A drying method, a moisture stability control method, and a vacuum drying apparatus for a methotrexate refined product

Abstract

The application belongs to the technical field of medicine. A drying method of methotrexate refined product is provided, comprising the following steps: S1, placing methotrexate refined wet product with the structure of formula I in a cavity of a vacuum drying device, and vacuumizing the cavity; S2, continuously introducing nitrogen gas with relative humidity of 60% to 70% into the cavity through an independent nitrogen gas supplement branch provided at an air inlet duct interface of the cavity; S3, maintaining the vacuum degree in the cavity at-0.07 MPa to-0.09 MPa; S4, controlling the temperature in the cavity at 55 DEG C to 65 DEG C, drying the methotrexate refined wet product under nitrogen protection and constant humidity environment, and ending the drying when the moisture content of the methotrexate is 9.0% to 10.5%. The application can stably control the methotrexate raw material in the target interval of 9.0% to 10.5% on the basis of determining the specific moisture interval corresponding to the stable existence of the methotrexate raw material.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of medicine, in particular to a drying method of methotrexate refined product, a moisture stability control method and a vacuum drying equipment. BACKGROUND

[0002] Methotrexate is chemically named N-[4-[[(2,4-diamino-6-pteridine) methyl] methylamino] benzoyl]-L-glutamic acid. It blocks the conversion of dihydrofolic acid into active tetrahydrofolic acid by competitive binding to dihydrofolate reductase, and tetrahydrofolic acid is an essential coenzyme for purine and thymine synthesis, which ultimately blocks the synthesis of DNA, RNA and protein, and inhibits the activity of rapidly proliferating cells. It is used for combined chemotherapy of acute lymphoblastic leukemia, non-Hodgkin's lymphoma, and solid tumors such as breast cancer, head and neck cancer, lung cancer, and choriocarcinoma. Intrathecal injection can also prevent and treat meningeal leukemia. It is also used for anchoring drugs for rheumatoid arthritis, and can also be used for the treatment of systemic lupus erythematosus, dermatomyositis and other diseases under certain circumstances.

[0003] According to the literature, there are many routes for synthesizing methotrexate.

[0004] Method 1: Post-synthesis pteridine ring method (A' + (B + C)) .

[0005] Method 2: One-pot method This route is a one-pot synthesis of methotrexate. It is equivalent to generating fragment A in situ, and then condensing with B + C fragments.

[0006] Method 3: Post-glutamic acid method Method 4: Condensation method (A + (B + C)) As can be seen from the above, in the existing technical research system, the synthesis process path of methotrexate has formed multi-dimensional exploration results, and the related reports of different reaction systems and purification schemes have gradually covered the basic preparation scene of the drug. However, after a comprehensive analysis of the existing public literature and industry research results, it is found that there is still a lack of systematic stability research on methotrexate with different moisture content (pharmacopoeia standard ≤12%) in the industry, which cannot accurately determine the moisture control threshold of methotrexate bulk drug, and the quality evolution law under different moisture conditions has not been established.

[0007] At the same time, methotrexate itself has the inherent characteristic of unstable chemical structure, and is prone to deterioration reactions such as oxidation and degradation. This characteristic is particularly prominent in the whole life cycle management of solid oral dosage forms: the stability of methotrexate raw material not only directly affects key process parameters such as mixing uniformity and particle forming efficiency in the preparation process, but also indirectly affects the long-term stability of finished dosage forms, causing a series of chain quality risks such as excessive levels of related substances and fluctuations in bioavailability, which ultimately directly affect the safety, therapeutic efficacy and whole life cycle quality control of the drug in clinical use.

[0008] Based on the aforementioned gaps in moisture research, we will establish matching moisture control standards and stability management systems, and develop a method to achieve stable drying that precisely controls the moisture range while meeting pharmacopoeia standards, thus possessing high industrial application value. Summary of the Invention

[0009] The purpose of this invention is to provide a stable moisture range for methotrexate raw materials, along with corresponding drying equipment and methods. This method enables the acquisition of stable methotrexate raw materials, allows for controllable modification of drying equipment and drying methods, and reduces degradation impurities during drying and storage.

[0010] This invention provides a method for drying methotrexate purified products, comprising the following steps: S1. Place the refined wet product of methotrexate with the structure of Formula I into the cavity of a vacuum drying device, and evacuate the cavity. S2. Nitrogen gas with a relative humidity of 60% to 70% is continuously introduced into the cavity through an independent nitrogen gas supply branch located at the air inlet of the cavity. S3. The opening of the air intake passage is adjusted in real time by a pressure feedback type electronic regulating valve installed in the cavity, so that the vacuum degree in the cavity is maintained at -0.07MPa~-0.09MPa. S4. Control the temperature inside the cavity to 55℃~65℃, and dry the refined wet product of methotrexate under nitrogen protection and constant humidity environment until the moisture content of the methotrexate is 9.0%~10.5% and then stop drying. Formula I.

[0011] In some specific embodiments, the moisture content is determined according to the Karl Fischer method.

[0012] In some specific embodiments, in step S2, the relative humidity of the nitrogen entering the cavity is controlled by a micro-vapor atomization component located at the inlet end of the nitrogen supply branch; preferably, the relative humidity of the nitrogen is 65%RH.

[0013] In some specific embodiments, the drying time is 11h to 13h.

[0014] In some specific embodiments, during the drying process, samples are taken every 30 minutes to determine the moisture content using the Karl Fischer method, and the relative humidity of the sampling and moisture measurement environment is controlled below 20%RH.

[0015] In some specific embodiments, the refined wet methotrexate is prepared by the following method: dissolving sodium methotrexate in water, adjusting the pH to 4.0-4.5 with sulfuric acid to precipitate crystals, filtering, and rinsing with acetone to obtain the refined wet methotrexate.

[0016] This invention provides a method for controlling the moisture stability of methotrexate raw material. The method described in any one of the above technical solutions is used to dry the refined wet product of methotrexate so that the moisture content of the dried product falls to 9.0%~10.5%.

[0017] This invention provides a vacuum drying device for implementing the drying method described in any of the above technical solutions, comprising a vacuum oven cavity, a vacuum system connected to the cavity, and a temperature control module, characterized in that: The cavity is provided with an air intake duct interface, and an independent nitrogen supply branch is connected to the air intake duct interface. The nitrogen supply branch is equipped with a micro-vapor atomization component, which is used to regulate the relative humidity of the nitrogen entering the cavity to 60%~70%RH. The cavity is equipped with a pressure sensor, and the nitrogen supply branch is equipped with a pressure feedback electronic regulating valve. The pressure feedback electronic regulating valve is connected to the pressure sensor signal and automatically adjusts the opening of the air intake passage in real time according to the pressure in the cavity, so that the vacuum degree in the cavity is maintained at -0.07MPa to -0.09MPa. The temperature control module is used to control the temperature inside the cavity at 55℃~65℃.

[0018] The present invention provides a methotrexate active pharmaceutical ingredient, wherein the moisture content of the active pharmaceutical ingredient is 9.0% to 10.5%, and the active pharmaceutical ingredient is prepared by the drying method described in any one of the above technical solutions.

[0019] In some specific embodiments, the drug includes the methotrexate active pharmaceutical ingredient as described in the above technical solution, as well as pharmaceutically acceptable excipients.

[0020] Compared with the prior art, the present invention provides a drying method for methotrexate refined products, comprising the following steps: S1, placing the methotrexate refined wet product having the structure of Formula I into the cavity of a vacuum drying device, and evacuating the cavity; S2, continuously introducing nitrogen gas with a relative humidity of 60%~70% into the cavity through an independent nitrogen gas supply branch set at the air inlet of the cavity; S3, adjusting the opening of the air inlet passage in real time through a pressure feedback type electronic regulating valve set in the cavity, so that the vacuum degree in the cavity is maintained at -0.07MPa~-0.09MPa; S4, controlling the temperature in the cavity to 55℃~65℃, and drying the methotrexate refined wet product under nitrogen protection and constant humidity environment until the moisture content of the methotrexate is 9.0%~10.5% and then ending the drying process. Based on the identification of the specific moisture range corresponding to the stable existence of methotrexate raw material, this invention further develops a drying equipment and supporting process conditions specifically for methotrexate refined products, targeting the inherent easy oxidation and degradation characteristics of methotrexate's chemical structure. This achieves a high degree of consistency in moisture content among different batches of raw materials during the production process, and can stably control it within the target range of 9.0% to 10.5%. Attached Figure Description

[0021] Figure 1 The moisture content of materials corresponding to different drying times; Figure 2 Stability data of EP impurity B over 6 months at different moisture levels; Figure 3 Stability data of EP impurity C under different moisture content over 6 months; Figure 4 Changes in the maximum unknown impurities in stability data over 6 months at different moisture levels; Figure 5 For equipment modification drawings; Figure 6 The images show a comparison between samples with a moisture content of 9.0-10.5% and those that have been over-dried; the left image shows a micrograph of the modified dried sample with a moisture content of 9.0-10.5%, while the right image shows a micrograph of the sample with a lower moisture content after direct drying. Detailed Implementation

[0022] This invention provides a drying method for methotrexate refined products, a method for controlling moisture stability, and a vacuum drying device. Those skilled in the art can refer to the content of this document and appropriately modify the process parameters to achieve these results. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and fall within the scope of protection of this invention. The methods and applications of this invention have been described through preferred embodiments. Those skilled in the art can clearly modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit, and scope of this invention to realize and apply the technology of this invention.

[0023] This invention first conducts a systematic study on the moisture stability of methotrexate raw materials. Through multi-gradient control experiments, it is determined that when the moisture content of methotrexate raw materials is controlled within the range of 9.0% to 10.5%, its overall storage and processing stability is significantly better than other moisture ranges. Based on this research, this invention further develops a special drying process suitable for refined methotrexate products, targeting the inherent characteristic of methotrexate's chemical structure that is prone to oxidative degradation.

[0024] The drying process involves targeted modifications to conventional vacuum drying equipment: an independent nitrogen supply branch is added to the air inlet interface of the vacuum oven cavity, and a micro-steam atomization component is configured at the nitrogen inlet end, which can precisely control the relative humidity of the nitrogen entering the oven under a sealed nitrogen protective atmosphere and maintain it stably within the range of 65±5%RH; in conjunction with the pressure feedback type electronic regulating valve set in the oven cavity, the opening of the air inlet passage can be automatically adjusted in real time to keep the vacuum degree inside the oven continuously and stably maintained within the range of -0.07MPa to -0.09MPa.

[0025] This drying method and its modified equipment are simple to operate and highly controllable in terms of parameters. They effectively avoid the defects of traditional direct drying processes, such as uneven moisture distribution in raw materials and crystal fragmentation due to rapid water loss. The process achieves complete synchronization between environmental humidity control and heat supply during drying. This technology significantly reduces the impurity formation rate of methotrexate during the drying process and precisely and stably controls the moisture content of the final product within the pharmacopoeia-specified range of 9.0% to 10.5%. Simultaneously, it fully ensures the intra-batch moisture uniformity and inter-batch consistency of methotrexate raw materials, demonstrating excellent adaptability for large-scale industrial production.

[0026] This invention provides a vacuum drying device for implementing the drying method described in any of the above technical solutions, comprising a vacuum oven cavity, a vacuum system connected to the cavity, and a temperature control module. The cavity is provided with an air intake duct interface, and an independent nitrogen supply branch is connected to the air intake duct interface. The nitrogen supply branch is equipped with a micro-vapor atomization component, which is used to regulate the relative humidity of the nitrogen entering the cavity to 60%~70%RH. The cavity is equipped with a pressure sensor, and the nitrogen supply branch is equipped with a pressure feedback electronic regulating valve. The pressure feedback electronic regulating valve is connected to the pressure sensor signal and automatically adjusts the opening of the air intake passage in real time according to the pressure in the cavity, so that the vacuum degree in the cavity is maintained at -0.07MPa to -0.09MPa. The temperature control module is used to control the temperature inside the cavity at 55℃~65℃.

[0027] The vacuum drying equipment provided by the present invention includes a vacuum oven cavity.

[0028] The vacuum oven cavity is made of corrosion-resistant and easy-to-clean stainless steel. Inside, there is a material tray or rack for placing the refined wet methotrexate, ensuring that the material is heated evenly during the drying process and that nitrogen can flow easily.

[0029] The vacuum system is connected to the cavity and is used to evacuate the cavity during the initial drying process and maintain the required negative pressure environment during the drying process. Preferably, the vacuum system includes a vacuum pump and connecting pipelines. The selected vacuum pump must be capable of rapidly reducing the pressure inside the cavity to below -0.09 MPa and possess stable and continuous operating performance.

[0030] The temperature control module includes a heating element and a temperature sensor. The heating element is arranged around the outer wall of the cavity or built into the cavity interlayer. The temperature sensor monitors the actual temperature inside the cavity in real time and feeds the signal back to the control system to achieve precise temperature control of 55℃~65℃. Preferably, the heating element adopts an electric heating tube or a heat transfer oil circulation heating method to ensure uniform temperature distribution and avoid local overheating that could lead to methotrexate degradation.

[0031] The micro-vapor atomization assembly includes a water storage unit, an atomizer, and a mixing chamber. The water storage unit provides deionized or purified water, the atomizer converts the water into micron-sized water mist, and the mixing chamber thoroughly mixes the water mist with the incoming nitrogen gas, thereby precisely controlling the relative humidity of the nitrogen gas. This assembly can automatically adjust the atomization volume according to a set value to ensure that the relative humidity of the nitrogen gas entering the chamber is stable within the range of 60%~70%RH, preferably 65%RH.

[0032] The pressure feedback electronic regulating valve employs a high-precision proportional-integral-derivative (PID) control algorithm, resulting in fast response and high adjustment accuracy. When the pressure inside the chamber fluctuates due to moisture evaporation or gas leakage, the pressure sensor instantly captures the change and transmits the signal to the controller. The controller then drives the electronic regulating valve to adjust its opening, increasing or decreasing the nitrogen supply, thereby dynamically balancing the pressure inside the chamber and maintaining it within the optimal drying range of -0.07MPa to -0.09MPa.

[0033] This invention provides a method for drying methotrexate purified products, comprising the following steps: S1. Place the refined wet product of methotrexate with the structure of Formula I into the cavity of a vacuum drying device, and evacuate the cavity. S2. Nitrogen gas with a relative humidity of 60% to 70% is continuously introduced into the cavity through an independent nitrogen gas supply branch located at the air inlet of the cavity. S3. The opening of the air intake passage is adjusted in real time by a pressure feedback type electronic regulating valve installed in the cavity, so that the vacuum degree in the cavity is maintained at -0.07MPa~-0.09MPa. S4. Control the temperature inside the cavity to 55℃~65℃, and dry the refined wet product of methotrexate under nitrogen protection and constant humidity environment until the moisture content of the methotrexate is 9.0%~10.5% and then stop drying. Formula I.

[0034] This invention provides a method for drying refined methotrexate products, firstly by preparing refined wet methotrexate.

[0035] In some specific embodiments, the refined wet methotrexate is prepared by the following method: dissolving sodium methotrexate in water, adjusting the pH to 4.0-4.5 with sulfuric acid to precipitate crystals, filtering, and rinsing with acetone to obtain the refined wet methotrexate.

[0036] In some embodiments, the mass-to-volume ratio of methotrexate sodium salt to water is 300g:600mL; the present invention does not limit the use of vacuum filtration and acetone rinsing, whichever is known to those skilled in the art is acceptable.

[0037] The purified wet product of methotrexate with the structure of Formula I is placed in the cavity of a vacuum drying device, and the cavity is evacuated.

[0038] The chamber is evacuated until the pressure inside reaches below -0.09 MPa to remove air and free moisture adhering to the surface of the material, creating a low-oxygen environment for subsequent nitrogen-protected drying.

[0039] Nitrogen gas with a relative humidity of 60% to 70% is continuously introduced into the cavity through an independent nitrogen supply branch located at the air inlet of the cavity.

[0040] Subsequently, the micro-vapor atomization component is activated, and nitrogen is introduced into the independent nitrogen supply branch. After atomization and mixing, the relative humidity of the nitrogen entering the chamber is stabilized at 60%RH~70%RH; specifically, it can be 61%RH, 62%RH, 63%RH, 64%RH, 65%RH, 66%RH, 67%RH, 68%RH, or 69%RH, preferably 65%RH. Nitrogen within this humidity range entering the chamber can effectively suppress excessive water loss of methotrexate crystals during the drying process, leading to lattice collapse or surface hardening, while also preventing excessive humidity from causing low drying efficiency or material agglomeration due to moisture absorption.

[0041] The opening of the air intake passage is adjusted in real time by a pressure feedback electronic regulating valve installed in the cavity, so that the vacuum degree in the cavity is maintained at -0.07MPa to -0.09MPa.

[0042] While introducing nitrogen gas at a constant humidity, a pressure sensor monitors pressure changes within the chamber in real time. When a pressure deviation from the set range is detected, the pressure feedback electronic regulating valve automatically adjusts its opening to precisely control the nitrogen supply, ensuring the vacuum level within the chamber is stably maintained between -0.07 MPa and -0.09 MPa. Specifically, it can be -0.07 MPa, -0.075 MPa, -0.08 MPa, -0.085 MPa, or -0.09 MPa, with -0.08 MPa being preferred. This vacuum range ensures effective evaporation and migration of moisture while preventing violent solvent boiling or material splashing due to excessively low pressure, and also prevents a decrease in drying rate caused by excessively high pressure.

[0043] The temperature inside the cavity is controlled at 55℃~65℃, and the refined wet methotrexate is dried under nitrogen protection and constant humidity environment until the moisture content of the methotrexate is 9.0%~10.5%.

[0044] In a specific embodiment, the temperature control module sets and maintains the cavity temperature at 55°C, 58°C, 60°C, 62°C, or 65°C, preferably 60°C. Within this temperature range, methotrexate exhibits good thermal stability, which is also conducive to the uniform migration of moisture. This negative pressure environment helps lower the boiling point of water, promotes rapid evaporation of moisture at lower temperatures, and reduces residual oxygen, further reducing the risk of oxidative degradation.

[0045] During the drying process, a small amount of sample was taken out through the sampling port every 30 minutes, and the moisture content was determined by Karl Fischer method in an environment where the relative humidity was controlled below 20%RH.

[0046] The drying time is 11h to 13h; specifically, it can be 11h, 11.5h, 12h, 12.5h or 13h, preferably 12h. When the moisture content is detected to drop to within the range of 9.0% to 10.5%, heating is stopped and the nitrogen supply branch is turned off. The vacuum state is maintained until the chamber temperature drops to room temperature before discharging to obtain the refined methotrexate product.

[0047] The relative humidity mentioned in this invention refers to the relative humidity measured at the inlet of the nitrogen supply branch before the nitrogen enters the cavity.

[0048] This invention provides a method for controlling the moisture stability of methotrexate raw material. The method described in any one of the above technical solutions is used to dry the refined wet product of methotrexate so that the moisture content of the dried product falls to 9.0%~10.5%.

[0049] For example, a method for controlling the moisture stability of methotrexate raw material includes: S1) The purified wet product of methotrexate was vacuum dried at 60°C, and samples were taken every 30 minutes to determine the moisture content by Karl Fischer method, so as to obtain a series of methotrexate samples with different moisture contents. For example, based on different sampling moisture determinations, 11 samples with moisture determinations of 7.0-7.5%, 7.5-8.0%, 8.0-8.5%, 8.5-9.0%, 9.0-9.5%, 9.5-10.0%, 10.0-10.5%, 10.5-11.0%, 11.0-11.5%, 11.5-12.0%, and 12.0-13.0% were selected for stability studies, and the moisture range was determined to be 9.0%~10.5%.

[0050] S2) The samples with different moisture contents obtained in S1) were subjected to stability testing at 30℃ and 65%RH. The contents of EP impurity B, EP impurity C and the largest unknown impurity in each sample were measured as the storage time increased. S3) Based on the results of the investigation in S2), the initial moisture range with the lowest impurity growth rate is determined to be 9.0%~10.5%, and the refined wet product of methotrexate is dried using the drying method described in any of the above technical solutions, so that the moisture content of the dried product falls to 9.0%~10.5%.

[0051] The present invention provides a methotrexate active pharmaceutical ingredient, wherein the moisture content of the active pharmaceutical ingredient is 9.0% to 10.5%, and the active pharmaceutical ingredient is prepared by the drying method described in any one of the above technical solutions.

[0052] The present invention has clearly described the above-mentioned drying method, and will not repeat it here.

[0053] The active pharmaceutical ingredient is in dihydrate crystal form, and after being stored at 30°C and 65%RH for 6 months, the content of EP impurity B is not greater than 0.15%, the content of EP impurity C is not greater than 0.15%, and the content of the largest unknown impurity is not greater than 0.05%.

[0054] In some specific embodiments, the drug includes the methotrexate active pharmaceutical ingredient as described in the above technical solution, as well as pharmaceutically acceptable excipients.

[0055] The dosage forms of the formulations corresponding to the active pharmaceutical ingredient (API) described in this invention can be tablets, capsules, granules, sterile powders for injection, or suspensions, etc. These dosage forms all utilize the methotrexate API with a specific moisture content (9.0%~10.5%) and high stability provided by this invention, ensuring the quality stability of the formulation during storage and use, and reducing the risk of reduced efficacy or safety due to API degradation. Those skilled in the art can select appropriate dosage forms for preparation based on clinical needs and formulation process characteristics.

[0056] This invention, based on the aforementioned method and having clearly defined the specific moisture range corresponding to the stable existence of methotrexate raw material, further develops a drying equipment and supporting process conditions specifically for methotrexate refined products, addressing the inherent oxidative degradation characteristics of methotrexate's chemical structure. Although the moisture content of commercially available methotrexate raw materials meets the pharmacopoeia's acceptable standard (≤12%), the moisture distribution range between different samples still significantly affects the product's key quality attributes. The core advantage of this invention lies in filling the research gap in the precise control of moisture content in methotrexate raw materials. Through the specifically developed stabilization drying equipment and process parameter system, a high degree of consistency in moisture content between different batches of raw materials during production is achieved, stably controlling it within the target range of 9.0%~10.5%. Even in extreme conditions of over-drying during the drying process, there will be no negative impact on the final moisture content and core quality attributes of the product, providing significant practical guidance for the large-scale industrial production of methotrexate.

[0057] It should be understood that the expression “one or more of…” individually includes each of the objects described after the expression, as well as various different combinations of two or more of the described objects, unless otherwise understood from the context and usage. The expression “and / or” combined with three or more described objects should be understood to have the same meaning, unless otherwise understood from the context.

[0058] The terms “including,” “having,” or “containing,” including the use of their grammatical synonyms, should generally be understood as open-ended and non-restrictive, for example, not excluding other unstated elements or steps, unless otherwise specifically stated or understood from the context.

[0059] In this application, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural.

[0060] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items.

[0061] It should be understood that the order of the steps or the order in which certain actions are performed is not important as long as the invention remains operational. Furthermore, two or more steps or actions can be performed simultaneously.

[0062] The use of any and all instances or exemplary language such as “e.g.” or “including” in this document is merely intended to better illustrate the invention and is not intended to limit the scope of the invention unless the claims are made. No language in this specification should be construed as indicating that any unclaimed element is essential to the practice of the invention.

[0063] Furthermore, the numerical ranges and parameters used to define the present invention are approximate values, and the relevant values ​​in the specific embodiments have been presented as precisely as possible. However, any value inevitably contains standard deviations due to individual test methods. Therefore, unless explicitly stated otherwise, it should be understood that all ranges, quantities, values, and percentages used in this disclosure are modified with the word "approximately". Here, "approximately" generally means that the actual value is within plus or minus 10%, 5%, 1%, or 0.5% of a specific value or range.

[0064] It should be understood that in the various embodiments of this application, the order of the above processes does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0065] The embodiments and comparative examples of this invention describe some examples, in which the embodiments illustrate certain implementations of the invention. However, this does not mean that the effects of the invention can only be achieved in these examples.

[0066] To further illustrate the present invention, the following describes in detail, with reference to embodiments, a drying method for methotrexate refined products, a method for controlling moisture stability, and a vacuum drying equipment provided by the present invention.

[0067] Preliminary Example (Preparation of Methotrexate Wet Product)

[0068] Add 300.0g of sodium methotrexate to a reaction flask, add 600ml of water and stir to dissolve. Adjust the pH to 4-4.5 with sulfuric acid, filter and wash with acetone to obtain wet methotrexate for later use.

[0069] Example 1 (Study on stability under different moisture conditions)

[0070] Place the above-mentioned wet product in a vacuum oven and dry it at 60℃. Maintain the indoor humidity below 20%RH, take samples every 30 minutes to test the moisture content, and then package the product. The moisture results are as follows: Figure 1 The above, Figure 1Moisture content of the material corresponding to different drying times. Based on the above moisture content, samples with moisture contents of 12.4%, 11.7%, 11.3%, 10.8%, 10.4%, 9.5%, 9.2%, 8.8%, 8.3%, 7.8%, and 7.3% were selected for stability testing (test conditions: 30℃, 65%RH). The data are as follows: 1) Changes in EP impurity B in stability data over 6 months at different moisture levels are shown below. Figure 2 The above, Figure 2 Stability data of EP impurity B over 6 months at different moisture levels.

[0071] For 11 samples with different initial moisture content (no impurity B detected in month 0), the EP impurity B data at three time points (January, February, and June) were analyzed using ANOVA. The core conclusions are as follows:

[0072] The initial moisture content and the long-term growth of impurities show a "U-shaped correlation": both excessively high and low moisture content will significantly accelerate the formation of EP impurity B, and 9.2%~10.5% is the optimal moisture range for controlling impurity B in this product.

[0073] 2) Changes in EP impurity C under different moisture content over 6 months are shown below. Figure 3 The above, Figure 3 The stability data of EP impurity C under different moisture content over 6 months: For 11 samples with different initial moisture content, EP impurity C data at four time points (0 months, 1 month, 2 months, and 6 months) were analyzed using ANOVA. The core conclusions are as follows:

[0074] The growth of impurity C showed significant stratification. After 2 months, the impurity values ​​of the high-moisture group (11.7%–12.4%) and the low-moisture group (7.3%–8.3%) both exceeded 0.12, while the impurity C values ​​of samples in the middle moisture range (9.2%–10.4%) remained at a low level of 0.07–0.08, demonstrating excellent stability. After 6 months of long-term storage, the 7.3% moisture sample had the highest impurity C value at 0.445, while the 9.5% moisture sample had the lowest at only 0.098. The impurity growth rate of samples at both ends, deviating from the optimal range, was much higher than that of samples in the middle range.

[0075] 3) The maximum impurity changes in stability data over 6 months at different moisture levels are as follows: Figure 4 The above, Figure 4 Changes in the maximum unknown impurities in stability data over 6 months at different moisture levels.

[0076] For 11 samples with different initial moisture content, the maximum unknown impurity data at four time points (0, 1, 2, and 6 months) were analyzed using ANOVA. The core conclusions are as follows:

[0077] The growth of the maximum unknown impurities over two months showed significant stratification. Impurity values ​​in both the high-moisture group (11.7%–12.4%) and the low-moisture group (7.3%–8.3%) exceeded 0.03, while the impurity values ​​in the middle moisture range (9.5%–10.4%) remained at a low level of 0.015–0.019, demonstrating excellent stability. In June, the 7.3% moisture sample had the highest impurity value at 0.076, while the 10.4% moisture sample had the lowest at only 0.016. The impurity growth rate in samples deviating from the optimal range at both ends was much higher than in the middle range, indicating a risk of the maximum unknown impurity exceeding the standard limit of 0.05% during long-term storage.

[0078] Methotrexate raw material contains two molecules of water of crystallization. According to the above studies on the stability of methotrexate with different moisture content, the initial moisture content and the long-term growth of impurities show a "U-shaped correlation": excessively high or low moisture content within the pharmacopoeia standard range will accelerate the formation of the largest unknown impurity. 9.0%~10.5% is the optimal moisture range for impurity control of this product.

[0079] Example 2 (Drying Experiment of Modified Equipment)

[0080] Equipment Modification: An independent nitrogen supply branch is added to the air inlet of the vacuum oven cavity. A micro-vapor atomization component is also installed at the nitrogen inlet, allowing for precise control of the relative humidity of the nitrogen entering the oven within a sealed nitrogen protective atmosphere, maintaining it stably within the range of 65±5%RH. Combined with a pressure feedback electronic regulating valve installed in the oven cavity, the opening of the air inlet passage can be automatically adjusted in real time, ensuring that the vacuum level inside the oven is continuously and stably maintained within the range of -0.07MPa to -0.09MPa. (See Modification section) Figure 5 , Figure 5 This is a diagram of the equipment modification.

[0081] The wet methotrexate raw material was placed in the modified oven described above. The oven temperature was adjusted to 55°C, and the steam atomization component was adjusted to precisely control the relative humidity of the nitrogen entering the oven and maintain it stably at 60% RH. The pressure feedback electronic regulating valve in the oven cavity ensures that the vacuum level inside the oven is continuously and stably maintained within the range of -0.07MPa to -0.09MPa. The drying time and corresponding moisture content are shown in the table below:

[0082] Example 3

[0083] The wet methotrexate raw material was placed in the modified oven described above. The oven temperature was adjusted to 55°C, and the steam atomization component was adjusted to precisely control the relative humidity of the nitrogen entering the oven and maintain it stably at 65% RH. The pressure feedback electronic regulating valve in the oven cavity ensures that the vacuum level inside the oven is continuously and stably maintained within the range of -0.07MPa to -0.09MPa. The drying time and corresponding moisture content are shown in the table below:

[0084] Example 4

[0085] The wet methotrexate raw material was placed in the modified oven described above. The oven temperature was adjusted to 55°C, and the steam atomization component was adjusted to precisely control the relative humidity of the nitrogen entering the oven to maintain it stably at 70% RH. The pressure feedback electronic regulating valve in the oven cavity ensures that the vacuum level inside the oven is continuously and stably maintained within the range of -0.07MPa to -0.09MPa. The drying time and corresponding moisture content are shown in the table below:

[0086] Example 5

[0087] The wet methotrexate raw material was placed in the modified oven described above. The oven temperature was adjusted to 60°C, and the steam atomization component was adjusted to precisely control the relative humidity of the nitrogen entering the oven and maintain it stably at 60%RH. The pressure feedback electronic regulating valve in the oven cavity ensures that the vacuum level inside the oven is continuously and stably maintained within the range of -0.07MPa to -0.09MPa. The drying time and corresponding moisture content are shown in the table below:

[0088] Example 6

[0089] The wet methotrexate raw material was placed in the modified oven described above. The oven temperature was adjusted to 60°C, and the steam atomization components were adjusted to precisely control the relative humidity of the nitrogen entering the oven and maintain it stably at 70%RH. The pressure feedback electronic regulating valve in the oven cavity ensures that the vacuum level inside the oven is continuously and stably maintained within the range of -0.07MPa to -0.09MPa. The drying time and corresponding moisture content are shown in the table below:

[0090] Example 7

[0091] The wet methotrexate raw material was placed in the modified oven described above. The oven temperature was adjusted to 65°C, and the steam atomization component was adjusted to precisely control the relative humidity of the nitrogen entering the oven and maintain it stably at 60%RH. The pressure feedback electronic regulating valve in the oven cavity ensures that the vacuum level inside the oven is continuously and stably maintained within the range of -0.07MPa to -0.09MPa. The drying time and corresponding moisture content are shown in the table below:

[0092] Example 8

[0093] The wet methotrexate raw material was placed in the modified oven described above. The oven temperature was adjusted to 65°C, and the steam atomization component was adjusted to precisely control the relative humidity of the nitrogen entering the oven and maintain it stably at 55%RH. The pressure feedback electronic regulating valve in the oven cavity ensures that the vacuum level inside the oven is continuously and stably maintained within the range of -0.07MPa to -0.09MPa. The drying time and corresponding moisture content are shown in the table below:

[0094] Example 9

[0095] The wet methotrexate raw material was placed in the modified oven described above. The oven temperature was adjusted to 70°C, and the steam atomization component was adjusted to precisely control the relative humidity of the nitrogen entering the oven and maintain it stably at 60% RH. The pressure feedback electronic regulating valve in the oven cavity ensures that the vacuum level inside the oven is continuously and stably maintained within the range of -0.07MPa to -0.09MPa. The drying time and corresponding moisture content are shown in the table below:

[0096] Comparative Example 1: Direct Vacuum Drying

[0097] The wet methotrexate raw material was placed in a vacuum oven, and the oven temperature was adjusted to 40℃. The drying time and corresponding moisture content are shown in the table below.

[0098] Comparative Example 2: Direct Vacuum Drying

[0099] The wet methotrexate raw material was placed in a vacuum oven, and the oven temperature was adjusted to 60℃. The drying time and corresponding moisture content are shown in the table below.

[0100] Comparative Example 3: Drying by directly introducing nitrogen gas

[0101] The wet methotrexate raw material was placed in a vacuum oven, the oven temperature was adjusted to 40℃, and nitrogen gas was directly introduced. The vacuum degree inside the oven was continuously and stably maintained within the range of -0.07MPa to -0.09MPa. The drying time and corresponding moisture content are shown in the table below:

[0102] Comparative Example 4: Direct Vacuum Drying

[0103] The wet methotrexate raw material was placed in a vacuum oven, the oven temperature was adjusted to 60℃, and nitrogen gas was directly introduced. The vacuum degree inside the oven was continuously and stably maintained within the range of -0.07MPa to -0.09MPa. The drying time and corresponding moisture content are shown in the table below:

[0104] Comparison micrographs as follows Figure 6 (Comparison of 9.0-10.5% moisture content and over-drying) The left image is a micrograph of the modified dried sample with a moisture content of 9.0-10.5%, while the right image is a micrograph of the sample with a lower moisture content after direct drying. As can be seen from the images, if over-drying is performed without controlling the inlet air humidity, the crystal structure of the product is prone to change, which can also lead to poor product stability.

[0105] By modifying the equipment and precisely controlling the humidity of the incoming gas, the relative humidity of the nitrogen entering the oven is kept stable at 65±5%RH, the vacuum degree inside the oven is kept stable within the range of -0.07MPa to -0.09MPa, and the drying temperature is 60±5℃. This ensures that the moisture content of the dried methotrexate raw material is kept stable in the range of 9.0% to 10.5%, and that it will not be over-dried even if the drying time is extended.

[0106] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for drying a refined methotrexate product, characterized in that, Includes the following steps: S1. Place the refined wet product of methotrexate with the structure of Formula I into the cavity of a vacuum drying device, and evacuate the cavity. S2. Nitrogen gas with a relative humidity of 60% to 70% is continuously introduced into the cavity through an independent nitrogen gas supply branch located at the air inlet of the cavity. S3. The opening of the air intake passage is adjusted in real time by a pressure feedback type electronic regulating valve installed in the cavity, so that the vacuum degree in the cavity is maintained at -0.07MPa~-0.09MPa. S4. Control the temperature inside the cavity to 55℃~65℃, and dry the refined wet product of methotrexate under nitrogen protection and constant humidity environment until the moisture content of the methotrexate is 9.0%~10.5% and then stop drying. Formula I.

2. The drying method according to claim 1, characterized in that, The moisture content was determined according to the Karl Fischer method.

3. The drying method according to claim 1, characterized in that, In step S2, the relative humidity of the nitrogen entering the cavity is controlled by a micro-vapor atomization component located at the inlet end of the nitrogen supply branch; preferably, the relative humidity of the nitrogen is 65%RH.

4. The drying method according to claim 1, characterized in that, The drying time is 11h to 13h.

5. The drying method according to claim 1, characterized in that, During the drying process, samples are taken every 30 minutes to determine the moisture content using the Karl Fischer method, and the relative humidity of the sampling and moisture measurement environment is controlled below 20%RH.

6. The drying method according to claim 1, characterized in that, The refined wet methotrexate is prepared by the following method: dissolving methotrexate sodium salt in water, adjusting the pH to 4.0-4.5 with sulfuric acid to precipitate crystals, filtering, and rinsing with acetone to obtain the refined wet methotrexate.

7. A method for controlling the moisture stability of methotrexate raw material, characterized in that, The refined wet product of methotrexate is dried using the drying method described in any one of claims 1 to 6, so that the moisture content of the dried product falls to 9.0% to 10.5%.

8. A vacuum drying device, comprising a vacuum oven cavity, a vacuum system connected to the cavity, and a temperature control module, characterized in that: The cavity is provided with an air intake duct interface, and an independent nitrogen supply branch is connected to the air intake duct interface. The nitrogen supply branch is equipped with a micro-vapor atomization component, which is used to regulate the relative humidity of the nitrogen entering the cavity to 60%~70%RH. The cavity is equipped with a pressure sensor, and the nitrogen supply branch is equipped with a pressure feedback electronic regulating valve. The pressure feedback electronic regulating valve is connected to the pressure sensor signal and automatically adjusts the opening of the air intake passage in real time according to the pressure in the cavity, so that the vacuum degree in the cavity is maintained at -0.07MPa to -0.09MPa. The temperature control module is used to control the temperature inside the cavity at 55℃~65℃.

9. A methotrexate raw material, characterized in that, The active pharmaceutical ingredient has a moisture content of 9.0% to 10.5%, and is prepared by the drying method according to any one of claims 1 to 6.

10. A pharmaceutical composition, characterized in that, It comprises the methotrexate active pharmaceutical ingredient as described in claim 9 and pharmaceutically acceptable excipients.

Images