RU2139294C1 - Method of preparing hydroxyethylated starch - Google Patents

Abstract

FIELD: blood substitutes. SUBSTANCE: invention relates to hemodynamic plasma substitute: hydroxyethylated starch with degree of substitution 0.5-0.7 and characteristic viscosity 0.14-0.18 is prepared by hydroxyethylation of amylopectin starch in presence of sodium or potassium chloride followed by acid hydrolysis, neutralization, clarification, reverse osmosis, ultrafiltration, sterilization, and drying. In particular, neutralized mass from hydrolysis stage is concentrated with regard to hydroxyethylated starch by ultrafiltration and/or reverse osmosis, after which ultrafiltration is repeated to remove soluble low- molecular organic and inorganic impurities. Sterilization is performed by thermal and/or microfiltering techniques, and sterilized solution, prior to be canned and resterilized, is concentrated by ultrafiltration and/or reverse osmosis. EFFECT: increased purity of product and facilitated controlling its characteristics.

Description

 The invention relates to the field of production of drugs, and in particular to a method for producing ethoxylated starch (OEC), which can be used as blood substitutes for antishock action - hemodynamic plasma substitutes.

Currently, pharmaceutical companies in various countries produce OEC-based preparations that have the following characteristics: Plasmotonin and Voleks (USA) with a mass-average molecular weight (M _w ) of 450,000 and a degree of substitution (C3) of 0.7-0.8; Plazmosteril (Germany) with M _w 450,000 and CZ 0.7-0.8; 6-HE (Japan) with M _w 200000 and CZ 0.6-0.7.

 Several methods are known for producing OECs. So in DE A1 1813571, 1969, a method for producing an OEC with a degree of substitution of CZ of 0.68-0.78 and an intrinsic viscosity of 0.19-0.27, which consists in starch obtained from waxy corn, is first hydrolyzed, then hydroxyethylated, or vice versa.

 However, it was found that when using the method obtained in DE C1 1813571, 1969, OEC, erythrocyte agglutination is observed, which indicates the adverse effect of such OEC on the peripheral circle of blood circulation. In addition, it was shown (WLThomson et. Al., Surg.Gynes Obstet. 131, 965-972, 1970) that the method obtained in DE A1 1813571, 1969, OEC is not a suitable plasma substitute, since it is not capable of light hydrolysis in the human body and remains in the body for a long time.

Patent RU 2021283 C1, 1994 describes a method for producing an OEC hydrolyzate fraction for the preparation of antishock blood substitutes, including acid hydrolysis, purification and concentration of the hydrolyzate by ultrafiltration. Ultrafiltration purification is performed at a pressure drop of 0.06 - 0.1 MPa and a temperature of 35-50 ^o C using membranes with a nominal molecular weight limit of retention of globular proteins of 5-30 kDa. Then the hydrolyzate is cooled to 20-30 ^o C and concentrated by ultrafiltration at a pressure drop of 0.1-0.15 MPa to an OEC content of 6 ± 0.5 wt.% On the same membranes.

 The disadvantage of this method is the implementation of ultrafiltration of the hydrolyzate without first leading to the optimal concentration of OEC in the solution, which can significantly impair the technical and economic parameters of the cleaning process.

 The closest in technical essence is the method DE A1, 2837067.4, 1979, of obtaining an OEC with CZ 0.50-0.55 and a characteristic viscosity of 0.09-0.14, which consists in the fact that aminopectin starch obtained from waxy corn is pasteurized, pasteurized starch is ethoxylated with ethylene oxide in the presence of alkali in order to obtain a degree of substitution with hydroxyethyl groups of 0.5-0.55, then the OEC is subjected to acid hydrolysis to achieve a characteristic viscosity of 0.09-0.14 without a significant change in C3 to obtain a low molecular weight OEC, or ystvuyut in reverse - is first carried out by acid hydrolysis, and then esterifying the latter case, the formation of less colored HES. The following are the stages of clarification with coal, purification of the solution from sulfates, chlorides, ethylene glycol, reverse osmosis antiseptic, concentration of the solution by OEC with reverse osmosis and drying. Additionally, it is possible to use ultrafiltration to clean the solution from pyrogenic macromolecular substances. Ultrafiltration is carried out before or after reverse osmosis. Preliminary sterilization of the reverse osmosis unit and treatment of the OEC solution with an antiseptic before reverse osmosis is recommended.

 The method of purification of an OEC solution with reverse osmosis from mineral salts makes it possible to obtain a better product compared to the method of purification of by-products by solvent extraction, for example, according to method JP C1, N 45-39833, 1970. The content of chlorides and sulfates in an OEC solution purified by reverse osmosis does not exceed 0.1% and 15 ppm, respectively.

 Obtained by the method of DE A1, 2837067.4, 1979, an OEC with CZ 0.50-0.55 and an intrinsic viscosity of 0.09-0.14 is a good plasma substitute and has a slight agglutinating effect, comparable to the action of physiological saline solution.

The disadvantages of this method of obtaining OEC are:
- high consumption of ethylene oxide, 2.5 times higher than the theoretically calculated amount;
- low efficiency and degree of purification by reverse osmosis of the OEC solution from low molecular weight organic and inorganic impurities, including an antiseptic;
- not a rational sequence in the process of cleaning the OEC solution with reverse osmosis, leading to the cost overrun of distilled water;
- the use of high pressures and a narrow temperature range during the operation of membrane equipment at the stage of cleaning the solution from low molecular weight soluble impurities.

 The objective of the present invention is to provide a method that allows to obtain a high-purity OEC with specified C3 and intrinsic viscosity, which has good technical and economic performance.

The problem is solved by carrying out the process of hydroxyethylation of amylopectin starch in the presence of sodium chloride or potassium chloride, concentration of the neutralized mass from the hydrolysis stage of ethoxylated starch by ultrafiltration and / or reverse osmosis, followed by purification from soluble low molecular weight organic and inorganic impurities or ultrafiltration with ultrafiltration microfiltration method, concentration by ultrafiltration and / or reverse osmosis or direction bottling and sterilization. The process of starch oxyethylation is carried out at 20-80 ^o C, and sodium chloride or potassium chloride is taken in an amount of 1.0-10.0% by weight of amylopectin starch. Clarification of the reaction mass may be carried out before and / or after purification from soluble low molecular weight organic and inorganic impurities.

Carrying out the process of hydroxyethylation at a temperature below 20 ^o C leads to a significant slowdown in its course, and an increase in temperature above 80 ^o C leads to a colored preparation.

 A decrease in the amount of sodium chloride or potassium chloride of less than 1% reduces the reaction rate, and an increase in its amount above 10% is not technologically justified.

 The process of obtaining an OEC in accordance with the proposed method is as follows: amylopectin starch and sodium chloride (potassium chloride) are loaded into a stainless steel apparatus, the mixture is stirred, and ethylene oxide is fed by supplying liquid ethylene oxide, at the end of this process, the reaction mass is fed to the hydrolysis apparatus where pyrogen-free water and hydrochloric acid are added with stirring; the acid hydrolysis process is carried out until the characteristic viscosity of 0.14-0.18 and the degree of substitution of 0.5-0.7. The resulting OEC solution is subjected to clarification by treatment with pyrogen-free coal and filtration. Then, the OEC solution is purified from highly dispersed mechanical and high molecular weight soluble impurities by ultrafiltration and concentrated by ultrafiltration and / or reverse osmosis. Next, the reaction mass is brought with pyrogen-free water to the optimal concentration of OEC for purification from low molecular weight soluble impurities. The resulting solution is purified by pyrogen-free water at the optimal concentration of OEC from low molecular weight organic and inorganic soluble impurities by ultrafiltration. The cleaned mass is either adjusted by dilution with pyrogen-free water or ultrafiltration concentration to 6%, sterilized by heat and / or microfiltration method and sent for bottling followed by sterilization, or sterilized by heat and / or microfiltration method, concentrated to an OEC content of more than 15% by ultrafiltration and / or reverse osmosis and dried. The concentration of OEC in the sterilized solution fed to the drying step may be less than 15% when using a spray dryer. The processes of clarification, filtering and ultrafiltration purification from highly dispersed mechanical and high molecular weight soluble impurities are carried out before and / or after ultrafiltration purification from low molecular weight soluble impurities.

 The present invention is illustrated by the following examples.

 Example 1

300 cm ^{3 of} pyrogen-free water are poured into a stainless steel apparatus, after which 200 g of amylopectin starch and 20 g of sodium chloride are loaded. The resulting mixture is heated to 85-90 ^o C and stirred for 20 minutes until a uniform paste is formed. Then the reaction mass is cooled to 40 ^o C, purged with an inert gas, such as nitrogen, to remove traces of air and served under a layer of paste for 1 hour 40 g of liquid ethylene oxide. During the supply of ethylene oxide in the apparatus maintain a temperature of 80 ± 5 ^o C at a pressure of 0.15 MPa. Upon completion of the ethylene oxide supply, the obtained ethoxylated starch is cooled to 20 ^° C. and purged with nitrogen to remove traces of ethylene oxide, after which the reaction mass is transferred to the stage of acid hydrolysis. After making the OEC in the apparatus for hydrolysis, with stirring, add 3 l of pyrogen-free water and 300 cm ^{3 of} 2N hydrochloric acid, the mass is heated to 65 ^o C and incubated for 2.0-2.5 hours at this temperature until the characteristic viscosity of 0.14- 0.18 and Sz 0.5-0.65.

Then the mass is cooled to 40-43 ^o C and neutralized with 300 cm ³ 2N sodium hydroxide solution.

Next, the OEC solution is clarified by treatment with pyrogen-free charcoal and filtered. Then the mass is cleaned of highly dispersed mechanical and high molecular weight soluble impurities at a pressure drop of 0.1-0.2 MPa on a Pall Filtron Centrasette ultrafiltration system using cassettes made on the basis of Sigma Series membranes with a nominal molecular weight retention limit (NMMP) of globular proteins 1.0 MDa. The concentrate containing high molecular weight components of OEC and mechanical impurities is sent for disposal. The filtrate with an OEC content of about 5% is concentrated to 12-14% OEC at a pressure drop of 0.4 MPa on a Pall Filtron Centrasette ultrafiltration system using cassettes made on the basis of Sigma Series membranes with NMMP 10 kD globular proteins. Then, the solution, without removing from the ultrafiltration system, is brought by dilution with pyrogen-free water to an OEC concentration of 8-10% and the ultrafiltration process is carried out to purify low molecular weight organic and inorganic soluble impurities. Purification was done apyrogenic water at a constant concentration of HES in the solution and a pressure differential of 4.0 MPa until the Cl ion content ^- in the liquid is less than 0.05% and the absence of low molecular weight glycols. Next, the purified solution is either diluted with pyrogen-free water to a concentration of 6%, then sent to the microfiltration sterilization stage using membrane filters with pore sizes of 0.1 μm, bottled with subsequent thermal sterilization, or microfiltered, concentrated by ultrafiltration at a pressure drop of 0.52 MPa to OEC content of more than 15%, then dried. The yield of the product is 65%; CZ - 0.55; intrinsic viscosity - 0.165.

 Example 2

 The process is conducted under the conditions of example 1 with the change in the fact that the OEC solution is purified from highly dispersed mechanical and high molecular soluble impurities on membranes with NMMP 500 kDa; concentrated and purified from low molecular weight impurities on membranes with NMMP 50 kDa. The resulting product is characterized by a narrower molecular weight distribution of the OEC than in example 1. The yield of the product is 60%; CZ - 0.6; intrinsic viscosity - 0.170.

 Example 3

 The process is carried out under the conditions of example 1 with the change in the fact that potassium chloride in the amount of 5% of the original starch is taken as a catalyst. The yield of the product is 63%; CZ - 0.5; intrinsic viscosity 0.175.

 Example 4

 The process is carried out under the conditions of example 1 with a change in the amount of sodium chloride catalyst, which is 2 g (1% of the loaded starch); ethylene oxide feed time is 4.5 hours at a pressure of 0.12 - 0.15 MPa; concentrated after purification from highly dispersed mechanical and high molecular soluble impurities, the OEC solution is further concentrated to an OEC content of about 20% by reverse osmosis on membranes with NMMP 100 Da at a pressure drop of 4.0 MPa. The resulting reaction mass has a pH of 6.8, a degree of substitution of 0.5 and an intrinsic viscosity of 0.164. The OEC color is darker than in Example 1. The product yield is 62%.

 Example 5

The process is carried out under the conditions of example 1 with the difference that the supply of ethylene oxide is carried out at a temperature of 20 - 25 ^o C and a pressure of 0.06 - 0.09 MPa; pyrogen-free water is added in an amount of 400 cm ³ to reduce the viscosity of the reaction mass at a temperature of 20 - 25 ^o C; the stage of purification of the OEC solution from highly dispersed mechanical and high molecular soluble impurities by ultrafiltration is excluded; the neutralized, clarified reaction mass is concentrated to an OEC content of about 20% by reverse osmosis on membranes with NMMP 100 Da at a pressure drop of 4.0 MPa; the purified OEC solution from low molecular weight organic and inorganic soluble impurities by ultrafiltration is concentrated by reverse osmosis on membranes with NMMP 100 Da at a pressure drop of 4.0 MPa to an OEC concentration of more than 20%, then dried. The yield of the product is 64.5%; CZ - 0.63; intrinsic viscosity - 0.170.

 Example 6

227 liters of pyrogen-free water are poured into a stainless steel autoclave and 65 kg of aminopectin starch and 6 kg of sodium chloride are loaded with stirring. The resulting mixture is heated to a temperature of 85 - 90 ^o C and stirred for 30 minutes until a uniform paste is formed. The reaction mass is cooled to 60 ^o C and purged with nitrogen three times, after which ethylene oxide begins to be fed at a pressure of 0.18-0.2 MPa. The feed time of 18 kg of ethylene oxide is 1.5 - 2.0 hours at a temperature of 65 - 75 ^o C. At the end of the supply of ethylene oxide at the same temperature and with stirring, give exposure for 2 hours. Then the reaction mass is cooled to 30-35 ^o C and transferred to the apparatus for hydrolysis. The resulting solution has a pH of 10.2; OEC degree of substitution is 0.62.

With stirring, 700 l of pyrogen-free water and 102 kg of 2N hydrochloric acid are added to the hydrolyzer, the solution is heated to a temperature of 60 - 65 ^° C and maintained at this temperature for 2.5 - 3.0 hours until the characteristic viscosity of 0.12 - 0.18 is reached.

Then the reaction mass is cooled to 50 ^o C and with stirring for 20-30 minutes pour 103 kg of 2N sodium hydroxide solution.

Obtained in the amount of 1109 kg, the neutral hydrolyzate solution is then clarified by treatment with pyrogen-free coal and a further technological process is carried out under the conditions of Example 1 with the change in that the purified 6% OEC solution is subjected to heat sterilization at a temperature of 121 ^o C for 20-30 minutes and dried in spray dryer. The yield of the product is 55%; CZ - 0.62; intrinsic viscosity 0.174.

Thus, the implementation of the process of obtaining the OEC according to the method described above has several significant advantages and allows
- synthesize an ethoxylated product with the required degree of substitution at a consumption of ethylene oxide is almost two times lower than in the case of using caustic soda as a catalyst;
- get lighter hydroxyethylation products;
- reduce the formation of side compounds of low molecular weight glycols (mono-, di - and triglycols);
- virtually eliminate the stage of neutralization at the end of the process of hydroxyethylation;
- increase the efficiency and degree of purification of the product from low molecular weight organic and inorganic soluble impurities with the rational organization of membrane processes and the use of membrane equipment operating at low pressure drops (up to 2.0 MPa) and a wide temperature range (from 5 ^o C to 120 ^o C )

Claims (4)

 1. The method of producing ethoxylated starch, including the ethoxylation of amylopectin starch, acid hydrolysis, neutralization, clarification, purification, concentration, sterilization and drying, characterized in that the ethoxylation of amylopectin starch is carried out in the presence of sodium chloride or potassium chloride, the neutralized mass is neutralized after the stage is neutralized with the hydrolyzed potassium chloride ethoxylated starch by ultrafiltration and / or reverse osmosis, then purified from soluble low molecular weight organic and inorganic impurities by ultrafiltration, subsequent sterilization is carried out by heat and / or microfiltration method, the sterilized solution is concentrated by ultrafiltration and / or reverse osmosis or sent to the bottling followed by sterilization. 2. The method of producing ethoxylated starch according to claim 1, characterized in that the process for the ethoxylation of amylopectin starch is carried out at 20 - 80 ^o C.  3. The method of producing ethoxylated starch according to claim 1, characterized in that sodium chloride or potassium chloride is taken in an amount of 1.0 to 10.0% by weight of amylopectin starch.  4. The method of producing ethoxylated starch according to claim 1, characterized in that the clarification of the reaction mass is carried out before and / or after purification from soluble low molecular weight organic and inorganic impurities.