Detection method of compound sodium picosulfate oral solution

Abstract

The invention relates to the technical field of pharmaceutical analysis, in particular to a detection method of a compound sodium picosulfate oral solution, which is used for detecting sodium picosulfate and related substances. The detection method comprises the following steps: carrying out liquid chromatography detection on the compound sodium picosulfate oral solution; the conditions of the liquid chromatography detection are as follows: (1) a chromatographic column is a reverse C18 chromatographic column or an efficiency equivalent column thereof; (2) taking a mixed solution of an ammonium acetate buffer salt solution and methanol as a mobile phase A and acetonitrile as a mobile phase B; wherein the pH value of the ammonium acetate buffer salt solution is 4.9 to 5.2; and (3) gradient elution is adopted. The quality detection method disclosed by the invention can be used for the preparation process of the compound sodium picosulfate oral solution and the quality control of the final product, is good in specificity, good in separation degree, high in sensitivity and good in reproducibility, and has important significance for evaluating the advantages and disadvantages of synthesis and preparation processes, controlling the quality of the final product and detecting a stable sample.

Description

Technical Field

[0001] This application relates to the technical field of pharmaceutical analysis, and particularly to a detection method for compound sodium picosulfate oral solution. Background Art

[0002] Sodium picosulfate is an irritant laxative, which can be metabolized into bis(p-hydroxyphenyl)-pyridyl-2-methane (BHPM) under the action of colonic bacteria, and BHPM can effectively promote intestinal peristalsis. The preparations of sodium picosulfate have various forms, including tablets, drops (oral solution) and granules.

[0003] The composition of sodium picosulfate granules includes sodium picosulfate, magnesium oxide and citric acid. Among them, magnesium oxide and citric acid react with water to form magnesium citrate, and magnesium citrate can effectively inhibit the loss of water with feces excretion, acting as an isosmotic agent for gastrointestinal water to play the role of an osmotic laxative, thus exerting a dual-effect laxative effect with sodium picosulfate. When sodium picosulfate granules are dissolved, a large amount of bubbles will be released and accompanied by heat release, and citric acid and magnesium oxide are unstable in the air, easily absorbing moisture in the air and deliquescing, causing drug deterioration. To solve the above defects, sodium picosulfate oral solution has been developed.

[0004] However, there is currently no detection method for compound sodium picosulfate oral solution to control its quality, so the technical content of this application is specifically proposed. Summary of the Invention

[0005] Based on this, one or more embodiments of this application provide a quality detection method for compound sodium picosulfate oral solution. This quality detection method has good specificity, good resolution, high sensitivity and good reproducibility, and can be used for the quality control of the preparation process and final product of compound sodium picosulfate oral solution.

[0006] The technical solution of this application includes the following content:

[0007] A detection method for compound sodium picosulfate oral solution, which is used to detect sodium picosulfate and related substances;

[0008] The detection method includes performing liquid chromatography detection on the compound sodium picosulfate oral solution;

[0009] The conditions for the liquid chromatography detection include:

[0010] (1) The chromatographic column is a reverse C18 chromatographic column or a column with equivalent efficiency;

[0011] (2) A mixed solution of ammonium acetate buffer solution and methanol is used as mobile phase A, and acetonitrile is used as mobile phase B; wherein, the pH value of the ammonium acetate buffer solution is 4.9 - 5.2;

[0012] (3) Gradient elution is adopted.

[0013] In some embodiments, the pH value of the ammonium acetate buffer salt solution is 5.0 - 5.1.

[0014] In some embodiments, in mobile phase A, the volume percentage of the ammonium acetate buffer salt solution is 90% - 98%, and the volume percentage of methanol is 2% - 10%.

[0015] In some embodiments, the ammonium acetate buffer salt solution contains ammonium acetate with a molar concentration of 25 mmol / L - 100 mmol / L.

[0016] In some embodiments, the preparation steps of the ammonium acetate buffer salt solution include:

[0017] After mixing ammonium acetate and water, glacial acetic acid is added in batches and mixed until the pH value is 4.9 - 5.2 to obtain the ammonium acetate buffer salt solution.

[0018] In some embodiments, the program of the gradient elution includes:

[0019] From 0 min to 8 min, the volume percentage of mobile phase A is maintained at 100%;

[0020] From 8 min to 12 min, the volume percentage of mobile phase A is reduced from 100% to 91% - 95%;

[0021] From 12 min to 20 min, the volume percentage of mobile phase A is maintained at 91% - 95%;

[0022] From 20 min to 30 min, the volume percentage of mobile phase A is reduced from 91% - 95% to 86% - 90%;

[0023] From 30 min to 45 min, the volume percentage of mobile phase A is reduced from 86% - 90% to 78% - 82%;

[0024] From 45 min to 55 min, the volume percentage of mobile phase A is reduced from 78% - 82% to 58% - 62%;

[0025] From 55 min to 58 min, the volume percentage of mobile phase A is reduced from 58% - 62% to 48% - 52%;

[0026] From 58 min to 58.1 min, the volume percentage of mobile phase A is reduced from 48% - 52% to 28% - 32%;

[0027] From 58.1 min to 62 min, maintain the volume percentage of the mobile phase A at 28% - 32%;

[0028] From 62 min to 62.1 min, increase the volume percentage of the mobile phase A from 28% - 32% to 100%;

[0029] From 62.1 min to 75 min, maintain the volume percentage of the mobile phase A at 100%.

[0030] In some embodiments, the conditions for the liquid chromatography detection further include at least one of the following conditions:

[0031] (1) The column temperature is 36°C - 40°C;

[0032] (2) The sample tray temperature is 5°C - 10°C.

[0033] In some embodiments, the conditions for the liquid chromatography detection further include at least one of the following conditions:

[0034] (1) The flow rate is 0.95 mL / min - 1.05 mL / min;

[0035] (2) The injection volume is 95 μL - 105 μL; and,

[0036] (3) The detection wavelength is 260 nm - 265 nm.

[0037] In some embodiments, the length of the chromatographic column is 240 mm - 260 mm, the diameter is 4.4 mm - 4.8 mm, and the particle size of the packing is 4 μm - 6 μm; and / or,

[0038] The model of the chromatographic column includes YMC-Pack ODS-A.

[0039] In some embodiments, the related substances include at least one of 4-hydroxybenzoic acid, impurity A, and impurity B, wherein,

[0040] The structure of the impurity A is

[0041] The structure of the impurity B is

[0042] In the detection method of the compound sodium picosulfate oral solution of the present application, by using a specific mobile phase and performing gradient elution within the pH range of the ammonium acetate buffer solution, sodium picosulfate and related substances in the oral solution can be effectively separated simultaneously, without the need to separately develop two detection conditions, thereby reducing the development cost and greatly shortening the detection time, and improving the detection efficiency. Moreover, this detection method has strong specificity, good resolution, high sensitivity, and good reproducibility, can detect the intermediate products and finished products of the compound sodium picosulfate oral solution, fully meet the requirements of the related substances inspection and decomposition product determination, has strong practicability in actual quality control work, and is of great significance for evaluating the advantages and disadvantages of the synthesis and formulation processes, final product quality control, and stability sample detection.

[0043] In addition, the detection method of the present application can directly sample and determine the compound sodium picosulfate oral solution, without the need for sample pretreatment or dilution, reducing the possibility of impurity introduction, thereby further improving the detection efficiency and effectively determining the impurities in the compound sodium picosulfate oral solution. Description of the Drawings

[0044] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0045] Figure 1 Chromatogram obtained by detecting the blank solution in the specificity investigation of the detection method of the compound sodium picosulfate oral solution in an embodiment of the present application;

[0046] Figure 2 Chromatogram obtained by detecting the blank excipient solution (without sodium picosulfate) in the specificity investigation of the detection method of the compound sodium picosulfate oral solution in an embodiment of the present application;

[0047] Figure 3 Chromatogram obtained by detecting the test solution in the specificity investigation of the detection method of the compound sodium picosulfate oral solution in an embodiment of the present application;

[0048] Figure 4 Chromatogram of the test solution spiked with the analyte in the specificity investigation of the detection method of the compound sodium picosulfate oral solution in an embodiment of the present application;

[0049] Figure 5In the specificity study of the detection method for the compound sodium picosulfate oral solution in an embodiment of the present application, the chromatograms obtained by detecting the test sample solution damaged by high temperature (from top to bottom are the blank solution, the raw material drug solution, the blank excipient, and the test sample solution damaged by high temperature);

[0050] Figure 6 In the specificity study of the detection method for the compound sodium picosulfate oral solution in an embodiment of the present application, the chromatograms obtained by detecting the test sample solution damaged by light (from top to bottom are the blank solution, the raw material drug solution, the blank excipient, and the test sample solution damaged by light);

[0051] Figure 7 In the specificity study of the detection method for the compound sodium picosulfate oral solution in an embodiment of the present application, the chromatograms obtained by detecting the test sample solution damaged by oxidation (from top to bottom are the blank solution, the raw material drug solution, the blank excipient, and the test sample solution damaged by oxidation);

[0052] Figure 8 In the specificity study of the detection method for the compound sodium picosulfate oral solution in an embodiment of the present application, the chromatograms obtained by detecting the test sample solution damaged by acid (from top to bottom are the blank solution, the raw material drug solution, the blank excipient, and the test sample solution damaged by acid);

[0053] Figure 9 In the specificity study of the detection method for the compound sodium picosulfate oral solution in an embodiment of the present application, the chromatograms obtained by detecting the test sample solution damaged by alkali (from top to bottom are the blank solution, the raw material drug solution, the blank excipient, and the test sample solution damaged by alkali);

[0054] Figure 10 The liquid chromatography detection diagrams of the system suitability solution, the reference preparation, and the blank excipient in Comparative Example 1 of the present application (from top to bottom are the system suitability solution, the reference preparation, and the blank excipient);

[0055] Figure 11 The liquid chromatography detection diagrams of the blank excipient, the reference preparation, and the API solution in Comparative Example 2 of the present application (from top to bottom are the blank excipient, the reference preparation, and the raw material drug solution). Detailed implementation manners

[0056] The present application will be further described below in conjunction with the implementation manners and examples. It should be understood that these examples are only used to illustrate the present application and not to limit the scope of the present application. In addition, it should be understood that after reading the content taught in the present application, those skilled in the art can make various changes or modifications to the present application, and these equivalent forms also fall within the protection scope of the appended claims of the present application.

[0057] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. The terms used in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0058] The term

[0059] Unless otherwise stated or in case of contradiction, the terms or phrases used herein have the following meanings:

[0060] As used herein, the alternative of the term "and / or" includes any one of two or more related listed items, as well as any and all combinations of the related listed items. The said any and all combinations include combinations of any two related listed items, any more related listed items, or all related listed items. It should be noted that when at least three items are connected by at least two conjunctions selected from "and / or", "or / and", "and / or", it should be understood that in this application, this technical solution undoubtedly includes the technical solution connected by "logical AND", and also undoubtedly includes the technical solution connected by "logical OR". For example, "A and / or B" includes three parallel solutions: A, B, and A + B.

[0061] In this application, "further" and the like are used for descriptive purposes, indicating differences in content, but should not be construed as limiting the scope of protection of this application.

[0062] In this application, among the technical features described in an open-ended manner, it includes a closed technical solution composed of the listed features, and also includes an open technical solution containing the listed features.

[0063] In this application, regarding numerical intervals (i.e., numerical ranges), unless otherwise specified, the optional numerical values are considered continuous within the above numerical intervals, and include the two numerical endpoints (i.e., the minimum value and the maximum value) of this numerical range, as well as each numerical value between these two numerical endpoints. Unless otherwise specified, when the numerical interval only refers to integers within the numerical interval, it includes the two endpoint integers of this numerical range, as well as each integer between the two endpoints. In addition, when multiple ranges are provided to describe features or characteristics, these ranges can be combined. In other words, unless otherwise specified, the ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein.

[0064] In this application, weight can be mass units well-known in the chemical industry such as μg, mg, g, kg, etc.

[0065] Research findings indicate that sodium picosulfate is itself highly soluble in water, has a high polarity, and exhibits weak retention ability in reverse-phase chromatography. If an acidic mobile phase is used, the more acidic it is, the less it retains. When using a basic mobile phase, the OH in the mobile phase - may react with Mg 2+ to form magnesium hydroxide precipitation, thereby clogging the chromatographic column. Therefore, it is rather difficult to detect sodium picosulfate in compound sodium picosulfate oral solution by reverse-phase chromatography. Meanwhile, the related substances in compound sodium picosulfate oral solution (such as 4-hydroxybenzoic acid) show the opposite retention pattern compared to sodium picosulfate in reverse-phase chromatography, where the more acidic it is, the more it retains, which causes great difficulties in the method development for sodium picosulfate and related substances.

[0066] Moreover, the applicant has found that the compound sodium picosulfate preparation is prone to precipitation in a phosphate mobile phase. For example, when the proportion of acetonitrile exceeds 40%, precipitation occurs, clogging the chromatographic column. It is speculated that the possible reason is the formation of magnesium phosphate precipitation. Additionally, the pKa of ammonium formate buffer is 3.75, and the buffering range is 2.75 - 4.75, resulting in the early elution of sodium picosulfate and making it difficult to separate from other substances in the compound sodium picosulfate preparation, leading to the ineffective separation of sodium picosulfate.

[0067] This application provides a detection method for compound sodium picosulfate oral solution, which is used to detect sodium picosulfate and related substances;

[0068] The detection method includes performing liquid chromatography detection on the compound sodium picosulfate oral solution;

[0069] The conditions for liquid chromatography detection include:

[0070] (1) The chromatographic column is a reverse C18 chromatographic column or a column with equivalent efficiency;

[0071] (2) A mixed solution of ammonium acetate buffer salt solution and methanol is used as mobile phase A, and acetonitrile is used as mobile phase B; among them, the pH value of the ammonium acetate buffer salt solution is 4.9 - 5.2

[0072] (3) Gradient elution is adopted.

[0073] The detection method of the compound sodium picosulfate oral solution according to the embodiments of the present application is used to simultaneously detect one or more related substances that may be contained therein. In this detection method, a mixed solution of an ammonium acetate buffer solution with a pH value of 4.9 - 5.2 and methanol is used as mobile phase A, and acetonitrile is used as mobile phase B for gradient elution. By using the ammonium acetate buffer solution with the above pH value and a suitable organic solvent as the mobile phase, and using a reverse C18 chromatographic column or a column with equivalent efficiency as the chromatographic column, sodium picosulfate and related substances can be effectively separated. Not only is the resolution between sodium picosulfate and its related substances high, avoiding premature elution of sodium picosulfate, but also precipitation reactions between magnesium ions and phosphate ions in the compound sodium picosulfate oral solution are avoided, reducing the phenomenon of precipitation and blockage during elution. In some embodiments, the pH value of the ammonium acetate buffer solution is 5.0 - 5.1, further ensuring the effective separation of sodium picosulfate and related substances and reducing the possibility of chromatographic column blockage.

[0074] In some embodiments, in mobile phase A, the volume ratio of the ammonium acetate buffer solution is 90% - 98%, and the volume ratio of methanol is 2% - 10%.

[0075] Optionally, the volume ratio of the ammonium acetate buffer solution can be selected from 90% - 98%, such as 90%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, etc., and the volume ratio of methanol can be selected from 2% - 10%, such as 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, etc. It can be understood that the sum of the volume ratio of the ammonium acetate buffer solution and the volume ratio of methanol is 100%.

[0076] In some embodiments, the ammonium acetate buffer solution contains ammonium acetate with a molar concentration of 25 mmol / L - 100 mmol / L.

[0077] Optionally, the molar concentration of ammonium acetate can be selected from 25 mmol / L - 100 mmol / L, such as 25 mmol / L, 30 mmol / L, 50 mmol / L, 60 mmol / L, 80 mmol / L, 100 mmol / L, etc.

[0078] In some embodiments, the preparation steps of the ammonium acetate buffer solution include:

[0079] After mixing ammonium acetate and water, glacial acetic acid is added in batches until the pH value is 5.0 - 5.1 to obtain the ammonium acetate buffer solution.

[0080] In some embodiments, the gradient elution program includes:

[0081] From 0 min to 8 min, maintain the volume percentage of mobile phase A at 100%;

[0082] From 8 min to 12 min, the volume percentage of mobile phase A is decreased from 100% to 91% - 95%;

[0083] From 12 min to 20 min, the volume percentage of mobile phase A is maintained at 91% - 95%;

[0084] From 20 min to 30 min, the volume percentage of mobile phase A is decreased from 91% - 95% to 86% - 90%;

[0085] From 30 min to 45 min, the volume percentage of mobile phase A is decreased from 86% - 90% to 78% - 82%;

[0086] From 45 min to 55 min, the volume percentage of mobile phase A is decreased from 78% - 82% to 58% - 62%;

[0087] From 55 min to 58 min, the volume percentage of mobile phase A is decreased from 58% - 62% to 48% - 52%;

[0088] From 58 min to 58.1 min, the volume percentage of mobile phase A is decreased from 48% - 52% to 28% - 32%;

[0089] From 58.1 min to 62 min, the volume percentage of mobile phase A is maintained at 28% - 32%;

[0090] From 62 min to 62.1 min, the volume percentage of mobile phase A is increased from 28% - 32% to 100%;

[0091] From 62.1 min to 75 min, the volume percentage of mobile phase A is maintained at 100%.

[0092] In some embodiments, the composition of the compound sodium picosulfate oral solution comprises water, sodium picosulfate, magnesium oxide, citric acid and amino acid compounds; the amino acid compounds are selected from one or a mixture of two of glycine and alanine.

[0093] In some embodiments, the mass concentration of sodium picosulfate in the compound sodium picosulfate oral solution is 0.01 mg / mL - 0.2 mg / mL.

[0094] Optionally, the mass concentration of sodium picosulfate can be selected from 0.01 mg / mL - 0.1 mg / mL, such as 0.01 mg / mL, 0.03 mg / mL, 0.05 mg / mL, 0.08 mg / mL, 0.1 mg / mL, etc.

[0095] In some embodiments, the column temperature is 36°C - 40°C.

[0096] Optionally, the column temperature can be selected from 36°C to 40°C, such as 36°C, 37°C, 38°C, 39°C, 40°C, etc.

[0097] In some embodiments, the sample tray temperature is 5°C to 10°C.

[0098] Optionally, the sample tray temperature can be selected from 5°C to 10°C, such as 5°C, 6°C, 7°C, 8°C, 9°C, 10°C, etc.

[0099] In some embodiments, the flow rate is 0.95 mL / min to 1.05 mL / min.

[0100] Optionally, the flow rate can be selected from 0.95 mL / min to 1.05 mL / min, such as 0.95 mL / min, 0.96 mL / min, 0.97 mL / min, 0.98 mL / min, 0.99 mL / min, 1 mL / min, 1.01 mL / min, 1.02 mL / min, 1.03 mL / min, 1.04 mL / min, 1.05 mL / min, etc.

[0101] In some embodiments, the injection volume is 95 μL to 105 μL.

[0102] Optionally, the injection volume can be selected from 95 μL to 105 μL, such as 95 μL, 96 μL, 97 μL, 98 μL, 99 μL, 100 μL, 101 μL, 102 μL, 103 μL, 104 μL, 105 μL, etc.

[0103] In some embodiments, the detection wavelength is 260 nm to 265 nm.

[0104] Optionally, the detection wavelength can be selected from 260 nm to 265 nm, such as 260 nm, 261 nm, 262 nm, 263 nm, 264 nm, 265 nm, etc.

[0105] In some embodiments, the length of the chromatographic column is 240 mm to 260 mm, the diameter is 4.4 mm to 4.8 mm, and the particle size of the packing is 4 μm to 6 μm.

[0106] In some embodiments, the model of the chromatographic column includes YMC-Pack ODS-A.

[0107] In some examples, the related substances include at least one of 4-hydroxybenzoic acid, impurity A, and impurity B, where:

[0108] The structure of impurity A is

[0109] The structure of impurity B is

[0110] In some specific embodiments, the detection method of compound sodium picosulfate oral solution comprises the following steps:

[0111] Take the compound sodium picosulfate oral solution to be tested as the test sample and conduct liquid chromatography detection; adopt the conditions of the above-mentioned liquid chromatography detection;

[0112] Take the reference substances of 4-hydroxybenzoic acid, impurity A and impurity B, dissolve them separately with a solvent to prepare each reference substance solution;

[0113] Conduct liquid chromatography detection on each reference substance solution respectively; confirm whether 4-hydroxybenzoic acid, impurity A and impurity B exist in the test sample;

[0114] Furthermore, if at least one of 4-hydroxybenzoic acid, impurity A and impurity B exists in the test sample, determine the content of the corresponding substance.

[0115] In some embodiments, the solvent comprises at least one of water and ethanol.

[0116] In some embodiments, the mass concentration of each reference substance solution is 57.5 μg / mL to 575 μg / mL.

[0117] In the detection method of the compound sodium picosulfate oral solution of the present application, by adopting a specific mobile phase and performing gradient elution within the pH range of the ammonium acetate buffer solution, it is possible to effectively separate sodium picosulfate and related substances in the oral solution simultaneously, without the need to separately develop two detection conditions, thereby reducing the development cost and greatly shortening the detection time, and improving the detection efficiency. Moreover, this detection method has strong specificity, good resolution, high sensitivity and good reproducibility, can detect the intermediate products and finished products of the compound sodium picosulfate oral solution, fully meets the requirements of the related substance inspection and decomposition product determination, has strong practicability in the actual quality control work, and is of great significance for evaluating the advantages and disadvantages of the synthesis and formulation processes, the quality control of the final product and the detection of stability samples.

[0118] In addition, the detection method of the present application can directly sample and determine the compound sodium picosulfate oral solution, without the need for sample pretreatment or dilution, reducing the possibility of impurity introduction, thereby further improving the detection efficiency and effectively determining the impurities in the compound sodium picosulfate oral solution.

[0119] The following are some specific examples.

[0120] I. Instruments and Samples

[0121] 1. Instruments and Reagents:

[0122] Instrument: Waters Arc-2998 series high performance liquid chromatograph;

[0123] Chromatographic column: YMC-Pack ODS-A, 4.6 mm × 250 mm, 5 μm;

[0124] Reagents: Ammonium acetate (analytical reagent grade), glacial acetic acid (analytical reagent grade), acetonitrile (chromatographic grade), methanol (chromatographic grade).

[0125] 2. Reference substances:

[0126] Sodium picosulfate working reference substance: sourced from Kreative Organics, with a content of 96.7%;

[0127] Sodium picosulfate impurity A reference substance: sourced from QCSRM, with a content of 94.30%;

[0128] Sodium picosulfate impurity B reference substance: sourced from QCSRM, with a content of 98.30%;

[0129] 4-Hydroxybenzoic acid reference substance: sourced from the National Institutes for Food and Drug Control, with a content of 100%;

[0130] Sodium picosulfate bulk drug, sourced from Kreative Organics, with a content of 100.2% (water content 3.81%).

[0131] 3. Samples:

[0132] Test sample: Compound sodium picosulfate oral solution, sourced from Shenzhen Beimei Pharmaceutical Co., Ltd., content specification: 175 mL / sodium picosulfate 10 mg;

[0133] Blank excipients (without sodium picosulfate and sodium benzoate): sourced from Shenzhen Beimei Pharmaceutical Co., Ltd., including citric acid, magnesium oxide, disodium edetate, sucralose, sodium metabisulfite, glycine, alanine, acesulfame potassium, sodium hydroxide;

[0134] Reference preparation: Compound sodium picosulfate oral solution, sourced from ASM Aerosol-Service AG, content specification: 160 mL / sodium picosulfate 10 mg.

[0135] II. Solution preparation

[0136] 1. Blank solution: Purified water.

[0137] 2. Diluent: Acetonitrile-water (8:92) (measure appropriate amounts of acetonitrile and water, mix well according to the ratio of 8:92 (V / V) to obtain).

[0138] 3. Sodium picosulfate reference stock solution: Weigh accurately about 23 mg of sodium picosulfate reference substance, place it in a 100 mL volumetric flask, dissolve it by ultrasonic treatment with the diluent and dilute to the mark, shake well, and it is ready.

[0139] 4. 4-Hydroxybenzoic acid reference stock solution: Weigh accurately about 15.5 mg of 4-hydroxybenzoic acid reference substance (calculated as C7H6O3), place it in a 100 mL volumetric flask, dissolve it by ultrasonic treatment with the diluent and dilute to the mark, shake well, and it is ready.

[0140] 5. Reference solution: Pipette accurately 2 mL of the sodium picosulfate reference stock solution into a 100 mL volumetric flask, dilute to the mark with the solvent, and shake well. Then pipette accurately 5 mL of the above solution into a 200 mL volumetric flask, accurately add 2 mL of the 4-hydroxybenzoic acid reference stock solution, dilute to the mark with the diluent, and shake well, and it is ready.

[0141] 6. Sensitivity solution: Pipette accurately 5 mL of the reference solution into a 10 mL volumetric flask, dilute to the mark with the diluent, and shake well, and it is ready.

[0142] 7. Impurity A reference stock solution: Take about 11.5 mg of Impurity A reference substance, weigh accurately, place it in a 20 mL volumetric flask, dissolve it by ultrasonic treatment with water and dilute to the mark, shake well, and it is ready.

[0143] 8. Impurity B reference stock solution: Take about 11.5 mg of Impurity B reference substance, weigh accurately, place it in a 200 mL volumetric flask, add 10 mL of ethanol, dissolve it by ultrasonic treatment, dilute to the mark with water, and shake well, and it is ready.

[0144] 9. Impurity reference stock solution: Pipette accurately 2 mL of the Impurity A reference stock solution and 2 mL of the Impurity B reference stock solution into a 20 mL volumetric flask, dilute to the mark with water, and shake well, and it is ready.

[0145] 10. Spiked test solution: Pipette accurately 2 mL of the impurity reference stock solution and 1 mL of the 4-hydroxybenzoic acid reference stock solution into a 100 mL volumetric flask, dilute to the mark with the test sample, shake well, filter through a PES membrane (0.45 μm, Φ13 mm), discard the first 7 mL of the initial filtrate, and take the subsequent filtrate, and it is ready.

[0146] 11. Test solution: Shake the test sample well, filter through a PES membrane (0.45 μm, Φ13 mm), discard the first 7 mL of the initial filtrate, and take the subsequent filtrate, and it is ready.

[0147] 12. Blank excipient solution: Shake the blank excipient well, filter through a PES membrane (0.45 μm, Φ13 mm), discard the first 7 mL of the initial filtrate, and take the subsequent filtrate, and it is ready.

[0148] 13. System suitability solution: Accurately measure 2 mL of the impurity reference stock solution and 1 mL of the 4-hydroxybenzoic acid reference stock solution, transfer them into a 100 mL volumetric flask, dilute to the mark with mobile phase A (see Example 1), and shake well to obtain.

[0149] III. Determination method and conditions

[0150] A detection method for compound sodium picosulfate oral solution for detecting sodium picosulfate and related substances. The detection method uses liquid chromatography, and the conditions of high performance liquid chromatography include:

[0151] (1) The chromatographic column is a reverse C18 chromatographic column or a column with equivalent efficiency;

[0152] (2) The column temperature is 36 °C to 40 °C;

[0153] (3) The flow rate is 0.95 mL / min to 1.05 mL / min;

[0154] (4) The injection volume is 95 μL to 105 μL;

[0155] (5) The sample tray temperature is 5 °C to 10 °C;

[0156] (6) The detection wavelength is 260 nm to 265 nm;

[0157] (7) Mobile phase A: The volume ratio of ammonium acetate buffer solution - methanol is (90 - 98)∶(2 - 10). The ammonium acetate buffer solution is adjusted to pH 4.9 - 5.2 with glacial acetic acid, and the ammonium acetate concentration in the ammonium acetate buffer solution is 25 mmol / L to 100 mmol / L;

[0158] (8) Mobile phase B: Acetonitrile;

[0159] (9) Gradient elution, and the elution program is shown in Table 1.

[0160] Table 1 Liquid phase elution program table

[0161] Time (min) Mobile Phase A (%) Mobile Phase B (%) 0 100 0 8 100 0 12 91～95 9～5 20 91～95 9～5 30 86～90 14～10 45 78～82 22～18 55 58～62 42～38 58 48～52 52～48 58.1 28～32 72～68 62 28～32 72～68 62.1 100 0 75 100 0

[0162] IV. Calculation method

[0163] 1. Impurity correction factor:

[0164]

[0165] Among them, CF is the impurity correction factor, A 匹可 is the peak area of sodium picosulfate, A 杂 is the peak area of the impurity, C 匹可 is the concentration of sodium picosulfate (μg / mL), C 杂is the concentration of the impurity (μg / mL).

[0166] 2. Impurity content:

[0167] The content percentage of the impurity in the sample relative to the labeled amount of sodium picosulfate is calculated by the external standard method of the main component with a correction factor (after deducting the solvent peak and excipient peaks), and the formula is as follows:

[0168]

[0169] where M st is the weighed amount of the sodium picosulfate reference substance (mg), P st is the content of the sodium picosulfate reference substance (%), V st is the dilution volume of the sodium picosulfate reference substance (mL), A st is the peak area of sodium picosulfate in the reference solution, As is the peak area of the impurity in the test solution, CF is the correction factor of the impurity, is the average F value of sodium picosulfate in reference solution 1 (n = 5), n s is the dilution factor of the test sample, V is the packaging volume of the test sample 175 mL, and L is the labeled amount of sodium picosulfate 10 mg.

[0170] 3. 4-Hydroxybenzoic acid content:

[0171] The content percentage of 4-hydroxybenzoic acid in the sample relative to the labeled amount of sodium benzoate is calculated by the external standard method, and the formula is as follows:

[0172]

[0173] where M st is the weighed amount of the 4-hydroxybenzoic acid reference substance (mg), P st is the content of the 4-hydroxybenzoic acid reference substance (%), V st is the dilution volume of the 4-hydroxybenzoic acid reference substance (mL), A st is the peak area of 4-hydroxybenzoic acid in the reference solution, As is the peak area of 4-hydroxybenzoic acid in the test solution, is the average F value of 4-hydroxybenzoic acid in reference solution 1 (n = 5), n s is the dilution factor of the test sample, V is the packaging volume of the test sample 175 mL, and L is the labeled amount of sodium picosulfate 10 mg.

[0174] 4. Sodium picosulfate content:

[0175] The content percentage of sodium picosulfate in the sample is calculated by the area normalization method, and the formula is as follows:

[0176]

[0177] where A匹可 The peak area of sodium picosulfate in the test solution, A 杂 The total peak area of impurities in the test solution.

[0178] 5. Recovery rate:

[0179]

[0180] 6. Relative standard deviation (RSD):

[0181]

[0182] where S is the standard deviation, is the arithmetic mean of the measurement results.

[0183] For the experimental parameters not specified in the following specific examples, the guidance given in this application document shall be preferentially referred to. It is also possible to refer to the experimental manuals in the art or other experimental methods known in the art, or the experimental conditions recommended by the manufacturer.

[0184] The raw materials and reagents involved in the following specific examples can be obtained commercially, or can be prepared by those skilled in the art according to known means.

[0185] V. Specific test content

[0186] Example 1

[0187] A detection method for compound sodium picosulfate oral solution, used to detect the contents of sodium picosulfate, 4-hydroxybenzoic acid, impurity A and impurity B in the compound sodium picosulfate oral solution. Liquid chromatography is used for detection. The conditions for liquid chromatography detection include: the chromatographic column is YMC C18, 250 mm × 4.6 mm, 5 μm, the trapping column is welch, 4.6 mm × 50 mm; the column temperature is 38 °C, the flow rate is 1.0 mL / min, the injection volume is 100 μL, the sample tray temperature is 5 °C, and the detection wavelength is 263 nm; mobile phase A: the volume ratio of ammonium acetate buffer solution - methanol is 95:5, mobile phase B: acetonitrile, where the ammonium acetate concentration of the ammonium acetate buffer solution is 100 mmol / L and the pH value is 5.05. The preparation method of the ammonium acetate buffer solution includes: weighing 7.7 g of ammonium acetate, adding 1000 mL of water to dissolve it, and then dropping acetic acid solution until the pH value is 5.05.

[0188] Gradient elution is adopted, and the elution program is shown in Table 2.

[0189] Table 2 Liquid phase elution program table

[0190]

[0191]

[0192] Example 2

[0193] Compared with Example 1, the pH was adjusted to 5.10, and other chromatographic conditions remained unchanged.

[0194] Example 3

[0195] Compared with Example 1, the pH was adjusted to 5.00, and other chromatographic conditions remained unchanged.

[0196] Example 4

[0197] Compared with Example 1, the flow rate was adjusted to 0.95 mL / min, and other chromatographic conditions remained unchanged.

[0198] Example 5

[0199] Compared with Example 1, the flow rate was adjusted to 1.05 mL / min, and other chromatographic conditions remained unchanged.

[0200] Example 6

[0201] Compared with Example 1, the column temperature was adjusted to 36 °C, and other chromatographic conditions remained unchanged.

[0202] Example 7

[0203] Compared with Example 1, the column temperature was adjusted to 40 °C, and other chromatographic conditions remained unchanged.

[0204] Example 8

[0205] Compared with Example 1, in mobile phase A, the volume ratio of ammonium acetate buffer solution to methanol was 98:2, and other chromatographic conditions remained unchanged.

[0206] Example 9

[0207] Compared with Example 1, in mobile phase A, the volume ratio of ammonium acetate buffer solution to methanol was 90:10, and other chromatographic conditions remained unchanged.

[0208] Example 10

[0209] Compared with Example 1, the concentration of ammonium acetate buffer was 50 mmol / L, the sample tray temperature was 10 °C, and the elution program is shown in the following table, and other chromatographic conditions remained unchanged.

[0210]

[0211]

[0212] Example 11

[0213] Compared with Example 1, the concentration of ammonium acetate buffer solution is 25 mmol / L, the temperature of the sample tray is 7 °C, and the elution program is shown in the following table. Other chromatographic conditions remain unchanged.

[0214] Time (min) Mobile Phase A (%) Mobile Phase B (%) 0 100 0 8 100 0 12 95 5 20 95 5 30 90 10 45 82 18 55 62 38 58 52 48 58.1 32 68 62 32 68 62.1 100 0 75 100 0

[0215] Comparative Example 1

[0216] This comparative example provides another detection method for compound sodium picosulfate oral solution, which is detected by liquid chromatography. The conditions for liquid chromatography detection include: the chromatographic column is Ultimate XB-C18, 250 mm × 4.6 mm, 5 μm, the trapping column is welch, 4.6 mm × 50 mm; the column temperature is 30 °C, the flow rate is 1.0 mL / min, the injection volume is 100 μL, the sample tray temperature is not set, the detection wavelength is 263 nm; mobile phase A is 25 mmol / L ammonium acetate buffer solution (pH value is 4.15), mobile phase B is acetonitrile, gradient elution is adopted, and the elution program is shown in Table 3. The reference preparation solution is prepared according to the method of the test solution.

[0217] Table 3 Liquid phase elution program table of Comparative Example 1

[0218] Time (min) Mobile Phase A (%) Mobile Phase B (%) 0 92 8 10 92 8 45 60 40 50 60 40 51 92 8 60 92 8

[0219] Comparative Example 2

[0220] This comparative example provides another detection method for compound sodium picosulfate oral solution, which is detected by liquid chromatography. The conditions for liquid chromatography detection include: the chromatographic column is Xtimate C18, 250 mm × 4.6 mm, 5 μm, the column temperature is 40 °C, the flow rate is 1.0 mL / min, the injection volume is 40 μL, the sample tray temperature is not set, the detection wavelength is 263 nm; the mobile phase is acetonitrile-disodium hydrogen phosphate dihydrate aqueous solution (45:55), isocratic elution is adopted, and the reference preparation solution is prepared according to the method of the test solution.

[0221] Among them, the preparation method of disodium hydrogen phosphate dihydrate aqueous solution: add 200 mg of cetyltrimethylammonium bromide to 2.3 g / L disodium hydrogen phosphate solution, and adjust the pH value to 7.5 with phosphoric acid.

[0222] Using the detection methods of the above examples and comparative examples, according to the calculation formula, the contents of sodium picosulfate and related substances are calculated respectively. The detection results of compound sodium picosulfate oral solution in each example and comparative example are shown in Table 4.

[0223] Table 4 Detection situation of the test solution spiked with standard substances in each example and comparative example

[0224]

[0225] FromFigure 10 , Figure 11 It can be seen that although the peak of sodium picosulfate does not appear too early in Comparative Example 1, there are unresolved peaks for sodium picosulfate; in Comparative Example 2, there are problems such as many peaks of blank excipients, too fast appearance of the main peak, impurity interference, and non-elution of 4-hydroxybenzoic acid, indicating that Comparative Example 1 and Comparative Example 2 cannot detect sodium picosulfate and related substances.

[0226] According to Table 4, compared with Example 1, in Examples 2 to 3, the pH of the ammonium acetate buffer solution was adjusted, and it was detected that the results did not change significantly, and the difference from the detection results of Example 1 was not large. It can be seen that the pH of the ammonium acetate buffer solution can be in the range of 5.0 to 5.1, and sodium picosulfate, 4-hydroxybenzoic acid, impurity A, and impurity B can be effectively separated and their contents detected. Compared with Example 1, in Examples 4 to 5, the flow rate of the mobile phase was adjusted, and it was detected that the results did not change significantly. It can be seen that within the flow rate range of 0.95 mL / min to 1.05 mL / min, sodium picosulfate, 4-hydroxybenzoic acid, impurity A, and impurity B can also be effectively separated and their contents detected.

[0227] Compared with Example 1, in Examples 6 to 9, the column temperature and the volume ratio of the ammonium acetate buffer solution and methanol in mobile phase A were adjusted, and it was detected that the results did not change significantly. When the column temperature is in the range of 36°C to 40°C and the volume ratio of the ammonium acetate buffer solution and methanol is in the range of (90 to 98):(2 to 10), sodium picosulfate, 4-hydroxybenzoic acid, impurity A, and impurity B can be effectively separated and their contents detected. Compared with Example 1, in Examples 10 to 11, the concentration of the ammonium acetate buffer solution and the sample tray temperature were adjusted simultaneously, and it was detected that the results did not change significantly, indicating that at this concentration of the ammonium acetate buffer solution and the sample tray temperature, sodium picosulfate, 4-hydroxybenzoic acid, impurity A, and impurity B in the compound sodium picosulfate oral solution can also be effectively separated and their contents detected. Therefore, the detection methods of the examples of the present application can all effectively separate and detect the contents of sodium picosulfate, 4-hydroxybenzoic acid, impurity A, and impurity B in the compound sodium picosulfate oral solution simultaneously.

[0228] VI. Buffer Salt Verification Test

[0229] To verify the mobile phase buffer salt solution of the present application, buffer solutions with different pH values were respectively prepared. 100 μL of the test sample was taken and placed in a 20 mL volumetric flask, 10 mL of the buffer solution was added, and acetonitrile was gradually added to continuously increase the acetonitrile ratio in the solution, while observing the precipitation situation. The results are shown in Table 5.

[0230] Table 5 Summary Table of Precipitation Results

[0231]

[0232] As can be seen from Table 5, when acetonitrile was added to the mixture of phosphate buffer solution and reference preparation until its proportion reached 40%, precipitation occurred, and no matter how the pH of the phosphate buffer solution was adjusted within the range (Serial numbers ① - ⑦), the precipitation could not disappear. See Serial numbers ⑧ to ⑩. In the mixture of acetate buffer solution and reference preparation, when the pH value of the acetate buffer solution was within the range of 4.8 - 6.0, no precipitation occurred even when acetonitrile was added until its proportion reached 40%. The above results indicate that in the detection method of this application, in the case where the test sample contains Mg 2+ and the mobile phase has a high proportion of acetonitrile, using ammonium acetate buffer solution with a pH value of 4.9 - 5.2 as the mobile phase effectively avoids the precipitation phenomenon and solves the problem of chromatographic column blockage generated in the traditional elution method.

[0233] In addition, using the detection method of Example 1, when the pH of the ammonium acetate buffer salt solution was adjusted to 4.8, 4-hydroxybenzoic acid was interfered by other excipient peaks; using the detection method of Example 1, when the pH of the ammonium acetate buffer salt solution was adjusted to 5.3, 5.5, and 6.0 respectively, 4-hydroxybenzoic acid had no retention, thereby verifying the feasibility of the detection method of this application and being able to effectively determine picosulfate sodium and related substances in compound picosulfate sodium oral solution.

[0234] VII. Method Validation

[0235] This part of the content is the method validation of the detection method (Example 1) of compound picosulfate sodium oral solution of this application.

[0236] 1. System Suitability

[0237] Inject 100 μL of the reference solution into the liquid chromatograph. Inject the reference solution continuously for 5 injections. Select the PDA detector and record the chromatogram. The results are shown in Table 6.

[0238] Table 6 Results of System Suitability

[0239]

[0240]

[0241] As can be seen from Table 6, in the 5 injections of the reference solution, the RSD of the peak area of 4-hydroxybenzoic acid was 0.3%, and the RSD of the peak area of picosulfate sodium was 2.0%, both less than 5.0%, meeting the requirements, indicating that the system precision of the detection method of compound picosulfate sodium oral solution of this application is good.

[0242] 2. Specificity (Study on Related Substances)

[0243] (1) Prepare the solution:

[0244] Impurity A positioning solution: Accurately measure 1 mL of impurity A stock solution, place it in a 200 mL volumetric flask, dilute to the scale with water, shake well, and obtain.

[0245] Impurity B localization solution: Accurately measure 1 mL of the impurity B stock solution, place it in a 200 mL volumetric flask, dilute to the scale with water, shake well, and obtain.

[0246] 4-Hydroxybenzoic acid positioning solution: Accurately measure 1 mL of 4-hydroxybenzoic acid stock solution, place it in a 50 mL volumetric flask, dilute to the scale with mobile phase A, shake well, and obtain.

[0247] Blank excipient solution 1 (without sodium picosulfate): Take the blank excipient (containing sodium benzoate), shake well, filter with a PES filter membrane (0.45μm, Φ13mm), discard 7mL of the initial filtrate, and take the subsequent filtrate.

[0248] Blank excipient solution 2 (without sodium picosulfate and sodium benzoate): Take the blank excipient (without sodium picosulfate and sodium benzoate), shake well, filter with a PES filter membrane (0.45μm, Φ13mm), discard 7mL of the initial filtrate, and take the subsequent filtrate.

[0249] (2) Take 100 μL of each solution and inject it into the liquid chromatograph, select the PDA detector, and record the chromatogram. The results are shown in Table 7 and Figures 1 to 4 .

[0250] Table 7 Specificity (Related Substance Research) Verification Results

[0251]

[0252] In Table 7, “——” and “N / A” mean not applicable.

[0253] According to Table 7, the blank solution has no interference with the detection, and the blank auxiliary solution 1 has no interference with the detection except 4-hydroxybenzoic acid; the blank auxiliary solution 2 has no interference with the detection. In the test solution, the minimum separation between the main peak and the adjacent peak is 13.51, and the minimum separation between the specific impurity and the adjacent peak is 3.54, both of which meet the requirements; in the test spiked solution, the retention time of each impurity is consistent with the retention time of the main peak of the corresponding impurity positioning solution, the minimum separation between the main peak and the adjacent peak is 8.11, and the minimum separation between the specific impurity and the adjacent peak is 3.57, which meets the requirements of "the minimum separation between the main peak and the adjacent peak shall not be less than 1.5, and the minimum separation between the specific impurity and the adjacent peak shall not be less than 1.0", indicating that the method has good specificity.

[0254] 3. Specificity (strong degradation)

[0255] After the test samples are destroyed by harsh conditions such as high temperature, acid, alkali, oxidation, and light, the relevant substances are determined to examine whether the chromatographic conditions can detect the degradation products produced.

[0256] (1) Preparation of solutions:

[0257] Undamaged test solution ① (abbreviation: "undamaged ①"): Shake the compound sodium picosulfate oral solution well, filter it through a PES membrane (0.45 μm, Φ13 mm), discard the first 7 mL of the filtrate, and collect the subsequent filtrate to obtain the solution.

[0258] Undamaged test solution ② (abbreviation: "undamaged ②"): Accurately measure 1 mL of water, place it in a 10 mL volumetric flask, dilute it to the mark with the compound sodium picosulfate oral solution, shake well, filter it through a PES membrane (0.45 μm, Φ13 mm), discard the first 7 mL of the filtrate, and collect the subsequent filtrate to obtain the solution.

[0259] Undamaged test solution ③ (abbreviation: "undamaged ③"): Accurately measure 2 mL of water, place it in a 10 mL volumetric flask, dilute it to the mark with the compound sodium picosulfate oral solution, shake well, filter it through a PES membrane (0.45 μm, Φ13 mm), discard the first 7 mL of the filtrate, and collect the subsequent filtrate to obtain the solution.

[0260] Acid-damaged test solution (abbreviation: "acid damage"): Accurately measure 1 mL of 10 mol / L hydrochloric acid solution, place it in a 10 mL volumetric flask, accurately add 8 mL of the compound sodium picosulfate oral solution, keep it in the dark, let it stand for 1 h, then dilute it to the mark with 10 mol / L sodium hydroxide solution, shake well, filter it through a PES membrane (0.45 μm, Φ13 mm), discard the first 7 mL of the filtrate, and collect the subsequent filtrate to obtain the solution.

[0261] Alkali-damaged test solution (abbreviation: "alkali damage"): Accurately measure 1 mL of 10 mol / L sodium hydroxide solution, place it in a 10 mL volumetric flask, accurately add 8 mL of the compound sodium picosulfate oral solution, keep it in the dark, let it stand for 2 h, then dilute it to the mark with 10 mol / L hydrochloric acid solution, shake well, filter it through a PES membrane (0.45 μm, Φ13 mm), discard the first 7 mL of the filtrate, and collect the subsequent filtrate to obtain the solution.

[0262] Oxidation-damaged test solution (abbreviation: "oxidation damage"): Accurately measure 1 mL of 30% hydrogen peroxide solution, place it in a 10 mL volumetric flask, dilute it to the mark with the compound sodium picosulfate oral solution, shake well, keep it in the dark, let it stand for 2 h, filter it through a PES membrane (0.45 μm, Φ13 mm), discard the first 7 mL of the filtrate, and collect the subsequent filtrate to obtain the solution.

[0263] High-temperature-damaged test solution (abbreviation: "high-temperature damage"): Take an appropriate amount of the compound sodium picosulfate oral solution, place it in a vial, cover it with a silicone stopper and press an aluminum cap, keep it in the dark, let it stand in an oven at 80 °C for 2 days, filter it through a PES membrane (0.45 μm, Φ13 mm), discard the first 7 mL of the filtrate, and collect the subsequent filtrate to obtain the solution.

[0264] Photodegradation of the test solution (hereinafter referred to as "photodegradation"): Take an appropriate amount of compound sodium picosulfate oral solution, place it in a transparent vial, cover it with a silicone stopper and press an aluminum cap, and irradiate it with light (4500lx ± 500lx) for 5 days. Filter it with a PES membrane (0.45μm, Φ13mm), discard the first 7mL of the filtrate, and take the subsequent filtrate to obtain the solution.

[0265] Solution of sodium picosulfate raw material: Take about 11.5mg of sodium picosulfate raw material, accurately weigh it, place it in a 200ml volumetric flask, add water and dissolve it by ultrasonic wave and dilute it to the scale, shake it well to obtain the solution.

[0266] (2) Detect the prepared solutions respectively under the chromatographic conditions of Example 1, record the chromatograms, and the results are shown in Table 8. Figures 5 to 9 .

[0267] Table 8 Results of forced degradation test - 1

[0268]

[0269] In Table 8, "ND" means not detected.

[0270] It can be seen from Table 8 that the resolution between the main peak and the adjacent impurity peaks is greater than 1.5, and the resolution between the specific impurity and the adjacent peaks is greater than 1.0, indicating that the detection method of the compound sodium picosulfate oral solution in this application has good specificity and can be used for the detection of sodium picosulfate and related substances in the strongly degraded test samples.

[0271] 4. Quantitation limit and detection limit

[0272] Take appropriate amounts of sodium picosulfate reference substance, 4-hydroxybenzoic acid reference substance, impurity A reference substance and impurity B reference substance respectively, dilute and dissolve them with the diluent, and gradually dilute them until the signal-to-noise ratio S / N of the main component is greater than 10 to obtain the quantitation limit solution, and when the signal-to-noise ratio S / N of the main component is greater than 3 to obtain the detection limit solution. The results are shown in Table 9 and Table 10.

[0273] Table 9 Results of detection limit

[0274] Compound Concentration (μg / mL) Equivalent to the concentration of the test solution S / N 4-Hydroxybenzoic acid 0.0157 0.003％ 30.83 Sodium picosulfate 0.0138 0.024％ 8.32 Impurity A 0.0237 0.040％ 17.73 Impurity B 0.0118 0.021％ 32.00

[0275] Table 10 Results of quantitation limit

[0276] Compound Concentration (μg / mL) Equivalent to the concentration of the test solution S / N 4-Hydroxybenzoic acid 0.0313 0.006％ 81.40 Sodium picosulfate 0.0276 0.05％ 23.08 Impurity A 0.0474 0.08％ 46.95 Impurity B 0.0235 0.04％ 41.00

[0277] According to the detection results in Table 9 and Table 10, the detection limit concentration of 4-hydroxybenzoic acid is 0.0157μg / mL, which is equivalent to 0.003% of the sodium benzoate concentration in the test solution, and S / N is 30.83; the quantitation limit concentration is 0.0313μg / mL, which is equivalent to 0.006% of the sodium benzoate concentration in the test solution, and S / N is 81.40. That is, the detection limit and quantitation limit of 4-hydroxybenzoic acid both meet the standards.

[0278] The detection limit concentration of sodium picosulfate is 0.0138 μg / mL, which is equivalent to 0.024% of the concentration of sodium picosulfate in the test solution, and the S / N is 8.32; the quantitation limit concentration is 0.0276 μg / mL, which is equivalent to 0.05% of the test solution concentration, and the S / N is 23.08. That is, both the detection limit and quantitation limit of sodium picosulfate meet the standards.

[0279] The detection limit concentration of impurity A is 0.0237 μg / mL, which is equivalent to 0.04% of the concentration of sodium picosulfate in the test solution, and the S / N is 17.73; the quantitation limit concentration is 0.0474 μg / mL, which is equivalent to 0.08% of the test solution concentration, and the S / N is 46.95. That is, both the detection limit and quantitation limit of impurity A meet the standards.

[0280] The detection limit concentration of impurity B is 0.0118 μg / mL, which is equivalent to 0.021% of the concentration of sodium picosulfate in the test solution, and the S / N is 32.00; the quantitation limit concentration is 0.0235 μg / mL, which is equivalent to 0.04% of the test solution concentration, and the S / N is 41.00. That is, both the detection limit and quantitation limit of impurity B meet the standards.

[0281] According to the above test results, it shows that the detection method of the compound sodium picosulfate oral solution in this application has good sensitivity.

[0282] 5. Repeatability investigation

[0283] Take 6 bottles of compound sodium picosulfate oral solution, prepare 6 portions of test solutions in parallel, inject samples respectively, and perform detection according to the chromatographic conditions in Example 1, and calculate the impurity content.

[0284] Table 11 Results of repeatability investigation

[0285]

[0286]

[0287] In Table 11, "ND" means not detected or not applicable.

[0288] According to Table 11, among the 6 portions of test solutions, the range of 4-hydroxybenzoic acid is 0.0 (<0.02%); the average content of impurity A is 0.12%, and the RSD is 6.2% (<20%); the average content of total impurities is 0.64%, and the RSD is 3.5% (<5%). That is, the above all meet the acceptable standards, indicating that the repeatability of the detection method of the compound sodium picosulfate oral solution in this application meets the requirements.

[0289] 6. Solution stability investigation

[0290] Take the test solution and examine it under refrigeration conditions at 5°C. Sampling and detection are carried out at different time points (0h, 15h, 28h, 35h, 43h), and the chromatogram is recorded.

[0291] Table 12 Results of the solution stability study

[0292]

[0293] In Table 12, "ND" means not detected, and "N / A" means not applicable; the change rate is the difference in peak areas between two time points / the peak area at 0h.

[0294] As can be seen from Table 12, under refrigeration conditions (5°C), although impurity B was not detected, compared with 0h, the absolute value of the change rate of the 4-hydroxybenzoic acid content exceeded 50% at 15 hours, and the absolute value of the change rate of the impurity A content exceeded 20% at 35 hours. This indicates that the test solution is still unstable under refrigeration conditions (5°C) and should be prepared and used immediately. It shows that the detection method for the compound sodium picosulfate oral solution in this application can be used for the solution stability study.

[0295] 7. Accuracy study

[0296] Quantitation limit stock solution: Accurately measure 2 mL of the impurity A stock solution, 5 mL of the 4-hydroxybenzoic acid stock solution, and 3 mL of the sodium picosulfate reference stock solution, place them in a 100 mL volumetric flask, dilute to the mark with water, and shake well.

[0297] Linear stock solution: Accurately measure 4 mL of the impurity A stock solution, 20 mL of the 4-hydroxybenzoic acid stock solution, and 1 mL of the sodium picosulfate reference stock solution, place them in a 200 mL volumetric flask, dilute to the mark with water, and shake well.

[0298] Quantitation limit accuracy solution: Accurately measure 2 mL of the quantitation limit stock solution, place it in a 50 mL volumetric flask, dilute to the mark with water, then accurately measure 2 mL of this solution, place it in a 20 mL volumetric flask, and dilute to the mark with blank excipient solution 2, and shake well; prepare 3 parallel samples.

[0299] 100% accuracy solution: Accurately measure 2 mL of the linear stock solution, place it in a 20 mL volumetric flask, dilute to the mark with blank excipient solution 2 (see the specificity section), and shake well; prepare 3 parallel samples.

[0300] 200% accuracy solution: Accurately measure 2 mL of the linear stock solution, place it in a 10 mL volumetric flask, dilute to the mark with blank excipient solution 2 (see the specificity section), and shake well; prepare 3 parallel samples.

[0301] 100% Accuracy Solution - Sodium Picosulfate: Accurately measure 2 mL of the sodium picosulfate linear stock solution, place it in a 20 mL volumetric flask, dilute to the mark with blank excipient solution 2 (see the specificity section), and shake well to obtain; prepare 3 portions in parallel.

[0302] 200% Accuracy Solution - Sodium Picosulfate: Accurately measure 2 mL of the sodium picosulfate linear stock solution, place it in a 10 mL volumetric flask, dilute to the mark with blank excipient solution 2 (see the specificity section), and shake well to obtain; prepare 3 portions in parallel.

[0303] Take 100 μL of each of the above solutions, inject into the liquid chromatograph, record the chromatogram, calculate the recovery rate and RSD of each solution by the external standard method, and the results are shown in Tables 14 to 17.

[0304] In the accuracy solutions, the recovery rates and RSDs of each impurity should meet the requirements in Table 13:

[0305] Table 13 Acceptance Criteria

[0306] Test results Individual recovery rate range RSD (n = 3) ≥0.1％ 90.0％～110.0％ ≤10％ ＜0.1％ 80.0％～120.0％ ≤20％ Quantification limit 70.0％～130.0％ ≤30％

[0307] Table 14 Results of the Accuracy Test for 4-Hydroxybenzoic Acid

[0308]

[0309] Table 15 Results of the Accuracy Test for Sodium Picosulfate

[0310]

[0311] Table 16 Results of the Accuracy Test for Impurity A

[0312]

[0313] Table 17 Results of the Accuracy Test for Impurity B

[0314]

[0315] As can be seen from the above table, for 4-hydroxybenzoic acid in the range of 0.0313 μg / mL to 3.1340 μg / mL (equivalent to 2% to 203% of the limit concentration, 0.006% to 0.6% of the concentration of sodium benzoate in the test sample), the recovery rate of the quantitation limit concentration is 71.6% to 74.2%, within the range of 70.0% to 130.0%, the RSD (n = 3) is 2% (< 30%); the recovery rate of the 100% concentration is 100.8% to 101.2%, within the range of 90.0% to 110.0%, the RSD (n = 3) is 1% (< 10%); the recovery rate of the 200% concentration is 100.8% to 101.3%, within the range of 90.0% to 110.0%, the RSD (n = 3) is 1% (< 10%).

[0316] In the range of 0.0276 μg / mL to 0.2302 μg / mL (equivalent to 24% to 201% of the limit concentration, sample concentration 0.05% to 0.4%), the recovery rate of the quantitation limit concentration is 94.3% to 102.2%. In the range of 70.0% to 130.0%, the RSD (n = 3) is 5% (<30%); the recovery rate of the 100% concentration is 93.9% to 100.6%. In the range of 90.0% to 110.0%, the RSD (n = 3) is 4% (<10%); the recovery rate of the 200% concentration is 96.6% to 102.4%. In the range of 90.0% to 110.0%, the RSD (n = 3) is 4% (<10%).

[0317] In the range of 0.0474 μg / mL to 2.3707 μg / mL (equivalent to 4% to 207% of the limit concentration, sample concentration 0.08% to 4%), the recovery rate of the quantitation limit concentration is 91.6% to 96.2%. In the range of 70.0% to 130.0%, the RSD (n = 3) is 3% (<30%); the recovery rate of the 100% concentration is 99.7% to 100.4%. In the range of 90.0% to 110.0%, the RSD (n = 3) is 1% (<10%); the recovery rate of the 200% concentration is 99.5% to 100.7%. In the range of 90.0% to 110.0%, the RSD (n = 3) is 1% (<10%).

[0318] In the range of 0.0235 μg / mL to 0.2349 μg / mL (equivalent to 21% to 206% of the limit concentration, sample concentration 0.04% to 0.41%), the recovery rate of the quantitation limit concentration is 95.9% to 107.1%. In the range of 70.0% to 130.0%, the RSD (n = 3) is 3% (<30%); the recovery rate of the 100% concentration is 96.8% to 98.7%. In the range of 90.0% to 110.0%, the RSD (n = 3) is 1% (<10%); the recovery rate of the 200% concentration is 98.2%. In the range of 90.0% to 110.0%, the RSD (n = 3) is 1% (<10%).

[0319] According to the above test results, 4-hydroxybenzoic acid, sodium picosulfate, impurity A, and impurity B all meet the acceptable standards, and the accuracy of the detection method for the compound sodium picosulfate oral solution in this application is good.

[0320] 8. Investigation of filter membrane adsorption

[0321] (1) Prepare the standard solution: Take an appropriate amount of the test solution, centrifuge (10000 rpm, 5 min), and take the supernatant as the standard solution.

[0322] (2) Preparation of the test solution: Filter an appropriate amount of the test sample through a PES membrane filter. Discard 1 mL, 3 mL, 5 mL, and 7 mL respectively, and take the subsequent filtrate.

[0323] Inject 100 μL of the above solution into the liquid chromatograph, record the chromatogram, and compare the peak areas of the test solution and the reference solution.

[0324] Table 18 Results of the membrane adsorption test

[0325]

[0326]

[0327] In Table 18, "ND" means not detected, and "N / A" means not applicable; the change rate is the difference in peak areas between two time points / the peak area at 0 h.

[0328] As can be seen from Table 18, when discarding 3 mL or more of the test sample solution using a PES membrane filter, the absolute value of the change rate of the detected amount of each impurity meets the acceptable standard, and the number of impurities is the same as that of the reference solution. In order to minimize the influence of filtration and reduce the risk of impurity adsorption by the membrane, 7 mL can be discarded using a PES membrane filter. Therefore, when filtering with a PES membrane (0.45 μm, Φ13 mm) in the detection method of this application, discarding 7 mL of the initial filtrate and taking the subsequent filtrate meet the requirements.

[0329] All the documents mentioned in this application are cited as references in this application, just as if each document was cited separately as a reference. Unless it conflicts with the purpose of this application and / or the technical solution, the cited documents involved in this application are cited in their entirety and for all purposes. When referring to cited documents in this application, the definitions of relevant technical features, terms, nouns, phrases, etc. in the cited documents are also cited. When referring to cited documents in this application, the examples and preferred methods of the relevant technical features cited can also be incorporated as references into this application, but only to the extent that this application can be implemented. It should be understood that when the cited content conflicts with the description in this application, this application shall prevail or be amended adaptively according to the description in this application.

[0330] The technical features of the above-described embodiments and examples can be combined in any suitable manner. For the sake of brevity of description, not all possible combinations of the technical features in the above-described embodiments and examples are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered to be within the scope described in this specification.

[0331] The above-described embodiments merely represent several implementation manners of the present application, but should not be construed as limiting the scope of the patent application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all fall within the protection scope of the present application. In addition, it should be understood that after reading the above teachings of the present application, those skilled in the art can make various changes or modifications to the present application, and the equivalent forms obtained also fall within the protection scope of the present application. It should also be understood that the technical solutions obtained by those skilled in the art through logical analysis, reasoning, or limited experiments based on the technical solutions provided by the present application are all within the protection scope of the appended claims of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the appended claims, and the specification can be used to explain the content of the claims.

Claims

1. A method for detecting compound sodium picosulfate oral solution, characterized in that: It is used to detect sodium picosulfate and related substances; The detection method comprises performing liquid chromatography detection on the compound sodium picosulfate oral solution; The conditions for the liquid chromatography detection include: (1) The chromatographic column is a reversed C18 column or a column with equivalent performance; (2) using a mixture of ammonium acetate buffer solution and methanol as mobile phase A, and acetonitrile as mobile phase B; wherein the pH value of the ammonium acetate buffer solution is 4.9 to 5.2; (3) Use gradient elution.

2. The detection method according to claim 1, characterized in that: The pH value of the ammonium acetate buffer salt solution is 5.0-5.

1.

3. The detection method according to claim 2, characterized in that: In the mobile phase A, the volume proportion of the ammonium acetate buffer solution is 90% to 98%, and the volume proportion of the methanol is 2% to 10%.

4. The detection method according to claim 3, characterized in that: The ammonium acetate buffered saline solution comprises ammonium acetate with a molar concentration of 25 mmol / L to 100 mmol / L.

5. The detection method according to claim 4, characterized in that: The preparation steps of the ammonium acetate buffered saline solution include: After ammonium acetate and water are mixed, glacial acetic acid is added in batches and mixed until the pH value reaches 5.0-5.1, thereby obtaining the ammonium acetate buffered salt solution.

6. The detection method according to claim 1, characterized in that: The procedure of the gradient elution includes: 0min~8min, maintaining the volume percentage of the mobile phase A at 100%; 8min-12min, the volume percentage of the mobile phase A is reduced from 100% to 91%-95%; 12min-20min, maintaining the volume percentage of the mobile phase A at 91%-95%; 20min to 30min, the volume percentage of the mobile phase A is reduced from 91% to 95% to 86% to 90%; 30min-45min, the volume percentage of the mobile phase A is reduced from 86%-90% to 78%-82%; 45min-55min, the volume percentage of the mobile phase A is reduced from 78%-82% to 58%-62%; 55min-58min, the volume percentage of the mobile phase A is reduced from 58%-62% to 48%-52%; 58min-58.1min, the volume percentage of the mobile phase A is reduced from 48%-52% to 28%-32%; 58.1min~62min, maintaining the volume percentage of the mobile phase A at 28%~32%; 62min-62.1min, the volume percentage of the mobile phase A increases from 28%-32% to 100%; From 62.1 min to 75 min, the volume percentage of the mobile phase A is maintained at 100%.

7. The detection method according to any one of claims 1 to 6, characterized in that: The conditions for the liquid chromatography detection also include at least one of the following conditions: (1) Column temperature is 36℃~40℃; (2) The sample pan temperature is 5℃~10℃.

8. The detection method according to any one of claims 1 to 6, characterized in that: The conditions for the liquid chromatography detection also include at least one of the following conditions: (1) Flow rate: 0.95 mL / min to 1.05 mL / min; (2) The injection volume is 95 μL to 105 μL; (3) The detection wavelength is 260nm~265nm.

9. The detection method according to any one of claims 1 to 6, characterized in that: The length of the chromatographic column is 240 mm to 260 mm, the diameter is 4.4 mm to 4.8 mm, and the particle size of the filler is 4 μm to 6 μm; and / or, The models of the chromatographic columns include YMC-Pack ODS-A.

10. The detection method according to any one of claims 1 to 6, characterized in that: The related substances include at least one of 4-hydroxybenzoic acid, impurity A and impurity B, wherein: The structure of impurity A is The structure of the impurity B is

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