Thiroxine sustained-release microsphere and preparation method thereof

Abstract

The invention provides a thyroxine sustained release microsphere and a preparation method thereof. The microsphere comprises thyroxine, a biocompatible high-molecular polymer and a solubilizing auxiliary material, the microsphere contains 1%-10% wt of thyroxine, 0.1%-5% wt of a solubilizing auxiliary material, and the balance of the biocompatible high-molecular polymer. The thyroxine is one or any combination of tetraiodothyronine (T4), triiodothyronine (T3) or pharmaceutically acceptable salts of the tetraiodothyronine (T4), the triiodothyronine (T3) and the pharmaceutically acceptable salts of the triiodothyronine (T3). According to the microsphere preparation, thyroxine and a biocompatible high-molecular polymer are organically combined together, the particle size of microspheres is uniform, and the microsphere preparation is injected into a body in an intramuscular injection or subcutaneous injection mode, so that a medicine is slowly released from a microsphere carrier, and the stable plasma concentration of thyroxine is maintained; potential adverse reactions possibly caused by a common oral preparation are reduced, and long-acting and stable release of the drug in vivo is realized. Meanwhile, the microsphere preparation can reduce the administration frequency and improve the medication compliance of patients.

Description

Technical Field

[0001] The invention relates to a thyroxine sustained-release microsphere and a preparation method thereof, and in particular to a long-acting drug-loaded microsphere preparation, belonging to the field of pharmaceutical preparations. Background Art

[0002] Thyroxine is a hormone secreted by the thyroid gland, which acts on almost all cells in the human body. Thyroxine can promote metabolism, maintain normal growth and development, and improve the body's sensitivity. It is mainly used clinically to treat cretinism, myxedema and other hypothyroidism.

[0003]

[0004] Thyroid cells synthesize and secrete thyroxine, including levothyroxine (T4) and liothyronine (T3). T4 accounts for the majority of the amount (about 80%), but it is T3 that is physiologically active at the tissue and cell level. T4 needs to be deiodinated by 5'-deiodinase to become T3 to exert its efficacy.

[0005] However, since T4 needs the action of deiodinase to work, it has a slow onset and weak effect, and it cannot quickly increase the body's thyroid hormone level when used alone. T3 has a fast onset and strong effect, and its metabolism is also fast, so it is easy to cause fluctuations in blood thyroid hormone levels. When the body's thyroid hormone level is too low, it will cause adverse reactions such as depression, fatigue, and difficulty concentrating; and when the body's thyroid hormone level is too high, it will cause adverse reactions such as pain, palpitations, and arrhythmias. Therefore, how to use thyroid hormone drugs reasonably and correctly is a clinical problem that needs to be solved urgently, so as to achieve the effect of sustainable release of thyroid hormone, no hysteresis period, and high safety.

[0006] Sustained-release preparations are a solution. Currently, there are few public reports on long-acting preparations such as thyroxine sustained-release microspheres or microencapsulation technology at home and abroad.

[0007] Chinese patent publication CN116831994A describes a lyophilized preparation of sodium levothyroxine sustained-release microspheres for injection, the preparation process of which is to directly dissolve sodium levothyroxine, poly(lactide-co-glycolide), polyvinyl alcohol and NaCl in water, and then prepare microspheres by centrifugation. In actual operation, the technical solution disclosed in the patent disclosure has the problem that poly(lactide-co-glycolide) is almost insoluble in water, and the content of sodium levothyroxine adsorbed by the polymer is also extremely low, which cannot meet the actual clinical use.

[0008] Chinese patent publication CN118201604A records a sustained-release injectable pharmaceutical preparation of levothyroxine and a preparation method thereof. The preparation process of levothyroxine and poly(lactide-co-glycolide) microparticles in the method uses methanol as a cosolvent and a single emulsion method to prepare microspheres. In the preparation process disclosed in the patent, the dosage of dichloromethane and methanol is extremely large, and the proportion of the raw material in the solvent system is less than 0.1%, which is extremely environmentally unfriendly and causes great difficulties in production.

[0009] Therefore, how to provide a sustained-release preparation of thyroxine so that patients can obtain a stable and lasting blood concentration of thyroxine becomes a problem. Summary of the invention

[0010] The purpose of the present invention is to provide a thyroxine sustained-release microsphere.

[0011] Another object of the present invention is to provide a method for preparing the above-mentioned thyroxine sustained-release microspheres.

[0012] The microspheres contain thyroxine, a biocompatible high molecular polymer and a solubilizing auxiliary material; the microspheres contain 1%-10% wt thyroxine, the microspheres contain 0.1%-5% wt solubilizing auxiliary material, and the remainder is the biocompatible high molecular polymer; the thyroxine is one of tetraiodothyronine (T4), triiodothyronine (T3) or a pharmaceutically acceptable salt thereof, or any combination thereof.

[0013] The inventors have found through long and arduous experiments that tetraiodothyronine (T4), triiodothyronine (T3) or one of their salts or any combination thereof can be well prepared into microsphere preparations with only an appropriate amount of solubilizing auxiliary material.

[0014] The solubilizing auxiliary material contained in the sustained-release microspheres is one of an alkaline agent and a cationic surfactant or any combination thereof.

[0015] The alkaline agent is preferably one of sodium hydroxide, potassium hydroxide, ammonia water, triethylamine, diethylamine, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate or any combination thereof; among them, the use of sodium hydroxide has the best effect.

[0016] The cationic surfactant is preferably one of lauryl-octadecyltrimethylammonium chloride, lauryl-octadecyltrimethylammonium bromide, benzyltrimethylammonium chloride or any combination thereof.

[0017] The pharmaceutically acceptable salt of thyroxine in the sustained-release microspheres is usually sodium salt, potassium salt, calcium salt or a combination thereof; preferably sodium salt.

[0018] The biocompatible high molecular polymer is one of poly(lactide), poly(glycolide), poly(lactide-glycolide), poly(lactic acid), poly(glycolic acid), poly(lactic acid-glycolic acid) or any combination thereof; the molar ratio of glycolide to lactide in the poly(lactide-glycolide) is (15-55):(85-45); preferably 50:50.

[0019] In some embodiments, the sustained-release microspheres of the present invention preferably have a drug loading of 4.5%-4.8%, and a drug loading rate of 81.8%-87.3%.

[0020] The particle size of the sustained-release microspheres of the present invention is 10 um to 100 um.

[0021] The microsphere preparation organically combines thyroxine with a biocompatible high molecular polymer, and the microspheres have uniform particle size. They are injected into the body by intramuscular injection or subcutaneous injection, so that the drug is slowly released from the microsphere carrier, thereby maintaining a stable blood concentration of thyroxine, reducing potential adverse reactions that may be caused by ordinary oral preparations, and achieving long-term and stable release of the drug in the body; at the same time, the microsphere preparation can reduce the frequency of administration and improve patients' medication compliance.

[0022] The method for preparing the sustained-release microspheres comprises the following steps:

[0023] a) preparing an oil phase: dissolving a biocompatible high molecular polymer in an organic solvent A to form an oil phase; the organic solvent A is one of dichloromethane, chloroform, ethyl acetate or a combination thereof;

[0024] b) preparing an inner aqueous phase: mixing thyroxine, a solubilizing auxiliary material and an organic solvent B with water to form a clear solution to obtain an inner aqueous phase; the organic solvent B is one of methanol, ethanol, ethylene glycol, glycerol, propylene glycol or a combination thereof;

[0025] c) preparing an external aqueous phase: dissolving a water-soluble polymer in water to obtain an external aqueous phase; the water-soluble polymer is one of polyvinyl alcohol (PVA), sodium carboxymethyl cellulose (CMC-Na), polyvinyl pyrrolidone (PVP), sodium polymethacrylate, sodium polyacrylate or a combination thereof;

[0026] d) preparing microspheres: mixing the inner aqueous phase with the oil phase to form colostrum; adding the colostrum to the outer aqueous phase to form a double emulsion; membrane emulsifying / high shearing the double emulsion to form a microsphere suspension; stirring the microsphere suspension, filtering, washing and drying to obtain thyroxine-containing sustained-release microspheres.

[0027] The mass volume ratio of the biocompatible high molecular polymer to the organic solvent A in the step a) is 1:(5-10); preferably 0.86 g / 4.5 mL.

[0028] The mass ratio of the thyroxine to the solubilizing auxiliary material in step b) is 50:(1-5); preferably 50:(2.5-3); and / or

[0029] The volume ratio of the organic solvent B to water is 1:(3-4); and / or

[0030] The mass volume ratio of the thyroxine to the organic solvent B is 1:2.

[0031] The mass ratio concentration of the solution formed by the high molecular polymer and water is 0.5%-5%, preferably 1%-1.5%.

[0032] The drying temperature in step d) is 5°C-25°C.

[0033] The microspheres provided by the present invention can be prepared in the form of sterile lyophilized powder, and the sterile lyophilized powder contains one or a combination of thyroxine microsphere composition, suspending agent, pH adjusting agent, isotonic adjusting agent, surfactant, and can be prepared by the following method: take the sustained-release microsphere composition, rinse with water for injection, transfer to a container, add suspending agent, pH adjusting agent, isotonic adjusting agent, surfactant, one or a combination thereof and appropriate amount of water for injection, stir evenly and dispense into a cillin bottle, freeze dry in a freeze dryer; freeze-dried product is capped to obtain sterile lyophilized powder. The suspending agent can be one or more of sodium carboxymethyl cellulose, polyvinyl alcohol, polyvinyl pyrrolidone, sodium alginate, and glycerol, the isotonic adjusting agent can be one or more of sodium chloride, glucose, mannitol, sorbitol, etc., and the surfactant is a non-ionic surfactant, such as a polysorbate series (such as polysorbate 80, polysorbate 60, etc.), a poloxamer series (such as poloxamer 188, poloxamer 124, etc.).

[0034] The thyroxine sustained-release microsphere preparation of the present invention can provide a pharmacological effect for at least two weeks to three months after a single administration. The preparation can be administered once every two weeks to once every three months, preferably once every two weeks or once every three months.

[0035] The purpose of the present invention is to provide a thyroxine microsphere preparation with a longer-acting effect and no hysteresis period and a preparation method thereof in order to meet the needs of clinical medication; the microsphere preparation of the present invention can reduce the frequency of administration, reduce the toxic and side effects of drugs, and improve the compliance and quality of life of patients. The preparation method of the present invention can achieve stable preparation of microspheres, can be scaled up for production, and is conducive to industrialization. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a scanning electron microscope image of a cross section of the T4-Na microspheres prepared in Example 1 of the present invention.

[0037] Figure 2 This is a full-view scanning electron microscope image of the T4-Na microspheres prepared in Example 1 of the present invention.

[0038] Figure 3 This is a full-view scanning electron microscope image of the T3-Na microspheres prepared in Example 2 of the present invention.

[0039] Figure 4 This is a particle size distribution diagram of T4-Na microspheres prepared in Example 1 of the present invention.

[0040] Figure 5 This is the in vitro 40°C cumulative release curve of the T4-Na microspheres prepared in Example 1 and Example 4 of the present invention.

[0041] Figure 6 This is the in vitro 40°C cumulative release curve of the T4-Na microspheres prepared in Example 1 and the T3-Na microspheres prepared in Example 2 of the present invention.

[0042] Figure 7 This is the in vitro 40°C cumulative release curve of the T4-Na microspheres prepared in Example 1 and Example 6 of the present invention.

[0043] Figure 8 This is the in vitro 40°C cumulative release curve of the T4-Na microspheres prepared in Example 1 and Example 7 of the present invention.

[0044] Fig. 9 1 is the pharmacokinetic curve of T4-Na microspheres prepared in Example 1 and Example 6 of the present invention in rats. DETAILED DESCRIPTION

[0045] For ease of understanding, the present invention will be described in detail below through specific drawings and embodiments. It should be particularly pointed out that the specific examples and drawings are only for illustration and do not constitute a limitation on the scope of the present invention. Obviously, those of ordinary skill in the art can make various modifications and changes to the present invention within the scope of the present invention based on the description herein, and these modifications and changes are also included in the scope of the present invention.

[0046] Example 1

[0047] Preparation of T4-Na microspheres

[0048] 50mg T4-Na (Azico Biophore, USP), 2.7mg NaOH and 100uL methanol were added to 340uL water for injection to form a clear aqueous phase; 0.86g glycolide-lactide copolymer (Evonik, 502H) was dissolved in 4.5mL dichloromethane to obtain an oil phase; the aqueous phase was added to the oil phase and dispersed by ultrasonic cell disruptor to obtain an emulsion; the above emulsion was added to 45mL PVA (Jiangxi Alpha, 17-88) 1.5% aqueous solution, and stirred at the same time to obtain a primary emulsion containing large microparticle blanks; the primary emulsion was passed through a rapid membrane emulsifier equipped with a 50μm pore diameter membrane tube and circulated 3 times. 405mL of PVA 1.5% aqueous solution was added. The above emulsion was dried in liquid at 5°C. After the drying in liquid was completed, the microspheres were washed and collected. The dry microspheres were obtained by vacuum freeze drying. The drug loading of the microspheres was 4.5%, and the drug loading rate was 81.8%.

[0049] Example 2

[0050] Preparation of T3-Na microspheres

[0051] 50mg T3-Na (Suzhou Fam Pharmaceutical), 2.7mg NaOH and 100ul methanol were added to 340ul water for injection to form a clear aqueous phase; 0.86g glycolide-lactide copolymer (Evonik, 502H) was dissolved in 4.5mL dichloromethane to obtain an oil phase; the aqueous phase was added to the oil phase and ultrasonically dispersed by an ultrasonic cell disruptor to obtain an emulsion; the above emulsion was added to 45mL PVA1.5% aqueous solution and stirred at the same time to obtain a primary emulsion containing large microparticle blanks; the primary emulsion was passed through a rapid membrane emulsifier equipped with a 50μm pore diameter membrane tube and circulated 3 times. 405mL of PVA1.5% aqueous solution was added. The above emulsion was dried in liquid at 5°C. After the drying in liquid was completed, the microspheres were washed and collected. The dry microspheres were obtained by vacuum freeze drying. The drug loading of the microspheres was 3.4% and the drug loading rate was 62.8%.

[0052] Example 3

[0053] Preparation of T4-Na microspheres

[0054] 50mg T4-Na, 2.5mg NaOH, 27.3mg octadecyltrimethylammonium chloride (Shanghai Yuanye, AR) and 100uL ethanol were added to 340uL water for injection to form a clear aqueous phase; 0.86g glycolide-lactide copolymer (Evonik, 502H) was dissolved in 4.5mL dichloromethane to obtain an oil phase; the aqueous phase was added to the oil phase and ultrasonically dispersed by an ultrasonic cell disruptor to obtain an emulsion; the above emulsion was added to 45mL PVA1.5% aqueous solution and stirred at the same time to obtain a primary emulsion containing large microparticle blanks; the primary emulsion was passed through a rapid membrane emulsifier equipped with a 50μm pore diameter membrane tube and circulated 3 times. 405mL of PVA1.5% aqueous solution was added. The above emulsion was dried in liquid at 5°C. After the drying in liquid was completed, the microspheres were washed and collected. The dry microspheres were obtained by vacuum freeze drying. The drug loading of the microspheres was 4.3% and the drug loading rate was 78.2%.

[0055] Example 4

[0056] Preparation of T4-Na microspheres

[0057] 50mg T4-Na, 2.7mg NaOH and 100uL methanol were added to 340uL water for injection to form a clear aqueous phase; 0.86g glycolide-lactide copolymer (Evonik, 502H) was dissolved in 4.5mL dichloromethane to obtain an oil phase; the aqueous phase was added to the oil phase and dispersed by ultrasonic cell disruptor to obtain an emulsion; the above emulsion was added to 45mL CMC-Na (Anhui Shanhe, SH-800) 1% aqueous solution, and stirred at the same time to obtain a primary emulsion containing large microparticle blanks; the primary emulsion was passed through a rapid membrane emulsifier equipped with a 50μm pore diameter membrane tube and circulated 3 times. 405mL of CMC-Na (Anhui Shanhe, SH-800) 1% aqueous solution was added. The above emulsion was dried in liquid at 25°C, and after the drying in liquid was completed, the microspheres were washed and collected. The dry microspheres were obtained by vacuum freeze drying. The drug loading of the microspheres was 4.8%, and the drug loading rate was 87.3%.

[0058] Example 5

[0059] Preparation of T4-Na microspheres

[0060] 50mg T4-Na, 2.7mg NaOH and 100uL methanol were added to 340uL water for injection to form a clear aqueous phase; 0.86g glycolide-lactide copolymer (Evonik, 502H) was dissolved in 4.5mL dichloromethane to obtain an oil phase; the aqueous phase was added to the oil phase, and an emulsion was obtained by ultrasonic dispersion using an ultrasonic cell disruptor; the above emulsion was added to 450mL PVA 1.5% aqueous solution, and a high shear emulsifier was used to maintain a speed of 10000rpm for 2min to prepare a microsphere suspension. The above emulsion was dried in liquid at 5°C, and after the liquid drying was completed, the microspheres were washed and collected. The dry microspheres were obtained by vacuum freeze drying. The drug loading of the microspheres was 4.6%, and the drug loading rate was 83.6%.

[0061] Example 6

[0062] Preparation of T4-Na microspheres

[0063] 50mg T4-Na, 2.7mg NaOH and 100uL methanol were added to 340uL water for injection to form a clear aqueous phase; 0.86g glycolide-lactide copolymer (Evonik, 501H) was dissolved in 4.5mL dichloromethane to obtain an oil phase; the aqueous phase was added to the oil phase and dispersed by ultrasonic cell disruptor to obtain an emulsion; the above emulsion was added to 45mL PVA1.5% aqueous solution and stirred at the same time to obtain a primary emulsion containing large microparticles; the primary emulsion was passed through a rapid membrane emulsifier equipped with a 50μm pore diameter membrane tube and circulated 3 times. 405mL of PVA1.5% aqueous solution was added. The above emulsion was dried in liquid at 5°C. After the drying in liquid was completed, the microspheres were washed and collected. The dry microspheres were obtained by vacuum freeze drying. The drug loading of the microspheres was 4.5% and the drug loading rate was 81.8%.

[0064] Example 7

[0065] Preparation of T4-Na microsphere freeze-dried powder injection

[0066] Prepare the freeze-dried suspension system according to the ratio in Table 1.

[0067] Table 1: Freeze-dried suspension system ratio

[0068] name / ml Configuration volume 100ml Mannitol 45mg 4.5g CMC-Na 7mg 0.7g Poloxamer 188 2mg 0.2g

[0069] Prepare microspheres according to Example 1, collect wet microspheres after washing, and send them for testing to determine the content. Add 1100ug / ml to the freeze-dried suspension system, stir and resuspend the microspheres. Pack them in 2ml vials, 1ml of freeze-dried microspheres per bottle. The freeze-drying process is shown in Table 2.

[0070] Table 2: Microsphere freeze-drying process

[0071]

[0072] After freeze-drying is completed, the cap is rolled and the freeze-dried powder injection is collected.

[0073] Comparative Example 1

[0074] Preparation of T4-Na microspheres

[0075] 50mg T4-Na and 200uL methanol were added to 680uL water for injection and ultrasonicated, and the solid was filtered out to obtain the aqueous phase; 0.86g glycolide-lactide copolymer (Evonik, 502H) was dissolved in 4.5mL dichloromethane to obtain the oil phase; 440uL of the aqueous phase was added to the oil phase, and the emulsion was obtained by ultrasonic dispersion by an ultrasonic cell disruptor; the above emulsion was added to 45mL PVA1.5% aqueous solution, and stirred at the same time to obtain a primary emulsion containing large microparticle blanks; the primary emulsion was passed through a rapid membrane emulsifier equipped with a 50μm pore diameter membrane tube and circulated 3 times. 405mL of PVA1.5% aqueous solution was added. The above emulsion was dried in liquid at 5°C, and after the drying in liquid was completed, the microspheres were washed and collected. The dry microspheres were obtained by vacuum freeze drying. The drug loading of the microspheres was 0.25%, and the drug loading rate was 4.5%.

[0076] Microsphere characterization and in vitro and in vivo release results

[0077] 1. Scanning Electron Microscope

[0078] The prepared PLGA microspheres were placed on a conductive tape and sprayed with gold (30 mV, 90 s) under vacuum conditions. The morphology was observed using a Hitachi S-3400N and a Hitachi / Regulus 8230 scanning electron microscope. T4-Na microspheres were prepared according to Example 1. The cross-sectional and full-view scanning electron microscope images of the microspheres are shown in the attached Figure 1 , Attachment Figure 2 The scanning electron microscope image of T3-Na microspheres prepared according to Example 2 is shown in the attached Figure 3 .

[0079] 2. Microsphere size

[0080] The prepared microspheres are dispersed in an appropriate dispersion solution, and the particle size is measured using a laser particle size analyzer. The particle size distribution of the microspheres prepared according to 1 is shown in the attached Figure 4 .

[0081] 3. Determination of drug loading in examples and control examples

[0082] Detection method: Take 10 mg of the reference substance of levothyroxine sodium, weigh it accurately, put it in a 100 ml volumetric flask, add an appropriate amount of diluent (acetonitrile-water-1M NaOH=500:500:2), dissolve it by ultrasonic and quantitatively dilute it to make a solution containing about 0.1 mg of levothyroxine sodium per 1 ml, which is the reference substance solution. Take this product, weigh it accurately, add an appropriate amount of diluent to dissolve it by ultrasonic and quantitatively dilute it to make a solution containing about 0.05 mg per 1 ml, which is the test solution.

[0083] Chromatographic column: Nanopore ChromCore120 C18, 4.6*150mm, 3μm; column temperature: 40℃;

[0084] Mobile phase: [10% methanol-0.025 M sodium dihydrogen phosphate buffer (pH = 3.0)]-methanol = 40:60;

[0085] Flow rate: 1.0 ml / min; detection wavelength: 225 nm; injection volume: 5 μL.

[0086] Accurately measure 5 μL of the test solution and the reference solution, inject them into the liquid chromatograph respectively, record the chromatogram, and calculate the content of levothyroxine sodium in the microspheres by the peak area according to the external standard method.

[0087] The drug loading results of the embodiments and control examples are shown in Table 3.

[0088] Table 3: Drug loading of Examples and Control Examples

[0089] Example 1 Example 3 Example 4 Example 5 Example 6 Comparative Example 1 Drug loading 4.5％ 4.3％ 4.8％ 4.6％ 4.5％ 0.25％

[0090] 4. Determination of in vitro release

[0091] Take about 40 mg of T4-Na microspheres, accurately weigh them, put them in a 50 ml sealed reagent bottle, add 20 ml of release medium (containing 0.1% SDS, 5% EtOH, PBS7.4 phosphate buffer), screw the cap tightly and mix well, and prepare three copies in parallel; the solution temperature is maintained at 40°C ± 0.5°C, and samples are taken in sequence at the 1st hour, 1st day, 2nd day, 3rd day, 5th day, 7th day, 14th day and 21st day after placement, accurately measure 2 ml of each solution, and add an equal volume of isothermal release medium at the same time, centrifuge at 15000 rpm, and take the supernatant as the test solution; according to the high performance liquid chromatography method (General Rules 0512 of Part IV of the 2015 edition of the Chinese Pharmacopoeia), the peak area of ​​the test sample is calculated based on the peak area of ​​the peak position of the reference sample, and the release amount of the product at different times is calculated by the peak area according to the external standard method.

[0092] The in vitro cumulative release curves of T4-Na microspheres prepared according to Example 1 and Example 4 at 40°C are shown in the attached Figure 5The results showed that the burst release rate of T4-Na microspheres could be significantly reduced by using CMC-Na as the external aqueous phase.

[0093] The in vitro cumulative release curves of the T4-Na microspheres prepared in Example 1 and the T3-Na microspheres prepared in Example 2 at 40°C are shown in the attached Figure 6 The results show that the preparation method used in the present invention can be applied to both T4-Na and T3-Na microspheres, and the release characteristics of the microspheres are similar.

[0094] The in vitro cumulative release curves of T4-Na microspheres prepared according to Examples 1 and 6 at 40°C are shown in the attached Figure 7 The results showed that different types of polymer materials can control the release of microspheres to different degrees, which can provide options for the development of preparations with different dosing cycles.

[0095] The in vitro cumulative release curves of T4-Na microspheres prepared according to Examples 1 and 7 at 40°C are shown in the attached Figure 8 The results showed that the addition of the freeze-dried suspension system did not destroy the release behavior of the microspheres, and the freeze-dried system was stable.

[0096] 5. Pharmacokinetic study in rats

[0097] The T4-Na microspheres prepared in Example 1 and Example 6 were suspended in a sterile solvent for suspension, with a microsphere concentration of about 40 mg / mL and a drug concentration of about 1.8 mg / mL. Male SD rats were randomly divided into groups according to body weight and administered via intramuscular injection of the rat hind legs. The rats were weighed and the dosage was calculated based on a dosage of 1 mL / kg.

[0098] The sampling scheme is shown in Table 4. After the blood sample is taken out, it is immediately transferred into a sodium heparinized 2 mL EP tube and centrifuged at 3000 rpm for 15 min. The upper plasma is taken and the plasma sample is frozen and stored in a -20°C refrigerator to facilitate the determination of blood drug concentration.

[0099] Table 4: Sampling scheme for microsphere administration in SD rats

[0100] Group PK time points IM -2d,-1d,0h,0.5h,6h,1d,2d,4d,6d,8d,10d,14d,17d,21d IM 21 days, the microspheres were removed from the thigh muscle and the residual drug was measured

[0101] The rat pharmacokinetic curves of T4-Na microspheres prepared according to Example 1 and Example 6 are shown in the attached Fig. 9 From the figure, we can see that the microspheres prepared in Example 1 can release the drug in rats for two weeks, and the microspheres prepared in Example 6 can release the drug in rats for one week. Both microspheres have no hysteresis period.

Claims

1. A thyroxine sustained-release microsphere, characterized in that: The microspheres contain thyroxine, biocompatible high molecular polymers and solubilizing auxiliary materials; The microspheres contain 1%-10%wt thyroxine; The thyroxine is one of tetraiodothyronine (T4), triiodothyronine (T3) or a pharmaceutically acceptable salt thereof or any combination thereof; The microspheres contain 0.1%-5%wt of dissolution-aiding auxiliary materials.

2. The sustained-release microspheres according to claim 1, characterized in that: The dissolution-aiding auxiliary material is one of sodium hydroxide, potassium hydroxide, ammonia water, triethylamine, diethylamine, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate or any combination thereof.

3. The sustained-release microspheres according to claim 1, characterized in that: The dissolution-aiding auxiliary material is one of dodecyltrimethylammonium chloride, dodecyltrimethylammonium bromide, benzyltrimethylammonium chloride or any combination thereof.

4. The sustained-release microspheres according to claim 1, characterized in that: The pharmaceutically acceptable salt is sodium salt, potassium salt, calcium salt or a combination thereof.

5. The sustained-release microspheres according to claim 1, characterized in that: The biocompatible high molecular polymer is one of poly(lactides), poly(glycolide), poly(lactide-glycolide), poly(lactic acid), poly(glycolic acid), poly(lactic acid-glycolic acid) or any combination thereof.

6. The sustained-release microspheres according to claim 5, characterized in that: The molar ratio of glycolide to lactide in the poly(lactide-glycolide) is (15-55):(85-45); preferably 50:

50.

7. The sustained-release microspheres according to claim 1, characterized in that: The drug loading amount of the microspheres is 4.5%-4.8%, and the drug loading rate is 81.8%-87.3%.

8. The sustained-release microspheres according to claim 1, characterized in that: The particle size of the microspheres is 10um to 100um.

9. The method for preparing the sustained-release microspheres according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: a) preparing an oil phase: dissolving a biocompatible high molecular polymer in an organic solvent A to form an oil phase; the organic solvent A is one of dichloromethane, chloroform, ethyl acetate or a combination thereof; b) preparing an inner aqueous phase: mixing thyroxine, a solubilizing auxiliary material and an organic solvent B with water to form a clear solution to obtain an inner aqueous phase; the organic solvent B is one of methanol, ethanol, ethylene glycol, glycerol, propylene glycol or a combination thereof; c) preparing an external aqueous phase: dissolving a water-soluble polymer in water to obtain an external aqueous phase; the water-soluble polymer is one of polyvinyl alcohol (PVA), sodium carboxymethyl cellulose (CMC-Na), polyvinyl pyrrolidone (PVP), sodium polymethacrylate, sodium polyacrylate or a combination thereof; d) preparing microspheres: mixing the inner aqueous phase with the oil phase to form colostrum; adding the colostrum to the outer aqueous phase to form a double emulsion; membrane emulsifying / high shearing the double emulsion to form a microsphere suspension; stirring the microsphere suspension, filtering, washing and drying to obtain thyroxine-containing sustained-release microspheres.

10. The preparation method according to claim 9, characterized in that: In the step a), the mass volume ratio of the biocompatible high molecular polymer to the organic solvent A is 1:(5-10); preferably 0.86g / 4.5mL; and / or The mass ratio of the thyroxine to the solubilizing auxiliary material in step b) is 50:(1-5); preferably 50:(2.5-3); and / or The volume ratio of the organic solvent B to water is 1:(3-4); and / or The mass volume ratio of the thyroxine to the organic solvent B is 1:2; and / or The mass ratio concentration of the solution formed by the water-soluble polymer and water in step c) is 0.5%-5%, preferably 1%-1.5%; and / or The drying temperature in step d) is 5°C-25°C.

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