A terminal cooling method for reducing dissolved oxygen of a compound amino acid injection, an injection prepared therefrom and application thereof

Abstract

The application discloses a terminal cooling method for reducing dissolved oxygen of a compound amino acid injection, and comprises the following steps: S1, pre-oxygen-removal and slow cooling stage: after sterilization, a spraying system is started, cooling medium treated by online degassing is sprayed from the bottom of a sterilization cabinet upwards, and the temperature of the center medicine liquid of an infusion bag is reduced to 65 DEG C-70 DEG C; S2, positive pressure control speed cooling stage: the cooling medium with a temperature of less than or equal to 12 DEG C is switched to spraying, nitrogen gas is introduced into the top of the sterilization cabinet and discharged from the bottom to replace, and countercurrent contact with the cooling medium is maintained; and the pressure in the sterilization cabinet is maintained to be 0.03-0.08 MPa higher than the saturated steam pressure corresponding to the temperature of the medicine liquid, so that the temperature of the center medicine liquid is reduced to 38 DEG C-42 DEG C; S3, terminal temperature balance cooling stage: spraying is stopped, and the infusion bag is naturally balanced and cooled to 25 DEG C-30 DEG C; and S4, micro-negative pressure nitrogen filling stage: the pressure in the sterilization cabinet is instantaneously reduced to micro-negative pressure, high-purity nitrogen gas is rapidly filled to restore normal pressure, and then the cabinet is discharged.

Description

Technical Field

[0001] This invention relates to the field of compound amino acid injection preparation technology, specifically to a terminal cooling method for reducing dissolved oxygen in compound amino acid injection, the injection prepared therefrom, and its application. Background Technology

[0002] Compound amino acid injections are a core product in parenteral nutrition therapy, typically containing 8% to 12% of various amino acids. Among them, cysteine ​​(or N-acetyl-L-cysteine), tryptophan, and other components are extremely sensitive to oxygen and are prone to oxidative degradation during high-temperature sterilization and long-term storage, leading to a decrease in content, darkening of solution color, formation of insoluble particles, or even precipitation, seriously affecting the safety and efficacy of clinical use.

[0003] To control the oxygen content in products, existing technologies mainly focus on the solution preparation and filling stages. For example, Chinese patent CN103340853A discloses an octadecyl amino acid injection containing a small amount of antioxidants and its preparation method. This method involves nitrogen bubbling and vacuuming followed by nitrogen purging of the water for injection and the drug solution in a preparation tank to control the dissolved oxygen in the drug solution before filling to no more than 0.1 ppm. Simultaneously, nitrogen purging is performed on the headspace of the infusion bag during filling and sealing. Chinese patent CN106860446B discloses a method for preparing a pediatric compound amino acid injection. This method involves pre-purging the water for injection at 85°C with nitrogen to reduce the dissolved oxygen value to below 6 mg / L during the preparation process. Under nitrogen atmosphere protection, the dissolution, mixing, filtration, and filling of each amino acid component are completed, ultimately controlling the dissolved oxygen value of the finished injection solution within the range of 1.0–2.5 mg / L. Chinese patent CN102302489B discloses a method for preparing a compound amino acid injection, which removes oxygen from the preparation equipment and dissolved oxygen in water by vacuuming and purging with nitrogen during the preparation process.

[0004] Regarding packaging materials and sterilization processes, Chinese patent CN104548153A discloses a method for filling and sterilizing soft-bag compound amino acid injection solution. This method employs a bag-making and filling-sealing integrated machine for vacuum-vacuum-nitrogen-filling cyclic filling, followed by sterilization at 121°C in a nitrogen atmosphere using a nitrogen-filled sterilizer, with cooling controlled at 50–65°C. This method utilizes nitrogen purging of the sterilizer before sterilization and provides an inert nitrogen atmosphere during sterilization to prevent external air from entering the bag. Furthermore, existing technologies also report high-barrier inner bags with oxygen-barrier layers (such as ethylene-vinyl alcohol copolymer EVOH layers) and oxygen absorbers to prevent external oxygen from permeating into the bag during storage.

[0005] However, in actual production, although the dissolved oxygen of the drug solution is strictly controlled before filling, the dissolved oxygen content of the finished product after final sterilization will still rebound significantly (usually rebounding to 2-5 mg / L, or even higher). This has become a key and long-neglected technical bottleneck that restricts the quality stability of amino acid soft bag products.

[0006] In-depth research revealed that the main cause of this rebound was the "oxygen re-dissolution effect" during the sterilization process. During moist heat sterilization (typically 121°C for 12 minutes) and the subsequent slow natural cooling, the medication and headspace gas inside the infusion bag are under high temperature and pressure. Although the initial headspace residual oxygen level is very low (e.g., ≤2.5%), at high temperatures, the molecular motion of the gas is intense, causing a shift in the dynamic equilibrium of its solubility in the liquid phase within the closed system. More importantly, the infusion bag itself is made of polymer materials. At temperatures above 110°C, the molecular chain movement of the bag material intensifies, increasing the free volume and leading to an exponential increase in its permeability coefficient for small molecules such as oxygen. This means that during sterilization and the slow cooling process, which lasts for several hours, a large amount of oxygen from the outside air permeates through the high-temperature bag material into the headspace and rapidly dissolves in the high-temperature medication, forming a vicious cycle of external oxygen – bag wall permeation – headspace enrichment – ​​medication re-dissolution. The slower the cooling process and the longer the high-temperature exposure time, the higher the total amount of oxygen permeation.

[0007] While CN104548153A utilizes a nitrogen-filled sterilizer, its cooling process only sets a final cooling temperature target, lacking precise control over the cooling rate and temperature range. Particularly during the cooling stage, as the temperature of the liquid medicine and the gas inside the bag decreases and their volume shrinks, a significant negative pressure difference easily forms between the inside and outside of the bag, causing a "breathing effect" in the bag. This pressure imbalance not only causes bag deformation but also forces the micropores in the bag wall into a stretched or open state under the pressure of external atmospheric pressure, significantly increasing the risk of infiltration of oxygen-containing gases. Existing technologies generally fail to recognize the destructive impact of pressure fluctuations during the cooling stage on the bag's barrier performance and do not provide effective control measures for this pressure imbalance.

[0008] Furthermore, existing cooling methods mostly employ natural cooling or simple spray cooling, resulting in slow cooling rates (it typically takes 40–80 minutes or even longer for the central solution temperature to drop from 121°C to 40°C), failing to effectively shorten the high-temperature exposure time. Simultaneously, trace amounts of oxygen may still remain in the headspace of the bag when cooling is nearly complete, and current technologies lack effective intervention measures for deep removal of residual oxygen in the headspace before removal from the container.

[0009] In conclusion, focusing solely on the initial dissolved oxygen before filling and the room-temperature barrier properties of packaging materials, while ignoring the surge in permeability caused by temperature changes during the high-temperature cooling window after sterilization, the "breathing effect" caused by pressure imbalance, and the accumulation of residual oxygen in the headspace, cannot fundamentally solve the problem of high dissolved oxygen in the final product. Summary of the Invention

[0010] The present invention aims to overcome at least one of the defects of the prior art and provide a terminal cooling method for reducing dissolved oxygen in compound amino acid injections, so as to solve the problem of high dissolved oxygen in the final product.

[0011] Specifically, this invention protects a terminal cooling method for reducing dissolved oxygen in compound amino acid injection solutions, applicable to infusion bags that have been filled, sealed, and terminally sterilized, comprising the following steps: S1. Pre-deoxygenation and slow cooling stage: After sterilization, the spray system is started. The cooling medium, which has been degassed online, is sprayed from the bottom of the sterilizer upwards to reduce the temperature of the infusion bag to 65℃~70℃.

[0012] This stage utilizes the temperature difference between the high-temperature liquid medicine and the low-temperature degassing cooling medium to achieve rapid heat transfer, allowing the liquid medicine to quickly pass through the high-temperature range with the highest oxygen permeability (>80℃), significantly shortening the high-temperature exposure time. Crucially, the cooling medium undergoes online degassing treatment, resulting in extremely low dissolved oxygen content (≤2mg / L). When in contact with the high-temperature gas phase inside the sterilizer, it actively absorbs the oxygen released due to high temperature and trace amounts of permeation from within the sterilizer due to the significant oxygen partial pressure difference. This achieves pre-deoxygenation during the initial cooling stage without the introduction of external nitrogen protection, reducing the oxygen load within the sterilizer at its source.

[0013] S2, Positive Pressure Controlled Cooling Stage: Switch to a cooling medium with a temperature ≤12℃ for spraying, and simultaneously turn on nitrogen to be introduced into the top of the sterilizer and discharged from the bottom for replacement, maintaining counter-current contact with the cooling medium; and maintain the pressure inside the sterilizer 0.03~0.08MPa higher than the saturated vapor pressure corresponding to the drug solution temperature, so that the temperature of the central drug solution drops to 38℃~42℃; the saturated vapor pressure is obtained by referring to a water vapor pressure gauge based on the drug solution temperature, or by real-time monitoring of the pure steam saturated pressure inside the cabinet by an online pressure sensor.

[0014] The positive pressure controlled cooling stage is the core window for oxygen barrier. This invention maintains a positive pressure environment higher than the saturated vapor pressure, physically counteracting the pressure drop inside the bag caused by temperature decrease, preventing bag deformation and micropore opening due to negative pressure, and effectively suppressing the "breathing effect." Simultaneously, nitrogen gas flows from top to bottom and sprays water from bottom to top in a counter-current contact. The degassed cooling water, acting as a highly efficient "oxygen capture medium," washes the nitrogen before it is discharged, further absorbing trace amounts of oxygen carried in the nitrogen, suppressing the oxygen concentration inside the cabinet to an extremely low level, achieving synergistic oxygen barrier effects of positive pressure seepage prevention and counter-current washing.

[0015] S3, Final Temperature Equilibrium Cooling Stage: Stop spraying and allow the infusion bag to naturally and evenly cool down to 25℃~30℃; This stage utilizes indirect heat exchange with air to avoid thermal shock to the bag due to rapid cooling, while ensuring that the temperature of the medicine solution transitions evenly to a suitable room temperature range for subsequent treatment.

[0016] S4. Micro-negative pressure nitrogen filling stage: The pressure inside the sterilizer is instantly reduced to a micro-negative pressure, then high-purity nitrogen is quickly introduced to restore normal pressure, and the product is then removed from the sterilizer. This stage utilizes the instantaneous micro-negative pressure state to induce a slight exhalation effect in the bag, extracting the high-oxygen-concentration boundary layer gas adhering to the bag surface and headspace. High-purity nitrogen is then used to fill the headspace, achieving deep replacement of residual oxygen and ensuring the product is in an extremely low-oxygen environment upon removal from the sterilizer.

[0017] Preferably, in step S1, the cooling medium is cooling water, the temperature of the cooling water is 20~30℃, and the cooling water undergoes online degassing treatment to achieve a dissolved oxygen content ≤2mg / L. The online degassing treatment employs a hollow fiber membrane degassing device from the prior art to control the dissolved oxygen content of the cooling water to ≤2mg / L.

[0018] Furthermore, in step S1, the temperature of the cooling medium in the spraying system dynamically changes according to a preset gradient within the range of 20~30℃: in the initial stage, the cooling medium is sprayed at 28~30℃; in the second stage, the temperature of the cooling medium is gradually reduced to 25~28℃; in the final stage, the cooling medium at 20~25℃ is sprayed until the temperature of the medicine in the center of the infusion bag drops to 65℃~70℃.

[0019] In some embodiments of the present invention, in step S1, the initial spraying time is 3-4 minutes; the second spraying time is 3-4 minutes; and the third spraying time is 2-4 minutes.

[0020] Preferably, in step S2, the temperature of the cooling medium is 8~10°C; the cooling time t ≤ 15 min. If the temperature is higher than 12°C, the cooling rate is insufficient and cannot quickly cross the high-temperature range (>80°C) where the oxygen permeability coefficient increases dramatically, leading to a rebound in dissolved oxygen. If the temperature is lower than 8°C, although cooling is faster, it can easily cause the infusion bag to deform due to excessive temperature difference. The cooling time t needs to be strictly controlled within ≤ 15 min because during this time period, the temperature of the medicine solution drops from about 70°C to about 40°C, which precisely avoids the natural decline in the permeability of the bag wall during the subsequent natural cooling stage. At the same time, through efficient heat exchange in a short time, the overall consumption of nitrogen in the cabinet is reduced.

[0021] More preferably, the sterilizer is a water bath sterilizer, and steps S1 to S4 are all performed under conditions where the oxygen concentration inside the sterilizer is less than 2%.

[0022] More preferably, the negative pressure in step S4 is -0.01 to -0.02 MPa, and the holding time is 15 to 30 seconds.

[0023] Furthermore, step S4 also includes a cycle of filling with nitrogen to restore normal pressure after applying a slight negative pressure, with the cycle number being 1 to 3 times.

[0024] The present invention also provides a compound amino acid injection, which is prepared by the above-mentioned terminal cooling method, and the compound amino acid injection prepared has a dissolved oxygen content ≤1.0mg / L after sterilization, and the compound amino acid injection has a tryptophan content retention rate ≥98% and a cysteine ​​content retention rate ≥97% after 6 months of accelerated testing at 40℃.

[0025] This invention also protects the application of the above-mentioned terminal cooling method for reducing dissolved oxygen in compound amino acid injections in soft-bag amino acid products, said soft-bag amino acid products comprising compound amino acid injections containing cysteine ​​or its analogues, tryptophan and sodium bisulfite.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Significantly Reduced Dissolved Oxygen Content in the Final Product: This invention constructs a triple deoxygenation mechanism through S1 pre-deoxygenation, S2 countercurrent washing, and S4 micro-negative pressure replacement. In particular, the cooling medium is reconstructed from a single heat exchange function to also have an active deoxygenation function. That is, the degassed cooling water forms a dynamic liquid film during spraying, which physically blocks and absorbs oxygen from the external environment of the bag; in S2, nitrogen comes into countercurrent contact with the cooling water to achieve convective washing and deoxygenation; and in S4, the micro-negative pressure drop further removes residual oxygen from the bag headspace and replaces it with high-purity nitrogen. The synergistic effect of the three mechanisms ensures that the dissolved oxygen in the final product is stably controlled below 1.0 mg / L, which is more than 80% lower than that of conventional processes (2-5 mg / L), significantly reducing the driving force of oxidative degradation from the root.

[0027] 2. Effectively suppress oxygen re-dissolution caused by "respiration effect": In the S2 stage, the present invention implements precise positive pressure compensation control to maintain the pressure inside the cabinet 0.03 to 0.08 MPa higher than the saturated vapor pressure corresponding to the temperature of the liquid medicine. This eliminates the negative pressure difference between the inside and outside of the bag during the cooling process, prevents the micropores of the bag wall from opening, and fundamentally blocks the path of external oxygen re-dissolution due to "respiration effect", ensuring that the deoxygenation results in the early stage are solidified during the cooling stage.

[0028] 3. Significantly improved long-term product stability: After 6 months of accelerated testing at 40℃, the compound amino acid injection prepared using this invention retains ≥96% of tryptophan and ≥95% of cysteine. The solution color changes very little, and the generation of insoluble particles is effectively delayed, effectively ensuring the safety and efficacy of clinical use. It is expected that the product's shelf life can be extended from the conventional 18 months to 24-36 months.

[0029] 4. Strong process compatibility and easy implementation: This invention does not require modification of the main structure of the water bath sterilizer. It can be achieved simply by optimizing the control program, adding an online cooling water degassing module, and adjusting the process parameters. It is fully compatible with existing mainstream production equipment, has low modification costs, good process reproducibility, and has significant industrial promotion value. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described below with reference to specific embodiments, but the scope of protection of this invention is not limited thereto. Experimental methods in the embodiments that do not specify specific conditions are generally performed under conventional conditions or according to the manufacturer's recommendations. Unless otherwise specified, all reagents and materials used are commercially available.

[0031] The following examples and comparative examples use 18 amino acid injection solutions (18AA) with the following formulation composition (per 1000 ml): The formula contains 3.1g of L-isoleucine, 4.2g of L-leucine, 5.6g of L-lysine acetate (equivalent to 4.3g of L-lysine), 3.5g of L-methionine, 4.5g of L-phenylalanine, 2.5g of L-threonine, 1.0g of L-tryptophan, 3.3g of L-valine, 5.0g of L-alanine, 6.5g of L-arginine, 2.5g of L-aspartic acid, 1.8g of glutamic acid, 1.2g of L-cysteine ​​hydrochloride (approximately 0.85g based on cysteine), 6.0g of glycine, 3.5g of L-histidine, 3.0g of L-proline, and 2.0g of L-serine, totaling 18 amino acids with a total amino acid content of approximately 61g / L. It also contains 0.5g of sodium bisulfite (an antioxidant), an appropriate amount of osmotic pressure regulator, and water for injection to a final volume of 1000ml. The formulation is a 100ml multilayer co-extruded infusion soft bag (containing an EVOH high-barrier layer), which is terminally sterilized (121℃, 12min) after filling and sealing.

[0032] The detection methods and indicators are as follows: Dissolved oxygen content was determined using a Mettler Toledo InPro6970 series dissolved oxygen electrode, in mg / L; headspace residual oxygen was determined using headspace gas chromatography, in volume percentage (%); tryptophan and cysteine ​​contents were determined using high-performance liquid chromatography (HPLC); insoluble particles were determined using the light obscuration method; solution color was determined by comparing with standard colorimetric solutions according to the first method (visual method) of General Chapter 0901 of the 2025 edition of the Chinese Pharmacopoeia, and the color number (Y1~Y7) was recorded; pH value was determined using a pH meter; transmittance was determined by ultraviolet-visible spectrophotometry at a wavelength of 430 nm; sodium bisulfite content was determined using the iodometric method. Accelerated testing conditions were 40℃±2℃, relative humidity 75%±5%, and storage for 6 months. The formula for calculating the content retention rate is: Retention rate (%) = Content after accelerated testing / Initial content × 100%. Five batches of samples were used for each test group, and the average value ± standard deviation was taken. All tests were conducted in accordance with the methods outlined in Part IV of the 2025 edition of the Chinese Pharmacopoeia.

[0033] Example 1 A terminal cooling method for reducing dissolved oxygen in 18 amino acid injection (18AA), applicable to 100ml multilayer co-extruded soft bags of 18 amino acid injection (18AA) that have been filled, sealed, and terminally sterilized (121℃, 12min), includes the following steps: S1. Pre-deoxygenation and slow cooling stage: After sterilization, start the spray system. Cooling water that has been degassed online (dissolved oxygen content ≤1.5mg / L) is sprayed from the bottom of the sterilizer upwards. The initial temperature of the cooling water is 30℃. After spraying for 3 minutes, it is cooled to 26℃ and sprayed for 4 minutes. Then it is cooled to 22℃ and sprayed for 3 minutes to reduce the temperature of the drug solution in the center of the infusion bag to 68℃.

[0034] S2, Positive Pressure Controlled Cooling Stage: Switch to spraying with cooling water at 10℃, and simultaneously turn on nitrogen (purity ≥99.9%) to be introduced into the top of the sterilizer and discharged from the bottom for replacement. The nitrogen flow rate is twice the volume of the sterilizer per hour, and it is kept in countercurrent contact with the cooling water. Maintain the pressure inside the sterilizer 0.05MPa higher than the saturated vapor pressure corresponding to the temperature of the medicine solution, and the cooling time is 12 minutes, so that the temperature of the central medicine solution drops to 40℃.

[0035] S3, Final Temperature Equilibrium Cooling Stage: Stop spraying and allow the infusion bag to naturally cool down to 28℃ in a nitrogen atmosphere.

[0036] S4. Micro-negative pressure nitrogen filling stage: Instantly reduce the pressure inside the sterilizer to -0.015MPa, maintain for 20s, then quickly fill with high-purity nitrogen (purity ≥99.99%) to restore normal pressure. Repeat once, then remove from the sterilizer.

[0037] All steps S1 to S4 are performed under conditions where the oxygen concentration inside the sterilizer is less than 2%.

[0038] Example 2 It is basically the same as Example 1, except that: In S1, the dissolved oxygen content of the deaerated cooling water is ≤2mg / L, the initial temperature is 28℃, and the three stages are sprayed at 28℃ for 3min, 25℃ for 3min, and 20℃ for 2min respectively, so as to reduce the temperature of the drug solution in the center of the infusion bag to 65℃.

[0039] In S2, the cooling water temperature is 8℃, and the pressure inside the sterilizer is maintained 0.03MPa higher than the saturated vapor pressure corresponding to the drug solution temperature. The cooling time is 15min, which reduces the temperature of the central drug solution to 42℃.

[0040] In S3, the temperature naturally balances and cools down to 25°C.

[0041] In S4, the slight negative pressure is -0.01MPa, maintained for 30s, and the cycle is repeated once.

[0042] Example 3 It is basically the same as Example 1, except that: In S1, the dissolved oxygen content of the deaerated cooling water is ≤1mg / L, the initial temperature is 30℃, and the three stages are sprayed at 30℃ for 4min, 28℃ for 4min, and 25℃ for 4min respectively, so as to reduce the temperature of the drug solution in the center of the infusion bag to 70℃.

[0043] In S2, the cooling water temperature is 12℃, the pressure inside the sterilizer is maintained 0.08MPa higher than the saturated vapor pressure corresponding to the drug solution temperature, and the cooling time is 10min, so that the temperature of the central drug solution drops to 38℃.

[0044] In S3, the temperature naturally balances and cools down to 30°C.

[0045] In S4, the slight negative pressure is -0.02MPa, maintained for 15s, and repeated 3 times.

[0046] Example 4 It is basically the same as Example 1, except that: Step S4: Instantly reduce the pressure inside the sterilizer to -0.015MPa, maintain this pressure for 20 seconds, then quickly fill with high-purity nitrogen (purity ≥99.99%) to restore normal pressure. Do not perform any circulation operations; remove the sterilizer directly.

[0047] Example 5 The process is basically the same as in Example 1, except that: in S1, the dissolved oxygen content of the deaerated cooling water is ≤1.8mg / L, the three-stage temperatures are 29℃, 26℃, and 21℃, and the spraying time for each stage is 3min; in S2, the cooling water temperature is 9℃, the pressure inside the sterilizer is maintained 0.06MPa higher than the saturated vapor pressure, and the cooling time is 13min; in S4, a slight negative pressure of -0.015MPa is maintained for 25s, and the cycle is repeated twice.

[0048] Comparative Example 1 (without online degassing treatment) The procedure is basically the same as in Example 1, except that the cooling water in step S1 is not subjected to online degassing treatment and the dissolved oxygen content is 8.5 mg / L (the level of conventional purified water). All other conditions are the same as in Example 1.

[0049] Comparative Example 2 (S1 No gradient, fixed temperature spray) The process is basically the same as in Example 1, except that in step S1, the cooling water is sprayed at a fixed temperature of 25°C (without gradient cooling) until the temperature of the central liquid drops to 68°C.

[0050] Comparative Example 3 (Step S1 omitted) It is basically the same as Example 1, except that: step S1, the pre-deoxygenation and slow cooling stage, is omitted; it directly enters the positive pressure controlled cooling stage, and the conditions of steps S2 to S4 are related to those of Example 1.

[0051] Comparative Example 4 (with nitrogen countercurrent displacement, without positive pressure control) The process is basically the same as in Example 1, except that in step S2, nitrogen is introduced into the top of the sterilizer and discharged from the bottom for replacement (nitrogen flow rate is the same as in Example 1), and it is kept in countercurrent contact with the cooling water, but the positive pressure control inside the sterilizer is not maintained (i.e., the pressure difference is not maintained at 0.05 MPa higher than the saturated vapor pressure corresponding to the drug solution temperature, but only normal pressure operation is maintained), and the cooling water temperature is 10°C and sprayed until the temperature of the central drug solution drops to 40°C.

[0052] Comparative Example 5 (with positive pressure control, without nitrogen countercurrent replacement) The process is basically the same as in Example 1, except that in step S2, the pressure inside the sterilization cabinet is maintained 0.05 MPa higher than the saturated vapor pressure corresponding to the temperature of the liquid medicine, but nitrogen is not introduced for replacement (the cabinet is in an air atmosphere and no inert gas protection is provided), and cooling water at a temperature of 10°C is sprayed until the temperature of the central liquid medicine drops to 40°C.

[0053] Comparative Example 6 (Positive pressure value out of range) The procedure is basically the same as in Example 1, except that in step S2, the pressure inside the sterilizer is maintained at 0.15 MPa higher than the saturated vapor pressure corresponding to the temperature of the liquid medicine (exceeding the range of 0.03 to 0.08 MPa as defined in claim 1). All other conditions are the same as in Example 1.

[0054] Comparative Example 7 (positive pressure value below the range: 0.02MPa) The method is basically the same as in Example 1, except that in step S2, the pressure inside the sterilizer is maintained at 0.02 MPa higher than the saturated vapor pressure corresponding to the temperature of the liquid medicine (0.03 to 0.08 MPa lower than the range of claims).

[0055] Comparative Example 8 (Spraying and nitrogen flow in the same direction, no backflow) The process is basically the same as in Example 1, except that in step S2, nitrogen gas is introduced from the bottom of the sterilizer (in the same direction as the cooling water spray, flowing in the same direction), instead of being introduced from the top and discharged from the bottom.

[0056] Comparative Example 9 (without S4 micro-negative pressure nitrogen purging step) The process is basically the same as in Example 1, except that after step S3, nitrogen is directly introduced into the sterilizer to restore normal pressure before the sterilizer is removed. The S4 micro-negative pressure nitrogen filling operation is not performed. All other conditions are the same as in Example 1.

[0057] Comparative Example 10 (Conventional Natural Cooling Process) After sterilization, instead of performing the step-by-step cooling operations S1 to S4, the sterilizer was allowed to cool naturally to room temperature. The temperature of the central solution was monitored and found to have naturally decreased from 121°C to 60°C in 45 minutes, with a total time of 65 minutes to reach 40°C. Before removing the product from the sterilizer, routine nitrogen purging was performed (oxygen concentration in the sterilizer <2%), and all other conditions were the same as in Example 1.

[0058] Comparative Example 11 (Conventional nitrogen purging sterilization cooling based on CN104548153A) The process was carried out according to Example 1 of CN104548153A: nitrogen purging was performed for 15 minutes before sterilization (nitrogen pressure 0.8 MPa), sterilization was performed at 121°C for 12 minutes, and after sterilization, nitrogen purging was performed to cool to 55°C, and then the mixture was allowed to cool naturally to room temperature before being removed from the sterilizer. The cooling process did not involve degassing cooling media, countercurrent nitrogen purging, positive pressure control based on saturated vapor pressure, or micro-negative pressure nitrogen purging.

[0059] The test results are shown in Table 1(a) and Table 1(b): Table 1(a) Relevant test results of Examples 1-5 and Comparative Examples 1-11

[0060] Table 1(b) Relevant test results of Examples 1-5 and Comparative Examples 1-11

[0061] 1. Experiment Summary: (1) Dissolved oxygen control effect In Examples 1-5, the initial dissolved oxygen after sterilization was 0.8-1.0 mg / L, which decreased to 0.95-1.45 mg / L after 6 months of accelerated sterilization. In Comparative Examples 1-9, the initial dissolved oxygen after sterilization was 1.4-2.0 mg / L, which decreased to 1.91-2.91 mg / L after 6 months of accelerated sterilization. In Comparative Example 10, the initial dissolved oxygen was as high as 3.6 mg / L after sterilization, which reached 4.86 mg / L after 6 months of accelerated sterilization. In Comparative Example 11, the initial dissolved oxygen was 2.5 mg / L after sterilization, which decreased to 3.55 mg / L after 6 months of accelerated sterilization.

[0062] Compared with Comparative Examples 1-9, the initial dissolved oxygen level after sterilization decreased by 0.4-1.2 mg / L, and the decrease after 6 months of accelerated sterilization decreased by 0.46-1.96 mg / L. Compared with Comparative Example 10 (natural cooling), the initial dissolved oxygen level after sterilization decreased by 2.6-2.8 mg / L (a decrease of 72.2%-77.8%), and the dissolved oxygen level after 6 months of accelerated sterilization decreased by 3.41-3.91 mg / L, a decrease of 70.2%-80.5%. Compared with Comparative Example 11 (CN104548153A), the initial dissolved oxygen level after sterilization decreased by 1.5-1.7 mg / L (a decrease of 60.0%-68.0%), and the decrease after 6 months of accelerated sterilization decreased by 2.10-2.60 mg / L (a decrease of 59.2%-73.2%). This indicates that the triple mechanism of "deaerated water pre-deoxygenation - positive pressure countercurrent oxygen inhibition - slight negative pressure final replacement" constructed in this invention not only reduces the initial oxygen content, but also effectively blocks the oxygen re-dissolution path during storage.

[0063] (2) Amino acid stability Due to effective control of dissolved oxygen, oxygen-sensitive tryptophan and cysteine ​​exhibited excellent stability after accelerated testing. The tryptophan retention rates in Examples 1-5 were 97.2%-98.9%, and the cysteine ​​retention rates were 95.9%-98.0%. In Comparative Example 10, the tryptophan and cysteine ​​retention rates were only 88.8% and 86.1%, respectively, the lowest among all experimental groups. Comparative Example 11 showed retention rates of 91.4% and 88.0%, respectively. Compared to Comparative Example 10, the examples showed an increase of 8.4-10.1% in tryptophan retention and 9.8-11.9% in cysteine ​​retention.

[0064] (3) Solution appearance quality The reduction in dissolved oxygen directly led to an improvement in the overall quality of the formulation. Examples 1-5 had a transmittance ≥95.9% and solution colors Y1-Y2. Comparative Example 10 had a transmittance of 92.4% and a solution color Y6; Comparative Example 11 had a transmittance of 94.1% and a solution color Y5. Example 1 had only 25 insoluble particles per container, while Comparative Example 10 had as many as 99 particles per container. This demonstrates that controlling dissolved oxygen is a core means of preventing oxidation discoloration, degradation product formation, and the generation of insoluble particles at the source.

[0065] (4) Influence of key process parameters ① Online degassing treatment: Compared with Example 1, the initial dissolved oxygen in Comparative Example 1 increased by 0.7 mg / L.

[0066] ② Gradient cooling: Compared with Example 1, Comparative Example 2 showed an initial increase of 0.6 mg / L in dissolved oxygen and an increase of 39 insoluble particles per container.

[0067] ③ Positive pressure control: Compared with Example 1, the initial dissolved oxygen in Comparative Example 4 increased by 0.8 mg / L; in Comparative Example 7, it increased by 0.9 mg / L; and in Comparative Example 6, it increased by 0.6 mg / L. This indicates that a positive pressure range of 0.03~0.08 MPa is optimal.

[0068] ④ Nitrogen countercurrent displacement: Compared with Example 1, the initial dissolved oxygen in Comparative Example 5 increased by 1.2 mg / L; compared with Example 1, the initial dissolved oxygen in Comparative Example 8 increased by 0.6 mg / L.

[0069] ⑤ Slight negative pressure nitrogen filling: Compared with Example 1, Comparative Example 9 initially showed an increase of 1.1 mg / L in dissolved oxygen, which increased by 1.58 mg / L after 6 months of accelerated nitrogen filling.

[0070] In summary, the four-stage terminal cooling method of this invention—S1 pre-deoxygenation and slow cooling, S2 positive pressure controlled-speed cooling, S3 final temperature equilibrium cooling, and S4 micro-negative pressure nitrogen purging—through the synergistic effect of online degassing cooling medium, gradient cooling, positive pressure compensation, nitrogen countercurrent washing, and micro-negative pressure deep replacement, can stably control the dissolved oxygen of the compound amino acid injection after sterilization to below 1.0 mg / L. Even after 6 months of accelerated testing, it remains ≤1.5 mg / L, significantly superior to existing technologies, and the long-term stability of the product is significantly improved.

[0071] The above embodiments are merely illustrative of the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the preferred embodiments above, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of the present invention should not depart from the spirit and scope of the present invention. Those skilled in the art can also make other changes within the spirit of the present invention and use them in the design of the present invention, as long as they do not deviate from the technical effects of the present invention. These changes made according to the spirit of the present invention should all be included within the scope of protection claimed by the present invention.

Claims

1. A terminal cooling method for reducing dissolved oxygen in compound amino acid injection solutions, applicable to infusion bags that have been filled, sealed, and terminally sterilized, characterized in that... Includes the following steps: S1. Pre-deoxygenation and slow cooling stage: After sterilization, start the spray system. The cooling medium, which has been degassed online, is sprayed from the bottom of the sterilizer upwards to reduce the temperature of the medicine in the center of the infusion bag to 65℃~70℃. S2, Positive Pressure Controlled Cooling Stage: Switch to a cooling medium with a temperature ≤12℃ for spraying, and simultaneously turn on nitrogen to be introduced into the top of the sterilizer and discharged from the bottom for replacement, maintaining counter-current contact with the cooling medium; and maintain the pressure inside the sterilizer 0.03MPa~0.08MPa higher than the saturated vapor pressure corresponding to the temperature of the liquid medicine, so that the temperature of the central liquid medicine drops to 38℃~42℃; S3, Final Temperature Equilibrium Cooling Stage: Stop spraying and allow the infusion bag to naturally cool down to 25℃~30℃; S4. Micro-negative pressure nitrogen filling stage: The pressure inside the sterilizer is instantly reduced to a micro-negative pressure, and then high-purity nitrogen is quickly filled in to restore normal pressure before the sterilizer is removed.

2. The terminal cooling method for reducing dissolved oxygen in compound amino acid injection according to claim 1, characterized in that, In step S1, the cooling medium is cooling water, the temperature of the cooling water is 20℃~30℃, and the cooling water is subjected to online degassing treatment with a dissolved oxygen content ≤2mg / L.

3. The terminal cooling method for reducing dissolved oxygen in compound amino acid injection according to claim 1, characterized in that, In step S1, the temperature of the cooling medium in the spraying system dynamically changes according to a preset gradient within the range of 20℃~30℃: in the initial stage, the cooling medium at 28℃~30℃ is used for spraying; in the second stage, the temperature of the cooling medium is gradually reduced to 25℃~28℃; in the final stage, the cooling medium at 20℃~25℃ is sprayed until the temperature of the medicine in the center of the infusion bag drops to 65℃~70℃.

4. The terminal cooling method for reducing dissolved oxygen in compound amino acid injection according to claim 1, characterized in that, In step S1, the spraying time in the initial stage is 3-4 minutes; the spraying time in the second stage is 3-4 minutes; and the spraying time in the third stage is 2-4 minutes.

5. The terminal cooling method for reducing dissolved oxygen in compound amino acid injection according to claim 1, characterized in that, In step S2, the temperature of the cooling medium is 8℃~10℃; the cooling time t≤15min.

6. The terminal cooling method for reducing dissolved oxygen in compound amino acid injection according to claim 1, characterized in that, The sterilizer is a water bath sterilizer, and steps S1 to S4 are all performed under conditions where the oxygen concentration inside the sterilizer is less than 2%.

7. The terminal cooling method for reducing dissolved oxygen in compound amino acid injection according to claim 1, characterized in that, The slight negative pressure in step S4 is -0.01MPa to -0.02MPa, and the holding time is 15 to 30 seconds.

8. The terminal cooling method for reducing dissolved oxygen in compound amino acid injection according to claim 7, characterized in that, Step S4 also includes a cycle of performing a slight negative pressure followed by nitrogen filling to restore normal pressure, with the cycle number being 1 to 3 times.

9. A compound amino acid injection, characterized in that, Prepared by the terminal cooling method according to any one of claims 1 to 8, wherein the dissolved oxygen content of the compound amino acid injection after sterilization is ≤1.0 mg / L, and the compound amino acid injection retains ≥96% of tryptophan, ≥95% of cysteine, ≤0.3 of pH value, ≥95% of light transmittance, and ≥85% of sodium bisulfite content after 6 months of accelerated testing at 40°C.

10. The application of a terminal cooling method for reducing dissolved oxygen in compound amino acid injection solutions in soft-bag amino acid products, characterized in that, The soft-bag amino acid product is a compound amino acid injection containing cysteine ​​or its analogues, tryptophan, and sodium bisulfite.

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