An eye wash solution containing phmb and a method of making the same

Abstract

The application discloses an eye lotion containing PHMB and a preparation method thereof, and belongs to the field of eye care preparations. The eye lotion takes PHMB as a bacteriostatic component, is matched with isotonicity regulators, buffers, humectants and EDTA2Na, and simultaneously adds trehalose and allantoin to construct a synergistic stable protection system. The eye lotion is prepared through a process flow of low-temperature light-shielding, preparation of a base liquid first and then addition of PHMB, two-stage sterilization filtration and aseptic filling. The application solves the technical problems that PHMB is easy to degrade in a liquid preparation, has poor stability, and the effective component is easy to attenuate after opening and use. Meanwhile, EDTA2Na and PHMB have a synergistic effect, trehalose and allantoin further stabilize the PHMB structure from a molecular level and inhibit oxidative degradation, so that the product can realize wide-spectrum and high-efficiency bacteriostasis at a low concentration. The obtained eye lotion is mild and non-irritating, clear and stable, and can still maintain stable physicochemical and bacteriostatic properties for a long time after opening, is suitable for industrial production, and can be used for daily eye cleaning, flushing, moisturizing and bacteriostatic care.

Description

Technical Field

[0001] This invention belongs to the field of eye care preparation technology, specifically relating to an eye wash containing PHMB and its preparation method. Background Technology

[0002] Eye wash is a topical liquid preparation used for eye cleaning, rinsing away foreign objects, relieving dryness and irritation, and providing antibacterial care. It is widely used in daily eye care and for relieving minor eye discomfort. With changing eye habits, the demand for eye care is increasing. However, commercially available eye washes generally have several technical defects: antibacterial ingredients are highly irritating and can easily damage the ocular mucosa with long-term use; the formula has poor stability, and problems such as turbidity, layering, and degradation of active ingredients can easily occur during storage; the osmotic pressure and pH value do not match human tears well, easily causing dryness and a foreign body sensation after use; and the production process lacks aseptic control, posing a risk of microbial contamination.

[0003] Polyhexamethylene biguanide hydrochloride (PHMB) is a broad-spectrum, low-toxicity, and low-irritant cationic antibacterial agent. It exhibits highly effective inhibitory effects against Staphylococcus aureus, Escherichia coli, and Candida albicans, and is gentle on the ocular mucosa, making it suitable for long-term use. However, PHMB exhibits poor stability in aqueous solutions and is easily affected by factors such as light, temperature, and ionic strength, leading to degradation, discoloration, or turbidity in formulations. This results in a decrease in antibacterial efficacy and may also generate harmful decomposition products. In particular, after the product is opened, continuous exposure to air, light, and trace metal ions accelerates the breakage and oxidative degradation of PHMB molecular chains, accompanied by a significant decrease in the system's pH, drastically shortening the normal usage cycle. This has been a long-standing technical challenge in the field. Current technologies lack a mild, stable, and scalable process for preparing PHMB-containing eye wash solutions that addresses these issues. The problems of pH decrease and decomposition product formation during long-term storage and use after opening are particularly difficult to resolve, limiting the widespread application of PHMB in eye care preparations. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides an eye wash containing PHMB and its preparation method. The resulting product is clear and transparent, highly effective in inhibiting bacteria, non-irritating to the eyes, and exhibits significantly improved storage stability and post-opening stability, making it suitable for continuous industrial production.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides an eye wash containing PHMB, comprising the following components in parts by weight: PHMB 0.001%–0.03%, isotonic conditioner 0.5%–1.2%, buffer 0.1%–0.5%, humectant 0.1%–1.0%, EDTA 2Na 0.01%–0.1%, trehalose 0.1%–0.3%, allantoin 0.01%–0.05%, the remainder being water for injection.

[0006] In a first aspect, the present invention provides a method for preparing an eye wash containing PHMB, comprising the following steps: (1) Under Class C clean area and Class A local operation conditions, add water for injection to a sterile preparation tank, control the temperature at 20℃~30℃, protect from light, and add isotonic conditioner, buffer, and EDTA in sequence. Add 2Na, trehalose, allantoin, and humectant, and stir until dissolved.

[0007] (2) Adding PHMB solution: Pre-dissolve PHMB in a small amount of water for injection, slowly add it dropwise to the mixing tank, stir at low speed in the dark for 10-30 minutes, and mix evenly.

[0008] (3) pH and osmotic pressure adjustment: The pH is finely adjusted to 6.5-7.8 with a buffer, and the osmotic pressure is controlled at 250-350 mOsmol / kg. The pH and osmotic pressure are highly matched with human physiological tears. People who wear contact lenses can use it directly without causing extra burden to the eyes.

[0009] (4) Sterilization filtration: The filter is pre-filtered through a 0.45 μm microporous membrane and then finely filtered through a 0.22 μm sterilization membrane.

[0010] (5) Aseptic filling: Filling, sealing, light inspection and packaging under aseptic conditions to obtain the finished eye wash solution.

[0011] Furthermore, the water for injection in step (1) is injection-grade purified water that meets the standards of Part IV of the 2025 edition of the Pharmacopoeia of the People's Republic of China. It is prepared by distillation using purified water as raw material and is sterile, pyrogen-free, and free of visible foreign matter.

[0012] Further, in step (1), the isotonic regulator is one or more of sodium chloride, potassium chloride, and mannitol.

[0013] Furthermore, in step (1), the buffer is a combination of disodium hydrogen phosphate and sodium dihydrogen phosphate or a combination of boric acid and borax.

[0014] Further, the moisturizer in step (1) is one or more of sodium hyaluronate, hydroxypropyl methylcellulose, glycerin and poloxamer.

[0015] Furthermore, the PHMB weight percentage is preferably 0.005% to 0.02%.

[0016] Furthermore, the entire preparation process is conducted in the dark, with a stirring speed of 50–150 rpm.

[0017] The beneficial effects of the technical solution provided by this invention are: 1. This invention uses a low concentration of PHMB as the antibacterial active ingredient, which broadly inhibits a variety of common pathogenic bacteria with an antibacterial rate of ≥99.9%. At the same time, it is friendly to the ocular surface and mucous membranes, and shows no irritation in rabbit eye irritation tests, proving that the product is mild and safe and suitable for long-term eye care.

[0018] 2. This invention, through scientific formulation, achieves a synergistic effect between PHMB and EDTA-2Na via a quadruple mechanism of membrane disruption, metal chelation, intracellular inhibition, and anti-biofilm action. This not only enhances the antibacterial effect but also significantly improves the stability of PHMB. Trehalose molecules, with their numerous free hydroxyl groups, can form intermolecular hydrogen bonds with guanidine and amino groups on the PHMB molecular chain, creating a weak protective encapsulation structure around the PHMB molecule. This structure blocks light, oxygen, and trace metal ions from contacting the PHMB molecule, inhibiting photodegradation and oxidative degradation. Allantoin can scavenge free radicals in the system and help stabilize the pH, slowing down pH drift induced by PHMB degradation. Together, these three components constitute a triple protection mechanism of "chelation stabilization - molecular encapsulation - antioxidation," solving the problems of easy degradation of PHMB in aqueous solution, pH decrease during storage, and the formation of decomposition products. After 6 months of accelerated testing and 12 months of long-term testing, the PHMB content remained above 99%.

[0019] 3. Trehalose has excellent moisturizing properties, while allantoin has soothing, anti-inflammatory, and ocular mucosal repairing effects. Together, they achieve stable protection of PHMB molecules and can synergistically enhance the moisturizing, soothing, and repairing effects of the ocular surface, reducing irritation with long-term use, and achieving a multi-functional integration of antibacterial, stabilizing, moisturizing, soothing, and repairing properties. Attached Figure Description

[0020] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0021] Figure 1 Comparison of the cornea and conjunctiva of the left and right eyes of New Zealand rabbit number 101; Figure 2 Comparison of the cornea and conjunctiva of the left and right eyes of New Zealand rabbit number 102; Figure 3 Comparison of the cornea and conjunctiva of the left and right eyes of New Zealand rabbit number 103; Figure 4 Comparison of the cornea and conjunctiva of the left and right eyes of New Zealand rabbit number 104; Figure 5 Comparison of the cornea and conjunctiva of the left and right eyes of New Zealand rabbit number 105; Figure 6Comparison of the cornea and conjunctiva of the left and right eyes of New Zealand rabbit number 201; Figure 7 Comparison of the cornea and conjunctiva of the left and right eyes of New Zealand rabbit number 202; Figure 8 Comparison of the cornea and conjunctiva of the left and right eyes of New Zealand rabbit number 203; Figure 9 Comparison of the cornea and conjunctiva of the left and right eyes of New Zealand rabbit number 204; Figure 10 A comparison of the cornea and conjunctiva of the left and right eyes of a New Zealand rabbit, number 205. Detailed Implementation

[0022] The present invention will be further illustrated below through specific embodiments. It should be noted that the following description is only for explaining the present invention and does not limit its content.

[0023] In this invention, "water for injection" refers to water for injection that conforms to the general rules of the Pharmacopoeia of the People's Republic of China (2025 edition). It is obtained by distillation from purified water, with a bacterial endotoxin content of less than 0.25 EU / ml and microbial limits meeting the requirements for sterility testing.

[0024] The purpose of using water for injection in this invention is that eye wash solutions are sterile preparations that come into direct contact with the ocular surface mucosa, requiring extremely high levels of sterility and endotoxin content. Experiments have shown that using purified water or ordinary clean water introduces trace amounts of endotoxins and microbial metabolites, posing not only safety risks to the eyes but also accelerating the degradation of PHMB and pH decrease during long-term storage. This invention strictly limits the use of water for injection, blocking the source of contamination affecting product stability and safety at the solvent source. This is one of the key factors ensuring long-term pH stability and preventing a significant decrease in PHMB content.

[0025] Example 1 (1) Formula (parts by weight): PHMB 0.01%, sodium chloride 0.85%, disodium hydrogen phosphate 0.15%, sodium dihydrogen phosphate 0.08%, sodium hyaluronate 0.1%, hydroxypropyl methylcellulose 0.2%, EDTA 2Na 0.03%, trehalose 0.15%, allantoin 0.02%, water for injection to 100%; (2) Preparation: Prepared according to the method of the present invention, under Class C clean area and Class A local operation conditions, control the solution temperature at 25℃, avoid light throughout the process, and stir at 80 rpm; adjust the pH to 7.2, the osmotic pressure to 285 mOsmol / kg, and then pre-filter through a 0.45 μm microporous membrane and fine filter through a 0.22 μm sterile membrane, aseptically fill, seal, inspect by light, and package to obtain the finished eye wash solution.

[0026] Example 2 (1) Formula (parts by weight): PHMB 0.008%, sodium chloride 0.8%, boric acid 0.2%, borax 0.05%, glycerin 0.3%, poloxamer 0.1%, EDTA 2Na 0.04%, trehalose 0.2%, allantoin 0.03%, water for injection to 100%; (2) Preparation: Same as in Example 1, except that the solution temperature is controlled at 22 °C, the stirring speed is 100 rpm, the pH is adjusted to 7.6, the osmotic pressure is 290 mOsmol / kg, and the remaining steps are the same as in Example 1.

[0027] Example 3 (1) Formula (parts by weight): PHMB 0.015%, sodium chloride 0.82%, phosphate buffer 0.25%, sodium hyaluronate 0.15%, EDTA 2Na 0.05%, trehalose 0.25%, allantoin 0.04%, water for injection to 100%; (2) Preparation: Same as in Example 1, except that the solution temperature is controlled at 28 °C, the stirring speed is 60 rpm, the pH is adjusted to 7.5, the osmotic pressure is 310 mOsmol / kg, and the remaining steps are the same as in Example 1.

[0028] Comparative Example 1 Same as Example 3, except that the preparation process is not light-protected, while the rest of the formula, preparation steps and parameters are the same as in Example 3.

[0029] Comparative Example 2: Same as Example 3, except that PHMB is added at 75℃~80℃ during the preparation process. All other formulations, preparation steps and parameters are the same as in Example 3.

[0030] Comparative Example 3: Same as Example 3, except that PHMB is added first in the preparation stage (high temperature stage) of the base solution. The rest of the formula, preparation steps and parameters are the same as in Example 3.

[0031] Comparative Example 4: Same as Example 3, except that EDTA-2Na is not added during the preparation process. All other formulations, preparation steps and parameters are the same as in Example 3.

[0032] Comparative Example 5: Same as Example 3, except that the preparation process is not light-protected and no EDTA-2Na is added. The rest of the formula, preparation steps and parameters are the same as in Example 3.

[0033] Performance testing Comparative Example 6: Same as Example 3, except that trehalose and allantoin are not added. All other formulas, preparation steps and parameters are the same as in Example 3.

[0034] The stability of the finished eye wash solutions obtained in Examples 1-3 and Comparative Examples 1-6 was tested. The test methods and results are as follows: 1. Appearance, pH, and osmotic pressure: Conventional testing methods were used. The appearance was visually inspected, the pH was measured using a pH meter, and the osmotic pressure was measured using an osmometer. The eye wash solutions obtained in Examples 1 to 3 were all colorless and clear liquids, without turbidity or precipitation. The pH value was between 6.8 and 7.6, and the osmotic pressure was between 260 and 320 mOsmol / kg, which met the design requirements and matched the physiological environment of human tears.

[0035] 2. The antibacterial performance of the product was evaluated using the antibacterial efficacy test method in Chapter 1121 of the General Section IV of the 2025 edition of the Pharmacopoeia of the People's Republic of China and the quantitative suspension antibacterial test method in WS / T 650-2019. The test strains were Escherichia coli (ATCC 25922), Staphylococcus aureus (ATCC 6538), and Candida albicans (ATCC 10231). The action time was 10 min, and the test was repeated 3 times. The results showed that the product had an antibacterial rate of ≥99.9% against all three strains, meeting the design requirements. Simultaneously, the synergistic effect of PHMB and EDTA-2Na was verified through MIC / MBC testing. Antibacterial performance: The eye wash solutions obtained in Examples 1-3 all had an antibacterial rate of ≥99.9% against Escherichia coli, Staphylococcus aureus, and Candida albicans. The MIC / MBC test results showed that the FICI of PHMB and EDTA-2Na used in combination was 0.375, exhibiting a significant synergistic effect.

[0036] 3. Stability: Using PHMB content as an indicator, accelerated testing (37℃±2℃) for 6 months and long-term testing (25℃±2℃) for 12 months were conducted on Example 3 and Comparative Examples 1-6, and the changes in PHMB content were monitored periodically.

[0037] 4. Stability test after opening: The samples of Example 3 and Comparative Example 6 were opened and placed under natural light at room temperature for 28 days, and the PHMB content and pH value were measured at regular intervals.

[0038] The results of the accelerated test (6 months) and long-term test (12 months) are shown in the table below: Table 1. Results of Stability (Accelerated) Tests Table 2. Results of the long-term stability test The stability (accelerated) test results showed that the PHMB content in Example 3 remained above 99% at all time points, reaching 99.34% after 6 months, indicating that the multi-synergistic stabilizing system of the present invention can effectively inhibit the degradation of PHMB under accelerated conditions. In Comparative Example 1 (without light protection), the PHMB content was 82.40% after 6 months, with a significantly faster degradation rate than in Example 3, indicating that light exposure is one of the main factors accelerating PHMB degradation. In Comparative Example 2 (PHMB added at 75℃~80℃) and Comparative Example 3 (PHMB added to the base solution first), the PHMB contents after 6 months were only 65.23% and 60.28%, respectively, far lower than in Example 3, indicating that the temperature and order of PHMB addition have a significant impact on its stability. The PHMB content in Comparative Example 4 (without EDTA-2Na) and Comparative Example 5 (without EDTA-2Na and not protected from light) was 62.31% and 59.68% respectively after 6 months, both significantly lower than that in Example 3, indicating that EDTA-2Na can effectively slow down the catalytic oxidative degradation of PHMB. The PHMB content in Comparative Example 6 (without trehalose and allantoin) was 78.52% after 6 months, still significantly lower than that in Example 3, indicating that the molecular encapsulation and antioxidant protection of trehalose and allantoin have an important impact. The results show that light, high temperature, improper order of drug addition, lack of EDTA-2Na and lack of trehalose and allantoin can accelerate the degradation of PHMB. The present invention achieves excellent stability through multiple synergistic mechanisms.

[0039] The stability (long-term) test results showed that the PHMB content of Example 3 remained above 99% at all time points, and reached 99.97% after 12 months, indicating that the product was highly stable under long-term storage conditions. The PHMB content of Comparative Example 1 was 81.68% after 12 months, and the degradation trend was consistent with the accelerated test. The PHMB contents of Comparative Examples 2 and 3 were only 63.29% and 60.28% after 12 months, respectively, further confirming that high temperature and improper dosing sequence damaged the stability of PHMB. The PHMB contents of Comparative Examples 4 and 5 were 62.31% and 59.68% after 12 months, respectively, verifying the indispensable synergistic stabilizing effect of EDTA-2Na. The PHMB content of Comparative Example 6 was 73.46% after 12 months, significantly lower than that of Example 3 (99.97%), which fully demonstrates that relying solely on EDTA-2Na chelation and light-shielding processes is insufficient to fully guarantee the stability of PHMB during long-term storage. The combination of trehalose and allantoin as a molecular-level stabilizing protective barrier is one of the key technical features of this invention. The above accelerated and long-term experimental results corroborate each other, systematically verifying the stabilizing effect of the "chelation stabilization-molecular encapsulation-antioxidation" triple synergistic mechanism of the present invention in PHMB eye wash solution.

[0040] Table 3 Results of the 28-day stability test in Kaifeng According to the stability test results after opening, in Example 3, after adding trehalose and allantoin, the relative PHMB content retention rate was not less than 98% after 28 days of opening and storage, the pH fluctuation was ≤0.3, and the physicochemical properties of the system remained stable. In contrast, in Comparative Example 6, without the addition of trehalose and allantoin, PHMB degradation was significant under the same conditions, with only 79.46% remaining after 28 days, and the pH shifted significantly. This fully demonstrates that the combination of trehalose and allantoin can synergistically protect PHMB at the molecular level, significantly inhibiting photodegradation, oxidative degradation, and pH shift after opening, thus solving the long-standing technical problem in the field of PHMB-containing eye wash solutions that are prone to failure and have poor stability after opening.

[0041] 5. Rabbit eye irritation test In each experimental group, the left eye of each animal was treated with this product via eye drops at a dose of 0.05 mL / eye / time, twice daily, with an interval of 5-10 minutes. A self-comparison method was used, with the right eye receiving 0.9% sodium chloride injection as a control group.

[0042] After restraining the rabbits, gently pull back the lower eyelids and use a 1 mL sterile syringe (accurate to 0.01 mL) with the needle removed to instill each group of medication into the conjunctival sac. Gently close the eyelids for about 1 second. Administer this product to the left eye and 0.9% sodium chloride injection to the right eye.

[0043] If no irritation symptoms are observed 72 hours after the last administration, the experiment can be terminated; if irritation symptoms appear in the animal's eyes, the recovery time should be extended by modifying the protocol, and the extended recovery period should not exceed 21 days.

[0044] Observation period: Local irritation reaction at the administration site was observed visually once a day before the first administration on the administration day and on non-administration days.

[0045] Observation time: 24 hours before the first dose, and 1, 2, 4, 24, 48 and 72 hours after the last dose. If any abnormalities occur during the administration period, the observation frequency should be increased appropriately.

[0046] Observation method: The examination tools included a handheld slit-lamp microscope, and fluorescein staining was used (the source, batch number, and expiration date were recorded in the original record and presented in the summary report). The score of the ocular reaction was recorded at each examination (Table 4).

[0047] Table 4. Scoring Standards for Eye Irritation Response According to the standards in Table 4, the irritation response scores of the cornea and conjunctiva of each animal in each group were added together to obtain the total score of the eye irritation response of all test animals in that group. The total score was then divided by the number of animals to obtain the final score of the eye irritation of the test product. The degree of irritation of the test product was then determined according to the standards in Table 5. The relevant experimental contents and results are shown in Tables 6 and 7.

[0048] Figure 1-10 The results of corneal and conjunctival tests in the left and right eyes showed no irritation in the rabbit eye irritation test, indicating that the product is mild and safe, and suitable for long-term eye care.

[0049] Table 5. Evaluation Criteria for Eye Irritation Table 6 Individual data on symptoms observed near rabbit cages in New Zealand Table 7 Individual data from New Zealand rabbit eye examinations Note: 0.9% sodium chloride injection was administered to the right eye, and the test sample was administered to the left eye.

Claims

1. An eye wash containing PHMB, characterized in that, It consists of the following components in parts by weight: PHMB 0.001%–0.03%, isotonic conditioner 0.5%–1.2%, buffer 0.1%–0.5%, humectant 0.1%–1.0%, EDTA 2Na 0.01%–0.1%, trehalose 0.1%–0.3%, allantoin 0.01%–0.05%, the remainder being water for injection.

2. The method for preparing the eye wash solution as described in claim 1, characterized in that, The following steps are adopted: (1) Add isotonicity adjuster, buffer, and EDTA to water for injection in sequence. 2Na, trehalose, allantoin, and humectant, stir until dissolved; (2) Dissolve PHMB in water for injection and add it dropwise to the mixed solution in step (1), and continue to stir until homogeneous; (3) Adjust the pH and osmotic pressure, and filter to obtain eye wash solution.

3. The preparation method according to claim 2, characterized in that, Steps (1), (2), and (3) are all carried out in a light-protected environment with the temperature controlled between 20°C and 30°C.

4. The preparation method according to claim 2, characterized in that, The isotonic regulator in step (1) is one or more of sodium chloride, potassium chloride and mannitol.

5. The preparation method according to claim 2, characterized in that, The buffer in step (1) is a combination of disodium hydrogen phosphate and sodium dihydrogen phosphate or a combination of boric acid and borax.

6. The preparation method according to claim 2, characterized in that, The moisturizer in step (1) is one or more of sodium hyaluronate, hydroxypropyl methylcellulose, glycerin and poloxamer.

7. The preparation method according to claim 2, characterized in that, The stirring time in step (2) is 10 to 30 minutes.

8. The preparation method according to claim 2, characterized in that, The stirring speed in steps (1) and (2) is 50 to 150 rpm.

9. The preparation method according to claim 2, characterized in that, In step (3), the pH is adjusted to 6.8-7.6 and the osmotic pressure is 260-320 mOsmol / kg.

10. The preparation method according to claim 2, characterized in that, The filtration in step (3) is first pre-filtered through a 0.45μm microporous membrane and then finely filtered through a 0.22μm sterilization membrane.

Images