CN113546060B - Naltrexone microspheres - Google Patents

Abstract

The invention discloses a naltrexone microsphere, and a preparation method thereof comprises the following steps: dissolving naltrexone and a degradable polymer containing a hydrophobic chain segment in an organic solvent to obtain a drug-containing polymer solution; mixing the drug-containing polymer solution and the water phase by using a microfluidic device to form an O/W type emulsion, and removing the organic solvent in the emulsion under the stirring condition; wherein the water phase contains a stabilizer, and the proportion of the stabilizer to the water phase is 0.1-5% (w/v); and after the organic solvent is completely volatilized, adding the obtained dispersion system into water for solidification to obtain the naltrexone microspheres. The microsphere overcomes the defects of nonuniform particle size distribution, irregular microsphere shape, high release burst and the like of the microsphere prepared by the traditional preparation method. In addition, the particle synthesis process of the microfluidic technology has highly controllable technological parameters, and is beneficial to the production and amplification of microspheres.

Description

Naltrexone microspheres

Technical Field

The invention relates to the technical field of pharmaceutical preparations, in particular to naltrexone microspheres.

Technical Field

Naltrexone is an opioid receptor antagonist, has pharmacodynamics similar to that of naloxone, has blocking effect on kappa-, delta-, mu-and other opioid receptors, can obviously weaken or completely block opioid receptors, and even reverses the effect generated by intravenous injection of opioid drugs. It can block the effect of drug re-taking and prevent or reduce re-taking. The structural formula is shown in the following formula.

Naltrexone preparation is mainly in form of tablet, and the treatment course lasts for half a year and 50mg should be taken daily. Therefore, the treatment course is long, and the medicine has certain toxicity to the liver. In order to improve the compliance of patients, the development of the long-acting microsphere of naltrexone has wider application prospect. Microspheres are matrix-type entities formed by dissolving or dispersing a drug in a polymeric material, with a particle size ranging from 1 to 250 μm. Generally prepared into suspension for injection or oral administration. The medicament has the following characteristics after micro-spheroidization: covering up the unpleasant odor of the medicine, improving the stability of the medicine, reducing the stimulation to the stomach or the inactivation of the medicine in the stomach, solidifying the liquid medicine for convenient storage or further preparing into other dosage forms, controlling the release rate of the medicine, and the like.

Common microsphere preparation methods include spray drying, emulsification-solvent evaporation, hot-melt extrusion, and phase separation. CN200710099359.9 patent uses O/W type emulsification-solidification method to prepare naltrexone microsphere with higher encapsulation efficiency, the protected microsphere contains 10% -50% of naltrexone base, 50% -90% of polylactic acid-glycolic acid copolymer (PLGA) and 0.1% -10% of polyvinyl alcohol (PVA); according to the results reported by Youngan et al (CN 02145144.3), the encapsulation efficiency of the naltrexone microspheres prepared by 35% feeding is 75% by using a single emulsion solvent evaporation method, but the microsphere uniformity and the morphology are poor. Therefore, the traditional process still has some defects at present, such as poor reproducibility among batches, non-uniform particle size distribution, difficult control of microsphere morphology, difference of embedding capacities of drugs with different properties, complex preparation process, low production efficiency and the like.

Disclosure of Invention

In view of the above disadvantages, the present invention aims to provide a naltrexone microsphere, which has a simple and rapid preparation method, and can effectively solve the problems of poor uniformity, irregular shape, etc. of the naltrexone microsphere.

In order to achieve the purpose, the invention provides the following technical scheme:

a naltrexone microsphere is prepared by the following steps:

a: dissolving naltrexone and a degradable polymer containing a hydrophobic chain segment in an organic solvent to obtain a drug-containing polymer solution; wherein, the mass ratio of the naltrexone to the degradable polymer is fixed as 1.97, and the concentration of the degradable polymer in the organic solvent is 2.5-50% (w/v);

b: dissolving a stabilizer in water to obtain an external water phase; wherein the concentration of the stabilizer is 0.5-5% (w/v);

c: respectively taking the drug-containing polymer solution and the water phase as an A pump solution and a B pump solution of an advection pump, setting the A pump and the B pump of the advection pump at certain flow rates, generating an O/W type emulsion by a microfluidic device, and removing an organic solvent in the emulsion under a stirring state; wherein, the phase A flow rate is set: the flow rate of the phase B is 1;

d: c, under the condition of stirring, adding the dispersion system obtained in the step c into water for curing to obtain the naltrexone sustained release microspheres; wherein the volume ratio of the dispersion system to water is 1-1.

Further, in the naltrexone microsphere, in the step a, the degradable polymer containing the hydrophobic chain segment is selected from one or more of polylactic acid-glycolic acid copolymer (PLGA), polylactic acid (PLA), polylactic acid-polyethylene glycol (PLA-PEG) and Polycaprolactone (PCL).

Further, in step a, the degradable polymer containing the hydrophobic segment is polylactic-co-glycolic acid (PLGA), the relative molecular mass of which is 5000-100000, wherein the molar ratio of polylactic acid to glycolic acid is 50-85.

Preferably, the PLGA relative molecular mass of the naltrexone microspheres is 12000-90000, more preferably 12000-21000.

Preferably, the molar ratio of polylactic acid to glycolic acid in the PLGA is 50 to 75, more preferably 75.

Further, in the naltrexone microspheres, in the step a, the organic solvent is one or more selected from dichloromethane, ethyl acetate, acetone, methyl ethyl ketone and tetrahydrofuran.

Preferably, the organic solvent is dichloromethane, ethyl acetate and acetone.

Further, in the naltrexone microspheres, in the step a, the degradable polymer containing the hydrophobic chain segment accounts for 0.5-20% (w/v) of the total mass of the drug-containing polymer solution; preferably 2.5-20%, when the concentration of the polymer is too low, the medicine is easy to leak in the preparation process, and the preparation of the microspheres is influenced.

Further, in the naltrexone microspheres, in the step b, the stabilizer is one or more selected from polyvinyl alcohol (PVA), polysorbate 20, polysorbate 80 (tween 80), polyethylene glycol and sodium dodecyl sulfate.

Preferably, in the naltrexone microspheres, the stabilizing agents are polyvinyl alcohol PVA and Tween 80, and the ratio of the PVA to the water phase is preferably 0.5-5% (w/v); more preferably 1% (w/v). The proportion of the Tween 80 to the water phase is preferably 0.1-0.3% (w/v); more preferably 0.1% (w/v).

Further, in step c, the phase a flow rate is 1; the flow rate range of the microfluidic A pump and the microfluidic B pump is 1-100 mL/min, more preferably the flow rate of the phase A is 6mL/min, the flow rate of the phase B is 18mL/min, the two-phase flow speed ratio directly influences the size of the droplet particle size, and when the AB phase is set to the above speed, the prepared microspheres have the highest encapsulation rate, good uniformity and regular shape.

Further, the volume ratio of the dispersion system of the step b to water is 1; more preferably 1.

Further, the diameter of the inner hole of the micro-fluidic controller in the step c is between 50 μm and 2mm, and is preferably between 100 μm and 1mm. The diameter of the inner bore of the microflow controller directly affects the particle size of the final microsphere.

Furthermore, the mean grain size of the naltrexone microspheres prepared by the method is 50-100 μm. When the microcapsule or microsphere with the grain diameter of less than 200 mu m is orally taken, no foreign body sensation is produced in the oral cavity, the smaller grain diameter has larger specific surface area, and the relative drug-loading capacity is large.

Furthermore, the drug in the naltrexone microspheres prepared by the invention can be slowly released for one month.

Furthermore, the naltrexone microspheres prepared by the invention are used for preparing an opioid receptor antagonist.

The scheme shows that the invention at least has the following beneficial effects: dissolving naltrexone and a degradable polymer containing a hydrophobic chain segment in an organic solvent, dissolving a stabilizer in water to form an external water phase, taking the formed oil phase and the external water phase as micro-fluidic A and B phase solutions respectively, setting certain flow rates of an A pump and a B pump according to a certain proportion, generating an O/W type emulsion through a micro-fluidic device, and removing the organic solvent in the emulsion under a stirring state; further curing with water to obtain naltrexone microspheres; the naltrexone microspheres prepared by the method have the advantages of high encapsulation rate, good slow release effect, uniform particle size, round shape and good reproducibility; meanwhile, the preparation method disclosed by the invention is low in production cost and high in efficiency.

Drawings

FIGS. 1-6 are micrographs of the emulsions of examples 2, 4, 5, 8, 9, and 12, in that order;

FIG. 7 is a scanning electron micrograph (200X on the left and 400X on the right) of microspheres obtained in example 4;

FIG. 8 is a scanning electron micrograph (left 200X, right 400X) of microspheres obtained in example 9; FIG. 9 is an in vitro cumulative release profile of naltrexone microspheres prepared in examples 4, 5, 9 and 12; fig. 10 is a graph showing the release of plasma drug concentration when the naltrexone microspheres prepared in example 9 were subjected to animal experiments.

Detailed Description

The following describes in detail a specific embodiment of the present invention with reference to the drawings, examples, and test examples. The following examples are intended to illustrate the invention, but are not intended to limit the scope of the invention.

1. Comparative preparation example

The following methods were used to prepare microspheres by the conventional emulsion solvent evaporation method, and examples 1-7 were prepared as comparative examples.

203.2mg of naltrexone and 400mg of polymer are weighed and dissolved in an organic solvent to form a polymer solution containing naltrexone, microspheres are prepared by adopting a traditional method, namely an emulsifying solvent volatilization method, the microspheres are dropwise added into a water phase containing a stabilizer under the stirring state to form an O/W emulsion, the emulsion is added into curing water at room temperature and is continuously stirred for 4 hours to volatilize the organic solvent, wherein the stirring speed is 300-500rpm. Volatilizing the organic solvent, standing, removing supernatant after the suspended matters settle, washing with water for three times, centrifuging, collecting microspheres, and freeze-drying. The recipe is given in table 1 below.

TABLE 1 recipe for different comparative examples

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Particle size and encapsulation efficiency of microspheres of comparative example:

particle size: an appropriate amount of the microspheres prepared in examples 1 to 7 was divided into three portions, each of which was suspended in an appropriate amount of 0.1% aqueous tween 80 solution, and the particle size of the microspheres was measured using a laser particle size distribution instrument.

The encapsulation efficiency is as follows: preparing 0.1mol/L hydrochloric acid solution, weighing 30mg naltrexone microspheres, putting the naltrexone microspheres into a 10mL centrifuge tube, adding 6mL 0.1mol/L hydrochloric acid solution, and shaking a vortex apparatus for 3min at the strength of 5; centrifuging by a centrifugal machine at 12000rpm for 15min, and performing high performance liquid analysis on the clear supernatant to obtain the concentration of the free drug; adding 2mL of dichloromethane into the precipitate for dissolving, transferring the precipitate into a 50mL volumetric flask, using dichloromethane for constant volume, shaking up, measuring 1mL of sample solution from the precipitate in a penicillin bottle, adding 4mL of 0.1mol/L hydrochloric acid solution, oscillating the vortex instrument for 3min at the intensity of 5, volatilizing DCM at the water bath temperature of 40 ℃, volatilizing dichloromethane, centrifuging by using a centrifugal machine, performing 10000rpm and 10min, taking supernatant into a 50 or 100mL volumetric flask, using hydrochloric acid for constant volume and uniform mixing, and performing high-efficiency liquid phase analysis to obtain the concentration of the drug-coated drug. The results are shown in Table 2, and the envelope ratio is calculated as follows:

TABLE 2 particle size and encapsulation efficiency of microspheres of comparative examples

Examples	Mean median diameter (μm)	Encapsulation efficiency (%)
			1	48.96	67.65
2	42.64	64.98
			3	41.46	65.23
4	78.60	75.63
			5	79.26	75.24
6	72.23	65.67
			7	69.54	67.65

The results in table 2 show that the microspheres prepared by the traditional method have large particle size difference and low encapsulation efficiency, and the experimental data also show that the concentration of PLGA has a large influence on the encapsulation efficiency of the microspheres under the same polymer condition, and when the concentration is high, the polymer solution can better wrap the drug, thereby improving the encapsulation efficiency; after comparing other factors, such as stabilizer type, curing fold, etc., the present study identified the preferred conditions in comparative example 4, which was applied in microfluidic technology as the conditions of the examples of the present invention.

2. Preparation examples of the present invention

A naltrexone microsphere is prepared by the following steps:

a: dissolving 2.03g of naltrexone and 4g of degradable polymer containing hydrophobic chain segments in dichloromethane to obtain a drug-containing polymer solution; the concentration of the degradable polymer in the organic solvent is 2.5-50% (w/v);

b: dissolving a stabilizer PVA in water to obtain an external water phase; wherein the concentration of the stabilizer is 1-5% (w/v);

c: respectively taking the drug-containing polymer solution and the water phase as an A pump solution and a B pump solution of an advection pump, setting the A pump and the B pump of the advection pump at certain flow rates, generating an O/W type emulsion by a microfluidic device, and removing an organic solvent in the emulsion under a stirring state; wherein, phase a flow rate is set: and the flow rate of the phase B is 1.

d: c, under the condition of stirring, adding the dispersion system obtained in the step c into water for solidification to obtain the naltrexone sustained release microspheres; wherein the volume ratio of the dispersion system to water is 1-1.

The formulations were as described in table 3 below.

TABLE 3 recipe for embodiments of the invention

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The particle size and encapsulation efficiency of the microspheres in the preparation examples of the present invention were measured by referring to the methods of comparative examples, and the results are shown in table 4 below.

TABLE 4 particle size and encapsulation efficiency of microspheres of examples of the invention

Examples	Mean median diameter (μm)	Encapsulation efficiency (%)
			8	78.96	78.65
9	76.34	89.23
			10	77.60	85.93
11	61.60	85.21
			12	92.26	87.51
13	71.23	82.01
			14	67.21	84.00
15	84.96	86.61
			16	62.00	82.90
17	79.71	71.02
			18	68.00	69.53

As shown in Table 4, the microspheres prepared by the method of the invention have uniform particle size and high encapsulation efficiency, and most of the microspheres exceed the encapsulation efficiency of 80% specified by pharmacopoeia.

3. Test example 1

Emulsion morphology and microsphere appearance.

The emulsion in the process of preparing microspheres in examples 2, 4, 5, 8, 9 and 12 was taken and observed by a microscope for the shape of emulsion droplets, and the results are shown in figures 1 to 6. As can be seen from FIGS. 1 to 6, the emulsions of examples 8, 9 and 12 prepared according to the protocol of the present invention have uniform and moderate particle size in comparison to the comparative proportions.

Taking a proper amount of the microspheres prepared in the embodiments 4 and 9, observing the surface morphology of the microspheres by using a scanning electron microscope, wherein the results are shown in the attached drawings 7 and 8, and the embodiment 9 means that the naltrexone sustained release microspheres prepared by the scheme provided by the invention have uniform particle size, round microspheres and good morphology.

4. Test example 2

Naltrexone microsphere cumulative release profile

The microsphere in vitro release medium was PBS (pH7.4) buffer containing 0.02% Tween 20, and the release volume was 50mL; 50mg of microspheres prepared in examples 4, 5, 9 and 12 were placed in a 50mL conical flask, 50mL of release medium was added, and the supernatant was subjected to high performance liquid chromatography at 4h, 1d, 2d, 3d, 7d, 14d, 21d, 28d \8230; \8230, time point sampling 1mL, centrifugation (12000rpm, 15min) to obtain 700. Mu.L of sample injection, the remaining microspheres were resuspended in 300. Mu.L of fresh medium and placed back in the 50mL conical flask for sustained shaking release, and all release medium was replaced every 7 days. The percent cumulative release was calculated and a release profile of percent cumulative release versus time was plotted, the results of which are shown in figure 9.

It can be seen from the figure that the microspheres obtained by the conventional preparation method, i.e. examples 4 and 5, have high burst release and poor release profile, while in contrast, the microspheres prepared by the microfluidic process parameters of the present invention, i.e. examples 9 and 12, have slow release of the drug from the microspheres, low burst release, gentle release profile, sustained slow release for one month and good in vitro release.

5. Test example 3

And testing the blood concentration of naltrexone microspheres in animals.

3 beagle dogs with the body mass of about 12kg are taken after fasting for 12h, the naltrexone microspheres prepared in the best example 9 are injected into beagle dogs in a mode of hip muscle deep injection according to the dose of 11.9mg/kg, blank blood is taken before administration, 3mL of blood is taken from forelimb veins after administration for 4h, 24 h, 48 h, 72 h, 168 h, 336 h, 504 h, 672 h, 840 h and 960h, the blood is placed in a test tube added with heparin, the blood is centrifuged for 10min at 4000r/min, plasma is separated, high performance liquid phase analysis is carried out, the concentration of the naltrexone in the blood is detected, and a blood concentration release curve graph is drawn, as shown in figure 10, the naltrexone microspheres disclosed by the invention have very good slow release effect in animals. If the naltrexone microsphere microspheres disclosed by the invention are used for preparing an opioid receptor antagonist, the frequency of taking the drug can be obviously reduced.

The results of the above examples and test examples show that the invention uses the microfluidic technology, optimizes the microfluidic parameters, and improves the defects of nonuniform particle size distribution, irregular microsphere shape, high release burst and the like of the microspheres prepared by the traditional preparation method. In addition, the particle synthesis process of the microfluidic technology has highly controllable technological parameters, and is beneficial to the production and amplification of microspheres.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that modifications can be made by those skilled in the art without departing from the principle of the present invention, and these modifications should also be construed as the protection scope of the present invention.

Claims (4)

1. A naltrexone microsphere, characterized by being prepared by the following steps:

a: dissolving naltrexone and a degradable polymer polylactic acid-glycolic acid copolymer containing a hydrophobic chain segment in a dichloromethane solvent to obtain a drug-containing polymer solution; wherein the relative molecular mass of the polylactic acid-glycolic acid copolymer is 12000, and the molar ratio of polylactic acid to glycolic acid is 75; the mass ratio of the naltrexone to the polylactic acid-glycolic acid copolymer is fixed to be 1.97, and the concentration of the polylactic acid-glycolic acid copolymer in dichloromethane is 2.5-20% (w/v);

b: dissolving a stabilizer PVA in water to obtain an external water phase; wherein the concentration of the stabilizer is 1-5% (w/v);

c: respectively taking the drug-containing polymer solution and the water phase as an A pump solution and a B pump solution of an advection pump, setting a certain flow rate of the A pump and the B pump of the advection pump, generating an O/W type emulsion by a microfluidic device, and removing an organic solvent in the emulsion in a stirring state; wherein, phase a flow rate is set: the flow rate of the phase B is 1; the two phases enter a micro mixer through a pipeline at a constant flow rate by an advection pump to be mixed to form an emulsion, and the organic solvent is volatilized after the emulsion is collected;

d: c, under the condition of stirring, adding the dispersion system obtained in the step c into water for curing to obtain the naltrexone sustained release microspheres; wherein the volume ratio of the dispersion system to water is 1-1.

2. Use of naltrexone microspheres as claimed in claim 1, in the preparation of an opioid receptor antagonist.

3. A naltrexone microsphere, characterized by being prepared by the following steps:

a: dissolving naltrexone and a degradable polymer polylactic acid-glycolic acid copolymer containing a hydrophobic chain segment in a dichloromethane solvent to obtain a drug-containing polymer solution; wherein the relative molecular mass of the polylactic acid-glycolic acid copolymer is 12000, and the molar ratio of polylactic acid to glycolic acid is 75; the mass ratio of the naltrexone to the polylactic acid-glycolic acid copolymer is fixed as 1.97, and the concentration of the polylactic acid-glycolic acid copolymer in dichloromethane is 2.5-20% (w/v);

b: dissolving a stabilizer PVA in water to obtain an external water phase; wherein the concentration of the stabilizer is 1-5% (w/v);

c: respectively taking the drug-containing polymer solution and the water phase as an A pump solution and a B pump solution of an advection pump, setting the A pump and the B pump of the advection pump at certain flow rates, generating an O/W type emulsion by a microfluidic device, and removing an organic solvent in the emulsion under a stirring state; wherein, phase a flow rate is set: the flow rate of the phase B is 1; the two phases enter a micro mixer through a pipeline at a constant flow rate by an advection pump to be mixed to form an emulsion, and the organic solvent is volatilized after the emulsion is collected;

d: c, under the condition of stirring, adding the dispersion system obtained in the step c into water for curing to obtain the naltrexone sustained release microspheres; wherein the volume ratio of the dispersion system to water is 1-1.

4. Use of naltrexone microspheres as claimed in claim 3 in the preparation of an opioid receptor antagonist.

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