A modified bromhexine hydrochloride inhalation solution with enhanced stability and a method for its preparation

Abstract

The application discloses a modified bromhexine hydrochloride inhalation solution with enhanced stability and a preparation method thereof, and belongs to the technical field of medical preparations. The inhalation solution is mainly prepared from a targeting impurity control modified bromhexine hydrochloride inclusion compound, a special composite buffer mother liquor for inhibiting impurity B, inhalation grade sodium chloride, pharmaceutical grade sodium hydroxide and water for injection, and the pH value of the finished product is 4.5-5.5. The application constructs a three-stage progressive modification system, covalently grafts a mercapto-activated L-cysteine derivative onto hydroxypropyl-gamma-cyclodextrin to prepare a functional carrier, and realizes molecular-level isolation of bromhexine hydrochloride through host-guest inclusion, thereby blocking the generation of impurity B of bromhexine hydrochloride from the whole path, and solving the core pain points of easy impurity exceeding, short effective period and airway irritation of the existing product. The application can realize long-acting stable storage for 36 months, is suitable for the existing industrial production line, and has high clinical application and industrialization values.

Description

Technical Field

[0001] This invention relates to the field of medical preparations technology, specifically to a modified bromhexine hydrochloride inhalation solution with enhanced stability and its preparation method. Background Technology

[0002] Bromhexine hydrochloride is a first-line mucolytic agent in clinical practice. It can specifically lyse mucopolysaccharide fibers in sputum, reducing sputum viscosity. It also has anti-inflammatory, antitussive, and bronchodilator effects, and is widely used in the treatment of respiratory diseases such as chronic obstructive pulmonary disease, bronchitis, and asthma. The inhaled solution formulation can deliver the drug directly to the lung lesions, with rapid onset of action, high local drug concentration, and few systemic side effects, making it the preferred formulation for the clinical application of bromhexine hydrochloride.

[0003] The current production and clinical application of bromhexine hydrochloride inhalation solution face three major technical challenges: First, bromhexine hydrochloride has extremely poor water solubility, with a solubility of only 0.04 mg / mL in water at 25°C. Existing formulations require the addition of solubilizers such as Tween-80 and surfactants to achieve dissolution, which can easily cause respiratory mucosal irritation and allergic reactions, making it unsuitable for sensitive populations such as children and asthma patients. Second, bromhexine hydrochloride is highly sensitive to light, heat, and oxygen, and is prone to oxidative degradation during high-temperature sterilization and long-term storage. **Impurity B (chemical name: 2-amino-3,5-dibromobenzaldehyde)** is the most significant degradation product, and this impurity is listed as a potential source of warning structures by the ICH M7 guidelines. Genotoxic impurities are irritating to the respiratory mucosa. The 2025 edition of the Chinese Pharmacopoeia strictly stipulates that their limit should not exceed 0.5%. Their rapid increase is the core reason for the product's related substances exceeding the limit and the shortened shelf life. Thirdly, in order to inhibit the growth of impurity B, the existing technology generally adopts the formulation design of "strong acid system (pH 3.0-4.0) + excessive free antioxidant + solubilizer". The strong acid system deviates too much from the physiological pH of the human respiratory tract (5.5-7.0), which can easily cause airway spasm and mucosal irritation. Free antioxidants are prone to self-oxidation and failure, which cannot achieve long-term stable impurity control. It is impossible to achieve "precise control of impurity B, long-term product stability and mild clinical use".

[0004] Therefore, developing a bromhexine hydrochloride inhalation solution that can block the formation of impurity B at the molecular level, achieve high drug solubility and stability in a near-physiological weakly acidic system, and has no irritation or sensitization risk is a technical challenge that urgently needs to be solved in this field. Summary of the Invention

[0005] To address existing problems, this application provides a modified bromhexine hydrochloride inhalation solution with enhanced stability and its preparation method. By constructing a three-stage progressive modification system, the generation of impurity B in bromhexine hydrochloride is blocked from the source, catalysis, and reaction pathway. Under a near-physiological weakly acidic system of 4.5-5.5, the high solubility, high stability, and low irritation of bromhexine hydrochloride are achieved, completely solving the core pain points of existing products.

[0006] This invention provides a modified bromhexine hydrochloride inhalation solution with enhanced stability, employing the following technical solution:

[0007] A modified bromhexine hydrochloride inhalation solution with enhanced stability is mainly made from the following raw materials: a targeted impurity-controlled modified bromhexine hydrochloride inclusion complex, a special composite buffer stock solution for impurity B inhibition, inhalation-grade sodium chloride, pharmaceutical-grade sodium hydroxide, and water for injection; the pH value of the inhalation solution is 4.5-5.5, the targeted impurity-controlled modified bromhexine hydrochloride inclusion complex is prepared by encapsulating bromhexine hydrochloride with a functionalized hydroxypropyl-γ-cyclodextrin carrier, and the functionalized hydroxypropyl-γ-cyclodextrin carrier is prepared by covalently grafting hydroxypropyl-γ-cyclodextrin with a thiol-activated L-cysteine ​​derivative.

[0008] Furthermore, the targeted impurity-controlled modified bromhexine hydrochloride inclusion complex is prepared by inclusion of functionalized hydroxypropyl-γ-cyclodextrin carrier and bromhexine hydrochloride at a mass ratio of 25:4, with an inclusion rate of ≥94%; the bromhexine hydrochloride is pharmaceutical grade with a purity of ≥99.5% and an initial content of impurity B of ≤0.05%.

[0009] Furthermore, the functionalized hydroxypropyl-γ-cyclodextrin carrier is prepared by reacting hydroxypropyl-γ-cyclodextrin with a thiol-activated L-cysteine ​​derivative at a mass ratio of 25:6, with a grafting rate ≥85%; the hydroxypropyl-γ-cyclodextrin is an inhalation-grade pharmaceutical excipient with a degree of substitution of 4.0-6.0, and its bacterial endotoxin meets the requirements for injection grade.

[0010] Furthermore, the thiol-activated L-cysteine ​​derivative is prepared by directional activation of L-cysteine ​​hydrochloride monohydrate with 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, with an activation degree ≥90%; the L-cysteine ​​hydrochloride monohydrate is pharmaceutical grade and meets the standards of the Chinese Pharmacopoeia.

[0011] Furthermore, the impurity B inhibition-specific composite buffer stock solution is prepared from sodium dihydrogen phosphate dihydrate, disodium hydrogen phosphate dodecahydrate, and water for injection. The stock solution has a pH of 5.0 and a buffer capacity of ≥0.02 mol / L·pH. Both sodium dihydrogen phosphate dihydrate and disodium hydrogen phosphate dodecahydrate are pharmaceutical grade and meet the standards of the Chinese Pharmacopoeia.

[0012] Furthermore, based on 1000ml of finished product, the amount of raw materials used is as follows: 13.5-15.5g of targeted impurity-controlled modified bromhexine hydrochloride inclusion complex, equivalent to 2.0g of bromhexine hydrochloride; 50.0ml of impurity B inhibition-specific composite buffer stock solution; 9.0g of inhalation-grade sodium chloride; appropriate amount of pharmaceutical-grade sodium hydroxide; and water for injection to 1000ml; the inhalation-grade sodium chloride is pharmaceutical-grade, conforms to the standards of the Chinese Pharmacopoeia, and is used as an isotonic regulator.

[0013] Furthermore, the finished inhalation solution has a specification of 2ml:4mg, and after being sterilized by moist heat at 121℃ for 15min, the increase of impurity B is ≤28%, and after long-term storage for 12 months, the content of impurity B is ≤0.12%, the respiratory irritation level is 0, and the sterility and bacterial endotoxins meet the requirements of the Chinese Pharmacopoeia inhalation preparation standards.

[0014] Secondly, the present invention provides a method for preparing a modified bromhexine hydrochloride inhalation solution with enhanced stability, employing the following technical solution:

[0015] A method for preparing a modified bromhexine hydrochloride inhalation solution with enhanced stability includes the following steps:

[0016] S1. Purge the liquid preparation tank with high-purity nitrogen for 30 minutes to purge the air inside the tank. Add 80% of the formula amount of water for injection. Cool down to below 30°C. Continuously purge with high-purity nitrogen throughout the process. Control the dissolved oxygen in the system to ≤0.5mg / L. Add the formula amount of inhalation-grade sodium chloride. Stir at 200rpm for 15 minutes until completely dissolved to obtain an isotonic basic solution.

[0017] S2. Add the prescribed amount of targeted controlled impurity modified bromhexine hydrochloride inclusion complex powder to the isotonic base solution, stir at 250 rpm in the dark for 20 min until completely dissolved, and obtain a clear drug main solution. Keep nitrogen protection throughout the process.

[0018] S3. Slowly add the prescribed amount of impurity B inhibition-specific composite buffer mother liquor to the main drug solution while stirring. After mixing evenly, take a sample to test the initial pH value of the system.

[0019] S4. Under constant temperature of 25℃±2℃, nitrogen purging and light protection, and continuous stirring, the pH value of the system is adjusted dropwise to 4.5-5.5 with a standardized 0.1mol / L pharmaceutical grade sodium hydroxide standard solution. Water for injection is added to the total volume. The system is stirred at 200rpm for 10min in the dark until it is homogeneous. The system is then filtered through a 0.22μm polyethersulfone sterile filter membrane. Nitrogen purging and light protection are maintained throughout the process.

[0020] S5. In an ISO 5 Class A clean environment, fill the filtrate into brown neutral borosilicate glass ampoules. Before filling, purge the ampoules with nitrogen to replace the air. After sealing, the headspace oxygen residue should be ≤1%. 100% leak detection and light inspection are required.

[0021] S6. Place the filled ampoules in a pulsating vacuum sterilizer and sterilize them at 121℃ for 15 minutes with an F0 value ≥ 12. Then, gradually cool them down to room temperature to obtain the finished bromhexine hydrochloride inhalation solution.

[0022] Furthermore, the preparation method of the targeted heterogeneous modified bromhexine hydrochloride inclusion complex includes the following steps:

[0023] S1. Preparation of thiol-activated L-cysteine ​​derivative: L-cysteine ​​hydrochloride monohydrate was dissolved in a 4:1 mixture of anhydrous ethanol and water for injection. Nitrogen gas was purged throughout the process to remove oxygen. 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride was added, and the mixture was stirred at 25°C in the dark for 3 hours to complete the directional activation of the carboxyl group. After filtration, concentration, washing, and drying, the thiol-activated L-cysteine ​​derivative was obtained.

[0024] S2. Preparation of functionalized hydroxypropyl-γ-cyclodextrin carrier: Hydroxypropyl-γ-cyclodextrin was added to water for injection, heated to 45℃ and stirred to dissolve, nitrogen gas was passed through to remove oxygen, thiol-activated L-cysteine ​​derivative was added, pH was adjusted to 5.0, and the reaction was carried out at 45℃ in the dark for 10 h to complete covalent grafting. After precipitation, washing, ultrafiltration purification, freeze drying and pulverization, functionalized hydroxypropyl-γ-cyclodextrin carrier was obtained.

[0025] S3. Preparation of targeted impurity-controlled modified bromhexine hydrochloride inclusion complex: Functionalized hydroxypropyl-γ-cyclodextrin carrier was added to water for injection, heated to 45℃ and stirred to dissolve, and nitrogen gas was purged to remove oxygen, resulting in an aqueous solution of the functionalized carrier; bromhexine hydrochloride was added to pharmaceutical-grade anhydrous ethanol and stirred to dissolve, resulting in an alcoholic solution of bromhexine hydrochloride; the alcoholic solution was slowly added dropwise to the carrier aqueous solution at a rate of 0.8 ml / min, and the reaction was carried out at 45℃ in the dark for 120 min to complete the inclusion. After de-alcoholization under reduced pressure, filtration, freeze-drying, and pulverization, the targeted impurity-controlled modified bromhexine hydrochloride inclusion complex was obtained.

[0026] Furthermore, the preparation method of the special composite buffer stock solution for impurity B inhibition is as follows: high-purity nitrogen gas is passed through water for injection for 15 minutes, the dissolved oxygen is controlled to be ≤0.5mg / L, the temperature is controlled to be below 25℃, pharmaceutical grade sodium dihydrogen phosphate dihydrate and disodium hydrogen phosphate dodecahydrate are added, stirred until completely dissolved, filtered through a 0.22μm sterile filter membrane, sealed and refrigerated at 2-8℃ for later use.

[0027] In summary, this application has the following beneficial effects:

[0028] 1. This invention constructs a three-stage progressive modification system, strictly following the core model of "targeted impurity-controlled modified bromhexine hydrochloride inclusion complex = bromhexine hydrochloride + functionalized hydroxypropyl-γ-cyclodextrin carrier; functionalized hydroxypropyl-γ-cyclodextrin carrier = hydroxypropyl-γ-cyclodextrin + thiol-activated L-cysteine ​​derivative", achieving precise blocking from the entire pathway of impurity B generation. The first stage of modification involves the targeted activation of L-cysteine, retaining its core functions of antioxidation and metal chelation, while endowing it with covalent grafting activity. The second stage of modification involves grafting the activated L-cysteine ​​onto the hydroxypropyl-γ-cyclodextrin port to prepare a carrier with three functions: molecular inclusion, targeted antioxidation, and metal chelation, solving the defect of free antioxidants being prone to self-oxidation and failure. The third stage of modification involves host-guest inclusion to encapsulate the bromhexine hydrochloride molecule within the hydrophobic cavity of the cyclodextrin, achieving molecular-level physical isolation. The three components work together to form an integrated protective structure of "cavity isolation - port blocking - catalytic elimination". After sterilization at 121℃, the increase of impurity B is only 25%, and the content of impurity B is only 0.10% after 12 months, which is far below the pharmacopoeia limit and more than 80% lower than the existing technology, completely solving the industry pain point of excessive impurity B in this product.

[0029] 2. This invention achieves unexpected synergistic effects through covalent grafting modification. The L-cysteine ​​derivative grafted onto the cyclodextrin port can be targeted and enriched around the drug molecule, forming in-situ protection at the core site of impurity B generation, simultaneously blocking the oxidative cleavage of bromhexine hydrochloride and secondary oxidation of intermediates. The impurity control efficiency is far higher than that of free and dispersed antioxidants. At the same time, the steric hindrance effect of cyclodextrin can effectively prevent the self-oxidation of thiol groups. The retention rate of active thiol groups reaches 86.2% after 12 months, which is 4.6 times that of free antioxidants, achieving long-term antioxidant impurity control for more than 12 months and solving the industry problem of short-term failure of free antioxidants.

[0030] 3. This invention requires no addition of any solubilizers, surfactants, or strong irritant pH adjusters. Through inclusion modification, the water solubility of bromhexine hydrochloride is increased from 0.04 mg / mL to over 20 mg / mL, completely solving the problem of low-temperature crystallization of the drug. The product's pH value is controlled within the near-physiological range of 4.5-5.5, and its respiratory irritation level is 0, making it safe for use in sensitive populations such as children and asthma patients. This achieves a balance between product stability and clinical safety.

[0031] 4. The preparation process of this invention is fully compatible with the existing industrial production line of bromhexine hydrochloride inhalation solution. No new equipment or major process changes are required. The quality is consistent and stable between batches. The product shelf life can be extended from the current 24 months to 36 months, which greatly reduces production, storage and transportation costs. It has extremely high industrialization value and clinical application value. Detailed Implementation

[0032] To make the technical solution and core advantages of the present invention clearer, the present invention will be further described in detail below with reference to preparation examples, embodiments, comparative examples, and performance tests. The described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] Unless otherwise specified, all raw materials used in the embodiments of this invention are commercially available pharmaceutical-grade conventional products that meet the requirements of the 2025 edition of the Chinese Pharmacopoeia and relevant standards for inhaled preparations; all experimental operations, unless otherwise specified, meet the requirements for sterile preparations in the Good Manufacturing Practice for Pharmaceuticals.

[0034] Controlled object description:

[0035] Impurity B in bromhexine hydrochloride is a core quality control related substance for bromhexine hydrochloride as specified in the 2025 edition of the Chinese Pharmacopoeia. Its chemical name is 2-amino-3,5-dibromobenzaldehyde, CAS number: 50910-55-9, molecular formula C7H5Br2NO, and molecular weight 278.93. More than 90% of this impurity originates from the oxidative degradation of bromhexine hydrochloride in the formulation. The specific pathway is as follows: the N-methylcyclohexylamine group in the bromhexine hydrochloride molecule undergoes oxidative cleavage, generating the intermediate 2-amino-3,5-dibromobenzaldehyde. This intermediate undergoes secondary oxidation under the catalysis of dissolved oxygen and trace transition metal ions, ultimately generating impurity B in bromhexine hydrochloride. The 2025 edition of the Chinese Pharmacopoeia stipulates that the limit for impurity B in this product must not exceed 0.5%, and its increase directly determines the quality and shelf life of the product.

[0036] raw material:

[0037] Some of the raw materials used in the preparation examples and embodiments: bromhexine hydrochloride (pharmaceutical grade, purity ≥99.5%, initial content of impurity B ≤0.05%, other related substances conform to the standards of the Chinese Pharmacopoeia, CAS No.: 611-75-6, purchased from Shanghai Yuanye Biotechnology Co., Ltd.); hydroxypropyl-γ-cyclodextrin (inhalation grade pharmaceutical excipient, degree of substitution 4.0-6.0, bacterial endotoxin meets the requirements for injection grade, non-hemolytic, non-respiratory irritant, conforms to USP / EP / CP standards, CAS No.: 128446-34-4, purchased from Zibo Qianhui Biotechnology Co., Ltd.); L-cysteine ​​hydrochloride monohydrate (pharmaceutical grade, conforms to the standards of the Chinese Pharmacopoeia, CAS No.: 7048-04-6, purchased from Shanghai Yuanye Biotechnology Co., Ltd.); 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (pharmaceutical grade activator, conforms to EP standards, non-inhalation toxicity, CAS No. 128446-34-4, purchased from Zibo Qianhui ... L-cysteine ​​hydrochloride monohydrate (pharmaceutical grade activator, conforms to EP standards, non-inhalation toxicity, CAS No. 128446-34-4, purchased from Zibo Qianhui Biotechnology Co., Ltd.); 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide Sodium dihydrogen phosphate dihydrate (pharmaceutical grade, conforming to the Chinese Pharmacopoeia standard, CAS No.: 13472-35-0, purchased from Jinan Yuanlian Chemical Co., Ltd.); disodium hydrogen phosphate dodecahydrate (pharmaceutical grade, conforming to the Chinese Pharmacopoeia standard, CAS No.: 10039-32-4, purchased from Nanjing Chemical Reagent Co., Ltd.); sodium chloride (inhalation grade pharmaceutical grade, conforming to the Chinese Pharmacopoeia standard, isotonicity adjuster, CAS No.: 7647-14-5, purchased from Shaanxi Mingcheng Pharmaceutical Co., Ltd.); sodium hydroxide (pharmaceutical grade, conforming to the Chinese Pharmacopoeia standard, used for pH fine-tuning, CAS No.: 1310-73-2, purchased from Xi'an Xinfengda Pharmaceutical Excipients Co., Ltd.); water for injection (as a solvent, conforming to the Chinese Pharmacopoeia standard, purchased from Shaanxi Didu Pharmaceutical Chemical Co., Ltd.).

[0038] Unless otherwise specified, all raw materials used in the examples and comparative examples are conventional products that can be purchased from the market.

[0039] I. Preparation Example

[0040] Preparation Example 1

[0041] Preparation steps of thiol-directed activated L-cysteine ​​derivatives:

[0042] S1. Take 10g of L-cysteine ​​hydrochloride monohydrate, add 120ml of a mixed solvent of anhydrous ethanol and water for injection, with a volume ratio of 4:1, stir at 25℃ and 200rpm for 15min until completely dissolved, and purge with high-purity nitrogen for 10min to remove oxygen and prevent thiol self-oxidation, to obtain L-cysteine ​​solution.

[0043] S2. Add 8g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride to the solution, stir at 300rpm for 3h at 25℃ in the dark to complete the carboxyl-directed activation reaction and generate a mercapto-activated L-cysteine ​​derivative solution. Nitrogen protection is maintained throughout the process.

[0044] S3. The reaction solution was filtered through a 0.22 μm organic filter membrane. The filtrate was concentrated to dryness under reduced pressure at 35 °C and -0.08 MPa. It was washed three times with three times the volume of cold anhydrous ethanol at 4 °C. After vacuum drying, the mercapto-directed activated L-cysteine ​​derivative powder was obtained.

[0045] Quality control indicators and testing methods:

[0046] 1. Activation degree ≥ 90%, detected by potentiometric titration: The instrument is an automatic potentiometric titrator with an accuracy of 0.001 grade, equipped with a calomel reference electrode and a glass indicating electrode; accurately weigh 0.5 g of this product, accurately add 20 ml of anhydrous ethanol-water mixed solvent, stir at 25℃ until completely dissolved, insert the electrode into the sample solution, and perform potentiometric titration with 0.1 mol / L hydrochloric acid standard titration solution, recording the volume consumed corresponding to the titration jump. Perform a blank test in the same way, and calculate the activation degree according to the formula: Activation degree = (actual molar amount of activated carboxyl groups / theoretical total molar amount of carboxyl groups) × 100%;

[0047] 2. Moisture content ≤ 2.0%, determined by Karl Fischer volumetric method according to General Chapter 0832, Method I, of the 2025 edition of the Chinese Pharmacopoeia.

[0048] Preparation Example 2

[0049] Preparation steps of functionalized hydroxypropyl-γ-cyclodextrin carrier:

[0050] S1. Take 25g of inhalation grade hydroxypropyl-γ-cyclodextrin, add 200ml of water for injection, heat to 45℃, stir at 300rpm for 20min until completely dissolved, and purge with high-purity nitrogen for 15min to remove oxygen, to obtain hydroxypropyl-γ-cyclodextrin aqueous solution.

[0051] S2. Take 6g of the mercapto-activated L-cysteine ​​derivative powder obtained in Preparation Example 1, add it to the above solution, adjust the pH of the system to 5.0 with 0.1mol / L sodium hydroxide solution, keep the reaction at 45℃ and stir at 350rpm in the dark for 10h to complete the amide bond covalent grafting reaction, and keep the nitrogen protection throughout the process.

[0052] S3. Cool the reaction solution to room temperature, add 8 times the volume of anhydrous acetone, let it stand for 2 hours to precipitate, filter and collect the precipitate, wash it 3 times with anhydrous acetone to completely remove unreacted thiol-activated L-cysteine ​​derivatives.

[0053] S4. The precipitate was reconstituted with water for injection and purified by ultrafiltration through an ultrafiltration membrane with a molecular weight cutoff of 5000 Da at an operating pressure of 0.2 MPa. The precipitate was washed five times with water for injection to remove small molecule impurities. The ultrafiltrate was freeze-dried at -40℃ and 0.08 MPa for 24 h and then pulverized through a 200-mesh sieve to obtain functionalized hydroxypropyl-γ-cyclodextrin carrier powder.

[0054] Quality control indicators and testing methods:

[0055] 1. Grafting rate ≥ 85%, detected by pre-column derivatization in high-performance liquid chromatography (HPLC): 4.6 mm × 250 mm, 5 μm C18 column; mobile phase: acetonitrile-0.05 mol / L potassium dihydrogen phosphate aqueous solution, volume ratio 15:85; detection wavelength: 412 nm; column temperature: 30℃; flow rate: 1.0 ml / min; injection volume: 20 μl; derivatization reagent: Ellman reagent; standard curve plotted using L-cysteine ​​standard; 10 mg of this sample accurately weighed for derivatization and injection; L-cysteine ​​mass corresponding to thiol groups in the sample calculated using the standard curve; grafting rate calculated using the formula: Grafting rate = (actual grafted L-cysteine ​​mass / theoretical maximum grafted L-cysteine ​​mass) × 100%;

[0056] 2. Moisture content ≤ 2.0%, detection method is the same as in preparation example 1.

[0057] Preparation Example 3

[0058] Preparation steps of targeted impurity-controlled modified bromhexine hydrochloride inclusion complex:

[0059] S1. Take 25g of the functionalized hydroxypropyl-γ-cyclodextrin carrier powder prepared in Preparation Example 2, add 200ml of water for injection, heat to 45℃, stir at 300rpm for 30min until completely dissolved, and pass high-purity nitrogen gas through for 15min to remove oxygen, to obtain an aqueous solution of the functionalized carrier.

[0060] S2. Take 4g of bromhexine hydrochloride, with an initial content of impurity B ≤0.05%, add 50ml of pharmaceutical grade anhydrous ethanol, stir at 25℃ in the dark for 15min until completely dissolved, to obtain bromhexine hydrochloride alcohol solution.

[0061] S3. Slowly add the bromhexine hydrochloride solution dropwise into the functionalized support aqueous solution at a rate of 0.8 ml / min, keep the temperature constant at 45℃ and stir at 350 rpm in the dark for 120 min to complete the host-guest inclusion reaction, and keep the process under nitrogen protection.

[0062] Ethanol was completely removed by rotary evaporation under reduced pressure at S4, 38℃, and -0.08MPa. The mixture was then filtered through a 0.22μm sterile filter membrane, freeze-dried under vacuum at -40℃ and 0.08MPa for 24 hours, and pulverized through a 200-mesh sieve to obtain a targeted impurity-controlled modified bromhexine hydrochloride inclusion complex powder.

[0063] Quality control indicators and testing methods:

[0064] 1. Inclusion rate ≥94%, detected by high performance liquid chromatography: chromatographic column: C18 column, 4.6mm × 250mm, 5μm; mobile phase: acetonitrile-0.02mol / L heptanesulfonate solution, pH adjusted to 3.0 with phosphoric acid, volume ratio 45:55; detection wavelength: 248nm; column temperature: 30℃; flow rate: 1.0ml / min; injection volume: 20μl; accurately weigh 0.5g of the sample, separate free bromhexine hydrochloride by methanol precipitation, determine total bromhexine hydrochloride content by ultrasonic disruption, and calculate inclusion rate using the formula: Inclusion rate = (1 - free bromhexine hydrochloride content / total bromhexine hydrochloride content) × 100%;

[0065] 2. The labeled content of bromhexine hydrochloride is 13.8% ± 2%, and the initial content of impurity B is ≤ 0.05%. The detection method is the same as that in the performance test module below.

[0066] 3. Moisture content ≤ 2.0%, detection method is the same as in preparation example 1.

[0067] Preparation Example 4

[0068] Preparation steps of bromhexine hydrochloride inclusion complex with ordinary hydroxypropyl-γ-cyclodextrin:

[0069] S1. Take 25g of ordinary inhalation grade hydroxypropyl-γ-cyclodextrin, add 200ml of water for injection, heat to 45℃, stir at 300rpm for 30min until completely dissolved, and pass high-purity nitrogen gas through for 15min to remove oxygen, to obtain an aqueous solution of ordinary hydroxypropyl-γ-cyclodextrin.

[0070] S2. Take 4g of bromhexine hydrochloride, with an initial content of impurity B ≤0.05%, add 50ml of pharmaceutical grade anhydrous ethanol, stir at 25℃ in the dark for 15min until completely dissolved, to obtain bromhexine hydrochloride alcohol solution.

[0071] S3. Following steps S3-S4 of Preparation Example 3, ordinary hydroxypropyl-γ-cyclodextrin-encapsulated bromhexine hydrochloride powder was prepared.

[0072] Quality control indicators: The inclusion rate was 94.1%, which was basically the same as that of Preparation Example 3. The only variable was whether the cyclodextrin was grafted with an L-cysteine ​​derivative. The inclusion rate detection method was the same as that of Preparation Example 3.

[0073] Preparation Example 5

[0074] Preparation steps of the mother liquor for inhibiting impurity B:

[0075] S1. Take 100ml of water for injection, purify it with high-purity nitrogen for 15min throughout the process, control dissolved oxygen ≤0.5mg / L, and keep the temperature below 25℃ throughout the process.

[0076] S2. Add 2.5g of pharmaceutical grade sodium dihydrogen phosphate dihydrate and 0.8g of disodium hydrogen phosphate dodecahydrate, stir at 200rpm for 10min until completely dissolved to obtain a buffer base solution with pH 5.0;

[0077] S3. After filtration through a 0.22μm sterile filter membrane, sealed and filled with nitrogen, and stored at 2-8℃ for later use, the product has a shelf life of 72 hours, yielding a special composite buffer mother liquor for inhibiting impurity B.

[0078] Quality control indicators and testing methods:

[0079] 1. The pH value of the mother liquor was 5.0±0.1, measured using a calibrated 0.01-grade precision pH meter;

[0080] 2. The buffer capacity is ≥0.02 mol / L pH. It is detected by potentiometric titration. The volume of 0.1 mol / L hydrochloric acid standard solution consumed when the pH value decreases by 1 unit is recorded, and the buffer capacity is calculated according to the formula.

[0081] 3. Dissolved oxygen ≤ 0.5 mg / L, measured using a calibrated portable dissolved oxygen meter.

[0082] II. Implementation Examples

[0083] All examples in this study describe the preparation of bromhexine hydrochloride inhalation solution. The formulation was designed for industrial production in 1000ml volumes, and the finished product specification is 2ml:4mg, which is completely consistent with the legal specification approved by the National Medical Products Administration. The core quality control objective was the full-cycle control of impurity B in bromhexine hydrochloride. All preparation operations were performed in an ISO 5.0 cleanroom environment, with the background environment being an ISO 7.0 cleanroom, meeting the requirements for sterile preparations under the Good Manufacturing Practice (GMP) for pharmaceuticals.

[0084] Example 1

[0085] Raw material formula (based on 1000ml of finished product):

[0086] Targeted impurity-controlled modified bromhexine hydrochloride inclusion complex was prepared in Example 3, yielding 14.5 g, equivalent to 2.0 g of bromhexine hydrochloride, with an initial impurity B content ≤0.05%.

[0087] The mother liquor for inhibiting impurity B was prepared in Example 5, yielding 50.0 ml.

[0088] Inhalation grade sodium chloride: 9.0g;

[0089] Pharmaceutical grade sodium hydroxide: appropriate amount;

[0090] Water for injection: Add up to 1000 ml.

[0091] Preparation steps:

[0092] S1. Purge the dispensing tank with high-purity nitrogen for 30 minutes in advance, completely evacuate the air in the tank, add 800 ml of water for injection, cool down to below 30 °C, continuously introduce high-purity nitrogen throughout the process, control the dissolved oxygen in the system ≤ 0.5 mg / L, and avoid the growth of impurity B caused by oxidation reaction; add the formulated inhalation-grade sodium chloride, stir at 200 rpm for 15 minutes until completely dissolved to obtain an isosmotic basic solution.

[0093] S2. Add the formulated targeted impurity-controlled modified ambroxol hydrochloride inclusion complex powder to the isosmotic basic solution, stir in the dark at 250 rpm for 20 minutes until completely dissolved to obtain a clear drug main solution, and maintain nitrogen protection throughout the process.

[0094] S3. Slowly add the formulated composite buffer mother liquor to the drug main solution, stir while adding, and after mixing evenly, take a sample to detect the initial pH value of the system.

[0095] S4. Under the conditions of constant temperature at 25 °C ± 2 °C, nitrogen filling and light protection, and continuous stirring, use a freshly prepared and volumetrically calibrated 0.1 mol / L pharmaceutical-grade sodium hydroxide standard solution, and add it dropwise to the system at a rate of 0.5 ml / min; pause stirring for 1 minute after adding 1 ml each time, and after the system is uniform, use a 0.01-level precision pH meter calibrated at two points to detect the pH value; when the pH value of the system approaches 4.8, reduce the dropping rate to 0.2 ml / min for fine adjustment drop by drop until the pH value of the system is stable within the range of 5.0 ± 0.2 for three consecutive detections, then stop dropping; add water for injection to make up to 1000 ml, stir in the dark at 200 rpm for 10 minutes until the system is uniform, and recheck that the dissolved oxygen in the system ≤ 0.5 mg / L; filter through a 0.22 μm polyethersulfone sterile filter membrane at the end, and immediately perform the bubble point integrity test on the filter membrane after filtration. If the bubble point value meets the filter membrane factory standard, it is judged as qualified, and nitrogen filling protection and light protection operations are maintained throughout the process.

[0096] S5. Under the ISO5-class A-level clean environment, fill the filtrate into brown neutral borosilicate glass ampoules, 2 ml per ampoule; before filling the ampoules, purge with high-purity nitrogen at 5 L / min for 10 s, and after filling, purge with nitrogen at 3 L / min for 5 s again and then immediately seal by melting. After melting, the residual oxygen in the headspace ≤ 1%, and 100% leak detection and lamp inspection are carried out.

[0097] S6. Place the filled ampoules in a pulsating vacuum sterilizer and sterilize them at 121℃ for 15 minutes with an F0 value ≥ 12. During the sterilization process, the ampoules are placed upside down, and the temperature fluctuation is controlled within ±0.5℃ throughout the sterilization process. After sterilization, the temperature is gradually reduced to room temperature. The temperature curve and F0 value of the sterilizer are fully inspected to ensure complete sterilization and obtain the finished bromhexine hydrochloride inhalation solution.

[0098] Finished product quality control indicators: pH value 5.0±0.2, bromhexine hydrochloride content 95.0%-105.0% of the labeled amount, impurity B≤0.10%, total impurities≤0.30%, sterility and endotoxin meet the pharmacopoeia requirements.

[0099] Example 2

[0100] Raw material formula (based on 1000ml of finished product):

[0101] Targeted impurity-controlled modified bromhexine hydrochloride inclusion complex was prepared in Example 3, yielding 13.5 g, equivalent to 2.0 g of bromhexine hydrochloride, with an initial impurity B content ≤0.05%.

[0102] The mother liquor for inhibiting impurity B was prepared in Example 5, yielding 50.0 ml.

[0103] Inhalation grade sodium chloride: 9.0g;

[0104] Pharmaceutical grade sodium hydroxide: appropriate amount;

[0105] Water for injection: Add to 1000ml.

[0106] Preparation steps: Same as in Example 1, except that the target value for pH fine-tuning in step S4 is 4.7±0.2. The remaining steps and quality control requirements are exactly the same as in Example 1, and the finished product bromhexine hydrochloride inhalation solution is obtained.

[0107] Example 3

[0108] Raw material formula (based on 1000ml of finished product):

[0109] Targeted impurity-controlled modified bromhexine hydrochloride inclusion complex was prepared in Example 3, yielding 15.5 g, equivalent to 2.0 g of bromhexine hydrochloride, with an initial impurity B content ≤0.05%.

[0110] The mother liquor for inhibiting impurity B was prepared in Example 5, yielding 50.0 ml.

[0111] Inhalation grade sodium chloride: 9.0g;

[0112] Pharmaceutical grade sodium hydroxide: appropriate amount;

[0113] Water for injection: Add to 1000ml.

[0114] Preparation steps: Same as in Example 1, except that the target value for pH fine-tuning in step S4 is 5.3±0.2. The remaining steps and quality control requirements are exactly the same as in Example 1, and the finished product bromhexine hydrochloride inhalation solution is obtained.

[0115] Example 4

[0116] Raw material formulation: Same as in Example 1. The target value for pH fine-tuning in step S4 is 4.5±0.2. The remaining steps and quality control requirements are exactly the same as in Example 1, resulting in the finished bromhexine hydrochloride inhalation solution.

[0117] Example 5

[0118] Raw material formulation: Same as in Example 1. The target value for pH fine-tuning in step S4 is 5.5±0.2. The remaining steps and quality control requirements are exactly the same as in Example 1, resulting in the finished bromhexine hydrochloride inhalation solution.

[0119] III. Comparative Example

[0120] All comparative examples used the formation and growth of bromhexine hydrochloride impurity B as the core control index to verify the targeted control effect of the modified system of the present invention on impurity B. Except for the parameters that were clearly adjusted, all other preparation environments, process steps and quality control standards of the comparative examples were completely consistent with those of Example 1, and the corresponding control samples were finally obtained.

[0121] Comparative Example 1

[0122] Raw material formula (based on 1000ml of finished product):

[0123] Bromhexine hydrochloride raw material: 2.0g, initial content of impurity B ≤0.05%;

[0124] The composite buffer stock solution, prepared in Example 5, yielded 50.0 ml.

[0125] Inhalation grade sodium chloride: 9.0g;

[0126] Pharmaceutical grade Tween-80: 2.0g, solubilizer;

[0127] Water for injection: Add to 1000ml.

[0128] Preparation steps: Except for step S2, which involves adding bromhexine hydrochloride raw material and Tween-80, the rest are the same as in Example 1. Finally, the pH is adjusted to 5.0±0.2 to obtain an unmodified bromhexine hydrochloride solution control sample.

[0129] Comparative Example 2

[0130] Raw material formulation: Same as in Example 1. The modified bromhexine hydrochloride inclusion complex was prepared by including bromhexine hydrochloride with ordinary hydroxypropyl-γ-cyclodextrin as in Preparation Example 4, without the L-cysteine ​​grafting step. The rest was the same as in Example 1, and a control sample was obtained.

[0131] Comparative Example 3

[0132] Raw material formulation: Same as in Example 1, except that functionalized hydroxypropyl-γ-cyclodextrin carrier is not used. Bromohexine hydrochloride, ordinary hydroxypropyl-γ-cyclodextrin, and L-cysteine ​​hydrochloride are directly physically mixed and fed into the sample. The rest is the same as in Example 1 to obtain the control sample.

[0133] Comparative Example 4

[0134] Raw material formulation: Same as in Example 1, except that the pH was adjusted to 3.0 with hydrochloric acid, and the rest was the same as in Example 1, to obtain the control sample.

[0135] Comparative Example 5

[0136] Raw material formulation: Same as in Example 1, except that the pH was adjusted to 6.5 with sodium hydroxide, and the rest was the same as in Example 1, to obtain the control sample.

[0137] Comparative Example 6

[0138] A domestically approved inhaled bromhexine hydrochloride solution, with a specification of 2ml:4mg, was selected as a commercially available control sample.

[0139] Comparative Example 7

[0140] Raw material formula (based on 1000ml of finished product):

[0141] Example 4 describes the preparation of bromhexine hydrochloride encapsulated in ordinary hydroxypropyl-γ-cyclodextrin, yielding 14.5 g, equivalent to 2.0 g of bromhexine hydrochloride, with an initial impurity B content ≤0.05%.

[0142] L-cysteine ​​hydrochloride monohydrate: 2.55 g, which is exactly the same as the molar amount of L-cysteine ​​corresponding to the 85% grafting rate of the functionalized hydroxypropyl-γ-cyclodextrin carrier in Example 1;

[0143] The mother liquor for inhibiting impurity B was prepared in Example 5, yielding 50.0 ml.

[0144] Inhalation grade sodium chloride: 9.0g;

[0145] Pharmaceutical grade sodium hydroxide: appropriate amount;

[0146] Water for injection: Add to 1000ml.

[0147] Preparation steps: Same as in Example 1, except that in step S2, ordinary hydroxypropyl-γ-cyclodextrin is added to encapsulate bromhexine hydrochloride powder and free L-cysteine ​​hydrochloride monohydrate. The remaining steps are completely the same. Finally, the pH is adjusted to 5.0±0.2 to obtain the control sample.

[0148] IV. Performance Testing

[0149] Samples from Examples 1-5 and Comparative Examples 1-7 were taken respectively, and all performance items were tested according to the following standard methods.

[0150] 1. Core detection methods:

[0151] Determination of bromhexine hydrochloride content: High performance liquid chromatography was used, and the chromatographic conditions were the same as those for inclusion rate detection in Preparation Example 3. The content of bromhexine hydrochloride was calculated by peak area according to the external standard method and expressed as a percentage of the labeled amount.

[0152] Detection of impurity B in bromhexine hydrochloride: The specific high-performance liquid chromatography method for bromhexine hydrochloride as specified in the 2025 edition of the Chinese Pharmacopoeia was adopted. The chromatographic column was an octadecylsilane-bonded silica gel packed column of 4.6 mm × 250 mm and 5 μm. The mobile phase was acetonitrile-water-triethylamine 420:580:1, and the pH was adjusted to 3.0 with phosphoric acid. The detection wavelength was 248 nm, the column temperature was 30 ℃, the flow rate was 1.0 ml / min, and the injection volume was 20 μl. The content of impurity B was calculated by peak area using the external standard method.

[0153] Total impurity detection: Under the same chromatographic conditions as impurity B detection, calculate the total impurity content using the self-comparison method;

[0154] Retention rate of active thiol groups: High performance liquid chromatography with Ellman reagent was used. Samples were taken at 0 months, 3 months, 6 months, and 12 months for analysis. Thiol group retention rate = (active thiol content at the detection time point / initial active thiol content at day 0) × 100%;

[0155] Stability testing: Accelerated stability was tested at 40℃±2℃ and RH75%±5% for 6 months, and long-term stability was tested at 25℃±2℃ and RH60%±10% for 12 months. Relevant indicators were measured and tested respectively.

[0156] Aseptic, endotoxin, respiratory irritation, hemolysis, acute inhalation toxicity, and fine particle dosage testing were all performed in accordance with the methods specified in the General Chapters of the 2025 Edition of the Chinese Pharmacopoeia and the Technical Guidelines for the Study of Drug Irritation, Allergy and Hemolysis.

[0157] 2. Test Results:

[0158] Table 1 (Results of core impurity B detection at day 0 and after sterilization at 121℃ for 15 min):

[0159] Test sample Initial content of impurity B on day 0 Content of impurity B after sterilization Increase in impurity B after sterilization Total impurities after sterilization Content retention rate Example 1 0.04% 0.05% 25% 0.06% 99.80% Example 2 0.04% 0.05% 25% 0.06% 99.80% Example 3 0.04% 0.05% 25% 0.07% 99.70% Example 4 0.04% 0.05% 27.50% 0.07% 99.70% Example 5 0.04% 0.05% 27.50% 0.07% 99.70% Comparative Example 1 0.04% 0.17% 325% 0.45% 97.80% Comparative Example 2 0.04% 0.10% 150% 0.20% 98.90% Comparative Example 3 0.04% 0.15% 275% 0.40% 98.20% Comparative Example 4 0.04% 0.12% 200% 0.25% 98.50% Comparative Example 5 0.04% 0.20% 400% 0.52% 96.20% Comparative Example 6 (Commercially Available) 0.06% 0.21% 250% 0.48% 97.50% Comparative Example 7 (Free Antioxidant Group) 0.04% 0.12% 200% 0.25% 98.60%

[0160] Table 2 (Core detection results of impurity B after 6 months of accelerated testing and 12 months of long-term testing):

[0161] Test sample Accelerate the content of impurity B in 6 months Impurity B content over a long period of 12 months Long-term 12-month retention rate of active thiol groups Total impurity content over a long period of 12 months Long-term 12-month content retention rate Crystallization at low temperature for 30 days Example 1 0.08% 0.10% 86.20% 0.21% 98.00% No precipitation Example 2 0.08% 0.09% 87.50% 0.20% 98.20% No precipitation Example 3 0.09% 0.11% 85.70% 0.22% 97.80% No precipitation Example 4 0.10% 0.12% 85.10% 0.23% 97.50% No precipitation Example 5 0.10% 0.12% 84.80% 0.23% 97.60% No precipitation Comparative Example 1 0.35% 0.52% - 0.79% 90.20% Trace precipitation Comparative Example 2 0.18% 0.25% - 0.35% 95.30% No precipitation Comparative Example 3 0.32% 0.48% 12.30% 0.75% 91.50% Trace precipitation Comparative Example 4 0.22% 0.30% - 0.42% 94.60% No precipitation Comparative Example 5 0.40% 0.58% - 0.85% 89.50% No precipitation Comparative Example 6 (Commercially Available) 0.38% 0.55% - 0.80% 89.70% Large amount of precipitation Comparative Example 7 (Free Antioxidant Group) 0.22% 0.30% 18.50% 0.45% 93.80% No precipitation

[0162] Table 3 (Results of other performance tests):

[0163] Test Project Example 1 Comparative Example 1 Comparative Example 6 (Commercially Available) Comparative Example 7 (Free Antioxidant Group) Properties Colorless, clear liquid, free of visible foreign matter. Colorless, clear liquid, free of visible foreign matter. Colorless, clear liquid, free of visible foreign matter. Colorless, clear liquid, free of visible foreign matter. pH value 5 5 4 5 Insoluble particles Compliant Compliant Compliant Compliant Microparticle Dosage 66.20% 57.30% 57.60% 65.80% Respiratory irritation level Level 0 Level 1 Level 1 Level 0 hemolytic Hemolysis rate < 5%, no agglutination Hemolysis rate < 5%, no agglutination Hemolysis rate < 5%, no agglutination Hemolysis rate < 5%, no agglutination Sterile / Endotoxin Compliant Compliant Compliant Compliant Acute inhalation toxicity Practically non-toxic Practically non-toxic Practically non-toxic Practically non-toxic

[0164] V. Results Analysis

[0165] 1. Verification of the effectiveness of core technologies

[0166] This invention achieves ultimate control over the entire path of bromhexine hydrochloride impurity B through a three-stage progressive modification system, with the following core effects:

[0167] The growth of impurity B during the sterilization process was completely suppressed: After sterilization by the 121℃ overkill method, the impurity B in Example 1 increased only from 0.04% to 0.05%, an increase of only 25%; while the unmodified comparative example 1 increased by 325%, and the commercially available product increased by 250%. This invention reduced the growth rate of impurity B during the sterilization process by more than 90%, completely solving the core industry pain point of excessive impurity B caused by high-temperature sterilization of this product;

[0168] The control effect of impurity B during long-term storage is significant: after 12 months of long-term storage, the content of impurity B in Example 1 is only 0.10%, which is far below the pharmacopoeia limit of 0.5%, and is only 19% of the unmodified comparative example 1 and 18% of the commercially available products, fully meeting the quality control requirements for a shelf life of 36 months.

[0169] Impurity B remains at extremely low levels throughout the entire lifecycle: From production to long-term storage, the content of impurity B in the product of this invention is consistently controlled below 0.12%, which is far below the quality control requirements for genotoxic impurities in the ICH M7 guidelines, significantly reducing the safety risks of the product.

[0170] 2. Verification of the necessity of covalent grafting modification

[0171] Comparative Example 7 used an exact equal amount of ordinary hydroxypropyl-γ-cyclodextrin to include and physically mix with equimolar amounts of free L-cysteine, as in Example 1. Only the form in which L-cysteine ​​existed was changed. The test results directly demonstrated the necessity and non-obviousness of the covalent grafting modification of this invention.

[0172] The difference in impurity control during sterilization is significant: after sterilization, the increase in impurity B in Comparative Example 7 reached 200%, which is 8 times that of Example 1. This proves that free L-cysteine ​​can only achieve non-targeted antioxidant protection of the entire system and cannot form precise protection against drug molecules under the severe oxidation conditions of high-temperature sterilization. In contrast, L-cysteine ​​derivatives covalently grafted onto the cyclodextrin port can form in-situ protection at the drug molecule inlet, simultaneously blocking drug oxidative breakage and secondary oxidation of intermediates. The impurity control efficiency is much higher than that of free antioxidants.

[0173] Significant differences were observed in long-term antioxidant activity: After 12 months of storage, the retention rate of active thiol groups in Comparative Example 7 was only 18.5%, while that in Example 1 reached 86.2%; the impurity B content in Comparative Example 7 was 0.30%, three times that of Example 1. These results demonstrate that free L-cysteine ​​is prone to auto-oxidation in aqueous solution, essentially losing its antioxidant activity after 3 months, leading to an accelerated growth phase of impurity B; while covalently grafted and fixed L-cysteine ​​derivatives can effectively prevent thiol auto-oxidation, achieving long-term antioxidant effects for more than 12 months—a technical effect that free antioxidants cannot achieve.

[0174] Clinical safety and industrialization value verification

[0175] This invention requires no addition of any solubilizers or surfactants. Its near-physiological weakly acidic system has a respiratory irritation level of 0, completely eliminating the airway irritation risks associated with the strong acidity and solubilizers in existing products. It can be safely used by sensitive populations such as children and asthma patients. At the same time, the product has no risk of low-temperature crystallization, and the nebulized lung deposition rate is increased by more than 15%. The production process is fully compatible with existing industrial production lines for bromhexine hydrochloride inhalation solution, requiring no additional equipment or major process changes. The quality is consistent and stable between batches, possessing extremely high industrialization and clinical application value.

[0176] Final conclusion

[0177] This invention successfully constructs an integrated protective structure of "cavity isolation-port blocking" through a three-level progressive modification system, blocking the formation of impurity B in bromhexine hydrochloride at the molecular level. This solves the technical problem of the prior art being unable to simultaneously achieve "impurity B control, product stability, and clinical mildness". The prepared bromhexine hydrochloride inhalation solution has excellent impurity B control, good long-term stability, and is mild and safe for clinical use. Compared with the prior art, it has outstanding substantive features and significant progress, and fully meets the requirements for invention patent authorization.

[0178] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A modified bromhexine hydrochloride inhalation solution with enhanced stability, characterized in that: It is mainly made from the following raw materials: targeted impurity-controlled modified bromhexine hydrochloride inclusion complex, impurity B inhibition-specific composite buffer stock solution, inhalation-grade sodium chloride, pharmaceutical-grade sodium hydroxide, and water for injection; the pH value of the inhalation solution is 4.5-5.5, the targeted impurity-controlled modified bromhexine hydrochloride inclusion complex is prepared by encapsulating bromhexine hydrochloride with a functionalized hydroxypropyl-γ-cyclodextrin carrier, and the functionalized hydroxypropyl-γ-cyclodextrin carrier is prepared by covalently grafting hydroxypropyl-γ-cyclodextrin with a thiol-activated L-cysteine ​​derivative.

2. The enhanced stability modified bromhexine hydrochloride inhalation solution according to claim 1, characterized in that: The targeted impurity-controlled modified bromhexine hydrochloride inclusion complex is prepared by inclusion of functionalized hydroxypropyl-γ-cyclodextrin carrier and bromhexine hydrochloride at a mass ratio of 25:4, with an inclusion rate of ≥94%; the bromhexine hydrochloride is pharmaceutical grade with a purity of ≥99.5% and an initial content of impurity B ≤0.05%.

3. The enhanced stability modified bromhexine hydrochloride inhalation solution according to claim 1, characterized in that: The functionalized hydroxypropyl-γ-cyclodextrin carrier is prepared by reacting hydroxypropyl-γ-cyclodextrin with a thiol-activated L-cysteine ​​derivative at a mass ratio of 25:6, with a grafting rate ≥85%; the hydroxypropyl-γ-cyclodextrin is an inhalation-grade pharmaceutical excipient with a degree of substitution of 4.0-6.0, and its bacterial endotoxin meets the requirements for injection grade.

4. The enhanced stability modified bromhexine hydrochloride inhalation solution according to claim 1, characterized in that: The thiol-activated L-cysteine ​​derivative is prepared by directional activation of L-cysteine ​​hydrochloride monohydrate with 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, with an activation degree ≥90%; the L-cysteine ​​hydrochloride monohydrate is pharmaceutical grade and meets the standards of the Chinese Pharmacopoeia.

5. The enhanced stability modified bromhexine hydrochloride inhalation solution according to claim 1, characterized in that: The impurity B inhibition-specific composite buffer stock solution is prepared from sodium dihydrogen phosphate dihydrate, disodium hydrogen phosphate dodecahydrate, and water for injection. The stock solution has a pH of 5.0 and a buffer capacity of ≥0.02 mol / L·pH. Both sodium dihydrogen phosphate dihydrate and disodium hydrogen phosphate dodecahydrate are pharmaceutical grade and meet the standards of the Chinese Pharmacopoeia.

6. The enhanced stability modified bromhexine hydrochloride inhalation solution according to claim 1, characterized in that: Based on 1000ml of finished product, the raw materials used are as follows: 13.5-15.5g of targeted impurity-controlled modified bromhexine hydrochloride inclusion complex, equivalent to 2.0g of bromhexine hydrochloride; 50.0ml of impurity B inhibition-specific composite buffer stock solution; 9.0g of inhalation-grade sodium chloride; appropriate amount of pharmaceutical-grade sodium hydroxide; and water for injection to 1000ml. The inhalation-grade sodium chloride is pharmaceutical-grade and conforms to the standards of the Chinese Pharmacopoeia, and is used as an isotonic regulator.

7. The enhanced stability modified bromhexine hydrochloride inhalation solution according to claim 1, characterized in that: The finished inhalation solution has a specification of 2ml:4mg. After being sterilized by moist heat at 121℃ for 15 minutes, the increase of impurity B is ≤28%. After long-term storage for 12 months, the content of impurity B is ≤0.12%. The respiratory irritation level is 0. The sterility and bacterial endotoxin content meet the requirements of the Chinese Pharmacopoeia for inhalation preparations.

8. The method for preparing the enhanced stability modified bromhexine hydrochloride inhalation solution according to any one of claims 1-7, characterized in that, Includes the following steps: S1. Purge the liquid preparation tank with high-purity nitrogen for 30 minutes to purge the air inside the tank. Add 80% of the formula amount of water for injection. Cool down to below 30°C. Continuously purge with high-purity nitrogen throughout the process. Control the dissolved oxygen in the system to ≤0.5mg / L. Add the formula amount of inhalation-grade sodium chloride. Stir at 200rpm for 15 minutes until completely dissolved to obtain an isotonic basic solution. S2. Add the prescribed amount of targeted controlled impurity modified bromhexine hydrochloride inclusion complex powder to the isotonic base solution, stir at 250 rpm in the dark for 20 min until completely dissolved, and obtain a clear drug main solution. Keep nitrogen protection throughout the process. S3. Slowly add the prescribed amount of impurity B inhibition-specific composite buffer mother liquor to the main drug solution while stirring. After mixing evenly, take a sample to test the initial pH value of the system. S4. Under constant temperature of 25℃±2℃, nitrogen purging and light protection, and continuous stirring, the pH value of the system is adjusted dropwise to 4.5-5.5 with a standardized 0.1mol / L pharmaceutical grade sodium hydroxide standard solution. Water for injection is added to the total volume. The system is stirred at 200rpm for 10min in the dark until it is homogeneous. The system is then filtered through a 0.22μm polyethersulfone sterile filter membrane. Nitrogen purging and light protection are maintained throughout the process. S5. In an ISO 5 Class A clean environment, fill the filtrate into brown neutral borosilicate glass ampoules. Before filling, purge the ampoules with nitrogen to replace the air. After sealing, the headspace oxygen residue should be ≤1%. 100% leak detection and light inspection are required. S6. Place the filled ampoules in a pulsating vacuum sterilizer and sterilize them at 121℃ for 15 minutes with an F0 value ≥ 12. Then, gradually cool them down to room temperature to obtain the finished bromhexine hydrochloride inhalation solution.

9. The preparation method according to claim 8, characterized in that, The preparation method of the targeted hybridization-controlled modified bromhexine hydrochloride inclusion complex includes the following steps: S1. Preparation of thiol-activated L-cysteine ​​derivative: L-cysteine ​​hydrochloride monohydrate was dissolved in a 4:1 mixture of anhydrous ethanol and water for injection. Nitrogen gas was purged throughout the process to remove oxygen. 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride was added, and the mixture was stirred at 25°C in the dark for 3 hours to complete the directional activation of the carboxyl group. After filtration, concentration, washing, and drying, the thiol-activated L-cysteine ​​derivative was obtained. S2. Preparation of functionalized hydroxypropyl-γ-cyclodextrin carrier: Hydroxypropyl-γ-cyclodextrin was added to water for injection, heated to 45℃ and stirred to dissolve, nitrogen gas was passed through to remove oxygen, thiol-activated L-cysteine ​​derivative was added, pH was adjusted to 5.0, and the reaction was carried out at 45℃ in the dark for 10 h to complete covalent grafting. After precipitation, washing, ultrafiltration purification, freeze drying and pulverization, functionalized hydroxypropyl-γ-cyclodextrin carrier was obtained. S3. Preparation of targeted impurity-controlled modified bromhexine hydrochloride inclusion complex: Functionalized hydroxypropyl-γ-cyclodextrin carrier was added to water for injection, heated to 45℃ and stirred to dissolve, and nitrogen gas was purged to remove oxygen, resulting in an aqueous solution of the functionalized carrier; bromhexine hydrochloride was added to pharmaceutical-grade anhydrous ethanol and stirred to dissolve, resulting in an alcoholic solution of bromhexine hydrochloride; the alcoholic solution was slowly added dropwise to the carrier aqueous solution at a rate of 0.8 ml / min, and the reaction was carried out at 45℃ in the dark for 120 min to complete the inclusion. After de-alcoholization under reduced pressure, filtration, freeze-drying, and pulverization, the targeted impurity-controlled modified bromhexine hydrochloride inclusion complex was obtained.

10. The preparation method according to claim 8, characterized in that, The preparation method of the special composite buffer stock solution for impurity B inhibition is as follows: high-purity nitrogen gas is passed through water for injection for 15 minutes, the dissolved oxygen is controlled to be ≤0.5mg / L, the temperature is controlled to be below 25℃, pharmaceutical grade sodium dihydrogen phosphate dihydrate and disodium hydrogen phosphate dodecahydrate are added, stirred until completely dissolved, filtered through a 0.22μm sterile filter membrane, sealed and refrigerated at 2-8℃ for later use.