloric acid.

[0003] Rebamipide is a compound with mucosal protective effects. It is mainly used clinically for mucosal protection, gastric and duodenal ulcer lesions, and the treatment of acute and chronic gastritis. Its therapeutic mechanism mainly includes stimulating the production of prostaglandins and mucins, enhancing mucosal protection, scavenging free radicals, inhibiting the production of inflammatory cytokines, and inhibiting the activation of neutrophils induced by various injuries. It is a very effective drug for the treatment of acute or chronic gastric ulcers. However, due to the poor water solubility of rebamipide and its low absorption rate in the body, the dosage must be increased to achieve the desired effect. If the dosage is increased and long-term use is taken, drug resistance will occur, side effects will be enhanced, and adverse consequences such as gastric mucosal hyperplasia will be caused.

[0004] Although rebamipide has problems such as poor water solubility and poor membrane permeability, its mechanism of action is different from other drugs for treating gastric ulcers. Clinical studies have shown that rebamipide has a strong ulcer healing effect and anti-Helicobacter pylori adhesion effect, and it has been confirmed that the occurrence of this effect depends on the distribution level of rebamipide in the gastrointestinal mucosa and mucus. In addition, rebamipide also has an inhibitory effect on the growth of gastric cancer. In addition to entering the blood circulation system to produce a therapeutic effect, it can also be dispersed directly at the lesion to reduce the dose and improve the therapeutic effect. Summary of the invention

[0005] The object of the present invention is to provide a preparation process of rebamipide tablets to solve the problems existing in the prior art.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] A preparation process of rebamipide tablets comprises the following preparation steps:

[0008] (1) Under a nitrogen atmosphere, 6-7 parts of BOC-lysine tert-butyl ester hydrochloride, 3-4 parts of isocyanoethyl methacrylate, and 50-60 parts of dichloromethane were mixed uniformly by weight, refluxed at 45-50°C and 200-300 r / min for 10-12 h, cooled to room temperature, filtered, and the filtrate was washed with pure water and saturated sodium chloride solution for 3-4 times respectively, and dried with anhydrous magnesium sulfate for 10-12 h to purify and obtain lysine monomer;

[0009] (2) By weight, 10-11 parts of lysine monomer, 0.2-0.3 parts of pentamethyldiethyltriamine, 6-7 parts of 2-bromoisobutyrate-terminated polylactic acid, and 40-45 parts of N,N-dimethylformamide were mixed evenly, and after freeze-thawing to remove oxygen, 0.12-0.15 parts of cuprous bromide were added under argon atmosphere, and the mixture was reacted at 40°C and 200-300 r / min for 12 h. The mixture was diluted with 40-50 parts of tetrahydrofuran and purified, and the solvent was removed by rotary evaporation. The mixture was dialyzed in pure water with a molecular weight cutoff of 2 KDa for 20-24 h, and the protecting group of the precipitate was removed by trifluoroacetic acid. The mixture was freeze-dried to obtain an amino acid amphiphilic block copolymer;

[0010] (3) Add 1-2 parts of rebamipide solution to 15-20 parts of 3 mg / mL amino acid amphiphilic block copolymer aqueous solution by weight, stir at 1000-1200 r / min for 30-40 min at room temperature, centrifuge for 3 times using an ultrafiltration centrifuge tube with a molecular weight cutoff of 5 KDa, and vacuum dry at 30-40°C for 6-8 h to obtain the rebamipide-loaded amphiphilic copolymer;

[0011] (4) Dissolve 5 parts of chitosan in 50-60 parts of 0.97wt% glacial acetic acid solution by weight, adjust the pH to 4.5, add 6-7 parts of 10wt% DL-DOPA aqueous solution, stir at 200-300r / min for 30-40min, add 50-60 parts of carbodiimide solution at 2-3 drops per second, react at room temperature at 500-600r / min for 4-5h, then adjust the pH to 5.0, dialyze with pure water for 2 days, dialyze with phosphate buffered saline for 4-5h, and then dialyze with pure water for 1 day, and obtain DOPA-modified chitosan after freeze-drying;

[0012] (5) Add 0.2-0.4 parts of 10 mg / mL DOPA-modified chitosan aqueous solution and 0.2-0.4 parts of 10 mg / mL bismuth nitrate aqueous solution to 10-20 parts of 10 mg / mL rebamipide-loaded amphiphilic copolymer aqueous solution, by weight, stir at 1000-1200 r / min for 6-8 min at room temperature, let stand for 2-3 h, filter, wash with pure water 3-4 times, and freeze-dry to prepare DOPA-modified chitosan-coated rebamipide;

[0013] (6) Coating rebamipide with DOPA-modified chitosan to prepare tablets to obtain rebamipide tablets.

[0014] As an optimization, the reaction process of the lysine monomer in step (1) is as follows:

[0015] .

[0016] As an optimization, the preparation method of the 2-bromoisobutyrate-terminated polylactic acid in step (2) comprises the following steps:

[0017] (A) By weight, 12-13 parts of ethylene glycol, 4-5 parts of triethylamine, and 40-50 parts of dichloromethane are mixed uniformly, 36-40 parts of a 25wt% dichloromethane solution of 2-bromoisobutyryl bromide are added dropwise at 3-5 drops per second, reacted at 200-300 r / min for 10-12 hours at room temperature, washed and extracted with 0.1 mol / L hydrochloric acid solution, the organic layer is taken, washed with pure water and saturated sodium chloride solution 2-3 times respectively, dried and purified to obtain 2-hydroxyethyl bromoisobutyrate;

[0018] (B) Under an argon atmosphere, 0.4-0.5 parts of 2-bromoisobutyric acid hydroxyethyl ester and 14-16 parts of DL-lactide were mixed uniformly by weight, and after removing oxygen, the temperature was raised to 130-135°C and kept warm for 30-40 min. 0.5 parts of 5 wt% stannous octoate toluene solution were added, and the reaction was continued at 200-300 r / min for 5-6 h. The product was dissolved with dichloromethane and precipitated with methanol, and the reaction was repeated 3 times. The product was dried in a vacuum at 30-40°C for 10-12 h to obtain terminal 2-bromoisobutyrate polylactic acid.

[0019] As an optimization, the reaction process of 2-bromoisobutyric acid hydroxyethyl ester in step (A) is as follows:

[0020] .

[0021] As an optimization, the reaction process of the 2-bromoisobutyrate-terminated polylactic acid in step (B) is as follows:

[0022] .

[0023] As an optimization, the reaction process of the amino acid amphiphilic block copolymer in step (2) is as follows:

[0024] .

[0025] As an optimization, the rebamipide solution in step (3) is prepared by uniformly mixing rebamipide, polylactic acid-glycolic acid copolymer, and dimethyl sulfoxide in a mass ratio of 1:4:550, and stirring at 200 r / min for 30 min at room temperature.

[0026] As an optimization, the chitosan deacetylation degree of step (4) is greater than 95%, and the viscosity is 100-200 mPa·s.

[0027] As an optimization, the carbodiimide solution in step (4) is prepared by uniformly mixing 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide, N-hydroxysuccinimide, pure water, and ethanol in a mass ratio of 1:(0.7~0.8):(20~25):(16~20).

[0028] As an optimization, the molecular weight cutoff of the dialysis in step (4) is 5 KDa.

[0029] As an optimization, the preparation method of the phosphate buffered saline solution in step (4) is as follows: 8.0 g of sodium chloride, 0.2 g of potassium chloride, 1.44 g of disodium hydrogen phosphate, and 0.24 g of potassium dihydrogen phosphate are dissolved in 800 mL of pure water, the pH value of the solution is adjusted to 7.4 with hydrochloric acid, and finally, pure water is added to make up to 1 L to obtain a phosphate buffered saline solution.

[0030] As an optimization, the DOPA-modified chitosan coated rebamipide in step (6) can also be made into capsules, granules, and powders.

[0031] As an optimization, the weight average molecular weight of the polylactic acid-glycolic acid copolymer is 5000, and the monomer ratio is 50:50.

[0032] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0033] When preparing the rebamipide tablets, the present invention comprises the following steps: firstly reacting BOC-lysine tert-butyl ester hydrochloride with isocyanoethyl methacrylate to obtain lysine monomer; reacting the lysine monomer with terminal 2-bromoisobutyrate polylactic acid to obtain an amino acid amphiphilic block copolymer; using the amino acid amphiphilic block copolymer to load rebamipide to obtain an amphiphilic copolymer loaded with rebamipide; reacting DOPA with chitosan to obtain DOPA-modified chitosan; coating the surface of the amphiphilic copolymer loaded with rebamipide with bismuth salt to obtain DOPA-modified chitosan-coated rebamipide; and then coating the rebamipide with DOPA-modified chitosan to prepare tablets to obtain the rebamipide tablets.

[0034] First, due to the amphiphilicity of amino acids, the amino acid amphiphilic block copolymer can effectively pass through the mucus layer of the gastric mucosa and disperse in the mucus layer, thereby increasing the distribution level of rebamipide in the mucus layer. At the same time, the presence of lysine groups also greatly enhances the ability of cell uptake, allowing the rebamipide loaded thereon to better enter the cell and exert its effect.

[0035] Secondly, DL-DOPA is grafted onto chitosan through an amidation reaction, which improves the antioxidant and anti-inflammatory capabilities of chitosan. At the same time, the polyphenol structure of DL-DOPA forms a metal-polyphenol network with the bismuth salt, which covers the surface of the drug. Because the amino acid amphiphilic block copolymer also has more amino and carboxyl groups, the bismuth salt will also form a coordination bond with it at the same time to improve the adhesion of the surface film layer; at the same time, the chitosan modified by DL-DOPA has good gastric mucosal adhesion ability, which can prolong the residence time on the gastric mucosa to increase the release level of rebamipide. At the same time, after entering the stomach, the metal-polyphenol network will be cleaved on the gastric mucosa to release the amphiphilic copolymer loaded with rebamipide, and the bismuth salt will form a new film with the polyphenol on the DOPA-modified chitosan in the acidic environment of the stomach and deposit on the gastric ulcer to protect the ulcer from erosion by gastric acid, Helicobacter pylori, etc., and at the same time protect the internal amphiphilic copolymer loaded with rebamipide to release rebamipide and exert its effect. DETAILED DESCRIPTION

[0036] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0037] The preparation method of the 2-bromoisobutyrate-terminated polylactic acid used in all the following examples and comparative examples is as follows:

[0038] (A) By weight, 12 parts of ethylene glycol, 4.5 parts of triethylamine and 45 parts of dichloromethane were mixed evenly, 36 parts of a 25wt% dichloromethane solution of 2-bromoisobutyryl bromide were added dropwise at a rate of 4 drops per second, the mixture was reacted at 300 r / min for 10 hours at room temperature, the mixture was washed and extracted with a 0.1 mol / L hydrochloric acid solution, the organic layer was taken, purified with pure water and saturated sodium chloride solution for 3 times respectively, dried and purified to obtain 2-hydroxyethyl bromoisobutyrate;

[0039] (B) Under an argon atmosphere, 0.4 parts of 2-bromoisobutyric acid hydroxyethyl ester and 16 parts of DL-lactide were mixed uniformly by mass, and after removing oxygen, the temperature was raised to 130°C and kept warm for 40 min. 0.5 parts of 5 wt% stannous octoate toluene solution were added, and the reaction was continued at 300 r / min for 6 h. The product was dissolved with dichloromethane and precipitated with methanol, and the reaction was repeated 3 times. The product was dried in vacuo at 40°C for 10 h to obtain terminal 2-bromoisobutyrate polylactic acid.

[0040] The carbodiimide solution used in all the following examples and comparative examples was prepared by uniformly mixing 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide, N-hydroxysuccinimide, pure water and ethanol in a mass ratio of 1:0.7:20:16. Embodiment 1:

[0041] A preparation process of rebamipide tablets, comprising the following preparation steps:

[0042] (1) Under a nitrogen atmosphere, 6 parts of BOC-lysine tert-butyl ester hydrochloride, 3 parts of isocyanoethyl methacrylate, and 50 parts of dichloromethane were mixed uniformly by weight, refluxed at 45°C and 200 r / min for 12 h, cooled to room temperature, filtered, and the filtrate was washed with pure water and saturated sodium chloride solution for 3 times respectively, and dried with anhydrous magnesium sulfate for 10 h to purify and obtain lysine monomer;

[0043] (2) By weight, 10 parts of lysine monomer, 0.2 parts of pentamethyldiethyltriamine, 6 parts of 2-bromoisobutyrate-terminated polylactic acid, and 40 parts of N,N-dimethylformamide were mixed evenly, and after freeze-thawing to remove oxygen, 0.12 parts of cuprous bromide were added under argon atmosphere, and the mixture was reacted at 40°C and 200 r / min for 12 h. The mixture was diluted with 40 parts of tetrahydrofuran and purified, and the solvent was removed by rotary evaporation. The mixture was dialyzed in pure water with a molecular weight cutoff of 2 KDa for 20 h, and the protecting group of the precipitate was removed by trifluoroacetic acid. The amino acid amphiphilic block copolymer was obtained after freeze-drying;

[0044] (3) By weight, 1 part of rebamipide solution was added to 15 parts of 3 mg / mL amino acid amphiphilic block copolymer aqueous solution, stirred at 1000 r / min for 40 min at room temperature, centrifuged three times using an ultrafiltration centrifuge tube with a molecular weight cutoff of 5 KDa, and vacuum dried at 30°C for 8 h to obtain an amphiphilic copolymer loaded with rebamipide;

[0045] (4) By weight, 5 parts of chitosan were dissolved in 50 parts of 0.97wt% glacial acetic acid solution, the pH was adjusted to 4.5, 6 parts of 10wt% DL-DOPA aqueous solution were added, and the mixture was stirred at 200r / min for 40min. 50 parts of carbodiimide solution were added at a rate of 2 drops per second. After the addition was completed, the mixture was reacted at 500r / min for 5h at room temperature, and then the pH was adjusted to 5.0. After being dialyzed with pure water for 2 days, it was dialyzed with phosphate buffered saline for 4h, and then dialyzed with pure water for 1 day. After being freeze-dried, DOPA-modified chitosan was obtained.

[0046] (5) Add 0.2 parts of 10 mg / mL DOPA-modified chitosan aqueous solution and 0.2 parts of 10 mg / mL bismuth nitrate aqueous solution to 10 parts of 10 mg / mL rebamipide-loaded amphiphilic copolymer aqueous solution, by mass, stir at 1000 r / min for 8 min at room temperature, let stand for 2 h, filter, wash with pure water 3 times, and freeze-dry to prepare DOPA-modified chitosan-coated rebamipide;

[0047] (6) Coating rebamipide with DOPA-modified chitosan to prepare tablets to obtain rebamipide tablets. Embodiment 2:

[0048] A preparation process of rebamipide tablets, comprising the following preparation steps:

[0049] (1) Under a nitrogen atmosphere, 6.5 parts of BOC-lysine tert-butyl ester hydrochloride, 3.5 parts of isocyanoethyl methacrylate, and 55 parts of dichloromethane were mixed uniformly by weight, refluxed at 50°C and 250 r / min for 11 hours, cooled to room temperature, filtered, and the filtrate was washed with pure water and saturated sodium chloride solution for 3 times respectively, and dried with anhydrous magnesium sulfate for 11 hours to purify and obtain lysine monomer;

[0050] (2) By weight, 10.5 parts of lysine monomer, 0.25 parts of pentamethyldiethyltriamine, 6.5 parts of 2-bromoisobutyrate-terminated polylactic acid, and 42 parts of N,N-dimethylformamide were mixed evenly, and after freeze-thawing to remove oxygen, 0.13 parts of cuprous bromide were added under argon atmosphere, and the mixture was reacted at 40°C and 250 r / min for 12 h. The mixture was diluted with 45 parts of tetrahydrofuran and purified, and the solvent was removed by rotary evaporation. The mixture was dialyzed in pure water with a molecular weight cutoff of 2 KDa for 22 h, and the protecting group of the precipitate was removed by trifluoroacetic acid. The amino acid amphiphilic block copolymer was obtained after freeze-drying.

[0051] (3) By weight, 1.5 parts of the rebamipide solution were added to 18 parts of a 3 mg / mL amino acid amphiphilic block copolymer aqueous solution, stirred at 1100 r / min for 35 min at room temperature, centrifuged three times using an ultrafiltration centrifuge tube with a molecular weight cutoff of 5 KDa, and vacuum dried at 35°C for 7 h to obtain an amphiphilic copolymer loaded with rebamipide;

[0052] (4) By weight, 5 parts of chitosan were dissolved in 55 parts of 0.97wt% glacial acetic acid solution, the pH was adjusted to 4.5, 6.5 parts of 10wt% DL-DOPA aqueous solution were added, and the mixture was stirred at 250r / min for 35min. 55 parts of carbodiimide solution were added dropwise at a rate of 2 drops per second. After the addition was completed, the mixture was reacted at 550r / min for 5h at room temperature, and then the pH was adjusted to 5.0. After being dialyzed with pure water for 2 days, it was dialyzed with phosphate buffered saline for 5h, and then dialyzed with pure water for 1 day. After being freeze-dried, DOPA-modified chitosan was obtained.

[0053] (5) To 15 parts of 10 mg / mL aqueous solution of the amphiphilic copolymer loaded with rebamipide, 0.3 parts of 10 mg / mL DOPA-modified chitosan aqueous solution and 0.3 parts of 10 mg / mL bismuth nitrate aqueous solution were added, by mass, and stirred at 1100 r / min for 7 min at room temperature, allowed to stand for 2.5 h, filtered, washed with pure water for 3 times, and freeze-dried to prepare DOPA-modified chitosan-coated rebamipide;

[0054] (6) Coating rebamipide with DOPA-modified chitosan to prepare tablets to obtain rebamipide tablets. Embodiment 3:

[0055] A preparation process of rebamipide tablets, comprising the following preparation steps:

[0056] (1) Under a nitrogen atmosphere, 7 parts of BOC-lysine tert-butyl ester hydrochloride, 4 parts of isocyanoethyl methacrylate, and 60 parts of dichloromethane were mixed uniformly by weight, refluxed at 50°C and 300 r / min for 10 h, cooled to room temperature, filtered, and the filtrate was washed with pure water and saturated sodium chloride solution for 4 times respectively, dried with anhydrous magnesium sulfate for 12 h, and purified to obtain lysine monomer;

[0057] (2) By weight, 11 parts of lysine monomer, 0.3 parts of pentamethyldiethyltriamine, 7 parts of 2-bromoisobutyrate-terminated polylactic acid, and 45 parts of N,N-dimethylformamide were mixed evenly, and after freeze-thawing to remove oxygen, 0.15 parts of cuprous bromide were added under argon atmosphere, and the mixture was reacted at 40°C and 300 r / min for 12 h. The mixture was diluted with 50 parts of tetrahydrofuran and purified, and the solvent was removed by rotary evaporation. The mixture was dialyzed in pure water with a molecular weight cutoff of 2 KDa for 24 h, and the protecting group of the precipitate was removed by trifluoroacetic acid. The amino acid amphiphilic block copolymer was obtained after freeze-drying;

[0058] (3) Add 2 parts of rebamipide solution to 20 parts of 3 mg / mL amino acid amphiphilic block copolymer aqueous solution by weight, stir at 1200 r / min for 30 min at room temperature, centrifuge three times with an ultrafiltration centrifuge tube with a molecular weight cutoff of 5 KDa, and vacuum dry at 40°C for 6 h to obtain rebamipide-loaded amphiphilic copolymer;

[0059] (4) By weight, 5 parts of chitosan were dissolved in 60 parts of 0.97wt% glacial acetic acid solution, the pH was adjusted to 4.5, 7 parts of 10wt% DL-DOPA aqueous solution were added, and the mixture was stirred at 300r / min for 30min. 60 parts of carbodiimide solution were added dropwise at 3 drops per second. After the addition was completed, the mixture was reacted at 600r / min for 4h at room temperature, and then the pH was adjusted to 5.0. After being dialyzed with pure water for 2 days, it was dialyzed with phosphate buffered saline for 5h, and then dialyzed with pure water for 1 day. After being freeze-dried, DOPA-modified chitosan was obtained.

[0060] (5) Add 0.4 parts of 10 mg / mL DOPA-modified chitosan aqueous solution and 0.4 parts of 10 mg / mL bismuth nitrate aqueous solution to 20 parts of 10 mg / mL rebamipide-loaded amphiphilic copolymer aqueous solution, by weight, stir at 1200 r / min for 6 min at room temperature, let stand for 3 h, filter, wash with pure water 4 times, and freeze-dry to prepare DOPA-modified chitosan-coated rebamipide;

[0061] (6) Coating rebamipide with DOPA-modified chitosan to prepare tablets to obtain rebamipide tablets.

[0062] Comparative Example 1:

[0063] The preparation process of the rebamipide tablets of Comparative Example 1 is different from that of Example 2 in that steps (1), (2) and (3) are not performed, and step (5) is modified as follows: 0.3 parts of 10 mg / mL DOPA-modified chitosan aqueous solution and 0.3 parts of 10 mg / mL bismuth nitrate aqueous solution are added to 15 parts of the rebamipide solution by mass, stirred at 1100 r / min for 7 min at room temperature, allowed to stand for 2.5 h, filtered, washed with pure water 3 times, and freeze-dried to obtain DOPA-modified chitosan-coated rebamipide. The remaining steps are the same as those of Example 2.

[0064] Comparative Example 2:

[0065] The preparation process of the rebamipide tablets of Comparative Example 2 is different from that of Example 2 in step (2). Step (2) is modified as follows: 10.5 parts of lysine monomer, 0.25 parts of pentamethyldiethyltriamine, 6.5 parts of 2-bromoisobutyrate-terminated polylactic acid, and 42 parts of N,N-dimethylformamide are mixed uniformly by weight, and after freezing and thawing to remove oxygen, 0.13 parts of cuprous bromide are added under an argon atmosphere, and the mixture is reacted at 40° C. and 250 r / min for 12 h, and then diluted with 45 parts of tetrahydrofuran and purified, and the solvent is removed by rotary evaporation, dialyzed in pure water with a molecular weight cutoff of 2 KDa for 22 h, and freeze-dried to obtain an amino acid amphiphilic block copolymer. The remaining steps are the same as those of Example 2.

[0066] Comparative Example 3:

[0067] The preparation process of the rebamipide tablets of Comparative Example 3 is different from that of Example 2 in that step (4) is not performed, and step (5) is modified as follows: 0.3 parts of 10 mg / mL chitosan aqueous solution and 0.3 parts of 10 mg / mL bismuth nitrate aqueous solution are added to 15 parts of 10 mg / mL rebamipide-loaded amphiphilic copolymer aqueous solution by mass, stirred at 1100 r / min for 7 min at room temperature, allowed to stand for 2.5 h, filtered, washed with pure water 3 times, and freeze-dried to obtain chitosan-coated rebamipide. Step (6) is modified as follows: chitosan-coated rebamipide is made into tablets to obtain rebamipide tablets. The remaining steps are the same as in Example 2.

[0068] Comparative Example 4:

[0069] The preparation process of the rebamipide tablets in Comparative Example 4 is different from that in Example 2 in that steps (4) and (5) are not performed, and step (6) is modified to: preparing tablets of the amphiphilic copolymer loaded with rebamipide, and preparing rebamipide tablets. The remaining steps are the same as those in Example 2.

[0070] In all the following test examples, the polylactic acid-glycolic acid copolymer used in each embodiment and test example was replaced by 20 wt % of red fluorescent rhodamine grafted polylactic acid-glycolic acid copolymer and 80 wt % of polylactic acid-glycolic acid copolymer.

[0071] The prepared rebamipide tablets were crushed and passed through a 200-mesh sieve, and the fine powder equivalent to 10 mg of rebamipide was weighed and dissolved in a phosphate buffered saline solution to prepare a rebamipide solution with a concentration of 1 mg / mL.

[0072] Test Example 1:

[0073] Cell uptake capacity test: GES-1 cells were grown in DMEM medium and cultured in a 37°C, 5% CO2 incubator. GES-1 cells were plated at 2×10 5 Each well was inoculated with 6-well plates and placed in an incubator for 1 day. After washing each well 3 times with preheated phosphate buffered saline, 1 mL of rebamipide solution was added and incubated for 2 h. After the incubation, the well was washed 3 times with phosphate buffered saline. The cells were collected by trypsin digestion, and the fluorescence intensity was quantitatively tested and the average value was recorded.

[0074] The results are shown in Table 1.

[0075] Table 1

[0076] Fluorescence intensity Fluorescence intensity Example 1 13452 Comparative Example 1 6527 Example 2 13867 Comparative Example 2 8234 Example 3 13384 Comparative Example 3 12875 Comparative Example 4 13475

[0077] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 4 in Table 1, it can be found that the rebamipide tablets prepared in the present invention have a high cellular uptake ability.

[0078] Comparison of the data in the table shows that the addition of amino acid block copolymers improves the cell uptake ability, allowing the drug to better enter the cell to take effect. At the same time, the deprotection of the amino acid block copolymer releases the amphiphilic properties of the amino acids. The amphiphilicity of the amino acids greatly improves the ability to pass through the mucus layer and be taken up by the cells. At the same time, the deprotected amino acid groups are also easier to be recognized and taken up by the cells.

[0079] Test Example 2:

[0080] Gastric ulcer treatment test: Male healthy BALB / c mice with a growth period of about 4 months and a body weight of about 28-30 g were selected. After fasting for 24 hours, they were supplied with water normally. Then, they were gavaged with 0.5 mL of pure water for the first time, and 0.5 mL of pure water was gavaged again after 3 hours. After 2 hours, 20 wt% acetic acid solution was gavaged at 0.025 mL / 10 g according to the weight of the mice to obtain a gastric ulcer mouse model.

[0081] The gastric ulcer mouse model was divided into groups of 6 mice per group. A control group composed of gastric ulcer mouse models and a blank group composed of normal mice were set up without treatment, and only 0.2 mL of normal saline was gavaged. Other gastric ulcer mouse models were treated with rebamipide solution gavage at a standard of 10 mg / kg, once a day for 7 consecutive days, during which time normal diet was restored. After the last administration, the mice were fasted for 24 hours and killed by dislocation of the neck. The peritoneal layer was lifted with tweezers and the abdomen of the mouse was cut open with sterile scissors. The stomach of the mouse was found under the liver. After it was completely removed, 1.0 mL of 4% neutral formaldehyde solution was extracted with a syringe and injected into the stomach from the cardia to fill the stomach. After it was placed in 4% neutral formaldehyde solution and soaked for 15 minutes, the stomach was cut open along the greater curvature of the stomach. The stomach contents were rinsed with sterile saline and the excess water was absorbed with absorbent paper. The stomach was unfolded and the gastric mucosal injury index was calculated. The ulcers in the gastric mucosa were observed under the microscope, and the ulcer index was calculated according to the Guth standard. The scores were given according to the size of the ulcer or erosion area: ① Every 3 punctate ulcers (mucosal defects less than 1mm or small hemorrhagic erosion spots, called punctate ulcers) were scored 1 point. ② Strip bleeding: The maximum long diameter of the ulcer and the maximum wide diameter perpendicular to the maximum long diameter were measured with a vernier caliper, and the product of the two was the ulcer index. For those with a width of 1mm, 1 point was given for every 1mm length; for those with a width of 2mm, 2 points were given for every 1mm length; for those with a width of 3mm, 3 points were given for every 1mm length. If the width of the lesion exceeded 4mm, it was counted in sections, and the sum of the scores of the length of the mucosal injury was used as the ulcer index. If the ulcer length was not an integer, the decimal part was rounded off, and the average value of each group was recorded.

[0082] Another mouse was selected for the experiment according to the above grouping and treatment process. This time, only one gavage treatment was performed and the mice were fasted after gavage. After 24 hours, the stomach tissue of the same size was taken from each mouse, and the fluorescence intensity thereon was quantitatively tested, and the average value was recorded.

[0083] The results are shown in Table 2.

[0084] Table 2

[0085] Ulcer Index Fluorescence intensity Example 1 4.17 5982 Example 2 3.67 6341 Example 3 3.83 6279 Comparative Example 1 9.5 3725 Comparative Example 2 12.33 3496 Comparative Example 3 13.83 1846 Comparative Example 4 12.5 1678 Control group 21.33 0 Blank Group 0 0

[0086] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 4 in Table 2, it can be found that the rebamipide tablets prepared in the present invention have good gastric ulcer treatment ability and gastric retention ability.

[0087] Comparison of the data in the table shows that the introduction of amino acid block copolymers, deprotection of amino acids, modification of chitosan and the coating formed by modified chitosan and bismuth salts all enhance the ability to treat gastric ulcers. At the same time, the fluorescence intensity data show that it has the ability to remain in the stomach for a long time, which increases the time for rebamipide to take effect and reduces the dosage. At the same time, the modification of chitosan and the coating formed by modified chitosan and bismuth salts play a major role in extending the retention time.

[0088] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A process for preparing rebamipide tablets, characterized in that: The method comprises the following preparation steps: (1) Under a nitrogen atmosphere, 6-7 parts of BOC-lysine tert-butyl ester hydrochloride, 3-4 parts of isocyanoethyl methacrylate, and 50-60 parts of dichloromethane were mixed uniformly by weight, refluxed at 45-50°C and 200-300 r / min for 10-12 h, cooled to room temperature, filtered, and the filtrate was washed with pure water and saturated sodium chloride solution for 3-4 times respectively, and dried with anhydrous magnesium sulfate for 10-12 h to purify and obtain lysine monomer; (2) By weight, 10-11 parts of lysine monomer, 0.2-0.3 parts of pentamethyldiethyltriamine, 6-7 parts of 2-bromoisobutyrate-terminated polylactic acid, and 40-45 parts of N,N-dimethylformamide were mixed evenly, and after freeze-thawing to remove oxygen, 0.12-0.15 parts of cuprous bromide were added under argon atmosphere, and the mixture was reacted at 40°C and 200-300 r / min for 12 h. The mixture was diluted with 40-50 parts of tetrahydrofuran and purified, and the solvent was removed by rotary evaporation. The mixture was dialyzed in pure water with a molecular weight cutoff of 2 KDa for 20-24 h, and the protecting group of the precipitate was removed by trifluoroacetic acid. The mixture was freeze-dried to obtain an amino acid amphiphilic block copolymer; (3) Add 1-2 parts of rebamipide solution to 15-20 parts of 3 mg / mL amino acid amphiphilic block copolymer aqueous solution by weight, stir at 1000-1200 r / min for 30-40 min at room temperature, centrifuge for 3 times using an ultrafiltration centrifuge tube with a molecular weight cutoff of 5 KDa, and vacuum dry at 30-40°C for 6-8 h to obtain the rebamipide-loaded amphiphilic copolymer; (4) Dissolve 5 parts of chitosan in 50-60 parts of 0.97wt% glacial acetic acid solution by weight, adjust the pH to 4.5, add 6-7 parts of 10wt% DL-DOPA aqueous solution, stir at 200-300r / min for 30-40min, add 50-60 parts of carbodiimide solution at 2-3 drops per second, react at room temperature at 500-600r / min for 4-5h, then adjust the pH to 5.0, dialyze with pure water for 2 days, dialyze with phosphate buffered saline for 4-5h, and then dialyze with pure water for 1 day, and obtain DOPA-modified chitosan after freeze-drying; (5) Add 0.2-0.4 parts of 10 mg / mL DOPA-modified chitosan aqueous solution and 0.2-0.4 parts of 10 mg / mL bismuth nitrate aqueous solution to 10-20 parts of 10 mg / mL rebamipide-loaded amphiphilic copolymer aqueous solution, by weight, stir at 1000-1200 r / min for 6-8 min at room temperature, let stand for 2-3 h, filter, wash with pure water 3-4 times, and freeze-dry to prepare DOPA-modified chitosan-coated rebamipide; (6) Coating rebamipide with DOPA-modified chitosan to prepare tablets to obtain rebamipide tablets.

2. The preparation process of a rebamipide tablet according to claim 1, characterized in that: The method for preparing the 2-bromoisobutyrate-terminated polylactic acid in step (2) comprises the following steps: (A) By weight, 12-13 parts of ethylene glycol, 4-5 parts of triethylamine, and 40-50 parts of dichloromethane are mixed uniformly, 36-40 parts of a 25wt% dichloromethane solution of 2-bromoisobutyryl bromide are added dropwise at 3-5 drops per second, reacted at 200-300 r / min for 10-12 hours at room temperature, washed and extracted with 0.1 mol / L hydrochloric acid solution, the organic layer is taken, washed with pure water and saturated sodium chloride solution 2-3 times respectively, dried and purified to obtain 2-hydroxyethyl bromoisobutyrate; (B) Under an argon atmosphere, 0.4-0.5 parts of 2-bromoisobutyric acid hydroxyethyl ester and 14-16 parts of DL-lactide were mixed uniformly by weight, and after removing oxygen, the temperature was raised to 130-135°C and kept warm for 30-40 min. 0.5 parts of 5 wt% stannous octoate toluene solution were added, and the reaction was continued at 200-300 r / min for 5-6 h. The product was dissolved with dichloromethane and precipitated with methanol, and the reaction was repeated 3 times. The product was dried in a vacuum at 30-40°C for 10-12 h to obtain terminal 2-bromoisobutyrate polylactic acid.

3. The preparation process of a rebamipide tablet according to claim 1, characterized in that: The rebamipide solution in step (3) is prepared by uniformly mixing rebamipide, polylactic acid-glycolic acid copolymer, and dimethyl sulfoxide in a mass ratio of 1:4:550, and stirring at 200 r / min for 30 min at room temperature.

4. The preparation process of a rebamipide tablet according to claim 1, characterized in that: The chitosan in step (4) has a deacetylation degree greater than 95% and a viscosity of 100-200 mPa·s.

5. The preparation process of a rebamipide tablet according to claim 1, characterized in that: The carbodiimide solution in step (4) is prepared by uniformly mixing 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide, N-hydroxysuccinimide, pure water and ethanol in a mass ratio of 1:(0.7-0.8):(20-25):(16-20).

6. The preparation process of a rebamipide tablet according to claim 1, characterized in that: The molecular weight cut-off of the dialysis in step (4) is 5 KDa.

7. The process for preparing rebamipide tablets according to claim 1, characterized in that: The preparation method of the phosphate buffered saline solution in step (4) is as follows: 8.0 g of sodium chloride, 0.2 g of potassium chloride, 1.44 g of disodium hydrogen phosphate, and 0.24 g of potassium dihydrogen phosphate are weighed and dissolved in 800 mL of pure water, the pH of the solution is adjusted to 7.4 with hydrochloric acid, and finally, pure water is added to make up to 1 L to obtain the phosphate buffered saline solution.

8. The process for preparing rebamipide tablets according to claim 3, characterized in that: The weight average molecular weight of the polylactic acid-glycolic acid copolymer is 5000, and the monomer ratio is 50:50.