Method for detecting content of carbomer in eye drops

Abstract

The invention belongs to the technical field of pharmaceutical analysis, and particularly relates to a method for detecting the content of carbomer in eye drops. The method comprises the following steps: by adopting a two-time washing and centrifugal separation mode, controlling the washing and centrifugal times, centrifugal conditions and washing volume, separating carbomer and brinzolamide from other auxiliary materials in the brinzolamide eye drops, obtaining the weights of carbomer and brinzolamide by adopting a drying and weighing mode, subtracting the weight of brinzolamide, and calculating the content of the auxiliary materials in the brinzolamide eye drops. And calculating to obtain the carbomer content in the sample. The method is suitable for detecting the carbomer content in the carbomer-containing brinzolamide eye drops, and is simple and convenient to operate, efficient, accurate and low in cost.

Description

Technical Field

[0001] The present invention belongs to the technical field of pharmaceutical analysis, and particularly relates to a method for detecting the content of carbomer in eye drops. Background Art

[0002] Brinzolamide is a new type of local heterocyclic sulfonamide carbonic anhydrase inhibitor, which has a strong affinity and inhibitory effect on carbonic anhydrase isozyme II (CAII) in human ciliary body. It can selectively, highly affinity and significantly inhibit the activity of carbonic anhydrase isozyme II, effectively reduce intraocular pressure, and has the advantages of high efficiency, low toxicity and small side effects. Its physiological pH value and suspension design make it favored by patients for its strong ocular comfort. Brinzolamide is often in the form of eye drops and is a good drug for treating ocular hypertension and relieving the elevated intraocular pressure of patients with open-angle glaucoma clinically.

[0003] In existing commercially available or in-research drugs, brinzolamide eye drops mainly consist of brinzolamide, mannitol, carbomer, tyloxapol, disodium edetate, benzalkonium chloride, sodium chloride, pH regulator and water. Carbomer is an ionic polymer, which is a copolymer of acrylic acid cross-linked polymer and polyalkyl sucrose or polyalkyl pentaerythritol. It has the advantages of stable properties, no irritation, no allergic reaction, etc. It has excellent gel properties after neutralization itself, so it is widely used as a pharmaceutical excipient. Common carbomers include types 934, 940, 941, 974P, 980, etc. Different viscosities affect their properties and application ranges. Carbomer 934 is a polyacrylic acid resin, which is stable at high viscosity and is often used in preparations such as emulsions and suspensions; Carbomer 940 has the characteristics of good variability, high viscosity, resistance to ion invasion and low temperature, and is suitable for emulsions and gels; Carbomer 941 has low viscosity, high clarity and good corrosion resistance, and is often used in gels and emulsions; Carbomer 974P can provide good adhesion and moisturizing effects and is often used in ophthalmic preparations; Carbomer 980 has high transparency and thickening properties and is often used in transparent or semi-transparent gels. However, carbomer belongs to high molecular compounds and can form a gel-like substance to cover the corneal surface, playing a role in protection and lubrication. However, excessive use will cause the cornea to be in a closed state for a long time, affecting normal metabolic functions, thus causing corneal epithelial damage and conjunctival congestion. Therefore, it is necessary to monitor the actual content and its changes of carbomer in brinzolamide eye drops during formulation development or drug storage.

[0004] With the development of analytical techniques, although carbomer is increasingly widely used in drug research, the currently reported methods for determining the content of carbomer are only the salting-out method and the high-performance liquid chromatography-evaporative light scattering method. The salting-out method requires the addition of a certain amount of alkali solution to make the carboxylic acid groups of carbomer in the gel exist in an ionic state, and then an excessive amount of metal salt solution is added to make the metal salt fully combine with the carboxylic acid groups in carbomer to form a complex. After removing the complex, the unbound metal salt is titrated with a complexometric titrant to calculate the content of carbomer in the sample. This method is cumbersome and time-consuming; compared with the salting-out method, the high-performance liquid chromatography-evaporative light scattering method is simpler in operation, but the detection equipment is expensive and the cost is high.

[0005] Therefore, in order to ensure that the carbomer content in brinzolamide eye drops is within a reasonable limit, a low-cost and simple and rapid method for detecting the carbomer content can be established. Summary of the Invention

[0006] In order to solve the above problems, the purpose of the present invention is to provide a method for detecting the carbomer content that is simple and convenient to operate, time-consuming short, and low-cost, mainly providing a quantitative detection method for carbomer in brinzolamide eye drops.

[0007] To achieve the above purpose, the present invention adopts the following technical solutions:

[0008] A method for detecting the carbomer content in eye drops, comprising the following steps:

[0009] (a) Quantitatively take the eye drops, adopt the method of washing with water twice and centrifuging, and discard the upper aqueous solution;

[0010] (b) Take the lower layer mixture and dry it to constant weight, and calculate according to the following formula:

[0011] Carbomer content (mg) = W1 - C 布 V0;

[0012] In the formula, W1 is the weight of the dried mixture (mg), C 布 is the concentration of the suspended drug in the eye drops (mg / ml), and V0 is the volume of the eye drops (ml); the eye drops are brinzolamide eye drops, and the brinzolamide eye drops are mainly composed of brinzolamide, carbomer, benzalkonium chloride, tyloxapol, disodium edetate, mannitol, and sodium chloride.

[0013] Furthermore, the purpose of adopting the method of washing with water twice and centrifuging in step (a) is to separate other soluble excipients in the eye drops from brinzolamide and carbomer. Among them, the ratio of the volume of the eye drops, the volume of water added in the first water wash, and the volume of water added in the second water wash is 1:9:2 - 1:9:8, preferably 1:9:2.

[0014] In some embodiments, the volumes of the eye drops, the water added for the first water wash, and the water added for the second water wash are 5 ml, 45 ml, and 10 ml, respectively.

[0015] Further, in the two - water - wash centrifugation method in step (a), the centrifugation speed is 10000 rpm to 16000 rpm, and the time is 10 min to 20 min; preferably, the centrifugation speed is 13000 rpm and the time is 15 min.

[0016] Further, the drying condition in step (b) is vacuum drying at 40°C to 80°C, preferably vacuum drying at 60°C.

[0017] Further, drying to constant weight in step (b) means that the difference in weight between two consecutive weighings does not exceed 0.1 mg.

[0018] In some embodiments, a method for detecting the content of carbomer in an eye drop includes the following steps: Mix 1 part of brinzolamide eye drops with 9 parts of water, centrifuge at 10000 rpm to 16000 rpm for 10 min to 20 min, discard the upper aqueous solution, take the lower mixture and mix it with 2 - 8 parts of water, centrifuge at 10000 rpm to 16000 rpm for 10 min to 20 min, discard the upper aqueous solution, take the lower mixture and perform vacuum drying at 60°C until constant weight, and calculate according to the following formula:

[0019] Carbomer content (mg)=W1 - C 布 V0;

[0020] In the formula, W1 is the weight of the dried mixture (mg), C 布 is the concentration of the suspended drug in the eye drops (mg / ml), and V0 is the volume of the eye drops (ml); the eye drops are brinzolamide eye drops, and the brinzolamide eye drops mainly consist of brinzolamide, carbomer, benzalkonium chloride, tyloxapol, disodium edetate, mannitol, and sodium chloride.

[0021] In some embodiments, a method for detecting the content of carbomer in an eye drop specifically includes the following steps: Mix 5 ml of brinzolamide eye drops with 45 ml of water, centrifuge at 13000 rpm for 15 min, discard the upper aqueous solution, take the lower mixture and mix it with 10 ml of water, centrifuge at 13000 rpm for 15 min, discard the upper aqueous solution, take the lower mixture and perform vacuum drying at 60°C until constant weight, and calculate according to the following formula:

[0022] Carbomer content (mg)=W1 - C 布 V0;

[0023] In the formula, W1 is the weight of the dried mixture (mg), C布 is the concentration of the suspended drug in the eye drops (mg / ml), and V0 is the volume of the eye drops (ml); the eye drops are brinzolamide eye drops, and the brinzolamide eye drops are mainly composed of brinzolamide, carbomer, benzalkonium chloride, tyloxapol, disodium edetate, mannitol, and sodium chloride.

[0024] The beneficial effects achieved by the present invention are:

[0025] (1) Carbomer and brinzolamide are separated from other excipients in brinzolamide eye drops by washing with water twice and centrifuging, and the weights of carbomer and brinzolamide are obtained by dry weighing, and the weight of carbomer is obtained by subtracting the weight of brinzolamide. Compared with the existing detection method, the detection cost of the method of the present invention is lower and the operation is faster and more convenient;

[0026] (2) By controlling the number of water washing centrifugation, centrifugation conditions and water washing volume, the content and range of carbomer in brinzolamide eye drops can be accurately determined (the recovery rate should be 80.0% to 120.0%), which can be effectively used to monitor the actual content and changes of carbomer in brinzolamide eye drops during formulation development or drug storage to ensure that the content of carbomer in brinzolamide eye drops is within a reasonable limit. DETAILED DESCRIPTION

[0027] The present invention is further described in detail in conjunction with the following specific examples, and the protection content of the present invention is not limited to the following examples. Without departing from the spirit and scope of the inventive concept, changes and advantages that can be thought of by those skilled in the art are included in the present invention, and the attached claims are the scope of protection. The process, conditions, reagents, experimental methods, etc. for implementing the present invention, except for the contents specifically mentioned below, are all common knowledge and common common sense in the art, and the present invention does not particularly limit the content.

[0028] The term "API" refers to the active pharmaceutical ingredient, which in the following examples of the present invention is brinzolamide.

[0029] In the present invention, the term "including" is an open expression, that is, including the contents specified in the present invention, but does not exclude other aspects. The term "part" is used to indicate the amount of a substance or component, which can be mass, volume or other appropriate units. "Part" is used as a relative unit to indicate the proportional relationship between the components.

[0030] In the present invention, "h" means hour; "min" means minute; "s" means second; "g" means gram; "ml" and "mL" both mean milliliter; and "rpm" means revolutions per minute.

[0031] In the present invention, the recovery rate (%) = (measured value / theoretical value) × 100%. Among them, the measured value is the content of the analyte measured by the analysis method, and the theoretical value is the content of the analyte theoretically present in the sample.

[0032] In a specific embodiment of the present invention, the weight of the centrifuge tube and the mixture after drying has been weighed twice continuously with an analytical balance with a precision of one ten-thousandth before weighing, and the weight difference does not exceed 0.1 mg, proving that the mixture is dried to a constant weight.

[0033] The source of brinzolamide eye drops: self-made or commercially purchased.

[0034] Example 1 Investigation of the content detection method of carbomer

[0035] A method for detecting the content of carbomer in eye drops, comprising the following steps:

[0036] (a) Quantitatively take the eye drops, adopt the method of washing with water and centrifuging, and discard the upper aqueous solution;

[0037] (b) Take the lower layer mixture and dry it to a constant weight, and calculate according to the following formula:

[0038] Carbomer content (mg) = W1 - C 布 V0;

[0039] In the formula, W1 is the weight of the mixture after drying (mg), C 布 is the concentration of the suspended drug in the eye drops (mg / ml), and V0 is the volume of the eye drops (ml); the eye drops are brinzolamide eye drops, and the brinzolamide eye drops mainly consist of brinzolamide, carbomer, benzalkonium chloride, tyloxapol, disodium edetate, mannitol, and sodium chloride.

[0040] Combined with Table 1 to define the key parameters of the above detection method (the number of times of washing with water and centrifuging, the volume of water added, centrifugation conditions, drying temperature), the carbomer content in brinzolamide eye drops is shown in Table 2. The results show that under the investigation conditions of the volume of water added, centrifugation speed, centrifugation time, and drying temperature for two washes with water, the measured carbomer weight is 0.0195 g to 0.0225 g, and the recovery rate is 97.01% to 111.94%, meeting the requirements; under the investigation conditions of one wash with water and three washes with water volume, the measured carbomer weight is 0.0135 g to 0.0305 g, and the recovery rate is 67.16% to 151.74%, not meeting the requirements, and the number of washes with water and the volume of washes with water should be controlled.

[0041] Table 1 Investigation method

[0042]

[0043] Table 2 Carbomer detection results under different investigation conditions

[0044]

[0045] Example 2 Detection of Carbomer Content in Carbomer Solution

[0046] Prepare carbomer solution: Weigh 0.207 g of carbomer, add 50 ml of water, and dissolve it thoroughly to obtain carbomer solution.

[0047] Using the above Method 1, the measured weight of carbomer in the carbomer solution was 0.0190 - 0.0210 g, showing no significant difference compared with the theoretical carbomer weight (0.0207 g), and the recovery rates were all within 80.0% - 120%. The specific data are shown in Table 3.

[0048] Table 3 Detection Results of Carbomer Content

[0049]

[0050] Test Example 1 Detection of Carbomer Content in Self - prepared Brinzolamide Eye Drops

[0051] According to the above Method 1, three self - prepared batches of brinzolamide eye drops were detected. The measured weight of carbomer in the brinzolamide eye drops showed basically no difference compared with the theoretical carbomer weight. The specific data are shown in Table 4.

[0052] Table 4 Detection Results of Carbomer Content

[0053]

[0054]

[0055] Test Example 2 Detection of Carbomer Content in Commercially Available Brinzolamide Eye Drops

[0056] Detect commercially available brinzolamide eye drops according to the above Method 1. The specific operation is as follows: Take 5 ml of brinzolamide eye drops, place them in a 50 - ml centrifuge tube, add 45 ml of water, shake for 1 min, centrifuge at 13000 rpm for 15 min, discard the supernatant, take the lower - layer mixture, add 10 ml of water, shake for 1 min, centrifuge at 13000 rpm for 15 min, discard the supernatant, and dry the lower - layer mixture in a vacuum drying oven at 60 °C and 0.1 MPa until constant weight. Operate in parallel for 2 portions, and take the API concentration or specification as the marked specification of the commercially available product.

[0057] The weight of carbomer in the same volume of commercially available brinzolamide eye drops measured by the method of the present invention showed basically no difference compared with the weight of carbomer measured by the salting - out method (refer to CN112461826B or CN115015143A). The specific data are shown in Table 5. It is proved that the method of the present invention can simply and effectively detect the carbomer content in eye drops, and the detection cost is lower.

[0058] Table 5 Detection Results of Carbomer Content

[0059]

[0060]

[0061] In summary, the method provided by the present invention can be accurately used for the determination of carbomer content in brinzolamide eye drops, with simple and convenient operation, short time consumption and low cost.

[0062] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A method for detecting the content of carbomer in eye drops, characterized in that It includes the following steps: (a) Quantitatively take eye drops, and adopt the method of washing with water twice and centrifuging, and discard the upper aqueous solution; (b) Take the lower-layer mixture and dry it to constant weight, and calculate according to the following formula: Content of carbomer (mg) = W1 - C 布 V0; Where W1 is the weight of the mixture after drying (mg), C 布 is the concentration of the suspended drug in the eye drops (mg / ml), and V0 is the volume of the eye drops (ml); the eye drops are brinzolamide eye drops, and the brinzolamide eye drops mainly consist of brinzolamide, carbomer, benzalkonium chloride, tyloxapol, disodium edetate, mannitol, and sodium chloride.

2. The method according to claim 1, characterized in that In step (a), the ratio of the volume of the eye drops, the volume of water added in the first water wash, and the volume of water added in the second water wash is 1:9:2 to 1:9:8, preferably 1:9:

2.

3. The method according to claim 2, wherein The volume of the eye drops, the volume of water added in the first water wash, and the volume of water added in the second water wash are 5 ml, 45 ml, and 10 ml respectively.

4. The method according to any one of claims 1 to 3, characterized in that, In the method of washing with water twice and centrifuging in step (a), the centrifugation speed is 10000 rpm to 16000 rpm, and the time is 10 min to 20 min; preferably, the centrifugation speed is 13000 rpm and the centrifugation time is 15 min.

5. The method according to any one of claims 1-4, characterized in that, The drying condition in step (b) is vacuum drying at 40°C to 80°C, preferably vacuum drying at 60°C.

6. The method according to any one of claims 1-5, characterized in that, In step (b), drying to constant weight means that the weight difference between two consecutive weighings does not exceed 0.1 mg.

7. The method according to any one of claims 1 to 6, characterized in that The method includes the following steps: Mix 1 part of brinzolamide eye drops with 9 parts of water, centrifuge at 10000 rpm to 16000 rpm for 10 min to 20 min, discard the upper aqueous solution, take the lower-layer mixture and mix it with 2 to 8 parts of water, centrifuge at 10000 rpm to 16000 rpm for 10 min to 20 min, discard the upper aqueous solution, take the lower-layer mixture and carry out vacuum drying to constant weight at 60°C, and calculate according to the following formula: Content of carbomer (mg) = W1 - C 布 V0; Where W1 is the weight of the mixture after drying (mg), C 布 is the concentration of the suspended drug in the eye drops (mg / ml), and V0 is the volume of the eye drops (ml); the eye drops are brinzolamide eye drops, and the brinzolamide eye drops mainly consist of brinzolamide, carbomer, benzalkonium chloride, tyloxapol, disodium edetate, mannitol, and sodium chloride.

8. The method according to any one of claims 1-7, characterized in that, The method includes the following steps: Mix 5 ml of brinzolamide eye drops with 45 ml of water, centrifuge at 13000 rpm for 15 min, discard the upper aqueous solution, take the lower-layer mixture and mix it with 10 ml of water, centrifuge at 13000 rpm for 15 min, discard the upper aqueous solution, take the lower-layer mixture and carry out vacuum drying to constant weight at 60°C, and calculate according to the following formula: Content of carbomer (mg) = W1 - C 布 V0; Where W1 is the weight of the mixture after drying (mg), C 布 is the concentration of the suspended drug in the eye drops (mg / ml), and V0 is the volume of the eye drops (ml); the eye drops are brinzolamide eye drops, and the brinzolamide eye drops mainly consist of brinzolamide, carbomer, benzalkonium chloride, tyloxapol, disodium edetate, mannitol, and sodium chloride.

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