Preparation method of sustained-release microparticles

Abstract

In the present invention, the whole preparation process of the sustained-release microparticles is at normal or low temperature, which is highly advantageous for the preparation of a polymer-based composition from a high-temperature-sensitive drug, particularly a protein, nucleic acid and peptide drug, and the bioactivity of the active substance can be maintained to the greatest extent throughout the process compared to the disclosed technology; at the same time, the prepared sustained-release microparticles have an excellent sustained-release effect close to zero order, and the drug concentration is stabilized during the release, which overcomes the defects that the microparticles obtained by the conventional S/O/W process of pre-preparing the drug microparticles have no drug release in the earlier stage and a rapid release of the drug in the later stage; and in addition, the sustained-release microparticles have higher drug loading rate and drug encapsulation rate.

What is claimed is: 
     
         1 . A preparation method of sustained-release microparticles, characterized by comprising the following steps:
 1) preparing a solid dispersion of a water-soluble drug and a biodegradable and biocompatible poorly water-soluble polymer;   2) dissolving the solid dispersion prepared in step 1) in an organic solvent C to form a solid dispersion emulsion, the organic solvent C being an organic solvent which is not capable of dissolving the water-soluble drug but capable of dissolving the poorly water-soluble polymer, has a boiling point lower than that of water and is insoluble or poorly soluble in water;   3) adding the solid dispersion emulsion obtained in step 2) into an surfactant-containing aqueous solution to form a uniform emulsion; and   4) solidifying microparticles in the emulsion by solvent volatilization or solvent extraction, collecting the microparticles, washing with ultrapure water several times to remove the surfactant attached to the surface of the microparticles, and drying to obtain the sustained-release microparticles.   
     
     
         2 . The preparation method of sustained-release microparticles according to  claim 1 , characterized in that the water-soluble drug is at least one of proteins, nucleic acids, and peptides having not more than 30 amino acid residues and derivatives or analogs thereof. 
     
     
         3 . The preparation method of sustained-release microparticles according to  claim 1 , characterized in that the poorly water-soluble polymer in step 1) comprises at least one of polyesters, polycarbonates, polyacetals, polyanhydrides, polyhydroxy fatty acids, and copolymers or blends thereof. 
     
     
         4 . The preparation method of sustained-release microparticles according to  claim 1 , characterized in that step 1) is carried out by the following steps:
 11) completely dissolving the biodegradable and biocompatible poorly water-soluble polymer and the water-soluble drug in an organic solvent A to form a mixed solution of the drug and the polymer; and   12) adding the mixed solution into an organic solvent B or adding the organic solution B into the mixed solution to produce a uniform and fine precipitate, collecting the precipitate, washing the precipitate with the organic solvent B several times, and removing the organic solvent B to obtain a solid dispersion of the water-soluble drug and the poorly water-soluble polymer, wherein the organic solvent B is incapable of dissolving the poorly water-soluble polymer and the water-soluble drug.   
     
     
         5 . The preparation method of sustained-release microparticles according to  claim 4 , characterized in that the organic solvent A is selected from at least one of glacial acetic acid, acetonitrile, trifluoroacetic acid and dimethyl sulfoxide; and
 the organic solvent B is selected from at least one of anhydrous diethyl ether, hexane and n-heptane.   
     
     
         6 . The preparation method of sustained-release microparticles according to  claim 1 , characterized in that in the solid dispersion, the mass ratio of the water-soluble drug to the poorly water-soluble polymer is 1:1 to 1:99. 
     
     
         7 . The preparation method of sustained-release microparticles according to  claim 1 , characterized in that the organic solvent C is selected from at least one of aliphatic hydrocarbons, halogenated hydrocarbons, fatty acid esters, aromatic hydrocarbons and ethers. 
     
     
         8 . The preparation method of sustained-release microparticles according to  claim 1 , characterized in that the method further comprises the step of adding an additive which is added during the process of preparing the solid dispersion in step 1) or during the process of preparing the solid dispersion emulsion in step 2); and the additive is 0.01-10% of the sum of the mass of the water-soluble drug and the poorly water-soluble polymer. 
     
     
         9 . The preparation method of sustained-release microparticles according to  claim 8 , characterized in that the additive comprises at least one of saccharides, amino acids, fatty acids, alcohols, antioxidants and buffering agents. 
     
     
         10 . Sustained-release microparticles obtained by the preparation method of sustained-release microparticles according to  claim 1 .