Method for preparing degradable drug-loaded microsphere for embolization, and product obtained therefrom

Abstract

A method for preparing a degradable drug-loaded microsphere for embolization and a product obtained therefrom, includes the steps of: dissolving a degradable material in an organic solvent, then adding a drug and mixing well to form a suspension or solution; then pouring the drug-containing suspension or solution into an aqueous solution of polyvinyl alcohol, stirring, and thereafter adding water twice for dilution, to prepare the degradable drug-loaded microsphere. The microsphere prepared by the present invention has the advantages of having a controllable particle size, a high drug loading capacity, and a regular spherical shape, being convenient for sieve sizing and accurate particle-size indication, and being accurately targeted to an embolized blood vessel, and the like, and thus has a good application prospect in interventional embolization therapy.

Claims

1. A method for preparing a degradable drug-loaded microsphere for embolization, comprising the steps of: (1) mixing a degradable material with an organic solvent to form a solution, adding a drug into the solution, and uniformly dispersing the drug to form a suspension or solution; (2) adding the aforementioned suspension or solution into an aqueous PVA solution, stirring, and thereafter adding water twice into the aqueous PVA solution for dilution to obtain a microsphere, wherein each time after the water is added the mixture is stirred; and (3) collecting, washing and drying the obtained microsphere to obtain the degradable drug-loaded microsphere for embolization, wherein in step (2), the volume of water added for the first time is 0.5-4 times larger than that of the aqueous PVA solution, and the volume of water added for the second time is 0.5-4 times larger than that of the aqueous PVA solution.

2. The method of claim 1, wherein the degradable material is one or more of poly(d,l-lactic-co-glycolic acid), poly(L-lactide-co-epsilon-caprolactone), polycaprolactone, methoxy poly(ethylene glycol)-poly(lactide), poly(d,l-lactide-co-glycolide)-b-poly(ethylene glycol)-b-poly(d,l-lactide-co-glycolide), polydioxanone and poly(trimethylene carbonate).

3. The method of claim 1, wherein the drug is one or more of anti-tumor drugs.

4. The method of claim 3, wherein the drug is one or more of paclitaxel, rapamycin, 5-fluorouracil, cisplatin, doxorubicin, irinotecan, oxaliplatin, docetaxel, gemcitabine, pirarubicin, epirubicin, avastin, rituximab, and lenalidomide.

5. The method of claim 3, wherein the drug is one or more of rapamycin, 5-fluorouracil, cisplatin, doxorubicin, irinotecan, pirarubicin and epirubicin.

6. The method of claim 1, wherein the organic solvent is a mixture of dichloromethane and a poor solvent, and the poor solvent is one or more of acetone, ethyl acetate, ethanol, n-heptane, isohexane, ether and silicone oil.

7. The method of claim 1, wherein in step (1) the concentration of the degradable material in the organic solvent is 0.2-0.7 g/ml, and preferably the concentration of the degradable material in the organic solvent is 0.3-0.5 g/ml.

8. The method of claim 1, wherein in step (1) the mass ratio of the drug to the degradable material is 0.1-3:1, and preferably the mass ratio of the drug to the degradable material is 0.1-1:1.

9. The method of claim 1, wherein in step (1) the drug is uniformly dispersed by using ultrasound.

10. The method of claim 1, wherein in step (2) the concentration of the aqueous PVA solution is 1-45 wt %, and preferably the concentration of the aqueous PVA solution is 8-15 wt %.

11. The method of claim 1, wherein in step (2), the volume ratio of the aqueous PVA solution to the suspension or solution of step (1) is 1.5-50:1, and preferably the volume ratio of the aqueous PVA solution to the suspension or solution of step (1) is 1.5-10:1, and more preferably the volume ratio of the aqueous PVA solution to the suspension or solution of step (1) is 1.5-3:1.

12. The method of claim 1, wherein in step (2) the stirring speed is 100-400 rpm.

13. The method of claim 1, wherein in step (2), after the suspension or solution is added into the aqueous PVA solution, the mixture is stirred for 1-15 min, then diluted with water, stirred for 1-30 min, then diluted with water again, and stirred for 1-150 min.

14. The method of claim 1, wherein in step (2), after the suspension or solution is added into the aqueous PVA solution, the mixture is stirred for 1-15 min, then diluted with water, stirred for 1-20 min, then diluted with water again, and stirred for 1-30 min.

15. The method of claim 1, wherein the obtained microsphere has a particle size of 100-2000 m.

16. A degradable drug-loaded microsphere for embolization prepared by the method for preparing the degradable drug-loaded microsphere for embolization of any of claim 1.

17. The degradable drug-loaded microsphere for embolization of claim 16, wherein the degradable drug-loaded microsphere for embolization has a degradation time of 20-60 days.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a diagram showing the morphology of the degradable drug-loaded microsphere for embolization as prepared in Example 4 of the present invention under an optical microscope.

(2) FIG. 2 is a diagram showing the morphology of the degradable drug-loaded microsphere for embolization as prepared in Example 10 of the present invention under an optical microscope.

(3) FIG. 3 is a diagram showing the morphology of the degradable drug-loaded microsphere for embolization as prepared in Example 13 of the present invention under an optical microscope.

(4) FIG. 4 is a standard curve of the concentration of 5-fluorouracil versus absorbance.

(5) FIG. 5 is a graph showing the relationship between the particle size range of the degradable drug-loaded microsphere for embolization as prepared in Example 4 and the content of 5-fluorouracil.

(6) FIG. 6 is a graph showing the relationship between the particle size range of the degradable drug-loaded microsphere for embolization as prepared in Example 13 and the content of 5-fluorouracil.

(7) FIG. 7 is a schematic diagram of the preparation process of the microsphere.

(8) FIG. 8 is a diagram showing the state of the freeze-dried degradable drug-loaded microsphere for embolization of Example 14 in the developer.

(9) FIG. 9 is a diagram showing the state of the degradable drug-loaded microsphere for embolization as prepared in Example 1 in the developer.

DESCRIPTION OF THE EMBODIMENTS

(10) The present invention provides a method for preparing a degradable drug-loaded microsphere for embolization. This method forms a degradable drug-loaded microsphere for embolization with a smooth surface by an improved solvent evaporation method in combination with a phase separation method, and the microsphere has a particle size of 100-2,000 m.

(11) The method for preparing the degradable drug-loaded microsphere for embolization is as follows:

(12) the degradable material is dissolved in an organic solvent to form a solution; a drug is added into the solution and subjected to ultrasonication to form a suspension or a solution; and the drug-loaded microsphere is prepared by a method of diluting the PVA solution in three steps, where the method of diluting the PVA solution in three steps refers to: pouring the drug-containing suspension or solution into a certain concentration of an aqueous PVA solution; stirring for a certain period of time; adding a certain volume of water into the mixture for the secondary stirring; adding a certain volume of water again for the third stirring after the secondary stirring is conducted for a certain period of time; washing to remove the PVA after the stirring is conducted for a certain period of time; and freeze-drying to obtain the degradable drug-loaded microsphere for embolization.

(13) Furthermore, the present invention provides a method for preparing a degradable drug-loaded microsphere for embolization, including the steps of:

(14) (1) dissolving a certain mass of a degradable material in an organic solvent to formulate a solution, where the degradable material is one or more of poly(d,l-lactic-co-glycolic acid) (PDLGA), poly(L-lactide-co-epsilon-caprolactone) (PLCL), polycaprolactone (PCL), methoxy poly(ethylene glycol)-poly(lactide) (MPEG-PDLGA) and poly(d,l-lactide-co-glycolide)-b-poly(ethylene glycol)-b-poly(d,l-lactide-co-glycolide) (PDLGA-PEG-PDLGA), polydioxanone, and poly(trimethylene carbonate)(PTMC) (the degradable material has a viscosity of 0.1-0.5 dl/g, and a weight average molecular weight of 20,000-100,000);

(15) (2) adding a drug into the aforementioned solution of the degradable material to form a suspension or solution, where the drug is one or more of paclitaxel, rapamycin, 5-fluorouracil, cisplatin, doxorubicin, irinotecan, oxaliplatin, docetaxel, gemcitabine, pirarubicin, epirubicin, avastin, rituximab, and lenalidomide; and

(16) (3) adding the suspension or solution of step (2) into a certain concentration of an aqueous PVA solution, stirring for a certain period of time, and then firstly adding a certain volume of water for the secondary stirring (i.e., the stirring for the second time), secondly adding a certain volume of water into the mixture for the third stirring (i.e., the stirring for the third time) after the secondary stirring is conducted for a certain period of time, stirring for a certain period of time and then collecting the microsphere, washing to remove the PVA, and freeze-drying to obtain the degradable drug-loaded microsphere for embolization.

(17) In the aforementioned step (1), the degradable material is dissolved in the organic solvent to formulate a solution. The organic solvent may be any organic solvent capable of dissolving the degradable material, and preferably the organic solvent of the present invention is a mixture of dichloromethane and a poor solvent of the degradable material, and the poor solvent is one or more of acetone, ethyl acetate, ethanol, n-heptane, isohexane, ether and silicone oil, and the like. In an embodiment of the present invention, the organic solvent of step (1) is a mixture of dichloromethane and acetone, a mixture of dichloromethane and ethyl acetate, a mixture of dichloromethane and ethanol, a mixture of dichloromethane and n-heptane, a mixture of dichloromethane and isohexane, a mixture of dichloromethane and ether, a mixture of dichloromethane and silicone oil, a mixture of dichloromethane, n-heptane and acetone, a mixture of dichloromethane, isohexane and acetone, a mixture of dichloromethane, ethyl acetate and acetone, a mixture of dichloromethane, ethanol and ether, or a mixture of dichloromethane, isohexane and silicone oil. The volume ratio of the poor solvent to the dichloromethane can be adjusted according to the size of the microsphere, the porosity, the drug loading capacity, the drug component, the concentration of the PVA solution, and the like conditions.

(18) In an embodiment of the present invention, the concentration of the degradable material in the organic solvent is 0.2-0.7 g/ml, for example 0.2 g/ml, 0.3 g/ml, 0.4 g/ml, 0.5 g/ml, 0.6 g/ml, and 0.7 g/ml. The concentration can be adjusted according to the drug composition, the concentration of the PVA solution, and the like conditions, and is preferably 0.3-0.5 g/ml.

(19) In an embodiment of the present invention, the drug is preferably one or more of rapamycin, 5-fluorouracil, cisplatin, doxorubicin, irinotecan, pirarubicin, and epirubicin. These drugs are hardly soluble or slightly soluble in water. In the present invention, the microsphere is formed by adding water stepwise for dilution, which reduces the probability of the drug entering the water phase, and increases the drug loading capacity. The increase in the drug loading capacity is more obvious for drugs which are hardly soluble or slightly soluble in water, and for drugs which are easily soluble in water, the present invention can also reduce the probability of the drug entering the aqueous phase, but the effect may not be as obvious as that on the hardly soluble or slightly soluble drugs.

(20) In an embodiment of the present invention, the mass ratio of the drug to the degradable material is: 0.1-3:1, for example 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.5:1, 2:1, 2.5:1, 3:1. The mass ratio is related to the drug loading capacity, and within such a range, as the dosage of the drug increases, the drug loading capacity begins to have an increasing trend, but as the dosage of the drug continues to increase, the drug loading capacity tends to be balanced. Preferably, the mass ratio of the drug to the degradable material is 0.1-1:1.

(21) In a certain embodiment of the present invention, the concentration of the aqueous PVA solution is 1 wt %-45 wt %, for example, 1 wt %, 2 wt %, 3 wt %, 5 wt %, 8 wt %, 10 wt %, 12 wt %, 15 wt %, 18 wt %, 20 wt %, 25 wt %, 30 wt %, 35 wt %, 40 wt %, 45 wt %. The concentration of the PVA aqueous solution has an influence on the encapsulation efficiency and drug loading capacity of the finally obtained microsphere. Preferably, the concentration of the aqueous PVA solution is 2-20 wt %, and more preferably 8-15 wt %. Furthermore, an appropriate temperature of the aqueous PVA solution can also be selected experimentally to increase the drug loading capacity and encapsulation efficiency.

(22) In an embodiment of the present invention, the volume ratio of the aqueous PVA solution to the suspension or solution of step (2) is 1.5-50:1, for example 1.5:1, 1.8:1, 3:1, 5:1, 7:1, 8:1, 9:1, 10:1, 12:1, 15:1, 20:1, 25:1, 30:1, 35:1, 40:1, 45:1, 50:1. The volume ratio has an influence on the encapsulation efficiency and drug loading capacity of the finally obtained microsphere, and is preferably 1.5-10:1, and more preferably 1.5-3:1.

(23) In an embodiment of the present invention, the volume of each of water added for the first time and the second time is 0.5-4 times, for example 0.5 times, 1 time, 2 times, 3 times, 4 times larger than that of the aqueous PVA solution. Such a volume ratio has an influence on the encapsulation efficiency and drug loading capacity of the finally obtained microsphere, and may be adjusted according to the actual situation.

(24) In an embodiment of the present invention, in step (3) the stirring speed is 100-400 rpm, for example 100 rpm, 150 rpm, 200 rpm, 250 rpm, 300 rpm, 350 rpm, 400 rpm. The stirring speed can adjust the particle size of the microsphere and can be adjusted as needed.

(25) In an embodiment of the present invention, in step (3), the mixture is stirred for 1-15 min, for example 1 min, 2 min, 5 min, 8 min, 10 min, 12 min, 15 min after the suspension or solution is added into the aqueous PVA solution. The mixture is stirred for 1-30 min, for example 1 min, 5 min, 10 min, 12 min, 15 min, 20 min, 25 min, 30 min, and preferably 1-20 min after the first addition of water. The mixture is stirred for 1-150 min, for example 1 min, 10 min, 15 min, 20 min, 25 min, 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min. 110 min, 120 min, 130 min, 140 min, 150 min, and preferably 1-30 min after the second addition of water. The stirring time is related to the encapsulation efficiency and drug loading capacity of the finally obtained microsphere, and can be adjusted according to actual situations.

(26) The present invention is further illustrated by the following listed specific Examples of the present invention, but these Examples are not intended to limit the present invention.

(27) The means used in the following Examples are means conventionally used in the art, unless otherwise stated. The reagents used in the Examples are all commercially available products. Unless otherwise stated, in the following Examples the concentrations are all mass concentrations, and the temperature of the aqueous PVA solution is room temperature.

(28) In the following Examples, the degradable material as used had an intrinsic viscosity of 0.25-0.45 dl/g and a weight average molecular weight of 20,000-100,000.

(29) In the following Examples, the actual drug loading capacity and encapsulation efficiency are calculated as:
actual drug loading capacity=mass of the drug in the microsphere/mass of the microsphere100%
encapsulation rate=actual drug loading capacity/theoretical drug loading capacity100%
theoretical drug loading capacity=mass of the drug as added/(mass of the drug as added+mass of the degradable material)100%

(30) where, the mass of the drug can be determined by an absorbance method, an atomic absorption method, high performance liquid chromatography, etc. depending on the specific drug.

Example 1

(31) (1) 10 g PDLGA (poly(d,l-lactic-co-glycolic acid)) with an intrinsic viscosity of 0.2 dl/g was weighed and added into 25 ml of a dichloromethane solvent to formulate a PDLGA solution at a concentration of 0.40 g/ml;

(32) (2) 6 g of 5-fluorouracil was weighed and added into the aforementioned solution, and subjected to ultrasonication to form a suspension;

(33) (3) the suspension prepared in step (2) was added into 50 ml of an aqueous PVA solution having a mass concentration of 2% at a rotation speed of 230 r/min, and stirred for 15 min;

(34) (4) 25 ml of water was firstly added into the solution of step (3) and continually stirred for 10 min; and then 25 ml of water was secondly added into the solution and continually stirred for 10 min; and

(35) (5) the microsphere was collected, washed, and freeze-dried to obtain the degradable drug-loaded microsphere for embolization.

(36) The freeze-dried degradable drug-loaded microsphere for embolization was placed into water, and bubbles were formed significantly, and the microsphere floated on the surface of a developer after being placed into the developer, as shown in FIG. 9.

(37) When the drug is 5-fluorouracil, the mass of the drug in the microsphere was determined by the absorbance method, and the method was:

(38) precisely weighed was 5 mg of a 5-fluorouracil standard, it was diluted to 250 ml by adding a phosphate buffer solution containing 0.1 mol/L HCl, and formulated to a standard solution at a concentration of 20 g/ml; an appropriate amount of the standard solution was taken and respectively diluted to concentrations of 5 g/ml, 10 g/ml, and 15 g/ml by adding the phosphate buffer solution containing 0.1 mol/L HCl. The absorption value was measured at 265 nm, with a phosphate buffer solution containing 0.1 mol/L HCl being used as a blank. Linear regression was performed on the absorbance A at a concentration C to obtain a regression equation.

(39) The obtained degradable drug-loaded microsphere for embolization was formulated to a solution by using the phosphate buffer solution of 0.1 mol/L HCl, and the absorbance at 265 nm was determined by the aforementioned method. The determined absorbance of the drug-loaded microsphere for embolization is substituted into the regression equation to obtain the drug concentration, and the drug concentration is converted into a mass of the drug, which is the mass of the drug in the microsphere.

(40) As calculated, the microsphere had an encapsulation efficiency of 13.3% and an actual drug loading capacity of 5.0%.

Example 2

(41) (1) 10 g PDLGA with an intrinsic viscosity of 0.2 dl/g was weighed and added into 25 ml of a dichloromethane solvent to formulate a PDLGA solution at a concentration of 0.40 g/ml;

(42) (2) 6 g of 5-fluorouracil was weighed and added into the aforementioned solution, and subjected to ultrasonication to form a suspension;

(43) (3) the suspension prepared in step (2) was added into 50 ml of an aqueous PVA solution having a mass concentration of 2% at a rotation speed of 230 r/min, and stirred for 20 min;

(44) (4) 50 ml of water was firstly added into the solution of step (3) and continually stirred for 10 min; and then 50 ml of water was secondly added into the solution and continually stirred for 10 min; and

(45) (5) the microsphere was collected, washed, and freeze-dried to obtain the degradable drug-loaded microsphere for embolization.

(46) The freeze-dried degradable drug-loaded microsphere for embolization was placed into water, and bubbles were formed significantly, and the microsphere floated on the surface of a developer after being placed into the developer.

(47) As calculated, the microsphere had an encapsulation efficiency of 13.1% and an actual drug loading capacity of 4.9%.

Example 3

(48) (1) 10 g PDLGA with an intrinsic viscosity of 0.2 dl/g was weighed and added into 15 ml of a dichloromethane solvent to formulate a PDLGA solution at a concentration of 0.67 g/ml;

(49) (2) 3 g of 5-fluorouracil was weighed and added into the aforementioned solution, and subjected to ultrasonication to form a suspension;

(50) (3) the suspension prepared in step (2) was added into 50 ml of an aqueous PVA solution having a mass concentration of 2% at a rotation speed of 230 r/min, and stirred for 10 min;

(51) (4) 100 ml of water was firstly added into the solution of step (3) and continually stirred for 10 min; and then 100 ml of water was secondly added into the solution and continually stirred for 10 min; and

(52) (5) the microsphere was collected, washed, and freeze-dried to obtain the degradable drug-loaded microsphere for embolization.

(53) The freeze-dried degradable drug-loaded microsphere for embolization was placed into water, and bubbles were formed significantly, and the microsphere floated on the surface of a developer after being placed into the developer.

(54) As calculated, the microsphere had an encapsulation efficiency of 13.4% and an actual drug loading capacity of 3.1%.

Example 4

(55) (1) 10 g PDLGA with an intrinsic viscosity of 0.2 dl/g was weighed and added into a mixed solvent of 17.5 ml of dichloromethane, 5 ml of acetone, and 2.5 ml of ethanol to formulate a PDLGA solution at a concentration of 0.40 g/ml;

(56) (2) 3 g of 5-fluorouracil was weighed and added into the aforementioned solution, and subjected to ultrasonication to form a suspension;

(57) (3) the suspension prepared in step (2) was added into 50 ml of an aqueous PVA solution having a mass concentration of 2% at a rotation speed of 230 r/min, and stirred for 10 min;

(58) (4) 100 ml of water was firstly added into the solution of step (3) and continually stirred for 20 min; and then 100 ml of water was secondly added into the solution and continually stirred for 20 min; and

(59) (5) the microsphere was collected, washed, and freeze-dried to obtain the degradable drug-loaded microsphere for embolization having a particle size ranging from 0.1-1.0 mm.

(60) FIG. 1 is a diagram showing the morphology of the degradable drug-loaded microsphere for embolization as obtained under an optical microscope, and it can be seen from the figure that the sphericity degree of the microsphere is good.

(61) FIG. 4 is a standard curve and linear regression equation of 5-fluorouracil concentration and absorbance. It can be seen from the figure that there is a good linear relationship between 5-fluorouracil and the absorbance in the concentration range of 0-20 g/ml, and the equation obtained from the linear relationship can be used to calculate the drug loading capacity of the drug-loaded microsphere.

(62) As calculated, the microsphere has the actual drug loading capacity of 22%, and the encapsulation efficiency=22%/23.08%100%=95.3%.

(63) As can be seen from the above data, the encapsulation efficiency and actual drug loading capacity of the present invention are greatly improved as compared with those of other literatures in the prior art in which the drug-loaded microsphere is prepared by using the emulsification-solvent volatilization method.

(64) FIG. 5 is a graph showing the relationship between respective particle size ranges of the obtained degradable drug-loaded microspheres for embolization and the 5-fluorouracil content of the microspheres. It can be seen from the figure that, the distribution of the microspheres in respective particle size ranges is relatively uniform, and accordingly microspheres having a narrower distribution of particle size can be obtained by using a sample sieve.

(65) The freeze-dried degradable drug-loaded microsphere for embolization was placed into water, and no bubble was formed, and the microsphere didn't float on the surface of a developer after being placed into the developer. Therefore, the microsphere is a solid sphere.

Example 5

(66) (1) 10 g PDLGA with an intrinsic viscosity of 0.4 dl/g was weighed and added into a mixed solvent of 20 ml of dichloromethane, 5 ml of acetone, and 1.7 ml of isohexane to formulate a PDLGA solution at a concentration of 0.37 g/ml;

(67) (2) 7 g of 5-fluorouracil was weighed and added into the aforementioned solution, and subjected to ultrasonication to form a suspension;

(68) (3) the suspension prepared in step (2) was added into 50 ml of an aqueous PVA solution having a mass concentration of 2% at a rotation speed of 230 r/min, and stirred for 10 min;

(69) (4) 100 ml of water was firstly added into the solution of step (3) and continually stirred for 20 min; and then 100 ml of water was secondly added into the solution and continually stirred for 20 min; and

(70) (5) the microsphere was collected, washed, and freeze-dried to obtain the degradable drug-loaded microsphere for embolization having a particle size ranging from 0.1-1.0 mm, and accordingly microspheres having a narrower distribution of particle size could be obtained by using a sample sieve.

(71) Morphological Observation:

(72) The freeze-dried degradable drug-loaded microsphere for embolization was placed into water, and no bubble was formed, and the microsphere didn't float on the surface of a developer after being placed into the developer. Therefore, the microsphere is a solid sphere.

(73) As calculated, the microsphere had an actual drug loading capacity of 39.7% and an encapsulation efficiency of 96.4%.

Example 6

(74) (1) 10 g PDLGA with an intrinsic viscosity of 0.45 dl/g was weighed and added into a mixed solvent of 20 ml of dichloromethane, 5 ml of acetone, and 1.7 ml of isohexane to formulate a PDLGA solution at a concentration of 0.37 g/ml;

(75) (2) 7 g of 5-fluorouracil was weighed and added into the aforementioned solution, and subjected to ultrasonication to form a suspension;

(76) (3) the suspension prepared in step (2) was added into 50 ml of an aqueous PVA solution having a mass concentration of 2% at a rotation speed of 210 r/min, and stirred for 10 min;

(77) (4) 100 ml of water was firstly added into the solution of step (3) and continually stirred for 20 min; and then 100 ml of water was secondly added into the solution and continually stirred for 20 min; and

(78) (5) the microsphere was collected, washed, and freeze-dried to obtain the degradable drug-loaded microsphere for embolization having a particle size ranging from 0.1-1.0 mm, and microspheres having a narrower distribution of particle size could be obtained by using a sample sieve.

(79) The freeze-dried degradable drug-loaded microsphere for embolization was placed into water, and no bubble was formed, and the microsphere didn't float on the surface of a developer after being placed into the developer. Therefore, the microsphere is a solid sphere.

(80) As calculated, the microsphere had an actual drug loading capacity of 39.9% and an encapsulation efficiency of 96.9%.

Example 7

(81) (1) 10 g PDLGA with an intrinsic viscosity of 0.25 dl/g was weighed and added into a mixed solvent of 20 ml of dichloromethane, 5 ml of acetone, and 1.7 ml of isohexane to formulate a PDLGA solution at a concentration of 0.37 g/ml;

(82) (2) 7 g of 5-fluorouracil was weighed and added into the aforementioned solution, and subjected to ultrasonication to form a suspension;

(83) (3) the suspension prepared in step (2) was added into 50 ml of an aqueous PVA solution having a mass concentration of 6% at a rotation speed of 210 r/min, and stirred for 10 min;

(84) (4) 100 ml of water was firstly added into the solution of step (3) and continually stirred for 20 min; and then 100 ml of water was secondly added into the solution and continually stirred for 20 min; and

(85) (5) the microsphere was collected, washed, and freeze-dried to obtain the degradable drug-loaded microsphere for embolization having a particle size ranging from 0.1-1.0 mm, and microspheres having a narrower distribution of particle size could be obtained by using a sample sieve.

(86) The freeze-dried degradable drug-loaded microsphere for embolization was placed into water, and no bubble was formed, and the microsphere didn't float on the surface of a developer after being placed into the developer. Therefore, the microsphere is a solid sphere.

(87) As calculated, the microsphere had an actual drug loading capacity of 40.5% and an encapsulation efficiency of 98.3%.

Example 8

(88) (1) 10 g PDLGA with an intrinsic viscosity of 0.35 dl/g was weighed and added into a mixed solvent of 20 ml of dichloromethane, 5 ml of acetone, and 1.7 ml of isohexane to formulate a PDLGA solution at a concentration of 0.37 g/ml;

(89) (2) 7 g of 5-fluorouracil was weighed and added into the aforementioned solution, and subjected to ultrasonication to form a suspension;

(90) (3) the suspension prepared in step (2) was added into 50 ml of an aqueous PVA solution having a mass concentration of 6% at a rotation speed of 210 r/min, and stirred for 5 min;

(91) (4) 100 ml of water was firstly added into the solution of step (3) and continually stirred for 30 min; and then 100 ml of water was secondly added into the solution and continually stirred for 30 min; and

(92) (5) the microsphere was collected, washed, and freeze-dried to obtain the degradable drug-loaded microsphere for embolization having a particle size ranging from 0.1-1.0 mm, and microspheres having a narrower distribution of particle size could be obtained by using a sample sieve.

(93) The freeze-dried degradable drug-loaded microsphere for embolization was placed into water, and no bubble was formed, and the microsphere didn't float on the surface of a developer after being placed into the developer. Therefore, the microsphere is a solid sphere.

(94) As calculated, the microsphere had an actual drug loading capacity of 40.5% and an encapsulation efficiency of 98.3%.

Example 9

(95) (1) 10 g PDLGA with an intrinsic viscosity of 0.35 dl/g was weighed and added into a mixed solvent of 20 ml of dichloromethane, 5 ml of acetone, and 1.7 ml of ethyl acetate to formulate a PDLGA solution at a concentration of 0.37 g/ml;

(96) (2) 7 g of 5-fluorouracil was weighed and added into the aforementioned solution, and subjected to ultrasonication to form a suspension;

(97) (3) the suspension prepared in step (2) was added into 50 ml of an aqueous PVA solution having a mass concentration of 15% at a rotation speed of 210 r/min, and stirred for 5 min;

(98) (4) 100 ml of water was firstly added into the solution of step (3) and continually stirred for 30 min; and then 100 ml of water was secondly added into the solution and continually stirred for 150 min; and

(99) (5) the microsphere was collected, washed, and freeze-dried to obtain the degradable drug-loaded microsphere for embolization having a particle size ranging from 0.1-1.0 mm, and microspheres having a narrower distribution of particle size could be obtained by using a sample sieve.

(100) The freeze-dried degradable drug-loaded microsphere for embolization was placed into water, and no bubble was formed, and the microsphere didn't float on the surface of a developer after being placed into the developer. Therefore, the microsphere is a solid sphere.

(101) As calculated, the microsphere had an actual drug loading capacity of 26.7% and an encapsulation efficiency of 64.8%.

Example 10

(102) (1) 10 g PDLGA with an intrinsic viscosity of 0.40 dl/g was weighed and added into a mixed solvent of 20 ml of dichloromethane, 5 ml of acetone, and 1.7 ml of ethyl acetate to formulate a PDLGA solution at a concentration of 0.37 g/ml;

(103) (2) 7 g of 5-fluorouracil was weighed and added into the aforementioned solution, and subjected to ultrasonication to form a suspension;

(104) (3) the suspension prepared in step (2) was added into 50 ml of an aqueous PVA solution having a mass concentration of 15% at a rotation speed of 210 r/min, and stirred for 10 min;

(105) (4) 100 ml of water was firstly added into the solution of step (3) and continually stirred for 20 min; and then 100 ml of water was secondly added into the solution and continually stirred for 20 min; and

(106) (5) the microsphere was collected, washed, and freeze-dried to obtain the degradable drug-loaded microsphere for embolization having a particle size ranging from 0.1-1.0 mm, and microspheres having a narrower distribution of particle size could be obtained by using a sample sieve.

(107) FIG. 2 is a diagram showing the morphology of the degradable drug-loaded microsphere for embolization as obtained under an optical microscope, and it can be seen from the figure that the sphericity degree of the microsphere is good.

(108) The freeze-dried degradable drug-loaded microsphere for embolization was placed into water, and no bubble was formed, and the microsphere didn't float on the surface of a developer after being placed into the developer. Therefore, the microsphere is a solid sphere.

(109) As calculated, the microsphere had an actual drug loading capacity of 40.6% and an encapsulation efficiency of 98.6%.

Example 11

(110) (1) 10 g PDLGA with an intrinsic viscosity of 0.40 dl/g was weighed and added into a mixed solvent of 20 ml of dichloromethane, 5 ml of acetone, and 1.7 ml of ethyl acetate to formulate a PDLGA solution at a concentration of 0.37 g/ml;

(111) (2) 7 g of 5-fluorouracil was weighed and added into the aforementioned solution, and subjected to ultrasonication to form a suspension;

(112) (3) the suspension prepared in step (2) was added into 50 ml of an aqueous PVA solution having a mass concentration of 15% at a rotation speed of 210 r/min, and stirred for 10 min;

(113) (4) 100 ml of water was firstly added into the solution of step (3) and continually stirred for 30 min; and then 100 ml of water was secondly added into the solution and continually stirred for 150 min; and

(114) (5) the microsphere was collected, washed, and freeze-dried to obtain the degradable drug-loaded microsphere for embolization having a particle size ranging from 0.1-1.0 mm, and microspheres having a narrower distribution of particle size could be obtained by using a sample sieve.

(115) The freeze-dried degradable drug-loaded microsphere for embolization was placed into water, and no bubble was formed, and the microsphere didn't float on the surface of a developer after being placed into the developer. Therefore, the microsphere is a solid sphere.

(116) As calculated, the microsphere had an actual drug loading capacity of 20.6% and an encapsulation efficiency of 50.0%.

Example 12

(117) (1) 10 g PDLGA with an intrinsic viscosity of 0.25 dl/g was weighed and added into a mixed solvent of 20 ml of dichloromethane, 5 ml of acetone, and 1.7 ml of n-heptane to formulate a PDLGA solution at a concentration of 0.37 g/ml;

(118) (2) 3.9 g of 5-fluorouracil and 3.9 g of rapamycin were weighed and added into the aforementioned solution, and subjected to ultrasonication to form a suspension;

(119) (3) the suspension prepared in step (2) was added into 50 ml of an aqueous PVA solution having a mass concentration of 10% at a rotation speed of 210 r/min, and stirred for 10 min;

(120) (4) 75 ml of water was firstly added into the solution of step (3) and continually stirred for 15 min; and then 75 ml of water was secondly added into the solution and continually stirred for 30 min; and

(121) (5) the microsphere was collected, washed, and freeze-dried to obtain the degradable drug-loaded microsphere for embolization having a particle size ranging from 0.1-1.0 mm, and microspheres having a narrower distribution of particle size could be obtained by using a sample sieve.

(122) The freeze-dried degradable drug-loaded microsphere for embolization was placed into water, and no bubble was formed, and the microsphere didn't float on the surface of a developer after being placed into the developer. Therefore, the microsphere is a solid sphere.

(123) As calculated, the drug loading capacity of 5-fluorouracil was 20.3%, the actual drug loading capacity of rapamycin was 20.3%, and the encapsulation efficiency was 92.7%.

Example 13

(124) (1) 5 g PDLGA with an intrinsic viscosity of 0.40 dl/g and 5 g PTMC (Poly(trimethylene carbonate)) with an intrinsic viscosity of 0.40 dl/g were weighed and added into a mixed solvent of 20 ml of dichloromethane, 5 ml of acetone, and 1.7 ml of ethyl acetate to formulate a mixed polymer solution at a concentration of 0.37 g/ml;

(125) (2) 7.8 g of 5-fluorouracil was weighed and added into the aforementioned mixed polymer solution, and subjected to ultrasonication to form a suspension;

(126) (3) the suspension prepared in step (2) was added into 50 ml of an aqueous PVA solution having a mass concentration of 13% at a rotation speed of 210 r/min at 4 C., and stirred for 10 min;

(127) (4) 75 ml of water was firstly added into the solution of step (3) and continually stirred for 15 min; and then 75 ml of water was secondly added into the solution and continually stirred for 30 min; and

(128) (5) the microsphere was collected, washed, and freeze-dried to obtain the degradable drug-loaded microsphere for embolization having a particle size ranging from 0.1-1.0 mm, and microspheres having a narrower distribution of particle size could be obtained by using a sample sieve.

(129) FIG. 3 is a diagram showing the morphology of the degradable drug-loaded microsphere for embolization as obtained under an optical microscope, and it can be seen from the figure that the sphericity degree of the microsphere is good.

(130) FIG. 6 is a graph showing the relationship between respective particle size ranges of the obtained degradable drug-loaded microspheres for embolization and the 5-fluorouracil content of the microspheres. It can be seen from the figure that, the distribution of the microspheres in respective particle size ranges is relatively uniform.

(131) The freeze-dried degradable drug-loaded microsphere for embolization was placed into water, and no bubble was formed, and the microsphere didn't float on the surface of a developer after being placed into the developer. Therefore, the microsphere is a solid sphere. As calculated, the microsphere had an actual drug loading capacity of 40.8% and an encapsulation efficiency of 93.1%.

Example 14

(132) (1) 10 g polycaprolactone (PCL) with an intrinsic viscosity of 0.40 dl/g was weighed and added into a mixed solvent of 20 ml of dichloromethane, 5 ml of acetone, and 1.7 ml of ethyl acetate to formulate a PCL solution at a concentration of 0.37 g/ml;

(133) (2) 8 g of cisplatin was weighed and added into the aforementioned solution, and subjected to ultrasonication to form a suspension;

(134) (3) the suspension prepared in step (2) was added into 50 ml of an aqueous PVA solution having a mass concentration of 12% at a rotation speed of 150 r/min, and stirred for 10 min;

(135) (4) 75 ml of water was firstly added into the solution of step (3) and continually stirred for 15 min; and then 75 ml of water was secondly added into the solution and continually stirred for 30 min; and

(136) (5) the microsphere was collected, washed, and freeze-dried to obtain the degradable drug-loaded microsphere for embolization having a particle size ranging from 0.1-1.0 mm, and microspheres having a narrower distribution of particle size could be obtained by using a sample sieve.

(137) The freeze-dried degradable drug-loaded microsphere for embolization was placed into a developer, the microsphere was uniformly dispersed in the developer without floating, and the results were as shown in FIG. 8.

(138) The actual mass of cisplatin in the microsphere was determined by using atomic absorption spectroscopy (AAS), and as calculated the obtained microsphere had an actual drug loading capacity of 38.2% and an encapsulation efficiency of 86.0%.

Example 15

(139) (1) 10 g methoxy poly(ethylene glycol)-poly(lactide) (MPEG-PDLGA) with an intrinsic viscosity of 0.40 dl/g was weighed and added into a mixed solvent of 20 ml of dichloromethane, 5 ml of acetone, and 1.7 ml of ethyl acetate to formulate a MPEG-PDLGA solution at a concentration of 0.37 g/ml;

(140) (2) 8 g of doxorubicin was weighed and added into the aforementioned solution, and subjected to ultrasonication to form a suspension;

(141) (3) the suspension prepared in step (2) was added into 50 ml of an aqueous PVA solution having a mass concentration of 10% at a rotation speed of 150 r/min, and stirred for 10 min;

(142) (4) 75 ml of water was firstly added into the solution of step (3) and continually stirred for 15 min; and then 75 ml of water was secondly added into the solution and continually stirred for 30 min; and

(143) (5) the microsphere was collected, washed, and freeze-dried to obtain the degradable drug-loaded microsphere for embolization having a particle size ranging from 0.1-1.0 mm, and microspheres having a narrower distribution of particle size could be obtained by using a sample sieve.

(144) The freeze-dried degradable drug-loaded microsphere for embolization was placed into water, and no bubble was formed, and the microsphere didn't float after being placed into a developer. Therefore, the microsphere is a solid sphere.

(145) The actual mass of doxorubicin in the microsphere was determined by using high performance liquid chromatography (HPLC), and as calculated the obtained microsphere had an actual drug loading capacity of 38.2% and an encapsulation efficiency of 86.0%.

Comparative Example

(146) (1) 10 g PDLGA with an intrinsic viscosity of 0.40 dl/g was weighed and added into a mixed solvent of 20 ml of dichloromethane, 5 ml of acetone, and 1.7 ml of ethyl acetate to formulate a PDLGA solution at a concentration of 0.37 g/ml;

(147) (2) 7 g of 5-fluorouracil was weighed and added into the aforementioned solution, and subjected to ultrasonication to form a suspension;

(148) (3) the suspension prepared in step (2) was added into 50 ml of an aqueous PVA solution having a mass concentration of 15% at a rotation speed of 210 r/min, and stirred for 10 min;

(149) (4) 200 ml of water was added into the solution of step (3) and continually stirred for 40 min, and then washed, and freeze-dried to obtain the degradable drug-loaded microsphere for embolization having a particle size ranging from 0.1-1.0 mm.

(150) The freeze-dried degradable drug-loaded microsphere for embolization was placed into water, and no bubble was formed, and the microsphere didn't float on the surface of a developer after being placed into the developer. Therefore, the microsphere is a solid sphere.

(151) As calculated, the microsphere had an actual drug loading capacity of 6% and an encapsulation efficiency of 14.6%.