CN113171346A

CN113171346A - Polylactic acid microsphere, injection and preparation method thereof

Info

Publication number: CN113171346A
Application number: CN202110023527.6A
Authority: CN
Inventors: 许明照; 徐育盈
Original assignee: Panion and BF Biotech Inc
Current assignee: Panion and BF Biotech Inc
Priority date: 2020-01-09
Filing date: 2021-01-08
Publication date: 2021-07-27
Also published as: TW202126331A; TWI769656B

Abstract

The present disclosure provides a method for preparing polylactic acid microspheres, comprising the following steps. A first solution is provided, and the first solution includes polylactic acid and an organic solvent. A second solution is provided comprising polyvinyl alcohol, sodium carboxymethyl cellulose, and an aqueous solution. The first solution is added to the second solution while stirring the second solution until the polylactic acid solidifies to form a plurality of polylactic acid microspheres. Polylactic acid microspheres were collected. The present disclosure also provides polylactic acid microspheres. Polylactic acid microspheres are aggregated from polylactic acid. The surface of the PLA microspheres is smooth and the particle size is between 30 microns and 100 microns. Using a specific proportion of polyvinyl alcohol and sodium carboxymethyl cellulose, polylactic acid microspheres with concentrated particle size distribution and smooth surface can be made, and the yield can reach 90%; in addition, the prepared injection not only shortens the rehydration time , It has better anti-agglomeration and needle penetration.

Description

Polylactic acid microsphere, injection and preparation method thereof

Technical Field

The present disclosure relates to polylactic acid microspheres and a method for preparing the same, and more particularly, to a method for preparing polylactic acid microspheres that achieve high yield and better injection performance.

Background

The main methods for preparing microspheres from biomacromolecules are currently: an emulsion solvent evaporation method, an emulsion solidification method, a desolvation method, or the like.

The emulsifying solvent volatilization method is that the aqueous solution containing biological macromolecules is mixed with organic solvent, then the mixture is prepared into emulsion by ultrasonic wave or oscillation method, and then the organic solvent is removed by rotary evaporation and other methods, thus obtaining microspheres. The emulsion solvent evaporation method has a low microsphere yield and risks of organic solvent residues, and has a poor coating rate for water-soluble drugs and water-soluble substances.

Nowadays, emulsion curing is usually used, and microspheres with different particle sizes and particle size distributions can be prepared according to different emulsion conditions. The method comprises adding water solution containing biomacromolecule into organic solvent such as vegetable oil or isooctane containing proper amount of emulsifier, stirring, ultrasonic wave or membrane emulsification to obtain water-in-oil emulsion, solidifying the liquid drop with heat or crosslinking agent (such as formaldehyde, glutaraldehyde), and separating to obtain solid microsphere. However, emulsion curing often results in microspheres with a broad particle size distribution and non-uniform size.

The injection containing microspheres is usually freeze-dried into powder, and is re-hydrated (reconstitution) when necessary, and the injection is applied to patients without being re-hydrated completely, which poses safety risk. When the microspheres have a broad particle size distribution and are not uniform in size, the time required for reconstitution is not easily assessed and there is a high risk of non-uniformity after reconstitution. In addition, in the current manufacturing process of injection preparation from biomacromolecules, it is often difficult to compromise the performance (e.g. needle penetration) of the injection if it is desired to meet the requirement of high microsphere yield.

Therefore, there is a need for improvement of the existing microspheres and the preparation method thereof, which can improve the properties of microspheres as injection, such as reconstitution property, needle permeability, and agglomeration resistance, while achieving high microsphere yield.

Disclosure of Invention

The invention provides a polylactic acid microsphere which is formed by gathering polylactic acid, the surface of the polylactic acid microsphere is smooth, and the particle size is between 30 and 100 micrometers.

The present invention also provides a method of preparing polylactic acid microspheres comprising the steps of: providing a first solution, wherein the first solution comprises polylactic Acid (PLA) and an organic solvent; providing a second solution comprising polyvinyl alcohol (PVA), sodium carboxymethylcellulose (SCMC) and an aqueous solution; adding the first solution to the second solution while stirring the second solution until the polylactic acid solidifies to form a plurality of polylactic acid microspheres; and collecting the polylactic acid microspheres.

In some embodiments, the weight percentage of the first solution is between 2.5% and 10% of the weight percentage of the polylactic acid in the first solution, based on 100%.

In some embodiments, the weight volume concentration (w/v) of the first solution is between 2.5% and 10% by weight volume concentration of the polylactic acid in the first solution, based on 100%.

In some embodiments, the polylactic acid comprises L-polylactic acid, D-polylactic acid, DL polylactic acid, or a combination of the foregoing.

In some embodiments of the invention, the organic solvent comprises dichloromethane, trichloromethane, ethyl acetate, or a combination thereof.

In some embodiments, the weight percentage of the second solution is 100%, the weight percentage of the polyvinyl alcohol in the second solution is between 0.5% and 2%, and the weight percentage of the sodium carboxymethyl cellulose in the second solution is between 0.1% and 2%.

In some embodiments, the weight volume concentration (w/v) of the second solution is 100%, the weight volume concentration of the polyvinyl alcohol in the second solution is between 0.5% and 2%, and the weight volume concentration of the sodium carboxymethyl cellulose in the second solution is between 0.1% and 2%.

In some embodiments, the step of adding the first solution to the second solution while stirring the second solution, the volume ratio between the second solution and the first solution is between 5:1 and 100: 1.

In some embodiments, the step wherein the first solution is added to the second solution while stirring the second solution, the first solution is added to the second solution at a rate of 5% to 35% of the first solution added per minute, with the volume of the first solution being 100%.

In some embodiments, the step of adding the first solution to the second solution while stirring the second solution is stirring the second solution at a rotation speed between 300rpm and 1500 rpm.

In some embodiments, wherein the step of collecting the polylactic acid microspheres comprises centrifugation or sieving.

In some embodiments, the step of collecting the polylactic acid microspheres further comprises freeze-drying the polylactic acid microspheres after centrifugation or sieving.

The invention also provides a polylactic acid microsphere which is prepared by the following steps: providing a first solution, wherein the first solution comprises polylactic acid and an organic solvent; providing a second solution, wherein the second solution comprises polyvinyl alcohol, sodium carboxymethyl cellulose and an aqueous solution; adding the first solution to the second solution while stirring the second solution to form polylactic acid microspheres; and collecting the polylactic acid microspheres.

In some embodiments, the weight percentage of the second solution is between 0.5% and 2% and the weight percentage of the sodium carboxymethyl cellulose is between 0.1% and 2% based on 100%.

In some embodiments, the first solution is added to the second solution while the second solution is stirred, the volume ratio between the second solution and the first solution being between 5:1 and 100: 1.

In some embodiments, the polylactic acid microspheres are spheroids and smooth surfaced and have a particle size between 30 microns and 100 microns.

The invention further provides an injection, which is prepared by the following steps: providing a plurality of polylactic acid microspheres; providing a suspension; mixing the polylactic acid microspheres and the suspension to obtain a microsphere suspension; and freeze-drying the microsphere suspension to obtain the injection.

In some embodiments, providing polylactic acid microspheres comprises the steps of: providing a first solution, wherein the first solution comprises polylactic acid and an organic solvent; providing a second solution, wherein the second solution comprises polyvinyl alcohol, sodium carboxymethyl cellulose and an aqueous solution; adding the first solution to the second solution while stirring the second solution until the polylactic acid solidifies to form polylactic acid microspheres; and collecting the polylactic acid microspheres.

In some embodiments, the suspension comprises a surfactant, a polymeric silicide, a sugar alcohol, and a dispersant.

In some embodiments, the surfactant comprises polysorbate 80(TWEEN 80), the polymeric silicide comprises polydimethylsiloxane, the sugar alcohol comprises mannitol, and the dispersant comprises sodium carboxymethylcellulose.

In some embodiments, the injectable formulation forms an injectable solution 2 to 10 minutes after reconstitution.

In some embodiments, the injectate can pass through a twenty-six G needle at a rate of 0.5 to 2 milliliters per minute.

In summary, the preparation method disclosed in the present invention uses specific proportions of polyvinyl alcohol and sodium carboxymethyl cellulose to prepare the polylactic acid microspheres with concentrated particle size distribution and smooth surface. In addition, the yield of the polylactic acid microspheres obtained by the preparation method can reach nine times. Compared with the commercially available product, the injection of the present disclosure has the advantages of shortened rehydration time, better anti-agglomeration property and needle penetration, and improved clinical applicability.

Drawings

In order to make the aforementioned and other objects, features, advantages and embodiments of the invention more comprehensible, the following description is given:

fig. 1 illustrates a flow diagram for preparing polylactic acid microspheres in one embodiment of the present disclosure.

Fig. 2A to 2D illustrate electron microscope images of a polylactic acid microsphere in an embodiment of the present disclosure.

Wherein the reference numerals are as follows:

step S1 …

Step S2 …

Step S3 …

Step S4 …

Detailed Description

In order to make the description of the invention more thorough and complete, embodiments and specific examples of the invention are described in detail below; it is not intended to be the only form in which the embodiments of the invention may be practiced or utilized. The various embodiments disclosed below may be combined with or substituted for one another where appropriate, and additional embodiments may be added to one embodiment without further recitation or description. In the following description, numerous specific details are set forth to provide a thorough understanding of the following embodiments. However, embodiments of the invention may be practiced without these specific details.

As used herein, the terms "a" and "an" can refer broadly to a single or a plurality of items, unless the context specifically states otherwise. It will be further understood that the terms "comprises," "comprising," "includes," "including" and similar terms, when used herein, specify the presence of stated features, regions, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of other features, regions, integers, steps, operations, elements, components, and/or groups thereof.

Although the methods disclosed herein are illustrated below as a series of acts or steps, the order in which the acts or steps are presented should not be construed as a limitation of the present invention. For example, certain operations or steps may be performed in a different order and/or concurrently with other steps. Moreover, not all operations, steps and/or features may be required to implement an embodiment of the present invention. Moreover, each operation or step described herein may include several sub-steps or actions.

Referring to fig. 1, the present disclosure provides a method for preparing a polylactic acid microsphere, comprising the steps of: step S1, providing a first solution, wherein the first solution comprises polylactic acid and an organic solvent; step S2, providing a second solution, wherein the second solution comprises polyvinyl alcohol, sodium carboxymethyl cellulose and an aqueous solution; step S3, adding the first solution to the second solution while stirring the second solution until the polylactic acid is solidified to form a plurality of polylactic acid microspheres; and a step S4 of collecting the polylactic acid microspheres.

In some embodiments, the polylactic acid comprises L-polylactic acid, D-polylactic acid, DL polylactic acid, or a combination of the foregoing. In some embodiments, the organic solvent comprises dichloromethane, trichloromethane, ethyl acetate, or a combination thereof.

In some embodiments, the weight percentage of the polylactic acid in the first solution is between 2.5% and 10%, such as 2.5%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or any value between the aforementioned adjacent values, when the weight percentage of the first solution is taken as 100%.

In some embodiments, the weight volume concentration (w/v) of the first solution is between 2.5% and 10%, such as 2.5%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or any number between the foregoing adjacent values, based on 100% weight volume concentration (w/v) of the polylactic acid in the first solution.

It should be noted that as the weight percentage or weight volume concentration of the polylactic acid in the first solution is higher, the yield of the polylactic acid microspheres is generally increased, but the risk of agglomeration of the polylactic acid microspheres is also increased. Therefore, during the preparation process, the weight percentage or weight volume concentration of the polylactic acid in the first solution needs to be controlled within a proper range.

In some embodiments, the weight percentage of the polyvinyl alcohol in the second solution is between 0.5% and 2%, such as 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, or any value between the foregoing adjacent values, when the weight percentage of the second solution is taken as 100%. The weight percentage of sodium carboxymethylcellulose in the second solution is between 0.1% and 2%, such as 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, or any value between the foregoing adjacent values.

In some embodiments, the weight volume concentration (w/v) of the second solution is between 0.5% and 2%, such as 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, or any number between the foregoing adjacent values, based on 100% of the weight volume concentration (w/v) of the second solution. The weight volume concentration (w/v) of sodium carboxymethylcellulose in the second solution is between 0.1% and 2%, such as 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, or any value between the aforementioned adjacent values.

It is worth mentioning that the presence of polyvinyl alcohol and sodium carboxymethylcellulose in the second solution simultaneously achieves the feature of a smooth surface of the polylactic acid microspheres, wherein the smoother the surface, the less prone to agglomeration, and furthermore, the higher the yield of the polylactic acid microspheres, for example, up to nine.

In some embodiments, the first solution is added to the second solution while the second solution is stirred, the volume ratio between the second solution and the first solution being between 5:1 and 100: 1. In other embodiments, the volume ratio between the second solution and the first solution is between 5:1 and 50:1, such as 5:1, 10:1, 20:1, 30:1, 40:1, 50:1, or any number between the foregoing adjacent numbers. It should be noted that when the weight percentages or weight to volume concentrations of polylactic acid, polyvinyl alcohol and sodium carboxymethylcellulose are fixed at specific values, the risk of agglomeration of the polylactic acid microspheres increases as the volume ratio between the second solution and the first solution decreases. Therefore, it is important to control the volume ratio between the second solution and the first solution in an appropriate range during the preparation process.

In some embodiments, the step of adding the first solution to the second solution while stirring the second solution may be performed according to the target yield, particle size and particle size distribution of the polylactic acid microspheres, and different equipment and parameter settings. For example, using a peristaltic pump (e.g., Thermo Fisher Scientific Dry-Bags)^TMUSA) at 25rpm to 50rpm and stirring the second solution with a stirrer (e.g. IKA EURO-ST 60C S001, Germany) at a speed between 300rpm and 1500rpm (e.g. 300rpm, 400rpm, 500rpm, 600rpm, 700rpm, 800rpm, 900rpm, 1000rpm, 1100rpm, 1200rpm, 1300rpm, 1400rpm, 1500rpm or any value in between the aforementioned adjacent values). The main purpose of the above parameter setting is to control the rate of addition of the first solution to the second solution at an appropriate and uniform rate and to control the rate of agitation of the second solution to obtain polylactic acid microspheres having a targeted particle size and a concentrated particle size distribution and to increase the yield of polylactic acid microspheres. If the first solution is added to the second solution at too high a rate, the risk of agglomeration of the polylactic acid microspheres may increase, thereby affecting the particle size of the polylactic acid microspheres and reducing the yield. The faster the stirring speed of the second solution, the more the shearing forceLarge, the particle size of the polylactic acid microspheres decreases. Specifically, the above-mentioned peristaltic pump adds the first solution to the second solution at a rotation speed of 25rpm to 50rpm, mainly for the purpose of controlling the amount added per unit time. The volume of the first solution is 100% by volume, and the first solution may be added to the second solution at a rate of 5% to 35% of the first solution per minute, preferably 5% to 15% of the first solution per minute, for example 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, or 15% of the first solution per minute.

In some embodiments, the step of collecting the polylactic acid microspheres comprises centrifugation or sieving. The centrifugation is to centrifuge the second solution of the polylactic acid microspheres at a suitable rotation speed (e.g., 2460Xg), and then remove the supernatant to obtain the polylactic acid microspheres. The sieving method is to separate the second solution of the polylactic acid microspheres through a sieve with an appropriate aperture to obtain the polylactic acid microspheres. In one embodiment, the step of collecting the polylactic acid microspheres further comprises obtaining the polylactic acid microspheres by a freeze-drying method after the centrifugation or sieving method. The freeze drying can remove excessive water and residual organic solvent, and increase storage stability.

As the content of the polyvinyl alcohol and the sodium carboxymethylcellulose increases, the viscosity of the second solution increases, and the collection rate of the polylactic acid microspheres decreases. In some embodiments, an electrolyte (e.g., sodium chloride) may be added to the second solution to reduce the viscosity of the second solution to increase the collection rate of the polylactic acid microspheres.

It is emphasized that the polylactic acid microspheres obtained by the above preparation method are spherical and have smooth surfaces under the field of view of an electron microscope at a voltage of 450 times to 1500 times of 5 kV. In some embodiments, the polylactic acid microspheres have a D50 (cumulative particle size percentage up to 50% corresponding to a particle size) size between 30 and 55 microns and a D90 (cumulative particle size percentage up to 90% corresponding to a particle size) between 60 and 100 microns.

The present disclosure also provides a polylactic acid microsphere comprising polylactic acid, wherein the polylactic acid microsphere is prepared by aggregating polylactic acid, and has a smooth surface when observed under a field of view of an electron microscope under a voltage of 450 times to 1500 times of 5kV, has a solid and smooth cross section when cut open, and has a particle size of 30 micrometers to 100 micrometers, preferably 30 micrometers to 80 micrometers, and more preferably 35 micrometers to 80 micrometers.

The present disclosure also provides an injection prepared by the following steps: providing a plurality of polylactic acid microspheres; providing a suspension; mixing the polylactic acid microspheres and the suspension to obtain a microsphere suspension; and freeze-drying the microsphere suspension to obtain the injection.

In some embodiments, the polylactic acid microspheres are prepared through the aforementioned steps S1 to S4, which are respectively step S1, providing a first solution, the first solution comprising polylactic acid and an organic solvent; step S2, providing a second solution, wherein the second solution comprises polyvinyl alcohol, sodium carboxymethyl cellulose and an aqueous solution; step S3, adding the first solution to the second solution while stirring the second solution until the polylactic acid is solidified to form a plurality of polylactic acid microspheres; and a step S4 of collecting the polylactic acid microspheres. The polylactic acid microspheres prepared through the steps S1 to S4 have a reduced rehydration time and improved needle penetration when prepared into an injection, compared to conventional polylactic acid microspheres. It is emphasized that the second solution comprises polyvinyl alcohol and sodium carboxymethyl cellulose to achieve the above effect.

In some embodiments, the suspension comprises a surfactant, a polymeric silicide, a sugar alcohol, and a dispersant. In some embodiments, the surfactant comprises Sodium Dodecyl Sulfate (SDS), a polysorbate (Tween) series (e.g., Tween 80), a Triton (Triton) series, a Nonylphenol (NP) series, or a combination of the foregoing. In some embodiments, the polymeric silicide comprises polydimethylsiloxane. In some embodiments, the sugar alcohol comprises mannitol. In some embodiments, the dispersant comprises sodium carboxymethyl cellulose. In some embodiments, the suspension may comprise mannitol, sodium carboxymethylcellulose, polysorbate 80, and polydimethylsiloxane. In one embodiment, the weight ratio between the sodium carboxymethylcellulose and the polylactic acid microspheres may be between 1:4 and 1:10, the weight ratio between the mannitol and the polylactic acid microspheres may be between 1:3 and 1:10, the weight ratio between the polysorbate 80 and the polylactic acid microspheres may be between 1:60 and 1:140, and the weight ratio between the polydimethylsiloxane and the polylactic acid microspheres may be between 1:80 and 1: 180. In some embodiments, when the weight ratio of the sodium carboxymethylcellulose to the polylactic acid microspheres is between 1:5.5 and 1:10, the weight ratio of the mannitol to the polylactic acid microspheres is between 1:4 and 1:6.5, the weight ratio of the polysorbate 80 to the polylactic acid microspheres is between 1:85 and 1:130, and the weight ratio of the polydimethylsiloxane to the polylactic acid microspheres is between 1:110 and 1:175, an injection with a rehydration time of less than 8 minutes and excellent needle penetration can be obtained.

In some embodiments, the injection is reconstituted 2 minutes to 10 minutes after which time the injection is formed and can be passed through a twenty-six G needle (about 0.26 mm inner diameter and about 0.46 mm outer diameter) at a rate of 0.5 to 2 milliliters (mL) per minute.

To further demonstrate the improved properties of the polylactic acid microspheres produced by the various embodiments of the present disclosure, the following tests were performed. It should be noted that the following examples are provided for illustrative purposes only and do not limit the present invention.

EXAMPLE one method of preparing polylactic acid microspheres

The specific formulation conditions of the polylactic acid microspheres are shown in table 1 below.

First, a dispersed phase (first solution) and a continuous phase (second solution) are prepared. The dispersed phase is prepared by adding polylactic acid (PLA) into Dichloromethane (DCM), and the continuous phase is prepared by adding polyvinyl alcohol (PVA) and sodium carboxymethylcellulose (SCMC) into water and mixing.

Next, the dispersed phase was pumped with a peristaltic pump (Thermo Fisher Scientific Dry-bats)^TMSimple Peristatic Pump Starter Pack, USA) was added to the continuous phase and mixed with a blender (IKA EURO-ST 60C S001, Germany) as a blendThe liquid is combined, and the unit of the rotating speed is rotation per minute (rpm). Although four different stirring conditions were used in this example, and the preparation of the polylactic acid microspheres was performed by dividing the stirring conditions into groups A-D (as shown in Table 1 below), one skilled in the art could adjust the parameter settings according to the properties of different machines.

During the stirring process, since dichloromethane is an organic solvent, it is volatilized, so that the polylactic acid is cured into polylactic acid microspheres. Finally, the mixture was centrifuged at 2460Xg for ten minutes to collect the polylactic acid microspheres, and the polylactic acid microspheres were subjected to a freeze-drying treatment to remove excess water and residual organic solvent and to facilitate preservation.

TABLE 1 preparation conditions of polylactic acid microspheres

EXAMPLE two method for preparing injection

Next, the polylactic acid microspheres obtained under four different preparation conditions (A-D) in example one were prepared as injection according to formulation a in Table 2 below. In addition, in order to simultaneously test the difference of different injection formulations, the polylactic acid microspheres of group C in table 1 were selected, and then the formulations b and C in table 2 below were prepared into injections. The specific preparation process is as follows.

First, 300 ml of an aqueous solution containing polysorbate 80(TWEEN 80), polydimethylsiloxane (dimethicone), D-mannitol (D-mannitol) and sodium carboxymethylcellulose (SCMC) was added to freeze-dried polylactic acid microspheres, and mixed uniformly to obtain a microsphere suspension. Then, the microsphere suspension is subjected to freeze drying treatment to obtain the injection. The freeze drying can remove water, and the water is recovered when the product is used, so that the storage stability is improved.

TABLE 2 formulation of injection

EXAMPLE III polylactic acid microspheres and Properties of injection

To further understand the characteristics of the polylactic acid microspheres and the injection obtained by the preparation methods of examples one and two, the appearance of the polylactic acid microspheres was observed under an electron microscope at a voltage of 5kV and under a field of view of 450 to 1500 times. Referring to fig. 2A to 2D, the visual fields are 470 times, 900 times, 950 times and 1300 times, respectively, and the surface of the pla microspheres is seen to be smooth. In addition, fig. 2C and 2D show that the inner structure is a solid and smooth cross section when the polylactic acid microspheres are cut.

Then, the yield and particle size of the polylactic acid microspheres prepared from groups a to D of example one were calculated, and the injection prepared from example two was compared with commercially available products 1 and 2 for their reconstitution time, agglomeration resistance after reconstitution, and needle penetration, and the results are shown in table 3 below:

TABLE 3 comparative tables between injection and commercially available products 1 and 2

In the column symbols of this table, "-" indicates no test, and "x" in the injection rate column indicates failure to pass, "+" indicates no needle compliance, and "+" indicates needle compliance.

The yield of the polylactic acid microspheres was calculated as the percentage of the weight of the finally prepared polylactic acid microspheres after freeze-drying, based on the amount of polylactic acid added during the preparation (i.e., the weight of polylactic acid added to formulate the dispersed phase in example one) as 100%. As a result, as shown in table 3 (yield of polylactic acid microspheres), the preparation method of the present disclosure can achieve a yield of polylactic acid microspheres of more than nine.

The particle size analysis of the polylactic acid microspheres was performed at room temperature using a laser particle size analyzer (Beckman Coulter LS 200, USA). The results are shown in table 3 (particle size), the polylactic acid microspheres obtained by the present disclosure had D50 between 30 and 55 microns and D90 between 60 and 100 microns.

The injection prepared in example two and commercial products 1 and 2 were added with 5 ml of redistilled water (ddH)₂O) rehydration, and calculating the time required by rehydration. As shown in table 3 (reconstitution time), the injectable formulations obtained according to the present disclosure had a shorter reconstitution time, i.e., a faster reconstitution speed, than those of commercial products 1 and 2.

The anti-agglomeration was tested as follows. First, the injection solutions prepared in groups A to D of example I, commercial product 1 and commercial product 2 were reconstituted with 5 ml of redistilled water, centrifuged at 48Xg for 30 seconds in an electric centrifuge, and then 1 ml of the fixed-point injection solution was taken and lyophilized. Then, the ratio of polylactic acid in the site-specific injection solution of the injection prepared by the groups a to D of the first example of the present application to the polylactic acid in the site-specific injection solution of the commercial products 1 and 2 was calculated using the polylactic acid content in the site-specific injection solution of the commercial products 1 and 2 as denominators. A larger ratio indicates a better agglomeration resistance of the injection. As a result, as shown in table 3 (anti-agglomeration property), the injection of the present disclosure is superior to the commercial products 1 and 2 in anti-agglomeration property.

The term "needle-through" as used herein means that the injectant can pass through the syringe barrel and needle without sticking to the barrel wall and blocking the needle. The test method is that 5 ml of redistilled water is added to each of the lyophilized injection of the present disclosure, commercial product 1 and commercial product 2, and then 1 ml is taken out and injected through a twenty-six G needle to test the needle penetration at different flow rates. The results show that the injection of the present disclosure, after reconstitution into an injection, has a needle penetration at an injection rate of 0.5 ml/min comparable to that of commercial products 1 and 2; at faster injection rates (1 ml/min and 2 ml/min), the needle penetration was better than that of commercial products 1 and 2.

EXAMPLE four method of preparing polylactic acid microspheres

In another embodiment, the polylactic acid microspheres are prepared in a manner similar to that of example one, except that the concentrations of the dispersed phase (first solution) and the continuous phase (second solution) are in terms of weight-volume concentrations, as shown in table 4 below.

TABLE 4 preparation conditions of polylactic acid microspheres

EXAMPLE V preparation of injection

Polylactic acid microspheres obtained under four different preparation conditions (A-D) in Table 4 of example four were prepared as injections according to formulation a of Table 2 of example two. In addition, in order to simultaneously test the differences of different injection formulations, the polylactic acid microspheres of group C in table 4 were selected and then prepared into injections by using formulation b and formulation C in table 2 in example two. The specific procedure was as described in example two above.

EXAMPLE VI Properties of the polylactic acid microspheres and the injection

In the same manner as in example three, the characteristics of the polylactic acid microspheres and the injection prepared by the preparation methods of example four and example five were analyzed. As a result, similar to fig. 2A to 2D, the surface of the polylactic acid microsphere was observed to be smooth in 470 times, 900 times, 950 times, and 1300 times of visual field, and the inner structure was a solid smooth cross section when the polylactic acid microsphere was cut.

Then, the yield and particle size of the polylactic acid microspheres prepared from groups a to D of example four were calculated, and the injection prepared from example five was compared with commercially available products 1 and 2 for their reconstitution time, agglomeration resistance after reconstitution, and needle penetration, and the results are shown in table 5 below:

TABLE 5 comparison of injection with commercially available products 1 and 2

The test methods and definitions of the properties in table 5 are the same as those described in the third embodiment.

As a result, the production of the polylactic acid microspheres according to the fourth embodiment can achieve a yield of more than nine, wherein the obtained polylactic acid microspheres have D50 ranging from 30 microns to 55 microns and D90 ranging from 60 microns to 100 microns. Further, the injection preparation obtained in example five had a shorter reconstitution time, i.e., a faster reconstitution speed, than those of commercial products 1 and 2, and the injection preparation obtained in example five had better agglomeration resistance than those of commercial products 1 and 2. The injection obtained in the fifth example had a needle penetration at an injection rate of 0.5 ml/min equivalent to that of commercially available products 1 and 2 after reconstitution into an injection solution; at faster injection rates (1 ml/min and 2 ml/min), the needle penetration was better than that of commercial products 1 and 2.

The present disclosure provides polylactic acid microspheres with a concentrated particle size distribution and smooth surfaces by using a specific ratio of polyvinyl alcohol and sodium carboxymethylcellulose in the continuous phase. In addition, the yield of the polylactic acid microspheres obtained by the preparation method can reach nine times. Compared with the commercially available product, the injection of the present disclosure has the advantages of shortened rehydration time, better anti-agglomeration property and needle penetration, and improved clinical applicability.

Although the present invention has been described with reference to particular embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. a polylactic acid microsphere, is characterized in that, this polylactic acid microsphere is formed by polylactic acid aggregation, and this polylactic acid microsphere surface is smooth, and particle size is between 30 microns to 100 microns.

2. a method for preparing polylactic acid microspheres, is characterized in that, comprises the following steps:

providing a first solution, the first solution comprising a polylactic acid and an organic solvent;

providing a second solution, the second solution comprises polyvinyl alcohol, sodium carboxymethyl cellulose and an aqueous solution;

adding the first solution to the second solution while stirring the second solution until the polylactic acid solidifies to form a plurality of polylactic acid microspheres; and

The plurality of polylactic acid microspheres are collected.

3. The method of claim 2, wherein the weight percentage of the first solution is based on 100%, and the weight percentage of the polylactic acid in the first solution is between 2.5% and 10%.

4. The method of claim 2, wherein the weight volume concentration of the first solution is based on 100%, and the weight volume concentration of the polylactic acid in the first solution is between 2.5% and 10%.

5. The method of claim 2, wherein the organic solvent comprises dichloromethane, chloroform, ethyl acetate, or a combination thereof.

6. The method according to claim 2, wherein the weight percentage of the second solution is based on 100%, the weight percentage of polyvinyl alcohol in the second solution is between 0.5% and 2%, and the carboxymethyl fiber The weight percentage of the plain sodium in the second solution is between 0.1% and 2%.

7. The method according to claim 2, wherein the weight volume concentration of the second solution is based on 100%, the weight volume concentration of polyvinyl alcohol in the second solution is between 0.5% and 2%, carboxymethyl The weight volume concentration of sodium cellulose in the second solution is between 0.1% and 2%.

8. The method according to claim 2, wherein the step of adding the first solution to the second solution while stirring the second solution, the volume ratio between the second solution and the first solution is between 5 :1 to 100:1.

9. The method according to claim 2, wherein the step of adding the first solution to the second solution while stirring the second solution is 5% per minute, taking the volume of the first solution as 100% The first solution was added to the second solution at a rate of 35% of the first solution.

10. The method of claim 2, wherein the step of adding the first solution to the second solution while stirring the second solution is to stir the second solution at a rotational speed between 300 rpm and 1500 rpm.

11. The method of claim 2, wherein the step of collecting the plurality of polylactic acid microspheres comprises centrifugation or sieving.

12. The method according to claim 11, wherein the step of collecting the plurality of polylactic acid microspheres further comprises obtaining the plurality of polylactic acid microspheres by a freeze-drying method after a centrifugation method or a sieving method.

13. A polylactic acid microsphere, characterized in that, prepared through the following steps:

adding the first solution to the second solution while stirring the second solution to form a plurality of polylactic acid microspheres; and

The plurality of polylactic acid microspheres are collected.

14. The polylactic acid microsphere of claim 13, wherein the weight percent of the first solution is in 100%, and the weight percent of the plurality of polylactic acids in the first solution is between 2.5% to 10% between.

15. The polylactic acid microsphere according to claim 13, wherein the weight percent of the second solution is based on 100%, the weight percent of polyvinyl alcohol is between 0.5% to 2%, the weight percentage of sodium carboxymethyl cellulose is 100%. The weight percent is between 0.1% and 2%.

16. The polylactic acid microsphere according to claim 13, wherein the weight volume concentration of the first solution is 100%, and the weight volume concentration of the plurality of polylactic acids in the first solution is between 2.5% and 10%. %between.

17. polylactic acid microspheres according to claim 13, wherein the weight volume concentration of this second solution is in 100%, and the weight volume concentration of polyvinyl alcohol in the second solution is between 0.5% to 2%, The weight volume concentration of sodium carboxymethyl cellulose in the second solution is between 0.1% and 2%.

18. The polylactic acid microsphere according to claim 13, wherein the first solution is added to the second solution, while stirring the second solution step, the volume ratio between the second solution and the first solution is between the Between 5:1 and 100:1.

19. The polylactic acid microsphere according to claim 13, wherein the polylactic acid microsphere is spherical and has a smooth surface, and the particle size is between 30 microns and 100 microns.

20. An injection, wherein the injection is prepared via the following steps:

Provide multiple polylactic acid microspheres;

provide a suspension;

mixing the plurality of polylactic acid microspheres and the suspension to obtain a microsphere suspension; and

The microsphere suspension is freeze-dried to obtain the injection.

21. The injection according to claim 20, wherein providing the plurality of polylactic acid microspheres comprises the following steps:

providing a second solution, the second solution comprising polyvinyl alcohol, sodium carboxymethyl cellulose and an aqueous solution;

The plurality of polylactic acid microspheres are collected.

22. The injection according to claim 20, wherein the suspension comprises a surfactant, a polymer silicide, a sugar alcohol and a dispersant.

23. The injection according to claim 22, wherein the surfactant comprises polysorbate 80, the polymer silicide comprises polydimethylsiloxane, the sugar alcohol comprises mannitol, and the dispersant comprises a carboxyl Sodium methylcellulose.

24. The injection according to claim 21, wherein an injection is formed 2 minutes to 10 minutes after rehydration.

25. The injection of claim 24, wherein the injection can pass through a twenty-six G needle at a rate of 0.5 to 2 milliliters per minute.