Drying preparation method of degarelix acetate

Abstract

The invention discloses a degarelix acetate drying preparation method, belongs to the technical field of polypeptide preparation, and particularly relates to a degarelix acetate drying preparation method. The method comprises the following steps: carrying out reversed-phase liquid chromatography purification on a degarelix acetate crude product prepared by adopting a polypeptide solid-phase synthesis method, and carrying out rotary evaporation concentration, depolymerization reconstruction, sedimentation pulping and vacuum drying treatment to obtain a degarelix acetate finished product. The finished degarelix acetate product treated by the method disclosed by the invention not only meets the quality standards of the original research medicine of degarelix acetate on solvent residue, moisture and purity, but also meets the viscosity and optical density standards of the original research medicine after the original research medicine is dissolved by a mannitol aqueous solution with the mass concentration of 2.5% at the concentration of 20mg / ml.

Description

Technical Field

[0001] This invention relates to the field of polypeptide preparation technology, specifically to a method for preparing degarelk acetate by drying. Background Technology

[0002] Degarelix acetate is a drug used to treat advanced prostate cancer. Its pharmacological action is primarily achieved through antagonism of gonadotropins. Physicochemically, degarelix acetate exhibits the ability to self-aggregate, forming a gel-like solution in aqueous solution. This self-aggregation ability allows it to form a reservoir at the injection site when injected subcutaneously or intramuscularly.

[0003] The self-packaging performance of a drug is related to the viscosity of the original drug. To ensure the performance of the drug formulation, the original drug of degarelc acetate must meet the following key quality requirements: 1) Acetic acid content in the range of 4.5% to 10%; 2) Moisture content below 10%; 3) After degarelc acetate is dissolved in a 2.5% mannitol aqueous solution at a concentration of 20 mg / ml, the viscosity should not exceed 3.20 mPas; 4) After degarelc acetate is dissolved in a 2.5% mannitol aqueous solution at a concentration of 20 mg / ml and allowed to stand for 2 hours, the optical density measured by a UV spectrophotometer at 350 nm should not exceed 0.10 Au. However, as a hydrophobic polypeptide, degarelic acid acetate molecules are prone to aggregation in aqueous environments through hydrophobic interactions. This process initially forms high-viscosity colloidal aggregates and eventually insoluble microparticles that cause excessive optical density. As a result, existing processes cannot simultaneously meet the quality requirements of all degarelic acid acetate drugs. Among these, maintaining stable optical density below 0.1 Au is a particularly pressing technical challenge.

[0004] Currently, the production process of the original degarelc acetate drug generally involves synthesizing a crude peptide using solid-phase or liquid-phase chromatography, followed by salt exchange and purification using reversed-phase chromatography to obtain high-purity degarelc acetate, and then concentration, depolymerization, and lyophilization to obtain the finished original degarelc acetate drug. In the preparation of injectable degarelc acetate, freeze-drying or spray drying are commonly used. Freeze-drying typically involves a concentration range of 10-35 g / L and a freeze-drying time of 5 days, resulting in a relatively long production cycle. Therefore, a drying method for degarelc acetate that can meet drug quality requirements, is suitable for large-scale production, and effectively shorten the production cycle is needed. Summary of the Invention

[0005] The purpose of this invention is to provide a drying preparation method for degarelc acetate, which not only ensures that the finished degarelc acetate meets the acetic acid content requirements specified by the original drug, reduces the moisture content in the finished degarelc acetate, effectively controls its viscosity after dissolving in mannitol aqueous solution, and stably controls the optical density below 0.1 Au, thereby ensuring that the finished degarelc acetate fully meets the quality standards of the original drug; at the same time, it significantly shortens the production cycle and realizes the large-scale industrial production of finished degarelc acetate.

[0006] The technical solution adopted by the present invention to achieve the above objectives is as follows: A method for preparing degarelic acid by drying includes: purifying crude degarelic acid prepared by a polypeptide solid-phase synthesis method by reversed-phase liquid chromatography, concentrating it by rotary evaporation to obtain a low-water-content viscous gel, adding acetic acid to the viscous gel and stirring until clear to obtain a depolymerization solution, stirring and slurrying with a settling liquid, and then vacuum drying to obtain degarelic acid; the settling liquid is methyl tert-butyl ether or n-heptane solution, the n-heptane solution is a mixture of n-heptane and anhydrous ethanol, the volume ratio of n-heptane to anhydrous ethanol is 1:1-9; the optical density of degarelic acid dissolved in mannitol aqueous solution is less than 0.060 Au.

[0007] This invention first purifies crude degarelc acetate using reversed-phase liquid chromatography to obtain a purified degarelc acetate intermediate. Subsequently, it is concentrated to a low-water-content viscous gel by rotary evaporation, efficiently removing the organic phase introduced during purification. Acetic acid is then added and stirred until clear, ensuring complete dissolution of the degarelc acetate and forming a homogeneous solution. A mixture of methyl tert-butyl ether or n-heptane / anhydrous ethanol is used as a settling agent to reduce the solubility of degarelc acetate in the system, causing it to precipitate from the solution as a solid, achieving secondary purification and yielding a loose solid suspension. Finally, vacuum drying at room temperature yields the finished degarelc acetate product. Compared to freeze-drying or spray drying, this significantly shortens the drying time, enabling large-scale industrial production. The degarelc acetate product obtained by this invention not only meets the original drug's quality requirements for solvent residue, moisture, and purity, but also meets the viscosity and optical density requirements of the original drug after dissolving in a 2.5% mannitol aqueous solution at a concentration of 20 mg / mL.

[0008] Preferably, the viscosity of degarelic acetate dissolved in an aqueous mannitol solution is less than 2.1 mPas.

[0009] Preferably, the acetic acid content in degarelic acid is less than 8.4%.

[0010] Preferably, the moisture content in the acetic acid sorbitol is less than 3.5%.

[0011] Preferably, the water bath temperature for rotary evaporation concentration is 25-45℃.

[0012] Preferably, the pressure of rotary evaporation concentration is below 20 mbar.

[0013] Preferably, the ratio of low-moisture viscous gel to acetic acid is 1g:1-10mL.

[0014] Preferably, the volume ratio of the depolymerization liquid to the sedimentation liquid is 1:2-20.

[0015] Preferably, the vacuum drying temperature is 20-30℃.

[0016] Preferably, the vacuum drying time is 12-24 hours.

[0017] Preferably, the drying method for preparing degarelic acid is as follows: S1. Purification: Crude degarelk was synthesized using a polypeptide solid-phase synthesis method. The crude degarelk was dissolved in acetic acid solution by stirring and filtration. The solution was purified by reversed-phase liquid chromatography. The fraction with a purity ≥98% was collected as the purification intermediate of the synthesized degarelk acetate.

[0018] S2. Rotary evaporation concentration: The purified intermediate solution of degarelic acid acetate is concentrated by rotary evaporation to obtain a thick gel with low water content.

[0019] S3, Depolymerization and Reconstruction: Dissolve the low-water-content viscous gel in acetic acid and stir until clear to obtain a depolymerization solution.

[0020] S4. Sedimentation and pulping: Add sedimentation liquid to the depolymerization liquid, stir and pulp to obtain a suspension.

[0021] S5. Vacuum drying: The suspension is dried by rotary evaporation until it becomes a solid, then crushed into a uniform powder and vacuum dried to obtain the degarelic acetate product.

[0022] More preferably, the mass concentration of the acetic acid solution in step S1 is 10-30%.

[0023] More preferably, in step S1, the ratio of crude degarelk product to acetic acid solution is 1 g: 2-10 mL.

[0024] More preferably, the reversed-phase liquid chromatography conditions in step S1 are as follows: a chromatographic column with a diameter of 40-60 mm; mobile phase A is an acetic acid solution with a mass concentration of 1-3%; and mobile phase B is acetonitrile. After sample loading, the salt is replaced with an ammonium acetate solution with a concentration of 25-40 g / L, followed by gradient elution with mobile phases A and B. The elution gradient program is as follows: the proportion of acetonitrile increases from 10-15% to 30-35% over 60-100 min at a flow rate of 40-60 mL / min; solution A is an ammonium acetate solution with a concentration of 20-40 mmol / L, and solution B is acetonitrile; 90-98% solution A and 2-10% solution B are eluted at a flow rate of 40-60 mL / min. Wash with n flow rate for 10 min, load sample with pump A, wash with 5-20% acetic acid solution for 1-5 min, wash with 25-40 g / L ammonium acetate solution for 10-20 min, wash with solution A for 10-20 min; elution method: elute with 10-20% acetonitrile for 2-10 min, increase the acetonitrile ratio from 10-15% to 30-35% within 60-100 min, detect and collect the fraction.

[0025] More preferably, the water bath temperature for rotary evaporation concentration in step S2 is 25-45°C.

[0026] More preferably, the pressure of rotary evaporation concentration in step S2 is less than 20 mbar.

[0027] More preferably, in step S3, the ratio of low-moisture viscous gel to acetic acid is 1g:1-10mL.

[0028] More preferably, the settling liquid in step S4 includes a solution of methyl tert-butyl ether or n-heptane.

[0029] More preferably, the n-heptane solution is a mixture of n-heptane and anhydrous ethanol, with a volume ratio of n-heptane to anhydrous ethanol of 1:1-9.

[0030] More preferably, the volume ratio of the depolymerization liquid to the sedimentation liquid in step S4 is 1:2-20.

[0031] More preferably, the vacuum drying temperature in step S5 is 20-30°C.

[0032] More preferably, the vacuum drying time in step S5 is 12-24 hours.

[0033] This invention, by purifying crude degarelc and then sequentially subjecting it to rotary evaporation concentration, depolymerization and reconstruction, sedimentation and pulping, and vacuum drying, achieves the following beneficial effects: the acetic acid content in the degarelc acetate product prepared by this invention is less than 8.4%, and the moisture content is less than 3.5%; after dissolving degarelc acetate in a 2.5% mannitol aqueous solution at a concentration of 20 mg / ml, the viscosity is less than 2.1 mPas; after dissolving degarelc acetate in a 2.5% mannitol aqueous solution at a concentration of 20 mg / ml and allowing it to stand for 2 hours, the optical density measured by a UV spectrophotometer at 350 nm is less than 0.060 Au. This demonstrates that the degarelc acetate product prepared by this invention simultaneously meets the quality requirements of its original drug. Furthermore, because this invention uses reverse-phase chromatography to purify the concentrate of the intermediate solution, followed by depolymerization and direct sedimentation and drying to obtain the solid, it allows for large-scale production, a short production cycle, and a significant cost advantage compared to freeze-drying processes. Attached Figure Description

[0034] Figure 1 The acetic acid content is expressed as a percentage (%).

[0035] Figure 2 Moisture content (%).

[0036] Figure 3 Viscosity (mPas).

[0037] Figure 4 It represents optical density (Au). Detailed Implementation

[0038] The present invention will now be described in further detail with reference to specific embodiments. The given embodiments are merely illustrative of the invention and not intended to limit its scope. The embodiments provided below can serve as a guide for further improvements by those skilled in the art and do not constitute a limitation on the invention in any way.

[0039] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0040] Example 1: A method for preparing degarelic acid by drying includes, S1. Purification: Crude degarelk was synthesized using a polypeptide solid-phase synthesis method. The crude degarelk was dissolved in acetic acid solution by stirring, filtered, and purified using reversed-phase liquid chromatography (RP-HPLC). The fraction with a purity ≥98% was collected as the purification intermediate for purified degarelk acetate. The acetic acid solution had a mass concentration of 20%, and the ratio of crude degarelk to acetic acid solution was 1 g: 5 mL. The R-HPLC conditions were: a 50 mm diameter column; Unisil 10-100 C18 packing material; mobile phase A: 2% acetic acid solution; mobile phase B: acetonitrile. After sample loading, the salt was replaced with a 32 g / L ammonium acetate solution, followed by gradient elution with mobile phases A and B. The elution gradient program was as follows: the acetonitrile ratio was increased from 13% to 33% over 80 min at a flow rate of 50 mL / min; solution A was a 30 mmol / L ammonium acetate solution, and solution B was acetonitrile; the sample was washed for 10 min with 95% solution A and 5% solution B at a flow rate of 50 mL / min, then loaded using pump A. After loading, the sample was washed for 3 min with a 10% acetic acid solution, then washed for 15 min with a 32 g / L ammonium acetate solution, and then washed for 15 min with solution A. The elution method was as follows: elution with 13% acetonitrile for 5 min, then the acetonitrile ratio was increased from 13% to 33% over 80 min, and the sample was detected at 280 nm. 50 mL of the fraction was collected.

[0041] S2. Rotary evaporation concentration: The purified intermediate solution of degarelic acid acetate was concentrated by rotary evaporation under water bath conditions of 35°C and pressure of 20mbar to obtain a thick gel with low water content.

[0042] S3. Depolymerization and Reconstruction: Dissolve the low-water-content viscous gel in acetic acid and stir until clear to obtain a depolymerized solution. The ratio of low-water-content viscous gel to acetic acid is 1 g: 3 mL.

[0043] S4. Sedimentation and Pulping: Add methyl tert-butyl ether to the depolymerization solution, stir and pulverize to obtain a suspension. The volume ratio of depolymerization solution to methyl tert-butyl ether is 1:2.

[0044] S5. Vacuum drying: The suspension is dried by rotary evaporation until it becomes a solid, then crushed into a uniform powder and vacuum dried at 25°C for 15 hours to obtain the degarelic acetate product.

[0045] Example 2: The method for preparing degarelic acid by drying is the same as in Example 1, except that in step S3, the ratio of low-moisture viscous gel to acetic acid is changed to 1 g: 1 mL.

[0046] Example 3: The method for preparing degarelic acid by drying is the same as in Example 1, except that in step S3, the ratio of low-moisture viscous gel to acetic acid is changed to 1g:10mL.

[0047] Example 4: The method for preparing degarelic acid by drying is the same as in Example 1, except that in step S4, methyl tert-butyl ether is replaced with a heptane solution, which is a mixture of heptane and anhydrous ethanol with a volume ratio of 1:1.

[0048] Example 5: The method for preparing degarelic acid by drying is the same as in Example 1, except that in step S4, methyl tert-butyl ether is replaced with a heptane solution, which is a mixture of heptane and anhydrous ethanol with a volume ratio of heptane to anhydrous ethanol of 1:9.

[0049] Example 6: The method for preparing degarelic acid by drying is the same as in Example 1, except that in step S4, the volume ratio of the depolymerization solution and methyl tert-butyl ether is changed to 1:20.

[0050] Example 7: The method for preparing degarelic acid by drying is the same as in Example 1, except that in step S4, methyl tert-butyl ether is replaced with a heptane solution, which is a mixture of heptane and anhydrous ethanol with a volume ratio of 1:1 and the volume ratio of the depolymerization solution to methyl tert-butyl ether is changed to 1:20.

[0051] Example 8: The method for preparing degarelic acid by drying is the same as in Example 1, except that in step S4, methyl tert-butyl ether is replaced with a heptane solution, which is a mixture of heptane and anhydrous ethanol with a volume ratio of heptane to anhydrous ethanol of 1:9, and the volume ratio of the depolymerization solution to methyl tert-butyl ether is changed to 1:20. All other conditions are the same as in Example 1.

[0052] Comparative Example 1: A method for preparing degarelic acid by drying includes, S1. Purification of Degarelk Acetate: Crude degarelk was synthesized using a polypeptide solid-phase synthesis method. The crude degarelk was dissolved in acetic acid solution by stirring, filtered, and purified by reversed-phase liquid chromatography (RP-HPLC). The fraction with a purity ≥98% was collected as the intermediate purification solution for the synthesized degarelk acetate. The acetic acid solution had a mass concentration of 20%, and the ratio of crude degarelk to acetic acid solution was 1 g: 5 mL. The R-HPLC conditions were: a 50 mm diameter column; Unisil 10-100 C18 packing material; mobile phase A: 2% acetic acid solution; mobile phase B: acetonitrile. After sample loading, the salt was replaced with a 32 g / L ammonium acetate solution, followed by gradient elution with mobile phases A and B. The elution gradient program was as follows: the acetonitrile ratio was increased from 13% to 33% over 80 min at a flow rate of 50 mL / min; solution A was a 30 mmol / L ammonium acetate solution, and solution B was acetonitrile; the sample was washed for 10 min with 95% solution A and 5% solution B at a flow rate of 50 mL / min, then loaded using pump A. After loading, the sample was washed for 3 min with a 10% acetic acid solution, then washed for 15 min with a 32 g / L ammonium acetate solution, and then washed for 15 min with solution A. The elution method was as follows: elution with 13% acetonitrile for 5 min, then the acetonitrile ratio was increased from 13% to 33% over 80 min, and the sample was detected at 280 nm. 50 mL of the fraction was collected.

[0053] S2. Concentration and drying of the intermediate purified degarelc acetate solution: Take the intermediate purified degarelc acetate solution, add acetic acid solution, and concentrate by rotary evaporation under a water bath at 35°C and a pressure of 20 mbar. After freeze-drying, degarelc acetate solution is obtained. The mass concentration of the acetic acid solution is 10%, and the volume ratio of the intermediate purified degarelc acetate solution to the acetic acid solution is 1:0.10.

[0054] Comparative Example 2: The method for preparing degarelk acetate by drying is the same as that for Comparative Example 1, except that in step S2, the volume ratio of the degarelk acetate purification intermediate solution to the acetic acid solution is changed to 1:0.15.

[0055] Comparative Example 3: The method for preparing degarelk acetate by drying is the same as that for Comparative Example 1, except that in step S2, the volume ratio of the degarelk acetate purification intermediate solution to the acetic acid solution is changed to 1:0.18.

[0056] Comparative Example 4: The method for preparing degarelk acetate by drying is the same as that for Comparative Example 1, except that in step S2, the volume ratio of the degarelk acetate purification intermediate solution to the acetic acid solution is changed to 1:0.20.

[0057] Comparative Example 5: The method for preparing degarelk acetate by drying is the same as that for Comparative Example 1, except that in step S2, the volume ratio of the degarelk acetate purification intermediate solution to the acetic acid solution is changed to 1:0.21.

[0058] Comparative Example 6: The method for preparing degarelk acetate by drying is the same as that for Comparative Example 1, except that in step S2, the volume ratio of the degarelk acetate purification intermediate solution to the acetic acid solution is changed to 1:0.24.

[0059] Comparative Example 7: The method for preparing degarelk acetate by drying is the same as that for Comparative Example 1, except that in step S2, the volume ratio of the degarelk acetate purification intermediate solution to the acetic acid solution is changed to 1:0.27.

[0060] Comparative Example 8: The method for preparing degarelk acetate by drying is the same as that for Comparative Example 1, except that in step S2, the volume ratio of the degarelk acetate purification intermediate solution to the acetic acid solution is changed to 1:0.3.

[0061] Experimental Example 1: Acetic acid content test: The degarelic acid products prepared in Examples 1, 4 and Comparative Examples 1-8 were subjected to reversed-phase liquid chromatography analysis to test the residual acetic acid content in the samples.

[0062] Figure 1 The acetic acid content (%) is shown. The results are as follows: Figure 1 As shown, the acetic acid content in the degarelc acetate product prepared in Example 1 of this invention is 8.4%, the acetic acid content in Example 4 is 8.1%, the acetic acid content in Comparative Example 1 is 6.1%, the acetic acid content in Comparative Example 2 is 7.7%, the acetic acid content in Comparative Example 3 is 4.8%, the acetic acid content in Comparative Example 4 is 5.9%, the acetic acid content in Comparative Example 5 is 4.9%, the acetic acid content in Comparative Example 6 is 5.3%, the acetic acid content in Comparative Example 7 is 5.1%, and the acetic acid content in Comparative Example 8 is 5.0%. Therefore, it can be seen that the acetic acid content in the degarelc acetate product treated by the method of this invention is all within the range of 4.5-10%, which meets the acetic acid content requirements specified by the original degarelc acetate drug.

[0063] Experimental Example 2: Moisture content test: The degarelic acetate products prepared in Examples 1, 4 and Comparative Examples 1-8 were analyzed by reversed-phase liquid chromatography to test the residual moisture content in the samples.

[0064] Figure 2 Moisture content (%). Results are as follows: Figure 2As shown, the moisture content of the degarelc acetate product prepared in Example 1 of this invention is 3.5%, the moisture content of Example 4 is 3%, the moisture content of Comparative Example 1 is 4.4%, the moisture content of Comparative Example 2 is 4.6%, the moisture content of Comparative Example 3 is 4.8%, the moisture content of Comparative Example 4 is 5.9%, the moisture content of Comparative Example 5 is 4.8%, the moisture content of Comparative Example 6 is 4.8%, the moisture content of Comparative Example 7 is 5.6%, and the moisture content of Comparative Example 8 is 5.0%. Therefore, it can be seen that the moisture content of the degarelc acetate product treated by the method of this invention is all below 10%, which meets the moisture content requirements specified by the original degarelc acetate drug.

[0065] Compared with Comparative Examples 1-8, the moisture content of the degarelc acetate products prepared in Examples 1 and 4 of this invention was significantly reduced. This is because Examples 1 and 4 of this invention employed rotary evaporation concentration, depolymerization and reconstruction, sedimentation and pulping, and vacuum drying after purification of the crude degarelc. In contrast, Comparative Examples 1-8 added acetic acid after purification of the crude degarelc, followed by rotary evaporation concentration and freeze-drying, without depolymerization and reconstruction or sedimentation and pulping. Therefore, the present invention's purification of the crude degarelc followed by rotary evaporation concentration, depolymerization and reconstruction, sedimentation and pulping, and vacuum drying helps to reduce the moisture content of the prepared degarelc acetate product.

[0066] Experimental Example 3: Viscosity test: The degarelix acetate products prepared in Examples 1, 4, 1, 2, and 4 were mixed with mannitol aqueous solution to obtain the degarelix acetate drugs corresponding to Examples 1, 4, 1, 2, and 4. The mass concentration of the mannitol aqueous solution was 2.5%, and the concentration of the degarelix acetate drugs in Examples 1, 4, 1, 2, and 4 was 20 mg / mL. The viscosity of the degarelix acetate drugs in Examples 1, 4, 1, 2, and 4 was tested using a rotational viscometer.

[0067] Figure 3 Viscosity (mPas). Results are as follows: Figure 3 As shown, the viscosity of Example 1 of this invention is 2.1 mPas, the viscosity of Example 4 is 1.5 mPas, the viscosity of Comparative Example 1 is 2.04 mPas, the viscosity of Comparative Example 2 is 1.94 mPas, and the viscosity of Comparative Example 4 is 2.05 mPas. Therefore, it can be seen that the viscosity of the degarelc acetate product treated by the method of this invention, after being dissolved in a 2.5% mannitol aqueous solution at a concentration of 20 mg / mL, is less than 3.20 mPas, which meets the viscosity requirements specified by the original degarelc acetate drug.

[0068] Based on the viscosity data from Examples 1, 4, 1, 2, and 4, it is evident that the viscosity of degarelic acetate significantly decreased after rotary evaporation concentration, depolymerization and reconstruction, sedimentation pulping, and vacuum drying. The technique using n-heptane solution as the sedimentation pulping liquid demonstrated superior performance and excellent viscosity control.

[0069] Experiment Example 4: Optical density test: The degarelix acetate products prepared in Examples 1, 4, and Comparative Examples 1-8 were mixed with mannitol aqueous solution to obtain the degarelix acetate drugs corresponding to Examples 1, 4, and 1-8. The mass concentration of the mannitol aqueous solution was 2.5%, and the concentration of the degarelix acetate drugs in Examples 1, 4, and 1-8 was 20 mg / mL. The degarelix acetate drugs in Examples 1, 4, and 1-8 were allowed to stand for 2 hours, and the optical density of the degarelix acetate drugs in Examples 1, 4, and 1-8 was measured at 350 nm using a UV spectrophotometer.

[0070] Figure 4 The optical density (Au) is shown in the results. Figure 3 As shown, the optical density of Example 1 of the present invention is 0.060 Au, the optical density of Example 4 is 0.055 Au, the optical density of Comparative Example 1 is 0.196 Au, the optical density of Comparative Example 2 is 1.76 Au, the optical density of Comparative Example 3 is 1.70 Au, the optical density of Comparative Example 4 is 0.12 Au, the optical density of Comparative Example 5 is 1.28 Au, the optical density of Comparative Example 6 is 1.34 Au, the optical density of Comparative Example 7 is 1.66 Au, and the optical density of Comparative Example 8 is 1.72 Au. It can be seen that the optical density of the degarelc acetate product treated by the methods of Examples 1 and 4 of the present invention is all below 0.10 Au, which meets the optical density requirement fixed by the original degarelc acetate drug. However, the optical density of the degarelc acetate treated by the methods of Comparative Examples 1-8 is all greater than 0.10 Au, which does not meet the optical density requirement fixed by the original degarelc acetate drug.

[0071] Optical density is a key indicator for measuring the number of insoluble particles, directly reflecting the intensity of light scattering and absorption in a solution. For injectable formulations like degarelix acetate that require dissolution before administration, excessively high optical density indicates the presence of too many insoluble particles, which may cause adverse reactions such as capillary embolism and inflammatory responses after injection. In drug quality control, maintaining the optical density of a drug below 0.1 Au is crucial for controlling insoluble particles and foreign matter in the solution and reducing the clinical injection risks caused by insoluble particles. However, degarelix acetate is a hydrophobic polypeptide whose molecules readily aggregate in an aqueous environment through hydrophobic interactions. Initially, this forms viscous, colloidal aggregates, eventually leading to insoluble particles that exceed the optical density limit. Therefore, achieving an optical density below 0.1 Au by dissolving the degarelix acetate product in a 2.5% mannitol solution to 20 mg / mL and allowing it to stand for 2 hours has become a pressing technical challenge.

[0072] Based on the optical density data from Comparative Examples 1-8, it can be seen that directly adding acetic acid to the purified crude degarelc, followed by rotary evaporation concentration and freeze-drying, results in a degarelc acetate product that not only fails to meet the fixed optical density requirements of the original degarelc acetate drug, but also exhibits significant fluctuations and low reproducibility. This indicates that the processing methods in Comparative Examples 1-8 lack stability.

[0073] This invention first uses reversed-phase liquid chromatography to purify crude degarelic acid to obtain a purified degarelic acid intermediate. Then, it is concentrated to a low-water-content viscous gel by rotary evaporation to efficiently remove the organic phase introduced during purification. Acetic acid is then added and stirred until clear, allowing the degarelic acid to fully dissolve and form a homogeneous solution. A mixture of methyl tert-butyl ether or n-heptane / anhydrous ethanol is used as a settling liquid to reduce the solubility of degarelic acid in the system, causing it to precipitate from the solution as a solid, achieving secondary purification and obtaining a loose solid suspension. This suspension is then vacuum dried to obtain the finished degarelic acid product. This process significantly and stably reduces the optical density of the finished degarelic acid product to below 0.1 Au, meeting the optical density requirements specified by the original degarelic acid drug manufacturer.

[0074] The conventional operations in the operation steps of this invention are well known to those skilled in the art and will not be described in detail here.

[0075] The embodiments described above provide a detailed explanation of the technical solutions of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any changes and modifications made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing degarelic acid by drying, characterized in that, include: The crude degarelic acid prepared by solid-phase polypeptide synthesis was purified by reversed-phase liquid chromatography. After rotary evaporation and concentration, a low-water-content viscous gel was obtained. Acetic acid was added to the viscous gel and stirred until clear to obtain a depolymerization solution. This solution was then stirred and slurried with a settling liquid, followed by vacuum drying to obtain degarelic acid acetate. The settling liquid was a solution of methyl tert-butyl ether or n-heptane, wherein the n-heptane solution was a mixture of n-heptane and anhydrous ethanol, with a volume ratio of n-heptane to anhydrous ethanol of 1:1-9. The optical density of the degarelic acid acetate dissolved in an aqueous mannitol solution was less than 0.060 Au.

2. The method for preparing degarelic acid by drying according to claim 1, characterized in that, The viscosity of the degarelic acetate dissolved in mannitol aqueous solution is less than 2.1 mPas.

3. The method for preparing degarelic acid by drying according to claim 1, characterized in that, The acetic acid content in the degarelic acid acetate is less than 8.4%.

4. The method for preparing degarelic acid by drying according to claim 1, characterized in that, The water content in the acetic acid galactopyrine is less than 3.5%.

5. The method for preparing degarelic acid by drying according to claim 1, characterized in that, The water bath temperature for the rotary evaporation concentration is 25-45℃.

6. The method for preparing degarelic acid by drying according to claim 1, characterized in that, The pressure of the rotary evaporation concentration is less than 20 mbar.

7. The method for preparing degarelic acid by drying according to claim 1, characterized in that, The ratio of the low-moisture viscous gel to acetic acid is 1g:1-10mL.

8. The method for preparing degarelic acid by drying according to claim 1, characterized in that, The volume ratio of the depolymerization liquid to the sedimentation liquid is 1:2-20.

9. The method for preparing degarelic acid by drying according to claim 1, characterized in that, The vacuum drying temperature is 20-30℃.

10. The method for preparing degarelic acid by drying according to claim 1, characterized in that, The vacuum drying time is 12-24 hours.

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