Nimodipine impurity G as well as preparation method and application thereof

Abstract

The invention provides a nimodipine analogue G with a brand new structure or a pharmaceutically acceptable salt thereof. And a pharmaceutical composition comprising nimodipine and the nimodipine analogue G; the invention also provides a preparation method of the nimodipine analogue G. The nimodipine analogue G is prepared by carrying out a reduction reaction on nimodipine and a reducing agent in the presence of a catalyst and a reaction solvent and then carrying out an oxidation reaction with an oxidizing agent. The application of the nimodipine analogue G in the field of medicine includes but not limited to impurity detection and quality control of nimodipine raw materials or preparations thereof, the impurity detection method can simultaneously separate and detect nine impurities, and for the nimodipine raw materials or the preparations thereof, especially injections and oral solutions, the nimodipine analogue G can be applied to the field of medicine. And the method has extremely important quality control guiding significance.

Description

Technical Field

[0001] The invention belongs to the field of nimodipine impurities, and specifically relates to a nimodipine impurity G and a preparation method and application thereof. Background Art

[0002] Nimodipine, chemically known as isopropyl-2-methoxyethyl-1,4-dihydro-2,6-dimethyl-4(3-nitrophenyl)-3,5-pyridinedicarboxylate, is a second-generation 1,4-dihydropyridine calcium channel antagonist. It is clinically used to prevent and treat ischemic nerve damage caused by cerebral vasospasm after subarachnoid hemorrhage, as well as senile brain function damage, migraine, sudden deafness, etc. It is the first choice for the treatment of cerebrovascular diseases.

[0003] Nimodipine is a dihydropyridine derivative, which is characterized by light instability. In order to control the quality of nimodipine API and related preparations, pharmacopoeias of various countries have made corresponding regulations on nimodipine impurities. The Chinese Pharmacopoeia discloses nimodipine impurity I and stipulates the impurity limit: impurity I≤0.5%, other single impurities≤1.0%, and total impurities≤2.0%. The European Pharmacopoeia discloses impurity A (corresponding to impurity I in the Chinese Pharmacopoeia), impurity B and impurity C, and stipulates the impurity limit: impurity C≤0.2%, other single impurities≤0.10%, and total impurities≤0.5%.

[0004]

[0005] It can be seen that in addition to impurities A, B, and C, there are many unknown impurities in nimodipine raw materials and related preparations. Luo Jing et al. [1] The impurities of nimodipine were studied, and their structures were determined by analytical methods such as HPLC-MS and NMR. A new impurity 2 was discovered for the first time. Riekes MK et al. [2] showed that nimodipine produces a variety of degradation products under acid degradation, alkaline degradation, and photodegradation conditions, but the specific structures of the degradation products were not studied.

[0006]

[0007] The inventors of the present application discovered p-hydroxybenzoic acid, methylparaben, impurity D, impurity F, and impurities E and G of a completely new structure during the research process of nimodipine API and related preparations, and impurities E, F, and G increased significantly during the stability period. Therefore, it is necessary to provide a nimodipine impurity G and a preparation method thereof for the quality control of nimodipine API and related preparations.

[0008]

[0009] References:

[0010] [1] Luo Jing, Liu Haijing, He Langchong, et al. Determination of related substances in nimodipine and its preparations by HPLC[J]. Journal of Pharmaceutical Analysis, 2007, 27(7): 1039-1042.

[0011] [2]Riekes MK, Rauber GS, Gislaine K, et al. Determination of Nimodipinein the Presence of its Degradation Products and Overall Kinetics through aStability-Indicating LC Method[J]. Journal of Chromatographic Science, 2013(6):511-516. Summary of the invention

[0012] The technical problem to be solved by the present invention is to provide a nimodipine impurity G with a completely new structure, a pharmaceutical composition comprising nimodipine and impurity G, a preparation method of impurity G, and application of impurity G in the medical field.

[0013] The above technical problems to be solved are achieved through the following technical solutions:

[0014] The present invention provides a nimodipine analogue, which is a compound represented by formula G or a pharmaceutically acceptable salt thereof:

[0015]

[0016] The present invention provides a pharmaceutical composition comprising nimodipine and nimodipine analog G.

[0017] Preferably, the content of nimodipine analog G in the pharmaceutical composition is ≤0.5%.

[0018] More preferably, the content of nimodipine analog G in the pharmaceutical composition is ≤0.3%.

[0019] Preferably, the pharmaceutical composition further comprises a solvent, and the solvent includes but is not limited to one or more of water and ethanol.

[0020] Preferably, the pharmaceutical composition further comprises a solubilizer, which includes but is not limited to one or more of glycerol, propylene glycol, and polyethylene glycol.

[0021] Preferably, the pharmaceutical composition further comprises an antibacterial agent, which includes but is not limited to one or more of methyl parahydroxybenzoate, ethyl parahydroxybenzoate, propyl parahydroxybenzoate, and butyl parahydroxybenzoate.

[0022] Preferably, the pharmaceutical composition further comprises a pH adjuster, which includes but is not limited to one or more of citric acid, sodium citrate, sodium monohydrogen phosphate, and sodium dihydrogen phosphate.

[0023] More preferably, the pharmaceutical composition further comprises the following components: ethanol, glycerol, methyl paraben and polyethylene glycol.

[0024] More preferably, the pharmaceutical composition further comprises the following components: ethanol, glycerol, methyl parahydroxybenzoate and polyethylene glycol, sodium monohydrogen phosphate, sodium dihydrogen phosphate and water.

[0025] More preferably, the pharmaceutical composition further comprises the following components: ethanol, polyethylene glycol, sodium citrate, citric acid and water.

[0026] The present invention also provides a method for preparing nimodipine analog G, and the reaction scheme is as follows:

[0027]

[0028] The reaction steps include: nimodipine and a reducing agent undergo a reduction reaction under the conditions of a catalyst and a reaction solvent, and then undergo an oxidation reaction with an oxidant to obtain impurity G.

[0029] Preferably, the reducing agent includes, but is not limited to, one or more of sodium borohydride, sodium cyanoborohydride, and potassium borohydride.

[0030] More preferably, the reducing agent is sodium borohydride.

[0031] Preferably, the catalyst includes, but is not limited to, one or more of palladium acetate and tetrakistriphenylphosphine palladium.

[0032] More preferably, the catalyst is palladium acetate.

[0033] Preferably, the reaction solvent includes, but is not limited to, one or more of water, ethanol, dichloromethane, methanol, and tetrahydrofuran.

[0034] More preferably, the reaction solvent is a mixed solvent of water and ethanol.

[0035] Preferably, the oxidant includes, but is not limited to, one or more of oxygen and hydrogen peroxide.

[0036] Furthermore, the preparation method of the nimodipine analog G provided by the present invention comprises the following steps:

[0037] 1) nimodipine and a reducing agent undergo a reduction reaction in the presence of a catalyst and a reaction solvent, and then undergo an oxidation reaction with an oxidant to obtain a crude impurity G;

[0038] 2) Dissolve the crude impurity G and purify it with a preparative liquid phase to obtain a pure impurity G.

[0039] Preferably, in step 1), the ratio of nimodipine, reducing agent and catalyst is 1:0.1-1:0.01-1 (w / w).

[0040] More preferably, in step 1), the ratio of nimodipine, reducing agent and catalyst is 1:0.18:0.5 (w / w).

[0041] Preferably, in step 1), the reduction reaction temperature is -10°C to 40°C, and the reaction time is 0.5h to 5h.

[0042] More preferably, in step 1), the reduction reaction temperature is 25° C. and the reaction time is 2 h.

[0043] Preferably, in step 1), the oxidation reaction temperature is 0°C to 40°C, and the reaction time is 1 to 3 hours.

[0044] More preferably, in step 1), the oxidation reaction temperature is 25° C. and the reaction time is 2 h.

[0045] Most preferably, step 1) is to take 2.0 g of nimodipine, 0.36 g of sodium borohydride, add 20 mL of water, 30 mL of ethanol, stir evenly at room temperature, then add 0.108 g of palladium acetate (dissolved in 5 mL of dichloromethane), stir and react at room temperature; react under oxygen conditions, add 20 mL of water to quench the reaction; filter after standing, dissolve the filter cake with dichloromethane, filter to remove the palladium acetate solid, and spin-dry the filtrate to obtain a yellow solid, which is the crude impurity G.

[0046] Preferably, the solvent for impurity G in step 2) includes, but is not limited to, one or more of dichloromethane, N,N-dimethylformamide, and tetrahydrofuran.

[0047] More preferably, the solvent for impurity G in step 2) is N,N-dimethylformamide.

[0048] Preferably, the liquid phase purification mobile phase in step 2) includes, but is not limited to, one or more of potassium dihydrogen phosphate, ammonium bicarbonate, water, methanol, and acetonitrile.

[0049] More preferably, in step 2), the mobile phase for liquid phase purification is 10 mmol / L aqueous ammonium bicarbonate solution and acetonitrile.

[0050] Most preferably, step 2) is to dissolve the crude impurity G with N,N-dimethylformamide and purify it with preparative liquid phase (C18 column, 19*250mm, mobile phase is 10mmol / L ammonium bicarbonate aqueous solution and acetonitrile, retention time 12.5min) to obtain pure impurity G.

[0051] The present invention also provides the application of nimodipine analog G in the medical field, and its uses include but are not limited to impurity detection and quality control of nimodipine raw materials or preparations thereof.

[0052] A nimodipine analog G can be used as nimodipine impurity G for detecting impurities in nimodipine raw materials or preparations.

[0053] Preferably, the impurity detection method is to detect nimodipine impurities by high performance liquid chromatography. The nimodipine impurities referred to herein include but are not limited to known impurities that have been disclosed (e.g., p-hydroxybenzoic acid, methylparaben, impurity A, impurity B, impurity C, impurity D, impurity F, etc.), and unknown impurities E and impurity G discovered by the applicant.

[0054] More preferably, when high performance liquid chromatography is used to detect nimodipine impurities, the chromatographic column is selected to use octadecylsilane bonded silica gel as a filler.

[0055] More preferably, when nimodipine impurities are detected by high performance liquid chromatography, the mobile phase is: potassium dihydrogen phosphate as mobile phase A, methanol-acetonitrile as mobile phase B, and linear gradient elution is performed as shown in the following table:

[0056]

[0057] More preferably, when nimodipine impurities are detected by high performance liquid chromatography, the mobile phase is: potassium dihydrogen phosphate as mobile phase A, methanol-acetonitrile as mobile phase B, and linear gradient elution is performed as shown in the following table:

[0058]

[0059] More preferably, the linear gradient elution is as follows:

[0060]

[0061] More preferably, when nimodipine impurities are detected by high performance liquid chromatography, the mobile phase is: potassium dihydrogen phosphate as mobile phase A, methanol-acetonitrile as mobile phase B, and linear gradient elution is performed as shown in the following table:

[0062]

[0063] More preferably, the linear gradient elution is as follows:

[0064]

[0065] More preferably, the concentration of potassium dihydrogen phosphate in the mobile phase is 5 to 10 mmol / L.

[0066] More preferably, the pH range of potassium dihydrogen phosphate in the mobile phase is 3.0.

[0067] More preferably, the chromatographic column has a specification of 4.6 mm×250 mm.

[0068] Most preferably, the chromatographic column is selected from Thermo Syncronis C18 (4.6×250 mm, 5 μm), AcchromTechUnitary C18 100A (4.6×250 mm, 5 μm), Agilent Zorbax sb-C18 (4.6×250 mm, 5 μm) or a chromatographic column with equivalent performance.

[0069] More preferably, the detection wavelength is 230 to 240 nm.

[0070] Most preferably, the detection wavelength is 235 nm.

[0071] More preferably, the column temperature is 28-32°C.

[0072] Most preferably, the column temperature is 30°C.

[0073] More preferably, the flow rate is 0.8 to 1.2 ml / min.

[0074] Most preferably, the flow rate is 1.0 ml / min.

[0075] A nimodipine analog G can be used as a standard substance or reference substance for nimodipine impurity G, and can be used for quality control of nimodipine raw materials or preparations, or for establishing quality standards.

[0076] Preferably, the nimodipine preparation is selected from a solid preparation, a semisolid preparation and a liquid preparation.

[0077] More preferably, the nimodipine preparation is selected from liquid preparations.

[0078] Most preferably, the nimodipine formulation is an injection or an oral solution.

[0079] Compared with the prior art, the beneficial effects of the nimodipine injection of the present invention are:

[0080] 1) The present application provides a nimodipine impurity G which is not disclosed in the prior art and has a completely new structure. The structure of the impurity G is confirmed by liquid chromatography-mass spectrometry, carbon nuclear magnetic resonance spectroscopy, and hydrogen nuclear magnetic resonance spectroscopy, and is a degradation impurity of nimodipine.

[0081] 2) The present application also provides a method for preparing impurity G, which can be prepared by a reduction reaction between nimodipine and a reducing agent in the presence of a catalyst and a reaction solvent, and then an oxidation reaction with an oxidant, and the pure impurity G can be obtained by preparative liquid phase purification, which can be used as a standard or reference substance for nimodipine degradation impurity G.

[0082] 3) The present application also provides a method for detecting impurity G or simultaneously detecting impurity G and other nimodipine impurities. By optimizing the mobile phase and elution gradient of high performance liquid chromatography, the technical effect of simultaneously separating and detecting 9 impurities (parahydroxybenzoic acid, methylparaben, impurity A, impurity B, impurity C, impurity D, impurity E, impurity F and impurity G) is achieved, so as to control the quality of nimodipine raw materials or their preparations and establish corresponding quality standards; in particular, it has extremely important quality control guiding significance for the currently marketed nimodipine injection and oral solution. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] Figure 1 is the mass spectrum of nimodipine impurity G in Example 2;

[0084] Figure 2 is the hydrogen nuclear magnetic resonance spectrum of the nimodipine impurity G in Example 2;

[0085] Figure 3 This is the detection result of nimodipine related substances in Example 3. DETAILED DESCRIPTION

[0086] The following are specific embodiments of the present invention, which further describe the technical solution of the present invention, but the protection scope of the present invention is not limited to these embodiments. Any changes or equivalent substitutions that do not deviate from the concept of the present invention are protected within the protection scope of the present invention.

[0087] The reagents and instruments used in the examples are all conventional reagents and instruments in the art and can be purchased through conventional channels. The following is only for illustration.

[0088] Reagents:

[0089] Nimodipine oral solution (Specification: 60mg / 20ml, Manufacturer: Arbor Pharmaceuticals)

[0090] p-Hydroxybenzoic acid (purity: 100.0%, manufacturer: Sigma)

[0091] Methylparaben (purity: 100.0%, manufacturer: Sigma)

[0092] Nimodipine impurity A (purity: 87.0%, manufacturer: China National Institute for Food and Drug Control)

[0093] Nimodipine impurity B (purity: 99.37%, manufacturer: GP)

[0094] Nimodipine impurity C (purity: 98.12%, manufacturer: GP)

[0095] instrument:

[0096] High performance liquid chromatograph (model: U3000, manufacturer: Thermo Fisher )

[0097] Liquid chromatography-mass spectrometry (Model: Thermo U3000 (Double Ternary) + Q-EXACTIVE, Manufacturer: Thermo Fisher Scientific, USA)

[0098] Nuclear magnetic resonance spectrometer (model: Bruker BioSpin GmbH 400MHz, manufacturer: Bruker, USA).

[0099] Example 1 Preparation of Impurity G

[0100] Take 2.0g of nimodipine and 0.36g of sodium borohydride, add 20mL of water and 30mL of ethanol, stir evenly at room temperature, then add 0.108g of palladium acetate (dissolved in 5mL of dichloromethane), stir and react at room temperature, and monitor the reaction by TLC. After the reaction is completed, react under oxygen conditions, and monitor the reaction by TLC. After the reaction is completed, add 20mL of water to quench the reaction, let it stand and filter, dissolve the filter cake with dichloromethane, filter to remove the palladium acetate solid, and spin-dry the filtrate to obtain a yellow solid, which is the crude impurity G (liquid phase purity 79.79%).

[0101] The crude impurity G was dissolved in N,N-dimethylformamide and purified by preparative liquid phase (C18 column, 19*250mm, mobile phase was 10mmol / L ammonium bicarbonate aqueous solution and acetonitrile, retention time 12.5min) to obtain the pure impurity G (purity: 97.46%, yield: 12.8%).

[0102]

[0103] Example 2 Characterization of Impurity G

[0104] The mass spectrum of impurity G is as follows Figure 1 As shown, the mass-to-charge ratio (m / z) of impurity G [M+H] + It is 789.1.

[0105] The H NMR spectrum of impurity G is as follows Figure 2 As shown, 1H-NMR(DMSO-d6,400MHz)δ8.90,8.96(s,2H,H-1,H-23),7.25-8.05(m,8H,H-18,H-19,H- 20,H-22,H-40,H-41,H-42,H-44), 4.93,4.96(s,2H,H-4,H-26), 4.80-4.84(m,2H,H-14,H -36), 3.45-4.08 (m, 8H, H-10, H-11, H-32, H-33), 3.19, 3.23 (s, 6H, H-12, H-34), 2.28, 2.3 0(s,12H,H-7,H-8,H-29,H-30),1.04-1.06,1.20-1.22(dd,12H,H-15,H-16,H-37,H-38).

[0106] Therefore, the molecular weight and structure of impurity G are as follows:

[0107]

[0108] Example 3

[0109] A method for detecting nimodipine-related substances comprises the following steps:

[0110] 1) Sample treatment: Take appropriate amounts of nimodipine, methylparaben, impurity A, impurity B, impurity C, impurity D, impurity E, impurity F and impurity G reference substances, dissolve them in methanol-acetonitrile-water (35:38:27) solvent and quantitatively dilute them to prepare a mixed solution containing approximately 300 μg nimodipine, 6 μg p-hydroxybenzoic acid, 200 μg methylparaben, 1.5 μg impurity A, 0.6 μg impurity B, 0.6 μg impurity C, 0.6 μg impurity D, 0.6 μg impurity E, 0.6 μg impurity F and 0.6 μg impurity G per 1 ml as the system suitability solution.

[0111] 2) High performance liquid chromatography detection: Take the sample solution in step 1) and inject it. The detection conditions are as follows:

[0112] Chromatographic column: Thermo Syncronis C18 (4.6×250mm, 5μm) or chromatographic column with equivalent performance;

[0113] Mobile phase: Use 5mmol / L potassium dihydrogen phosphate (adjust pH to 3.0 with phosphoric acid) as mobile phase A, methanol-acetonitrile (50:50) as mobile phase B, and linear gradient elution according to the following table:

[0114]

[0115] Detection wavelength: 235nm;

[0116] Column temperature: 30°C;

[0117] Flow rate: 1.0ml / min;

[0118] Injection volume: 20 μl.

[0119] Example 4

[0120] A method for detecting nimodipine-related substances comprises the following steps:

[0121] 1) Sample treatment: Take appropriate amounts of nimodipine, methylparaben, impurity A, impurity B, impurity C, impurity D, impurity E, impurity F and impurity G reference substances, dissolve them in methanol-acetonitrile-water (35:38:27) solvent and quantitatively dilute them to prepare a mixed solution containing approximately 300 μg nimodipine, 6 μg p-hydroxybenzoic acid, 200 μg methylparaben, 1.5 μg impurity A, 0.6 μg impurity B, 0.6 μg impurity C, 0.6 μg impurity D, 0.6 μg impurity E, 0.6 μg impurity F and 0.6 μg impurity G per 1 ml as the system suitability solution.

[0122] 2) High performance liquid chromatography detection: Take the sample solution in step 1) and inject it. The detection conditions are as follows:

[0123] Chromatographic column: Thermo Syncronis C18 (4.6×250mm, 5μm) or chromatographic column with equivalent performance;

[0124] Mobile phase: Use 5mmol / L potassium dihydrogen phosphate (adjust pH to 3.0 with phosphoric acid) as mobile phase A, methanol-acetonitrile (50:50) as mobile phase B, and linear gradient elution according to the following table:

[0125]

[0126] Example 5-6 Elution gradient investigation

[0127] On the basis of Example 3, the effect of the elution gradient on the separation and detection of each impurity was investigated.

[0128] The inspection process is as follows:

[0129] Example 5: The difference from Example 3 is that the linear gradient elution is as follows:

[0130]

[0131] Example 6: The difference from Example 3 is that the linear gradient elution is as follows:

[0132]

[0133]

[0134] The results of the investigation are as follows Figure 3 As shown in Table 1:

[0135] Table 1. Results of elution gradient investigation of nimodipine related substances detection method

[0136]

[0137] The results of elution gradient investigation showed that

[0138] ① When the elution gradient shown in Example 5 was selected, impurity G did not appear and could not be separated;

[0139] ② When the elution gradient shown in Example 6 is selected, impurities D and F merge and cannot be separated;

[0140] ③ When the elution gradient shown in Example 3 or Example 4 is selected, impurity G can be separated and detected, and the simultaneous separation and detection of 9 related substances of nimodipine can also be achieved: p-hydroxybenzoic acid, methylparaben, impurity A, impurity B, impurity C, impurity D, impurity E, impurity F, and impurity G.

[0141] Example 6 Detection of Related Substances in Nimodipine Oral Solution

[0142] The method established in Example 3 or Example 4 was used to detect the related substances in the nimodipine oral solution after being placed under long-term stability conditions (temperature 25° C., relative humidity 60%) for 24 months.

[0143] The detection process is as follows:

[0144] 1) Sample treatment: Take an appropriate amount of nimodipine oral solution, weigh it accurately, dissolve it in methanol-acetonitrile-water (35:38:27) solvent and quantitatively dilute it to make a solution containing about 0.3 mg of nimodipine per 1 ml.

[0145] 2) High performance liquid chromatography detection: Same as Example 3

[0146] The test results are shown in Table 3:

[0147] Table 3. Stability results of nimodipine oral solution

[0148]

[0149] The stability results show that the detection method for related substances established in Example 3 (taking Example 3 as an example, but not limited to this, also including Example 4) can be used to separate and detect related substances in nimodipine oral solution. The long-term stability of related substances impurities A, impurity E, impurity F and impurity G increased significantly after 24 months, indicating that it is necessary to establish the limits of the aforementioned impurities (especially impurity G) to carry out quality control of nimodipine raw materials or their preparations (especially liquid preparations).

Claims

1. A nimodipine analogue, which is a compound represented by formula G or a pharmaceutically acceptable salt thereof:

2. A pharmaceutical composition comprising nimodipine and the nimodipine analog G according to claim 1.

3. The pharmaceutical composition according to claim 2, characterized in that The content of the nimodipine analogue G is ≤0.5%.

4. A method for preparing the nimodipine analog G according to claim 1, wherein the reaction scheme is as follows: The reaction steps include: Nimodipine and the reducing agent undergo a reduction reaction in the presence of a catalyst and a reaction solvent, and then undergo an oxidation reaction with an oxidant to produce impurity G.

5. The method for preparing the nimodipine analog G according to claim 4, characterized in that: The catalyst includes but is not limited to one or more of palladium acetate and tetrakistriphenylphosphine palladium; preferably, the catalyst is palladium acetate.

6. The method for preparing the nimodipine analog G according to claim 4, characterized in that: The reaction solvent includes, but is not limited to, one or more of water, ethanol, dichloromethane, methanol, and tetrahydrofuran; preferably, the reaction solvent is a mixed solvent of water and ethanol.

7. Use of the nimodipine analog G according to claim 1 in the medical field, including but not limited to use for impurity detection, quality control of nimodipine raw materials or their preparations.

8. Use of the nimodipine analog G as claimed in claim 7 in the medical field, including as nimodipine impurity G for detecting impurities in nimodipine raw materials or their preparations.

9. The use of the nimodipine analog G in the medical field as claimed in claim 8, wherein the impurity detection method is to detect nimodipine impurities by high performance liquid chromatography.

10. The use of the nimodipine analog G in the medical field as claimed in claim 9, wherein the chromatographic conditions for detecting nimodipine impurities by high performance liquid chromatography are as follows: Chromatographic column selection: Octadecylsilane bonded silica gel as filler. Further preferably, the mobile phase is selected as follows: potassium dihydrogen phosphate as mobile phase A, methanol-acetonitrile as mobile phase B, and linear gradient elution is performed as shown in the following table:

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