Microparticles containing physiologically active peptide, method for preparing the same, and pharmaceutical composition comprising the same

1. A method for preparing physiologically active peptide-containing microparticle comprising:

1) mixing a physiologically active peptide with an ionic water-soluble polymer in an aqueous medium to form an ionic complex of the physiologically active peptide and the water-soluble polymer;

2) drying the ionic complex of the physiologically active peptide and the water-soluble polymer obtained in step 1);

3) homogeneously mixing the ionic complex of the physiologically active peptide and the water-soluble polymer obtained in step 2) with a biodegradable, water-insoluble polymer in a non-aqueous solvent; and

4) removing the non-aqueous solvent from the resulting solution obtained in step 3) to obtain microparticles;

wherein the water-soluble polymer has a number average molecular weight of 500 to 5,000 daltons, and is the compound represented by Formula 2 or 6 below:

RO—CHZ—[COO—CHX] p —[COO—CHY′] q —COO—CHZ—COOM  [Formula 2]

wherein X is methyl group; Y′ is hydrogen atom or phenyl group; p is an integer of 0 to 25 and q is an integer of 0 to 25 provided that p+q is an integer of 5 to 25; R is hydrogen atom, or acetyl group, benzoyl group, decanoyl group, palmitoyl group, methyl group or ethyl group; M is H, Na, K, or Li; and Z is hydrogen atom, methyl group or phenyl group,

YO—[—C(O)—(CHX) a —O—] m —C(O)—R—C(O)—[—O—(CHX′) b —C(O)—] n —OZ  [Formula 6]

wherein each of X and X′ is independently hydrogen, alkyl or aryl; each of Y and Z is independently H, Na, K, or Li; each of m and n is independently an integer of 0 to 95 provided that 5<m+n<100; each of a and b is each independently an integer of 1 to 6; and R is substituted or unsubstituted —(CH 2 ) k — in which k is an integer of 0 to 10, divalent alkenyl having 2 to 10 carbon atoms, divalent aryl having 6 to 20 carbon atoms, or a combination thereof,

wherein the biodegradable, water-insoluble polymer has a weight average molecular weight of 10,000 to 100,000 daltons, and is one or more selected from the group consisting of polylactide, polyglycolide, poly(lactide-co-glycolide), polyorthoester, polycaprolactone, polydioxanone polyalkylcarbonate, polyanhydride and copolymers thereof, and

wherein the microparticle has a uniform particle size of between 30 μm and 100 μm, a drug encapsulation ratio of between 35% and 85%, and exhibits decreased initial drug release amounts of less than 20% and superior long-term continuous release properties of greater than 40% after 14 days.

2. The method according to claim 1 , wherein the non-aqueous solvent is selected from the group consisting of methylene chloride, ethyl acetate, chloroform, acetone, N-methyl-2-pyrrolidone, N,N-dimethylformamide, tetrahydrofuran, dimethyl sulfoxide, hexafluoroisopropanol and mixtures thereof.

3. The method according to claim 1 , wherein step 4) comprises:

4-1) filling a plurality of microwells placed in a water-soluble microtemplate with the solution obtained in step 3);

4-2) removing the non-aqueous solvent from the solution filled in the microwells to solidify the biodegradable, water-insoluble polymer; and

4-3) collecting microparticles from the microtemplate.

4. The method according to claim 3 , wherein the water-soluble microtemplate is produced from one or more water-soluble polymers selected from the group consisting of gelatin, polyvinyl alcohol, agarose, poly(N-isopropyl acrylamide), alginate and mixtures thereof.

5. The method according to claim 3 , wherein, in step 4-3), the collection of microparticles is carried out by dissolving the microtemplate in an aqueous medium.

6. The method according to claim 1 , wherein step 4) comprises:

4-i) adding the resulting solution obtained in step 3) dropwise to an aqueous solution of the water-soluble polymer in the presence of a surfactant with stirring to remove the non-aqueous solvent and obtain microparticle.

7. The method according to claim 1 , wherein the water-soluble polymer has a number average molecular weight of 500 to 3,000 daltons.

8. The method according to claim 1 , wherein the physiologically active peptide is selected from the group consisting of luteinizing hormone-releasing hormone (LHRH) agonists, somatostatin and analogs thereof, glucagon-like peptides (GLP), parathyroid hormone and analogs thereof, insulin-like growth factors, epidermal growth factors, platelet-derived growth factors, fibroblast growth factors, transforming growth factors, growth hormone releasing factors, amylin analogs, peptide YY (PYY), protein synthesis-stimulating peptides, gastrin inhibitory peptides, vasoactive intestinal peptides, and pharmaceutically acceptable salts thereof.

9. The method according to claim 1 , wherein the physiologically active peptide is present in an amount of 1.0 to 10% by weight with respect to the total weight of the microparticles.

10. The method according to claim 1 , wherein the content of the ionic complex is 4% by weight to 40% by weight, based on the total weight of the microparticles.

11. The method according to claim 1 , wherein the physiologically active peptide and the ionic water-soluble polymer are mixed with a mixing ratio of 1:1 to 10 as a molar ratio.

12. The method according to claim 1 , wherein the water-soluble polymer is the compound represented by Formula 2.

13. The method according to claim 1 , wherein the water-soluble polymer is PLA-COONa.