Icodextrin and preparation method thereof

Abstract

The invention relates to icodextrin and a preparation method thereof, and the method comprises the following steps: starch gelatinization: adding purified water and starch into a reaction tank, heating to 80-100 DEG C, and gelatinizing for 0.4-2 hours; adding alpha-amylase into the reaction tank, and continuously reacting for 0.5-2 hours at the same temperature; adding a certain amount of hydrochloric acid into the reaction tank, and continuously reacting for 0.8-3 hours at the same temperature; quenching reaction: adding alkali into the reaction tank to adjust the pH value to 5-7 to obtain a reaction solution; ultrafiltration: filtering the reaction liquid cooled to the room temperature through a plate-and-frame filter, and then performing ultrafiltration through a 1000-5000 Dalton ultrafiltration membrane; decoloring: adding activated carbon into the ultrafiltration residual liquid, decoloring, and filtering to obtain a decolored and filtered solution; spray drying: carrying out spray drying on the decolorized and filtered solution to obtain icodextrin; the method does not need to control the proportion of alpha (1-6) glucosidic bonds in starch raw materials, the raw materials are easy to obtain, and the method is more suitable for commercial production.

Description

Technical Field

[0001] The present invention relates to the technical field of pharmaceutical preparation, in particular to icodextrin and a preparation method thereof. Background Art

[0002] Icodextrin is a （1-4） and α below 10% （1-6） A glycosidically bonded starch-type water-soluble glucose polymer with a weight-average molecular weight of 13,000 to 19,000 Daltons and a number-average molecular weight of 5,000 to 6,500 Daltons. Icodextrin peritoneal dialysis fluid prepared using icodextrin is suitable for continuous ambulatory peritoneal dialysis (CAPD) in patients with end-stage renal disease (ESRD).

[0003] At present, the preparation methods of icodextrin are mainly divided into two categories: acid preparation and enzyme preparation: Chinese patents with publication numbers CN103467608B and CN105131135B have reported on the preparation of icodextrin using an acid process. However, both methods suffer from the following problems: the acid hydrolysis of starch is drastic, resulting in poor selectivity and difficulty in controlling the degree of reaction. Consequently, the molecular weight distribution is very broad, and subsequent molecular weight screening using an ultrafiltration process results in significant losses, leading to low yields.

[0004] The Chinese patent publication number CN106397616A discloses a method of first using α-amylase to enzymatically hydrolyze α （1-4） Glycosidic bonds, the main chain of the original starch is broken down into fragments, and then hydrolyzed using debranching enzymes α （1-6） The method uses two enzymes, α-amylase and debranching enzyme, to react. Since the two enzymes need to react under different temperature and pH conditions, the method is complicated to operate and is not suitable for industrial scale-up.

[0005] The Chinese patent CN114605563A only uses α-amylase to perform enzymatic hydrolysis to prepare icodextrin. However, if the icodextrin (α （1-6） The proportion of glycosidic bonds is less than 10%), and the α （1-6） The proportion of glycosidic bonds is no more than 5%. （1-6） When the proportion of glycosidic bonds is 8.70%, the α （1-6） The proportion of glycosidic bonds is as high as 15.60%, which does not meet the requirements of α （1-6） Therefore, this method needs to control the proportion of α （1-6） The proportion of glycosidic bonds and the source of raw materials are relatively narrow, making it unsuitable for industrial scale-up. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide an icodextrin and a preparation method thereof.

[0007] In order to solve the above problems, the technical solution adopted by the present invention is: A method for preparing icodextrin comprises the following steps: (1) Starch gelatinization: Add purified water and starch to a reaction tank, stir and heat it. After 1.5-2.5 hours, heat it from room temperature to 80-100°C and gelatinize it at this temperature for 0.4-2 hours. Preferably, heat it to 90-94°C after 2 hours and gelatinize it for 0.5 hours. (2) Enzymatic hydrolysis: Add a certain amount of α-amylase to the reaction tank and continue the reaction at the same temperature for 0.5-2 hours, preferably 1 hour; (3) Acid inactivation: Add a certain amount of hydrochloric acid to the reaction tank and continue the reaction at the same temperature for 0.8-3 hours, preferably 1 hour; (4) Quenching the reaction: adding alkali to the reaction tank to adjust the pH to 5-7 to obtain a reaction solution; preferably, the pH is adjusted to 6; (5) Ultrafiltration: The reaction solution cooled to room temperature is first filtered through a plate and frame filter, and then ultrafiltered through a 1000-5000 Dalton ultrafiltration membrane; preferably, ultrafiltration is performed through a 3000 Dalton ultrafiltration membrane; (6) Decolorization: adding activated carbon to the ultrafiltration residual liquid, decolorizing, and filtering to obtain a decolorized and filtered solution; (7) Spray drying: The decolorized and filtered solution is spray dried to obtain icodextrin.

[0008] As an embodiment of the present invention, in step (1), the starch is selected from corn starch, waxy corn starch, wheat starch, sweet potato starch or potato starch.

[0009] As an embodiment of the present invention, in step (1), the mass ratio of starch to purified water is 1:(5~15).

[0010] As an embodiment of the present invention, in step (2), the α-amylase is selected from thermostable α-amylase.

[0011] As an embodiment of the present invention, in step (2), the amount of α-amylase added is 0.03-0.08% of the mass of starch added in step (1); preferably 0.05%.

[0012] As an embodiment of the present invention, in step (3), the amount of hydrochloric acid added is 1-3% of the mass of the starch added in step (1), preferably 1.5%; the concentration of the hydrochloric acid is 35% to 38%, preferably 37%.

[0013] As an embodiment of the present invention, in step (4), the base is a sodium hydroxide solution with a concentration of 4-6 mol / L.

[0014] As an embodiment of the present invention, in step (6), the amount of activated carbon added is 3-10% of the mass of starch added in step (1); preferably 5%; As an embodiment of the present invention, in step (6), the decolorization temperature is 30-70°C, preferably 40-45°C; and the decolorization time is 10 min-60 min, preferably 30 min.

[0015] As an embodiment of the present invention, the feed temperature of the spray drying is 20-50°C, the air inlet temperature is 150-220°C, preferably 170-180°C; and the air outlet temperature is 80-110°C, preferably 88-95°C.

[0016] In a second aspect, an icodextrin prepared by the preparation method according to claim 1 is provided.

[0017] The beneficial effects of adopting the above technical solution are: In the present invention, after starch and water are mixed and gelatinized, α-amylase is used to perform enzymatic hydrolysis reaction, and the hydrochloric acid aqueous solution quenches the enzyme activity while also hydrolyzing the α-amylase. （1-6） The glycosidic bond is neutralized with alkali to terminate the reaction, and then the molecular weight is screened by ultrafiltration membrane, and finally spray-dried to obtain icodextrin. After testing, the α （1-6） The proportion of glycosidic bonds is less than 10%, the weight average molecular weight is 13,000 to 19,000 Daltons, and the number average molecular weight is 5,000 to 6,500 Daltons, meeting pharmaceutical standards.

[0018] Therefore, the method provided by the present invention uses only one α-amylase to hydrolyze starch, which is simple to operate and easy to control; in addition, the use of hydrochloric acid aqueous solution to quench the enzyme activity will also hydrolyze α （1-6） Glycosidic bond, achieving multiple uses of one acid; in addition, the α （1-6） The proportion of glycosidic bonds is less than 10%, so there is no need to control the α （1-6） The proportion of glycosidic bonds and the easy availability of raw materials make it more suitable for commercial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is the nuclear magnetic spectrum of the starch used in Example 1.

[0020] Figure 2 This is the nuclear magnetic spectrum of icodextrin obtained in Example 1.

[0021] Figure 31 is the molecular weight and molecular weight distribution spectrum of icodextrin obtained in Example 1.

[0022] Figure 4 It is the NMR spectrum of the starch used in Example 2.

[0023] Figure 5 This is the nuclear magnetic spectrum of icodextrin obtained in Example 2.

[0024] Figure 6 1 is the molecular weight and molecular weight distribution spectrum of icodextrin obtained in Example 2.

[0025] Figure 7 This is the nuclear magnetic spectrum of icodextrin obtained in Example 3.

[0026] Figure 8 3 is the molecular weight and molecular weight distribution spectrum of icodextrin obtained in Example 3.

[0027] Figure 9 This is the NMR spectrum of icodextrin obtained in Example 4.

[0028] Figure 10 1 is the molecular weight and molecular weight distribution spectrum of icodextrin obtained in Example 4.

[0029] Figure 11 This is the nuclear magnetic spectrum of icodextrin obtained in Comparative Example 1. DETAILED DESCRIPTION

[0030] In order to make the objectives, technical solutions and advantages of the present invention more clear, the invention is clearly and completely described below in conjunction with specific embodiments.

[0031] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0032] Example 1 A method for preparing icodextrin comprises the following steps: (1) Starch gelatinization: Add 80 kg of purified water and 8 kg of wheat starch into the reaction tank, stir and heat it up. After 2.2 hours, heat it from room temperature to 90 °C and gelatinize it at this temperature for 0.5 hours. (2) Enzymatic hydrolysis: 5 g of thermostable α-amylase was added to the reaction tank and the reaction was continued at the same temperature for 1 h. The thermostable α-amylase was purchased from Novozymes. (3) Acid inactivation: Add 120 g of 35.5% hydrochloric acid to the reaction tank and keep the reaction warm for 1 hour; (4) Quenching the reaction: adding a 5 mol / L sodium hydroxide solution to the reaction tank to adjust the pH to 6.0 to obtain a reaction solution; (5) Ultrafiltration: The reaction solution cooled to room temperature is first filtered through a plate and frame filter, and the filtrate is then ultrafiltered through a 3000 Dalton ultrafiltration membrane; (6) Decolorization: Add 400 g of activated carbon to the ultrafiltration residual liquid, stir at 45 °C for 30 min, and filter to obtain a decolorized and filtered solution; (7) Spray drying: The inlet air temperature of the spray dryer was controlled at 180°C and the outlet air temperature was controlled at 95°C. The decolorized and filtered solution was spray dried to obtain 3.77 kg of icodextrin with a yield of 47.1%.

[0033] Using deuterated DMSO as solvent, the ¹H-NMR of starch raw materials (wheat raw materials) was measured, such as Figure 1 As shown, at this time α （1-4） The chemical shift of hydrogen at position 1 corresponding to the glycosidic bond is 5.2 ppm, and α （1-6） The chemical shift of hydrogen at position 1 corresponding to the glycosidic bond is 4.8 ppm; Figure 1 It can be seen that α （1-6） Glycosidic bonds account for 8.26%; Using deuterated H2O as solvent, the ¹H-NMR of icodextrin products was measured, such as Figure 2 As shown, at this time α （1-4） The chemical shift of hydrogen at position 1 corresponding to the glycosidic bond is 5.4 ppm, and α （1-6） The chemical shift of hydrogen at position 1 corresponding to the glycosidic bond is 5.0 ppm; Figure 2 It can be seen that α （1-6） Glycosidic bonds account for 7.41%.

[0034] Figure 3 The molecular weight and molecular weight distribution spectrum of icodextrin obtained in this example (Shimadzu LC-2030plus) are shown in FIG. Figure 3 Analysis showed that the weight average molecular weight of the obtained icodextrin was 16766, and the number average molecular weight was 5957.

[0035] Example 2 A method for preparing icodextrin comprises the following steps: (1) Starch gelatinization: Add 60 kg of purified water and 8 kg of corn starch to the reaction tank, stir and heat it up. After 2 hours, heat it from room temperature to 88 °C and gelatinize it at this temperature for 0.5 hours. (2) Enzymatic hydrolysis: 6 g of thermostable α-amylase was added to the reaction tank and gelatinization was continued at the same temperature for 1.5 h. The thermostable α-amylase was purchased from Novozymes. (3) Acid inactivation: Add 100 g of 37.3% hydrochloric acid to the reaction tank and keep the reaction warm for 2 h; (4) Quenching the reaction: adding a 4 mol / L sodium hydroxide solution to the reaction tank to adjust the pH to 5.5 to obtain a reaction solution; (5) Ultrafiltration: The reaction solution cooled to room temperature is first filtered through a plate and frame filter, and the filtrate is then ultrafiltered through a 2000 Dalton ultrafiltration membrane; (6) Decolorization: Add 500 g of activated carbon to the ultrafiltration residual liquid, stir at 40 °C for 60 min, and filter to obtain a decolorized and filtered solution; (7) Spray drying: The inlet air temperature of the spray dryer was controlled at 170°C and the outlet air temperature was controlled at 90°C. The decolorized and filtered solution was spray dried to obtain 3.92 kg of icodextrin with a yield of 49.0%.

[0036] Using deuterated DMSO as solvent, the ¹H-NMR of starch raw material (corn starch) was measured, such as Figure 4 As shown, at this time α （1-4） The chemical shift of hydrogen at position 1 corresponding to the glycosidic bond is 5.2 ppm, and α （1-6） The chemical shift of hydrogen at position 1 corresponding to the glycosidic bond is 4.8 ppm; Figure 4 It can be seen that α （1-6） Glycosidic bonds account for 9.09%; Using deuterated H2O as solvent, the ¹H-NMR of icodextrin products was measured, such as Figure 5 As shown, at this time α （1-4） The chemical shift of hydrogen at position 1 corresponding to the glycosidic bond is 5.4 ppm, and α （1-6） The chemical shift of hydrogen at position 1 corresponding to the glycosidic bond is 5.0 ppm; Figure 5 It can be seen that α （1-6） Glycosidic bonds account for 8.11%.

[0037] Figure 6 The molecular weight and molecular weight distribution spectrum of icodextrin obtained in this example (Shimadzu LC-2030plus) are shown in FIG. Figure 6 Analysis showed that the weight average molecular weight of the obtained icodextrin was 15589 and the number average molecular weight was 5266.

[0038] Example 3 A method for preparing icodextrin comprises the following steps: (1) Starch gelatinization: 60 kg of purified water and 8 kg of wheat starch (same as in Example 1) were added to a reaction tank and heated while stirring. After 1.5 h, the temperature was raised from room temperature to 80 °C and gelatinized at this temperature for 2 h. (2) Enzymatic hydrolysis: 2.4 g of thermostable α-amylase was added to the reaction tank and the reaction was continued at the same temperature for 0.5 h; the thermostable α-amylase was the same as in Example 1; (3) Acid inactivation: Add 240 g of 35% hydrochloric acid to the reaction tank and keep the reaction warm for 1 hour; (4) Quenching the reaction: adding a 6 mol / L sodium hydroxide solution to the reaction tank to adjust the pH to 5.0 to obtain a reaction solution; (5) Ultrafiltration: The reaction solution cooled to room temperature is first filtered through a plate and frame filter, and the filtrate is then ultrafiltered through a 1000 Dalton ultrafiltration membrane; (6) Decolorization: Add 240 g of activated carbon to the ultrafiltration residual liquid, stir at 70 °C for 10 min, and filter to obtain a decolorized and filtered solution; (7) Spray drying: The inlet air temperature of the spray dryer was controlled at 150°C and the outlet air temperature was controlled at 80°C. The decolorized and filtered solution was spray dried to obtain 3.63 kg of icodextrin with a yield of 45.4%.

[0039] ¹H-NMR of starch raw materials (wheat starch), such as Figure 1 As shown; Using deuterated H2O as solvent, the ¹H-NMR of icodextrin products was measured, such as Figure 7 As shown, at this time α （1-4） The chemical shift of hydrogen at position 1 corresponding to the glycosidic bond is 5.4 ppm, and α （1-6） The chemical shift of hydrogen at position 1 corresponding to the glycosidic bond is 5.0 ppm; Figure 7 It can be seen that α （1-6） Glycosidic bonds account for 6.54%.

[0040] Figure 8 The molecular weight and molecular weight distribution spectrum of icodextrin obtained in this example (Agilent 1260 Infinity II) are shown in FIG. Figure 8 Analysis showed that the weight average molecular weight of the obtained icodextrin was 15121, and the number average molecular weight was 5803.

[0041] Example 4 (1) Starch gelatinization: 120 kg of purified water and 8 kg of corn starch (same as in Example 2) were added to a reaction tank, and the temperature was raised from room temperature to 100 °C after 2.5 h, and gelatinized at this temperature for 0.4 h; (2) Enzymatic hydrolysis: 6.4 g of thermostable α-amylase was added to the reaction tank and gelatinization was continued at the same temperature for 2 h. The thermostable α-amylase was the same as in Example 2. (3) Acid inactivation: Add 80 g of 38% hydrochloric acid to the reaction tank and keep warm for 2 h; (4) Quenching the reaction: adding a 6 mol / L sodium hydroxide solution to the reaction tank to adjust the pH to 7.0 to obtain a reaction solution; (5) Ultrafiltration: The reaction solution cooled to room temperature is first filtered through a plate and frame filter, and the filtrate is then ultrafiltered through a 5000 Dalton ultrafiltration membrane; (6) Decolorization: Add 800 g of activated carbon to the ultrafiltration residual liquid, stir at 30 °C for 55 min, and filter to obtain a decolorized and filtered solution; (7) Spray drying: The inlet air temperature of the spray dryer was controlled at 220°C and the outlet air temperature was controlled at 110°C. The decolorized and filtered solution was spray dried to obtain 3.60 kg of icodextrin with a yield of 45.0%.

[0042] ¹H-NMR of starch raw materials (corn starch), such as Figure 4 As shown; Using deuterated H2O as solvent, the ¹H-NMR of icodextrin products was measured, such as Figure 9 As shown, at this time α （1-4） The chemical shift of hydrogen at position 1 corresponding to the glycosidic bond is 5.4 ppm, and α （1-6） The chemical shift of hydrogen at position 1 corresponding to the glycosidic bond is 5.0 ppm; Figure 9 It can be seen that α （1-6） Glycosidic bonds account for 8.26%.

[0043] Figure 10 The molecular weight and molecular weight distribution spectrum of icodextrin obtained in this example (Agilent 1260 Infinity II) are shown in FIG. Figure 10 Analysis showed that the weight average molecular weight of the obtained icodextrin was 16222, and the number average molecular weight was 5721.

[0044] Comparative Example 1 A method for preparing icodextrin comprises the following steps: (1) Starch gelatinization: 80 kg of purified water and 8 kg of wheat starch (same as in Example 1) were added to a reaction tank, and the temperature was raised from room temperature to 90 °C after 2.2 h, and gelatinized at this temperature for 0.5 h; (2) Enzymatic hydrolysis: 5 g of thermostable α-amylase (same as in Example 1) was added to the reaction tank and the reaction was continued at the same temperature for 1 h. (3) Acid inactivation: Add 50 g of 35.5% hydrochloric acid to the reaction tank and keep the reaction warm for 1 hour; (4) Quenching the reaction: adding a 5 mol / L sodium hydroxide solution to the reaction tank to adjust the pH to 6.0 to obtain a reaction solution; (5) Ultrafiltration: The reaction solution cooled to room temperature is first filtered through a plate and frame filter, and the filtrate is then ultrafiltered through a 3000 Dalton ultrafiltration membrane; (6) Decolorization: Add 400 g of activated carbon to the ultrafiltration residual liquid, stir at 45 °C for 30 min, and filter to obtain a decolorized and filtered solution; (7) Spray drying: Control the inlet air temperature of the spray dryer to 180°C and the outlet air temperature to 95°C, and spray dry the decolorized and filtered solution to obtain icodextrin.

[0045] Using deuterated H2O as solvent, the ¹H-NMR of icodextrin products was measured, such as Figure 11 As shown, at this time α （1-4） The chemical shift of hydrogen at position 1 corresponding to the glycosidic bond is 5.4 ppm, and α （1-6） The chemical shift of hydrogen at position 1 corresponding to the glycosidic bond is 5.0 ppm; Figure 11 It can be seen that α （1-6） The proportion of glycosidic bonds is 11.50%, which does not meet the requirements.

[0046] Comparative Example 2 A method for preparing icodextrin comprises the following steps: (1) Starch gelatinization: Add 60 kg of purified water and 8 kg of corn starch (same as in Example 2) into a reaction tank, stir while heating, and after 2 h, heat from room temperature to 75 °C and gelatinize at this temperature for 0.2 h; (2) Enzymatic hydrolysis: Add 2 g of thermostable α-amylase (same as in Example 2) to the reaction tank and continue gelatinization at the same temperature for 1.5 h; (3) Acid inactivation: Add 100 g of 37.3% hydrochloric acid to the reaction tank and keep the reaction warm for 2 h; (4) Quenching the reaction: adding a 4 mol / L sodium hydroxide solution to the reaction tank to adjust the pH to 5.5 to obtain a reaction solution; (5) Ultrafiltration: The reaction solution cooled to room temperature is first filtered through a plate and frame filter, and the filtrate is then ultrafiltered through a 2000 Dalton ultrafiltration membrane; (6) Decolorization: Add 500 g of activated carbon to the ultrafiltration residual liquid, stir at 40 °C for 60 min, and filter to obtain a decolorized and filtered solution; (7) Spray drying: Control the inlet air temperature of the spray dryer to 170°C and the outlet air temperature to 90°C, and spray dry the decolorized and filtered solution to obtain icodextrin.

[0047] Analysis showed that the weight average molecular weight of the obtained icodextrin product was 23833, and the number average molecular weight was 13826. Both the weight average and number average molecular weights were large, and the product was unqualified.

[0048] Comparative Example 3 A method for preparing icodextrin comprises the following steps: (1) Starch gelatinization: Add 60 kg of purified water and 8 kg of corn starch (same as in Example 2) into a reaction tank, stir while heating, and after 2 hours, heat from room temperature to 95 °C and gelatinize at this temperature for 0.5 hours; (2) Enzymatic hydrolysis: 8 g of thermostable α-amylase (same as in Example 2) was added to the reaction tank and gelatinization was continued at the same temperature for 1.5 h. (3) Acid inactivation: Add 100 g of 37.3% hydrochloric acid to the reaction tank and keep the reaction warm for 2 h; (4) Quenching the reaction: adding a 4 mol / L sodium hydroxide solution to the reaction tank to adjust the pH to 5.5 to obtain a reaction solution; (5) Ultrafiltration: The reaction solution cooled to room temperature is first filtered through a plate and frame filter, and the filtrate is then ultrafiltered through a 2000 Dalton ultrafiltration membrane; (6) Decolorization: Add 500 g of activated carbon to the ultrafiltration residual liquid, stir at 40 °C for 60 min, and filter to obtain a decolorized and filtered solution; (7) Spray drying: Control the inlet air temperature of the spray dryer to 170°C and the outlet air temperature to 90°C, and spray dry the decolorized and filtered solution to obtain icodextrin.

[0049] Analysis showed that the weight average molecular weight of the obtained icodextrin product was 12278, and the number average molecular weight was 3754. Both the weight average and number average molecular weights were small, and the product was unqualified.

[0050] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art may still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing icodextrin, characterized in that: The following steps are involved: (1) Starch gelatinization: Add purified water and starch to the reaction tank, stir and heat it. After 1.5-2.5 hours, heat it from room temperature to 80-100℃ and gelatinize it at this temperature for 0.4-2 hours. (2) Enzymatic hydrolysis: Add a certain amount of α-amylase to the reaction tank and continue the reaction at the same temperature for 0.5-2 hours; (3) Acid inactivation: Add a certain amount of hydrochloric acid to the reaction tank and continue the reaction at the same temperature for 0.8-3 hours; (4) Quenching the reaction: adding alkali to the reaction tank to adjust the pH to 5-7 to obtain a reaction solution; (5) Ultrafiltration: The reaction solution cooled to room temperature is first filtered through a plate and frame filter, and then ultrafiltered through a 1000-5000 Dalton ultrafiltration membrane; (6) Decolorization: adding activated carbon to the ultrafiltration residual liquid, decolorizing, and filtering to obtain a decolorized and filtered solution; (7) Spray drying: The decolorized and filtered solution is spray dried to obtain icodextrin.

2. The method for preparing icodextrin according to claim 1, wherein In step (1), the starch is selected from corn starch, glutinous corn starch, wheat starch, sweet potato starch or potato starch.

3. The method for preparing icodextrin according to claim 1 or 2, wherein: In step (1), the mass ratio of starch and purified water added is 1:(5-15).

4. The method for preparing icodextrin according to claim 1, wherein In step (2), the α-amylase is selected from thermostable α-amylase.

5. The method for preparing icodextrin according to claim 1 or 3, wherein: In step (2), the amount of α-amylase added is 0.03-0.08% of the mass of starch added in step (1).

6. The method for preparing icodextrin according to claim 1, wherein In step (3), the amount of hydrochloric acid added is 1-3% of the mass of the starch added in step (1); the concentration of the hydrochloric acid is 35%-38%.

7. The method for preparing icodextrin according to claim 1, wherein In step (6), the amount of activated carbon added is 3-10% of the mass of starch added in step (1).

8. The method for preparing icodextrin according to claim 1 or 7, wherein: In the step (6), the decolorization temperature is 30-70°C, and the decolorization time is 10 min-60 min.

9. The method for preparing icodextrin according to claim 1, wherein In step (7), the air inlet temperature of the spray dryer is 150-220°C, and the air outlet temperature is 80-110°C.

10. Icodextrin obtained by the preparation method according to any one of claims 1 to 9.

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