Preparation method and application of high-purity low-concentration fluorescein sodium aqueous solution
By employing solvent-free synthesis and low-temperature gradient dissolution methods, combined with antioxidants and dynamic membrane filtration, the problems of impurities and stability in sodium fluorescein aqueous solution have been solved, enabling the preparation of high-purity, low-concentration solutions suitable for ophthalmic diagnosis and industrial production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-20
- Publication Date
- 2026-04-10
AI Technical Summary
Existing sodium fluorescein aqueous solutions suffer from residual impurities and poor stability, affecting safety and solution clarity. Current purification methods are complex and difficult to meet injection-grade requirements.
Fluorescein was synthesized under solvent-free conditions, purified using a diacetylation-saponification-salting process, dissolved in a low-temperature gradient, and with the addition of antioxidants. Impurity content was controlled and stability was improved through dynamic membrane filtration and low-temperature sterilization.
It achieves a total impurity content of ≤0.1%, high solution clarity, improved stability, significantly reduced allergy risk, is suitable for ophthalmic diagnosis, and has a simple process and reduced cost.
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Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of pharmaceutical chemistry, in particular to a preparation method of high-purity low-concentration sodium fluorescein aqueous solution and application thereof. BACKGROUND
[0002] Sodium fluorescein (C 20 H 10 Na2O5) is a fluorescent probe widely used in ophthalmic imaging, cell labeling and biosensing. The existing preparation method focuses on the synthesis of raw materials (such as the condensation reaction of phthalic anhydride and resorcinol), but there is less research on the purity control and stability optimization of finished solution. For example: 1. Impurity problem: impurities such as phthalic anhydride and resorcinol remaining in the traditional process can easily cause allergic reactions and affect the safety of injection solution.
[0003] 2. Solution stability: sodium fluorescein is easily degraded under acidic or high-temperature conditions, resulting in a decrease in fluorescence intensity.
[0004] 3. Process defects: the existing refining methods (such as activated carbon adsorption and acid-base crystallization) are complex to operate and difficult to meet the clarity requirements of injection-grade solution.
[0005] Therefore, there is an urgent need to develop an efficient, low-toxic and high-stability preparation method for 1-6% sodium fluorescein aqueous solution. SUMMARY
[0006] In view of the deficiencies of the prior art, the present application provides a preparation method of high-purity low-concentration sodium fluorescein aqueous solution and application thereof, which solves the problems of impurities and poor stability in the existing sodium fluorescein aqueous solution.
[0007] To achieve the above purpose, the present application is implemented by the following technical scheme: a preparation method of high-purity low-concentration sodium fluorescein aqueous solution and application thereof, including raw material pretreatment, solution configuration and stability optimization: The raw material pretreatment includes: synthesizing fluorescein from phthalic anhydride and resorcinol under solvent-free conditions, then purifying the fluorescein through a double acetylation-saponification-salting process, and controlling the pH to 8.0 to improve the salting efficiency; The solution configuration includes: dissolving high-purity sodium fluorescein (purity ≥ 99.5%) in water for injection, using a low-temperature gradient dissolution method to reduce the risk of thermal degradation, accurately controlling the concentration to 1-6% (w / v), and verifying the solution clarity through ultraviolet-visible spectrophotometry (600 nm absorbance ≤ 0.45); The stability optimization comprises: adding 0.05-0.1% antioxidant, inhibiting oxidative decomposition, prolonging shelf life, adopting dynamic membrane filtration sterilization, avoiding fluorescence quenching caused by high-temperature sterilization, and finally obtaining high-purity low-concentration fluorescein sodium aqueous solution.
[0008] Preferably: The low-temperature gradient dissolution method is: stirring at 2-8 DEG C for 30 minutes; The dynamic membrane is: 0.22 mu m filter membrane; The solvent-free synthesis is: 190-210 DEG C melt reaction. Beneficial effects
[0009] 1. Impurity control: combined with activated carbon adsorption (0.1% dosage, reflux for 30 minutes) and acid-base crystallization (pH 1-2 crystallization, pH 8.5-9.0 redissolution), the total amount of impurities is ≤0.1%.
[0010] 2. Stability improvement: through pH 8.0-9.0 buffer system and low-temperature operation, the solution is stored at 4 DEG C in the dark for 6 months, and the content decrease rate is ≤1.0%.
[0011] 3. Safety enhancement: using injection grade purified water (conductivity ≤1.1 mu S / cm), and meeting the sterility requirements of Chinese Pharmacopoeia. BRIEF DESCRIPTION OF DRAWINGS
[0012] Figure 1 It is a schematic diagram of the corneal fluorescein sodium staining examination procedure of the existing fluorescein sodium test paper on the market. DETAILED DESCRIPTION
[0013] The technical solutions in the embodiments of the present application will be described below in conjunction with the embodiments of the present application and the drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.
[0014] The present application provides a technical solution: a preparation method of high-purity low-concentration fluorescein sodium aqueous solution and its application, comprising raw material pretreatment, solution preparation and stability optimization: The raw material pretreatment comprises: synthesizing fluorescein under solvent-free conditions by using phthalic anhydride and resorcinol, then purifying the fluorescein through diacetylation-saponification-salting process, and controlling pH 8.0 to improve salting efficiency; The solution configuration comprises: dissolving high-purity fluorescein sodium (purity ≥ 99.5%) in water for injection, using a low-temperature gradient dissolution method to reduce the risk of thermal degradation, accurately controlling the concentration to 1-6% (w / v), and verifying the solution clarity by ultraviolet-visible spectrophotometry (600 nm absorbance ≤ 0.45). The stability optimization comprises: adding 0.05-0.1% antioxidant to inhibit oxidative decomposition and prolong shelf life, using dynamic membrane filtration sterilization to avoid fluorescence quenching caused by high-temperature sterilization, and finally obtaining high-purity low-concentration fluorescein sodium aqueous solution. Clinical advantages: Low impurity content (phthalic anhydride residue ≤ 0.01%), significantly reducing the risk of allergy; High solution clarity, suitable for corneal staining, fundus angiography and nanoprobes labeling; Industrial advantages: Simple process, no need for complex post-treatment, suitable for large-scale production; Raw material utilization rate ≥ 95%, cost reduction of 20%-30%.
[0015] Further: The low-temperature gradient dissolution method is: stirring at 2-8°C for 30 minutes; The dynamic membrane is: 0.22 μm filter membrane; The synthesis under solvent-free conditions is: melt reaction at 190-210°C.
[0016] By the skilled in the art, the raw materials in the case are processed, the specific use and operation sequence should be referred to the following working principle, the detailed operation means is the public technical knowledge in the art, the following mainly introduces the working principle and process. Examples
[0017] Preparation of 1% fluorescein sodium aqueous solution: Take 1.0 g of fluorescein sodium, dissolve in 100 mL of pre-cooled (4°C) water for injection, stir for 30 minutes until completely dissolved, add 0.03 g of trehalose, adjust the pH to 8.0, filter out, and determine the content by high performance liquid chromatography (HPLC) to be 99.8%, the ultraviolet absorbance (600 nm) is 0.42, and the visible foreign matter inspection meets the standard of Chinese Pharmacopoeia.
[0018] Stability test: Accelerated test: store at 40°C / 75% RH for 3 months, the solution color has no significant change, the content remains ≥ 99.0%.
[0019] Long-term test: store at 25°C / 60% RH for 12 months, the fluorescence intensity attenuation rate is ≤ 5%.
[0020] Now the diagnosis of the patient uses the sodium fluorescein test paper, in the use process, the test paper will contact the patient's eye, cause the patient to be uncomfortable, and the design uses the sodium fluorescein aqueous solution to directly point the eye, and it will not cause the influence to the patient's eye.
[0021] Corneal fluorescein sodium staining examination procedure: 1. Use physiological saline to wet the test paper; 2. Advise the subject to look upwards, and use the wet sterile sodium fluorescein ophthalmic test paper to be placed on the patient's inferior fornix conjunctiva (do not irritate the cornea); 3. After staining, instruct the patient to blink several times, so that the sodium fluorescein is evenly distributed on the ocular surface; 4. Under cobalt blue light irradiation, keep the Beijing illumination intensity stable, and use a slit lamp microscope to observe the number, distribution and morphology of high fluorescent points on the corneal epithelium, which can also be observed through a yellow filter; 5. It is suggested that the examiner complete the corneal staining division within 5 minutes after the sodium fluorescein staining.
[0022] It should be noted that in this text, relational terms such as first and second are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "contain" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or equipment. Without more limitations. The statement "including a limited element" does not exclude the existence of another identical element in the process, method, article or equipment including the element.
[0023] Although embodiments of the present application have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and alterations can be made thereto without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.
Claims
1. A method for preparing a high-purity, low-concentration sodium fluorescein aqueous solution and its application, characterized in that, This includes raw material pretreatment, solution preparation, and stability optimization. The raw material pretreatment includes: synthesizing fluorescein using phthalic anhydride and resorcinol under solvent-free conditions, and then purifying fluorescein through a diacetylation-saponification-salting process, controlling the pH to 8.0 to improve the salting efficiency; The solution preparation includes: dissolving high-purity sodium fluorescein (purity ≥99.5%) in water for injection, using a low-temperature gradient dissolution method to reduce the risk of thermal degradation, precisely controlling the concentration to 1-6% (w / v), and verifying the clarity of the solution by ultraviolet-visible spectrophotometry (600 nm absorbance ≤0.45); The stability optimization includes: adding 0.05-0.1% antioxidant to inhibit oxidative decomposition and extend shelf life; using dynamic membrane filtration sterilization to avoid fluorescence quenching caused by high-temperature sterilization; and finally obtaining a high-purity, low-concentration sodium fluorescein aqueous solution.
2. The method for preparing a high-purity, low-concentration sodium fluorescein aqueous solution according to claim 1 and its application, characterized in that: The low-temperature gradient dissolution method is as follows: stirring at 2-8℃ for 30 minutes; The dynamic membrane is a 0.22 μm filter membrane; The solvent-free synthesis is carried out by a melt reaction at 190-210℃.