A donepezil sustained-release formulation and its preparation method

Abstract

This invention belongs to the field of pharmaceutical technology, specifically relating to a donepezil sustained-release formulation and its preparation method. The method uses donepezil, a biodegradable polymer, an amphiphilic polymer, and a stabilizer, which are mixed, sheared, cured, and freeze-dried to produce donepezil microsphere lyophilized powder. This formulation achieves controlled, sustained-release of donepezil, with good microsphere properties and high stability. Furthermore, the preparation method is simple and easily scaled up for industrial production.

Description

Technical Field

[0001] This invention belongs to the field of pharmaceutical technology, specifically relating to a donepezil sustained-release formulation and its preparation method. Background Technology

[0002] Donepezil, used to treat mild to moderate Alzheimer's disease, is an acetylcholinesterase inhibitor. It works by inhibiting the breakdown of acetylcholine, increasing the concentration of acetylcholine in the brain, thereby improving cognitive function and memory. Since its development by Eisai Co., Ltd. of Japan in 1983, donepezil has been marketed in various dosage forms, including tablets, orally disintegrating tablets, granules, and dry syrup. These dosage forms are primarily administered orally and are suitable for most patients; however, for patients with swallowing difficulties or those requiring long-term medication, oral dosage forms have poorer adherence.

[0003] To improve medication adherence and optimize drug release characteristics in Alzheimer's patients, it is necessary to develop various novel drug delivery systems. Microsphere formulations, which encapsulate drugs within a micron-sized polymer matrix, offer great flexibility through multiple routes such as oral, injection, or topical administration. However, they also face several technical bottlenecks: for example, the physicochemical properties of donepezil may result in low encapsulation efficiency within microspheres; the selection of polymer materials and uneven microsphere particle size distribution make controlling the drug release rate difficult; and the preparation process involves emulsification, solvent evaporation, or spray drying, which are technically challenging and result in high production costs.

[0004] CN201480020234.0 discloses a non-oral pharmaceutical composition containing donepezil, which achieves sustained-release by adding a poorly soluble salt of donepezil, such as sine, naphthalene disulfonate, or dihydroxynaphthalene salt, as a controlled-release agent. The results show that the dissolution rate of the drug is delayed with increasing concentration of the poorly soluble salt.

[0005] CN201880029854.9 discloses a sustained-release injection formulation containing donepezil, which contains two or more types of microspheres. These microspheres contain polylactide with different intrinsic viscosities, and the intrinsic viscosity of the polylactide is controlled to be 0.16–0.75 dL / g to achieve sustained release. This patent requires strict control of the intrinsic viscosity of the polylactide, and the preparation method is cumbersome with harsh process conditions.

[0006] CN201880037391.0 discloses a method for preparing biodegradable microspheres with improved stability and storage stability. This method involves preparing an emulsion comprising a dispersed phase and a continuous phase, followed by strictly removing a portion of the continuous phase containing organic solvent extracted from the dispersed phase at a removal rate of 2–200% (v / v) per minute, while simultaneously supplying fresh aqueous solution to replace the continuous phase, thereby avoiding residual organic solvent in the microspheres. This preparation method is cumbersome and requires strict control of the removal rate; otherwise, the morphology, molecular weight, and quality of the product will be affected.

[0007] CN202080077303.7 discloses a microsphere for sustained release, which improves the drug encapsulation rate within the microsphere by preventing drug crystal formation around or on the surface of the microsphere, thereby preventing excessive drug release in the initial stage during administration.

[0008] CN202280067500.X discloses a sustained-release microsphere containing donepezil. By dispersing donepezil in two layers of dispersed phases with different drug loadings, microspheres with varying drug loadings are prepared, thereby achieving sustained release of the active ingredient. This preparation method is complex and requires strict control of the drug loading in different microspheres; otherwise, the sustained-release effect will be affected.

[0009] Given the problems existing in donepezil sustained-release formulations, there is an urgent need to provide a formulation and preparation method that can solve the problems of difficulty in controlling donepezil release rate, complex microsphere preparation process, and easy drug precipitation on microsphere surface. Summary of the Invention

[0010] In view of the technical problems in the prior art, the present invention provides a donepezil sustained-release formulation and its preparation method. The formulation can achieve controlled and sustained release of donepezil, with good microsphere properties and high stability. At the same time, the preparation method is simple and easy to realize industrial scale-up production.

[0011] The technical solution of the present invention is as follows: a method for preparing donepezil sustained-release formulation, comprising the following steps: adding donepezil and a biodegradable polymer to an organic solvent and stirring until completely dissolved to obtain a biodegradable substance solution; dissolving an amphiphilic polymer and a stabilizer in water for injection to obtain an amphiphilic substance solution and adjusting the pH; mixing and shearing the biodegradable substance solution and the amphiphilic substance solution to obtain an emulsion; vacuum solidifying the emulsion, sieving and washing the microspheres to remove the amphiphilic substance and stabilizer, and freeze-drying to obtain donepezil microsphere lyophilized powder.

[0012] In the method, the weight ratio of donepezil to the biodegradable polymer is 1:1.2 to 7.5, preferably 1:4 to 6.

[0013] In the method, the biodegradable polymer is selected from one or more of lactide-glycolic acid copolymer (PLGA), polyhydroxyalkanoate (PHA), or polylactide copolymer (PLA).

[0014] Preferably, in the method, the weight-average molecular weight of PLGA is 30-70 kDa, and more preferably 50 kDa.

[0015] Preferably, in the method, the weight-average molecular weight of PHA is 15-40 kDa, more preferably 30 kDa.

[0016] Preferably, in the method, the weight-average molecular weight of PLA is 30-80 kDa, and more preferably 50 kDa.

[0017] In the method, the organic solvent is a mixture of dichloromethane and an alcohol solvent, and the volume ratio of dichloromethane to alcohol solvent is 1:0.1 to 0.5.

[0018] Preferably, in the method, the alcohol solvent is tert-butanol, isopropanol, or n-propanol.

[0019] Preferably, in the method, the weight ratio of donepezil to the volume ratio of the organic solvent is 1:20 to 40, where the weight is in g and the volume is in mL.

[0020] Preferably, in the method, the pH is adjusted to 8.5–9.5.

[0021] In the method, the amphiphilic polymer is distearylphosphatidylethanolamine-polyethylene glycol (DSPE-PEG), polycaprolactone-polyethylene glycol (PCL-PEG), or polylactic acid-polyethylene glycol (PLLA-PEG).

[0022] Preferably, in the method, the weight ratio of the lipid portion to the PEG portion in the amphiphilic polymer is 1:0.5 to 0.95.

[0023] Preferably, in the method, the molecular weight of the PEG portion in the amphiphilic polymer is 2000, 3400, or 5000 Da.

[0024] Preferably, in the method, the amount of polycaprolactone in PCL-PEG is 4000-7000 Da, more preferably 6000 Da.

[0025] Preferably, in the method, the molecular weight of polylactic acid in PLLA-PEG is 4000-6000 Da, more preferably 5000 Da.

[0026] In the method, the mass fraction of the amphiphilic polymer in the amphiphilic substance solution is 0.3% to 3.0%.

[0027] In the method, the volume ratio of the degradable substance solution to the amphiphilic substance solution is 1:10 to 250.

[0028] In the method, the reagent for adjusting pH is an aqueous solution of hydrochloric acid, phosphoric acid, lactic acid, citric acid, sodium hydroxide, or potassium hydroxide.

[0029] In the method, the stabilizer is mannitol, glucose, or glycerol.

[0030] In the method, the mass fraction of the stabilizer in the amphiphilic substance solution is 5-10%.

[0031] Preferably, in the method, the shearing rate of the high-speed shearing is 2000-5000 r / min.

[0032] Preferably, in the method, the vacuum curing process is as follows: drying at 40-50°C and a vacuum degree of 0.01-0.05 MPa for 2-7 hours.

[0033] Preferably, in the method, the steps of sieving and washing the microspheres are as follows: the microsphere emulsion is sieved through a vibrating screen, and after sieving, the microspheres on the lower screen are rinsed with water for injection. After rinsing the microspheres with water for injection 5 to 8 times, the microspheres on the lower screen are transferred to a freeze-drying tray and placed in a freeze dryer for freeze-drying.

[0034] Preferably, in the method, the freeze-drying process is as follows: pre-freezing at -40 to -45°C for 2 to 3 hours; sublimation drying: evacuating the freeze dryer and maintaining a vacuum of 0.20 ± 0.02 mbar, raising the temperature to -10 to 30°C at 10°C / h, and maintaining this temperature for 10 to 15 hours; desorption drying: evacuating the freeze dryer and maintaining a vacuum of 0.10 ± 0.02 mbar, raising the temperature to 30 to 50°C, continuing drying for 10 to 20 hours, followed by ultimate vacuum for 2 hours, and then removing the product from the freezer.

[0035] The amphiphilic polymer in this invention can be purchased, prepared using existing techniques, or prepared in-house using the following method. As long as the weight-average molecular weight and polymer ratio meet the requirements, it can be used to prepare the microspheres of this invention. The source is not limited. A method for preparing the amphiphilic polymer is provided below:

[0036] The lipid moiety to PEG moiety in the amphiphilic polymer was added sequentially to a reactor that had been thoroughly dried at 130°C for 2 hours, with a weight ratio of 1:0.5 to 0.95. The reactor was sealed, pressurized with dry nitrogen to >2 kg, and heated to 150°C for 2 hours. After cooling, dichloromethane was added to dissolve and dilute the mixture, followed by the addition of water for injection. The mixture was stirred at room temperature for 24 hours. After standing and separating the layers, the dichloromethane layer was dried with anhydrous magnesium sulfate and filtered. The filtrate was concentrated to dryness, dissolved in water for injection, and a blank polymer micelle solution was obtained. The solution was concentrated by ultrafiltration and freeze-dried to obtain the target product, the amphiphilic polymer.

[0037] Compared with the prior art, the present invention has the following outstanding advantages:

[0038] 1. The donepezil microspheres obtained by this invention have good properties, with round morphology, smooth surface, and uniform particle size;

[0039] 2. This invention achieves controlled and sustained release of donepezil by regulating the spatial distribution of the drug in the microspheres, with the drug concentrated at the center of the microspheres;

[0040] 3. The preparation method of the present invention is simple and easy to scale up for industrial production. Attached Figure Description

[0041] Figure 1 The Raman spectrum of donepezil microspheres obtained in Example 1 of this invention. Detailed Implementation

[0042] The following specific embodiments further illustrate the present invention, but do not limit the scope of the present invention in any way. Those skilled in the art can make various modifications or improvements based on the basic idea of ​​the present invention, but as long as they do not depart from the basic idea of ​​the present invention, they are all within the scope of the present invention.

[0043] Example 1

[0044] 1) Add 1.2g donepezil and 4.8g PLGA (Mw: 50kDa) to 36mL of mixed organic solvent (dichloromethane: tert-butanol volume ratio of 1:0.3) and stir until completely dissolved to obtain a degradable substance solution;

[0045] 2) Weigh 30.0g of PLLA-PEG (where the Mw of PLLA and PEG are 5000Da and 3400Da respectively, and the weight ratio of PLLA to PEG is 1:0.7) and add it to 1200g of water for injection. Stir to dissolve, then add 120g of mannitol and stir until completely dissolved. Adjust the pH to 9.0 with sodium hydroxide solution or hydrochloric acid solution, and then make up to 1500g with water for injection. Stir well to obtain the amphiphilic substance solution.

[0046] 3) The biodegradable substance solution and the amphiphilic substance solution were placed in a shearing machine for high-speed shearing at a shearing rate of 4000 r / min to obtain an emulsion;

[0047] 4) Vacuum solidify the emulsion: dry at 45°C and vacuum degree 0.01~0.05MPa for 5h; then sieve and wash the microspheres. After sieve, rinse the microspheres on the lower screen with water for injection. After washing the microspheres 6 times, transfer the microspheres on the lower screen to a freeze-drying tray for later use.

[0048] 5) The microspheres obtained in step 4) are freeze-dried according to the following procedure: pre-freeze at -40 to -45℃ for 3 hours; sublimation drying: evacuate the freeze dryer and maintain a vacuum of 0.20±0.02mbar, raise the temperature to -10 to 30℃ at 10℃ / h, and maintain for 10 hours; desorption drying: evacuate the freeze dryer and maintain a vacuum of 0.10±0.02mbar, raise the temperature to 30 to 50℃, continue drying for 15 hours, then apply ultimate vacuum for 2 hours. After removal from the freezer, the microspheres are freeze-dried powder.

[0049] Example 2

[0050] 1) Add 1.2g donepezil and 1.4g PLA (Mw: 50kDa) to 24mL of mixed organic solvent (dichloromethane:isopropanol volume ratio of 1:0.1) and stir until completely dissolved to obtain a degradable substance solution;

[0051] 2) Weigh 4.5g of DSPE-PEG (where the Mw of PEG is 2000Da and the weight ratio of DSPE to PEG is 1:0.5) and add it to 1200g of water for injection. Stir to dissolve, then add 75g of glucose and stir until completely dissolved. Adjust the pH to 8.5 with potassium hydroxide solution or lactic acid solution, and then make up to 1500g with water for injection. Stir well to obtain the amphiphilic substance solution.

[0052] 3) The biodegradable substance solution and the amphiphilic substance solution were placed in a shearing machine for high-speed shearing at a shearing rate of 2000 r / min to obtain an emulsion;

[0053] 4) Vacuum solidify the emulsion: dry at 50°C and vacuum degree of 0.01~0.05MPa for 2h; then sieve and wash the microspheres. The microsphere emulsion is sieved through a vibrating screen. After sieving, the microspheres on the lower screen are rinsed with water for injection. After washing the microspheres 5 times, the microspheres on the lower screen are transferred to a freeze-drying tray for later use.

[0054] 5) The microspheres obtained in step 4) are freeze-dried according to the following procedure: pre-freeze at -40 to -45℃ for 2 hours; sublimation drying: evacuate the freeze dryer and maintain a vacuum of 0.20±0.02mbar, raise the temperature to -10 to 30℃ at 10℃ / h, and maintain for 15 hours; desorption drying: evacuate the freeze dryer and maintain a vacuum of 0.10±0.02mbar, raise the temperature to 30 to 50℃, continue drying for 10 hours, then apply ultimate vacuum for 2 hours. After removal from the freezer, the microspheres are freeze-dried powder.

[0055] Example 3

[0056] 1) Add 1.2g donepezil, 4.5g PHA (Mw: 30kDa) and 4.5g PLGA (Mw: 50kDa) to 48mL of mixed organic solvent (dichloromethane: n-propanol volume ratio of 1:0.5) and stir until completely dissolved to obtain a degradable substance solution;

[0057] 2) Weigh 45.0g of PCL-PEG (where the Mw of PCL and PEG are 6000Da and 5000Da respectively, and the weight ratio of PCL to PEG is 1:0.95) and add it to 1200g of water for injection. Stir to dissolve, then add 150g of glycerol and stir until completely dissolved. Adjust the pH to 9.5 with sodium hydroxide solution or phosphoric acid solution, and then make up to 1500g with water for injection. Stir well to obtain the amphiphilic substance solution.

[0058] 3) The biodegradable substance solution and the amphiphilic substance solution were placed in a shearing machine for high-speed shearing at a shearing rate of 5000 r / min to obtain an emulsion;

[0059] 4) Vacuum solidify the emulsion: dry at 40°C and vacuum degree 0.01~0.05MPa for 7h; then sieve and wash the microspheres. The microsphere emulsion is sieved through a vibrating screen. After sieving, the microspheres on the lower screen are rinsed with water for injection. After washing the microspheres 8 times, the microspheres on the lower screen are transferred to a freeze-drying tray for later use.

[0060] 5) The microspheres obtained in step 4) are freeze-dried according to the following procedure: pre-freeze at -40 to -45℃ for 3 hours; sublimation drying: evacuate the freeze dryer and maintain a vacuum of 0.20±0.02mbar, raise the temperature to -10 to 30℃ at 10℃ / h, and maintain for 10 hours; desorption drying: evacuate the freeze dryer and maintain a vacuum of 0.10±0.02mbar, raise the temperature to 30 to 50℃, continue drying for 20 hours, then apply ultimate vacuum for 2 hours. After removal from the freezer, the microspheres are freeze-dried powder.

[0061] Example 4

[0062] 1) Add 1.2g donepezil and 10.8g PLGA (Mw: 50kDa) to 36mL of mixed organic solvent (dichloromethane: tert-butanol volume ratio of 1:0.3) and stir until completely dissolved to obtain a degradable substance solution;

[0063] 2) Weigh 30.0g of PLLA-PEG (where the Mw of PLLA and PEG are 5000Da and 3400Da respectively, and the weight ratio of PLLA to PEG is 1:0.7) and add it to 1200g of water for injection. Stir to dissolve, then add 120g of mannitol and stir until completely dissolved. Adjust the pH to 9.0 with sodium hydroxide solution or hydrochloric acid solution, and then make up to 1500g with water for injection. Stir well to obtain the amphiphilic substance solution.

[0064] 3) The biodegradable substance solution and the amphiphilic substance solution were placed in a shearing machine for high-speed shearing at a shearing rate of 4000 r / min to obtain an emulsion;

[0065] 4) Vacuum solidification of the emulsion: drying at 45°C and vacuum degree 0.01~0.05MPa for 5h; then sieving and washing the microspheres: sieving the microsphere emulsion through a vibrating screen, rinsing the microspheres on the lower screen with water for injection after sieving, washing the microspheres 6 times, and then transferring the microspheres on the lower screen to a freeze-drying tray for later use.

[0066] 5) The microspheres obtained in step 4) are freeze-dried according to the following procedure: pre-freeze at -40 to -45℃ for 3 hours; sublimation drying: evacuate the freeze dryer and maintain a vacuum of 0.20±0.02mbar, raise the temperature to -10 to 30℃ at 10℃ / h, and maintain for 10 hours; desorption drying: evacuate the freeze dryer and maintain a vacuum of 0.10±0.02mbar, raise the temperature to 30 to 50℃, continue drying for 15 hours, then apply ultimate vacuum for 2 hours. After removal from the freezer, the microspheres are freeze-dried powder.

[0067] Example 5

[0068] 1) Add 1.2g donepezil and 4.8g PLGA (Mw: 50kDa) to 36mL of mixed organic solvent (dichloromethane: tert-butanol volume ratio of 1:0.3) and stir until completely dissolved to obtain a degradable substance solution;

[0069] 2) Weigh 90.0g of PLLA-PEG (where the Mw of PLLA and PEG are 5000Da and 3400Da respectively, and the weight ratio of PLLA to PEG is 1:0.7) and add it to 1200g of water for injection. Stir to dissolve, then add 120g of mannitol and stir until completely dissolved. Adjust the pH to 9.0 with sodium hydroxide solution or hydrochloric acid solution, and then make up the volume to 1500g with water for injection. Stir well to obtain the amphiphilic substance solution.

[0070] 3) The biodegradable substance solution and the amphiphilic substance solution were placed in a shearing machine for high-speed shearing at a shearing rate of 4000 r / min to obtain an emulsion;

[0071] 4) Vacuum solidification of the emulsion: drying at 45°C and vacuum degree 0.01~0.05MPa for 5h; then sieving and washing the microspheres: sieving the microsphere emulsion through a vibrating screen, rinsing the microspheres on the lower screen with water for injection after sieving, washing the microspheres 6 times, and then transferring the microspheres on the lower screen to a freeze-drying tray for later use.

[0072] 5) The microspheres obtained in step 4) are freeze-dried according to the following procedure: pre-freeze at -40 to -45℃ for 3 hours; sublimation drying: evacuate the freeze dryer and maintain a vacuum of 0.20±0.02mbar, raise the temperature to -10 to 30℃ at 10℃ / h, and maintain for 10 hours; desorption drying: evacuate the freeze dryer and maintain a vacuum of 0.10±0.02mbar, raise the temperature to 30 to 50℃, continue drying for 15 hours, then apply ultimate vacuum for 2 hours. After removal from the freezer, the microspheres are freeze-dried powder.

[0073] Example 6

[0074] 1) Add 1.2g donepezil and 4.8g PLGA (Mw: 50kDa) to 36mL of mixed organic solvent (dichloromethane: tert-butanol volume ratio of 1:0.3) and stir until completely dissolved to obtain a degradable substance solution;

[0075] 2) Weigh 30.0g of PLLA-PEG (where the Mw of PLLA and PEG are 5000Da and 3400Da respectively, and the weight ratio of PLLA to PEG is 1:0.7) and add it to 1200g of water for injection. Stir to dissolve, then add 120g of mannitol and stir until completely dissolved. Adjust the pH to 11.0 with sodium hydroxide solution or hydrochloric acid solution, and then make up the volume to 1500g with water for injection. Stir well to obtain the amphiphilic substance solution.

[0076] 3) The biodegradable substance solution and the amphiphilic substance solution were placed in a shearing machine for high-speed shearing at a shearing rate of 4000 r / min to obtain an emulsion;

[0077] 4) Vacuum solidification of the emulsion: drying at 45°C and vacuum degree 0.01~0.05MPa for 5h; then sieving and washing the microspheres: sieving the microsphere emulsion through a vibrating screen, rinsing the microspheres on the lower screen with water for injection after sieving, washing the microspheres 6 times, and then transferring the microspheres on the lower screen to a freeze-drying tray for later use.

[0078] 5) The microspheres obtained in step 4) are freeze-dried according to the following procedure: pre-freeze at -40 to -45℃ for 3 hours; sublimation drying: evacuate the freeze dryer and maintain a vacuum of 0.20±0.02mbar, raise the temperature to -10 to 30℃ at 10℃ / h, and maintain for 10 hours; desorption drying: evacuate the freeze dryer and maintain a vacuum of 0.10±0.02mbar, raise the temperature to 30 to 50℃, continue drying for 15 hours, then apply ultimate vacuum for 2 hours. After removal from the freezer, the microspheres are freeze-dried powder.

[0079] Comparative Example 1

[0080] 1) Add 1.2g donepezil and 4.8g PLGA (Mw: 50kDa) to 36mL of dichloromethane and stir until completely dissolved to obtain a degradable solution;

[0081] 2) Weigh 30.0g of PLLA-PEG (where the Mw of PLLA and PEG are 5000Da and 3400Da respectively, and the weight ratio of PLLA to PEG is 1:0.7) and add it to 1200g of water for injection. Stir to dissolve, then add 120g of mannitol and 2.3mL of tert-butanol. Stir until completely dissolved, then adjust the pH to 9.0 with sodium hydroxide solution or hydrochloric acid solution. Finally, use water for injection to make up to 1500g. Stir well to obtain the amphiphilic substance solution.

[0082] 3) The biodegradable substance solution and the amphiphilic substance solution were placed in a shearing machine for high-speed shearing at a shearing rate of 4000 r / min to obtain an emulsion;

[0083] 4) Vacuum solidification of the emulsion: drying at 45°C and vacuum degree 0.01~0.05MPa for 5h; then sieving and washing the microspheres: sieving the microsphere emulsion through a vibrating screen, rinsing the microspheres on the lower screen with water for injection after sieving, washing the microspheres 6 times, and then transferring the microspheres on the lower screen to a freeze-drying tray for later use.

[0084] 5) The microspheres obtained in step 4) are freeze-dried according to the following procedure: pre-freeze at -40 to -45℃ for 3 hours; sublimation drying: evacuate the freeze dryer and maintain a vacuum of 0.20±0.02mbar, raise the temperature to -10 to 30℃ at 10℃ / h, and maintain for 10 hours; desorption drying: evacuate the freeze dryer and maintain a vacuum of 0.10±0.02mbar, raise the temperature to 30 to 50℃, continue drying for 15 hours, then apply ultimate vacuum for 2 hours. After removal from the freezer, the microspheres are freeze-dried powder.

[0085] Comparative Example 2

[0086] 1) Add 1.2g donepezil and 4.8g PLGA (Mw: 50kDa) to 36mL of mixed organic solvent (dichloromethane: tert-butanol volume ratio of 1:0.3) and stir until completely dissolved to obtain a degradable substance solution;

[0087] 2) Weigh 30.0g of polyvinyl alcohol and add it to 1200g of water for injection. Stir to dissolve, then add 120g of mannitol and stir until completely dissolved. Adjust the pH to 9.0 with sodium hydroxide solution or hydrochloric acid solution, and then make up to 1500g with water for injection. Stir well to obtain the amphiphilic substance solution.

[0088] 3) The biodegradable substance solution and the amphiphilic substance solution were placed in a shearing machine for high-speed shearing at a shearing rate of 4000 r / min to obtain an emulsion;

[0089] 4) Vacuum solidification of the emulsion: drying at 45°C and vacuum degree 0.01~0.05MPa for 5h; then sieving and washing the microspheres: sieving the microsphere emulsion through a vibrating screen, rinsing the microspheres on the lower screen with water for injection after sieving, washing the microspheres 6 times, and then transferring the microspheres on the lower screen to a freeze-drying tray for later use.

[0090] 5) The microspheres obtained in step 4) are freeze-dried according to the following procedure: pre-freeze at -40 to -45℃ for 3 hours; sublimation drying: evacuate the freeze dryer and maintain a vacuum of 0.20±0.02mbar, raise the temperature to -10 to 30℃ at 10℃ / h, and maintain for 10 hours; desorption drying: evacuate the freeze dryer and maintain a vacuum of 0.10±0.02mbar, raise the temperature to 30 to 50℃, continue drying for 15 hours, then apply ultimate vacuum for 2 hours. After removal from the freezer, the microspheres are freeze-dried powder.

[0091] Comparative Example 3

[0092] 1) Add 1.2g donepezil and 4.8g PLGA (Mw: 50kDa) to 36mL of mixed organic solvent (dichloromethane: tert-butanol volume ratio of 1:0.3) and stir until completely dissolved to obtain a degradable substance solution;

[0093] 2) Weigh 30.0g of PLLA-PEG (where the Mw of PLLA and PEG are 5000Da and 3400Da respectively, and the weight ratio of PLLA to PEG is 1:0.7) and add it to 1200g of water for injection. Stir to dissolve. After stirring until completely dissolved, adjust the pH value to 9.0 with sodium hydroxide solution or hydrochloric acid solution. Then, use water for injection to make up to 1500g. Stir well to obtain the amphiphilic substance solution.

[0094] 3) The biodegradable substance solution and the amphiphilic substance solution were placed in a shearing machine for high-speed shearing at a shearing rate of 4000 r / min to obtain an emulsion;

[0095] 4) Vacuum solidification of the emulsion: drying at 45°C and vacuum degree 0.01~0.05MPa for 5h; then sieving and washing the microspheres: sieving the microsphere emulsion through a vibrating screen, rinsing the microspheres on the lower screen with water for injection after sieving, washing the microspheres 6 times, and then transferring the microspheres on the lower screen to a freeze-drying tray for later use.

[0096] 5) The microspheres obtained in step 4) are freeze-dried according to the following procedure: pre-freeze at -40 to -45℃ for 3 hours; sublimation drying: evacuate the freeze dryer and maintain a vacuum of 0.20±0.02mbar, raise the temperature to -10 to 30℃ at 10℃ / h, and maintain for 10 hours; desorption drying: evacuate the freeze dryer and maintain a vacuum of 0.10±0.02mbar, raise the temperature to 30 to 50℃, continue drying for 15 hours, then apply ultimate vacuum for 2 hours. After removal from the freezer, the microspheres are freeze-dried powder.

[0097] Comparative Example 4

[0098] 1) Add 1.2g donepezil and 4.8g PLGA (Mw: 50kDa) to 36mL of mixed organic solvent (dichloromethane: tert-butanol volume ratio of 1:0.3) and stir until completely dissolved to obtain a degradable substance solution;

[0099] 2) Weigh 30.0g of PLLA-PEG (where the Mw of PLLA and PEG are 5000Da and 3400Da respectively, and the weight ratio of PLLA to PEG is 1:0.7) and add it to 1200g of water for injection. Stir to dissolve, then add 120g of mannitol and stir until completely dissolved. Measure the pH value as 4.5, then use water for injection to make up to 1500g. Stir well to obtain the amphiphilic substance solution.

[0100] 3) The biodegradable substance solution and the amphiphilic substance solution were placed in a shearing machine for high-speed shearing at a shearing rate of 4000 r / min to obtain an emulsion;

[0101] 4) Vacuum solidification of the emulsion: drying at 45°C and vacuum degree 0.01~0.05MPa for 5h; then sieving and washing the microspheres: sieving the microsphere emulsion through a vibrating screen, rinsing the microspheres on the lower screen with water for injection after sieving, washing the microspheres 6 times, and then transferring the microspheres on the lower screen to a freeze-drying tray for later use.

[0102] 5) The microspheres obtained in step 4) are freeze-dried according to the following procedure: pre-freeze at -40 to -45℃ for 3 hours; sublimation drying: evacuate the freeze dryer and maintain a vacuum of 0.20±0.02mbar, raise the temperature to -10 to 30℃ at 10℃ / h, and maintain for 10 hours; desorption drying: evacuate the freeze dryer and maintain a vacuum of 0.10±0.02mbar, raise the temperature to 30 to 50℃, continue drying for 15 hours, then apply ultimate vacuum for 2 hours. After removal from the freezer, the microspheres are freeze-dried powder.

[0103] Comparative Example 5

[0104] 3.5 g of the biocompatible polymer Resomer R203H and 1.5 g of donepezil were mixed with 9.2 g of dichloromethane and stirred for at least 30 min to dissolve completely. The continuous phase was an aqueous solution containing 1% (w / v) polyvinyl alcohol (viscosity: 4.8 to 5.8 mPa·s) and 30% (v / v) ethanol. The container containing the continuous phase was connected to an emulsification device equipped with a membrane (wherein the membrane has pores with a diameter of 40 μm), and the prepared dispersed phase was injected simultaneously to generate microspheres in the suspension. The resulting microsphere suspension was placed in a preparation vessel and stirred at 200 rpm. The temperature of the membrane emulsification device and the preparation vessel was maintained at 25°C. When the injection of the dispersed phase was complete, stirring was continued for 30 min. In this step, while leaving 5 mL of continuous phase, 455 mL of the remaining continuous phase was removed, and an equal amount of new continuous phase was added. The organic solvent was removed while maintaining the temperature at 40°C for 3 h. After removing the organic solvent, the temperature of the microsphere suspension was lowered to 25°C. The microsphere suspension was washed three times with deionized water to remove residual polyvinyl alcohol, and then lyophilized to obtain the microspheres.

[0105] Example 1: Investigation of the properties of donepezil microspheres and residual organic solvents

[0106] 1) Microsphere morphology observation

[0107] Take an appropriate amount of the cured microsphere emulsion and observe the morphology of the microspheres using an optical microscope. Adhere the conductive adhesive to the sample stage, take an appropriate amount of lyophilized microsphere powder and evenly coat it on the conductive adhesive, place it in an ion sputtering instrument, sputter gold for 90 seconds, and then observe the surface morphology of the microspheres under a scanning electron microscope at 10 kV.

[0108] 2) Microsphere size determination

[0109] Take an appropriate amount of lyophilized microsphere powder and place it in a dispersant (purified water is commonly used in the laboratory). After stirring and dispersing, add it to a Malvern laser particle size analyzer for particle size measurement. The parameters are set as follows: occlusion between 10% and 20%, rotation speed of 2800 rpm, and measurement is performed after the occlusion stabilizes. The sample refractive index is 1.578, the medium refractive index is 1.330, the absorptivity is 0.000, the background measurement time is 10 seconds, and the sample measurement time is 10 seconds. The span of the microspheres = (Dv) 90 -Dv 10 ) / Dv 50 .

[0110] 3) Determination of residual solvent in microspheres

[0111] Test solution: Weigh approximately 100 mg of this product accurately, place it in a headspace vial, accurately add 2 ml of dimethyl sulfoxide, seal, and determine the residual solvent.

[0112] Reference solution: Weigh appropriate amounts of isopropanol, dichloromethane, tert-butanol and n-propanol accurately, add dimethyl sulfoxide to quantitatively dilute to prepare a mixed solution containing approximately 0.25 mg isopropanol, 0.03 mg dichloromethane, 0.175 mg tert-butanol and 0.25 mg n-propanol per 1 ml. Accurately measure 2 mL, place in a headspace bottle and seal.

[0113] Chromatographic conditions: A capillary column with 6% cyanopropylphenyl-94% dimethylpolysiloxane (or similar polarity, 30m × 0.32mm × 1.8μm) as stationary phase; initial temperature 40℃, maintained for 5 minutes, then increased to 200℃ at a rate of 20℃ / min, maintained for 5 minutes; injection port temperature 200℃; detector temperature 250℃; detector was a flame ionization detector; headspace vial equilibration temperature 80℃, equilibration time 30 minutes; carrier gas nitrogen; column flow rate 2.0 mL / min; split ratio 10:1; injection volume 1.0 mL.

[0114] Table 1. Microsphere measurement results for each embodiment and comparative embodiment.

[0115]

[0116]

[0117] The results show that the microspheres obtained in each embodiment of the present invention have small particle size, uniform size, good morphology and properties, and low organic solvent residue. In Comparative Example 1, the organic solvent residue may be high because no alcohol solvent was added to the oil phase. In Comparative Example 2, polyvinyl alcohol was used in the aqueous phase, which had poor mixing effect with degradable substances during microsphere preparation, resulting in uneven microsphere size and high dichloromethane and alcohol solvent residues. In Comparative Example 3, no stabilizer was added, and the obtained microspheres not only had poor morphology, being elliptical, but also uneven size. In Comparative Example 5, the microspheres obtained using different preparation methods had higher organic solvent residues.

[0118] Experimental Example 2: Investigation of the in vitro drug release rate of donepezil formulation

[0119] Accurately weigh approximately 10 mg of donepezil microspheres and place them in 30 mL of HEPES buffer (pH 7.4). Place the solution in a 37°C water bath at 100 rpm and shake at different time points. Take 1 mL of the solution at each time point and add the same amount of HEPES buffer. Filter the collected filtrate through a 0.45 μm syringe filter. Inject 20 μL of the solution into an HPLC system and calculate the donepezil microsphere release rate based on the filtrate concentration.

[0120] Table 2 shows the results of in vitro drug release rate measurements for each embodiment and comparative embodiment.

[0121]

[0122]

[0123] The results show that the microspheres obtained in each embodiment of the present invention have good dissolution properties. In Comparative Example 1, the addition of alcohol solvent to the aqueous phase during preparation affected the concentrated distribution of donepezil within the microspheres, resulting in a shorter sustained-release time. In Comparative Example 2, polyvinyl alcohol was used instead of the amphiphilic substance, which, when mixed with the degradable substance, resulted in poor mixing during microsphere preparation, affecting the distribution of donepezil within the microspheres and leading to incomplete dissolution. In Comparative Example 3, no stabilizer was added, resulting in unevenly sized microspheres and incomplete dissolution. In Comparative Example 4, the lack of pH adjustment led to dispersed distribution of donepezil within the microspheres, shortening the sustained-release time. Comparative Example 5, using a different preparation method, exhibited the drawback of incomplete dissolution.

[0124] Experimental Example 3

[0125] Raman spectroscopy testing instruments and methods:

[0126]

[0127] Sample detection: Take an appropriate amount of donepezil microspheres, cut them open, place the processed microspheres on a glass slide, and put the prepared sample into Raman spectroscopy for sample detection.

[0128] The donepezil microspheres obtained in Example 1 were used for testing, and the results are as follows: Figure 1 As shown. The preparation method provided by this invention achieves the formation of a significant drug-enriched region in the core of donepezil by controlling the spatial distribution of the drug in the microspheres. This core-shell distribution feature effectively establishes a concentration gradient for drug release, thereby achieving precise control over donepezil release kinetics.

Claims

1. A method for preparing a sustained-release preparation of donepezil, characterized by, The method comprises the following steps: adding donepezil and biodegradable polymer into an organic solvent, stirring until the biodegradable substance solution is fully dissolved; dissolving amphiphilic polymer and stabilizer in water for injection to obtain an amphiphilic substance solution, adjusting pH; Mixing the biodegradable substance solution and the amphiphilic substance solution, shearing to obtain an emulsion; Vacuum solidification of the emulsion, screening and washing to remove the amphiphilic substance and the stabilizer, and freeze-drying to obtain donepezil microspheres freeze-dried powder; in the method, the biodegradable polymer is selected from one or more of poly(lactide-co-glycolide), polyhydroxyalkanoate or poly(lactide-co-glycolide), the weight ratio of donepezil to biodegradable polymer is 1:1.2-9, the amphiphilic polymer is distearoylphosphatidylethanolamine-polyethylene glycol, polycaprolactone-polyethylene glycol or poly-l-lactic acid-polyethylene glycol, the organic solvent is a mixture of dichloromethane and alcohol solvent, the volume ratio of dichloromethane to alcohol solvent is 1:0.1-0.5, the alcohol solvent is tert-butyl alcohol, isopropyl alcohol or n-propanol, the pH is adjusted to 8.5-9.5, the volume ratio of the biodegradable substance solution to the amphiphilic substance solution is 1:10-250, the stabilizer is mannitol, glucose or glycerol, the weight ratio of donepezil to the organic solvent is 1:20-40, wherein the weight is in grams and the volume is in milliliters, and the mass fraction of the amphiphilic polymer in the amphiphilic substance solution is 0.3-3.0%.

2. The method of claim 1, wherein, In the method, the weight ratio of donepezil to biodegradable polymer is 1:4-6.

3. The method of claim 1, wherein, In the method, the weight ratio of the lipid part to the PEG part in the amphiphilic polymer is 1:0.5-0.95.

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