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Claims for Patent: 4,728,721

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Claims for Patent: 4,728,721

Title: Polymer, production and use thereof
Abstract:The present invention provides a biodegradable high molecular polymer characterized in that the content of water-soluble low molecular compounds, as calculated on the assumption that said compounds each is a monobasic acid, is less than 0.01 mole per 100 grams of said high molecular polymer. The thus-obtained molecular polymer has good aging stability and can be used advantageously as an excipient for pharmaceutical preparations.
Inventor(s): Yamamoto; Masaki (Osaka, JP), Okada; Hiroaki (Osaka, JP), Ogawa; Yasuaki (Osaka, JP), Miyagawa; Tsutomu (Saitama, JP)
Assignee: Takeda Chemical Industries, Ltd. (Osaka, JP) Wako Pure Chemical Industries, Ltd. (Osaka, JP)
Application Number:06/858,040
Patent Claims: 1. A biodegradable high molecular polymer useful as an excipient in producing a pharmaceutical preparation comprising a copolymer or homopolymer of about 50-100 mole percent of lactic acid and about 50-0 mole percent of glycolic acid having a weight average molecular weight of about 2,000 to 50,000 and wherein the content of water-soluble low molecular compounds, as calculated on the assumption that each of said compounds is a monobasic acid, is less than 0.01 mole per 100 grams of said high molecular polymer.

2. The biodegradable high molecular polymer according to claim 1, wherein the high molecular polymer has an inherent viscosity of about 0.05-0.5 dl/g as determined with a 0.5 weight percent chloroform solution thereof and a weight average molecular weight of about 5,000-35,000.

3. A method of producing a biodegradable high molecular polymer according to claim 1, which method comprises removing by extraction of water-soluble low molecular compounds from a biodegradable high molecular polymer containing not less than 0.01 mole of water-soluble low molecular compounds per 100 grams thereof, as calculated on the assumption that each of said compounds is a monobasic acid, using water or a mixture of water and an organic solvent readily soluble in water.

4. The method according to claim 3 wherein the organic solvent readily soluble in water is a member selected from the group consisting of acetone, methanol, ethanol, tetrahydrofuran, acetonitrile and ethyl acetate.

5. The method according to claim 4, wherein the organic solvent readily soluble in water is ethanol.

6. The method according to claim 3, wherein a ratio of the mixture of water and organic solvent readily soluble in water (v/v) is about 100/0 to 100/100.

7. The method according ot claim 3, wherein the biodegradable high molecular polymer containing the water-soluble low molecular compounds is dissolved in advance in an organic solvent.

8. The method according to claim 3, wherein the removing by extraction of the water-soluble low molecular compounds is conducted under stirring.

9. The method according to claim 3, wherein the removing by extraction of the water-soluble low molecular compounds is conducted at a temperature of about 0.degree. to 90.degree. C.

10. The method according to claim 7, wherein the biodegradable high molecular polymer containing water-soluble low molecular compounds is dissolved in the 3 to 20 time amount (w/v) of an organic solvent, then the solution is poured into water under stirring at a temperature about 20.degree. to 70.degree. C. to remove the trace amount of water soluble low molecular compounds from the biodegradable high molecular polymer.

11. The biodegradable high molecular polymer according to claim 1, which is produced by removing by extraction of water-soluble low molecular compounds from a biodegradable high molecular polymer containing not less than 0.01 mole of water-soluble low molecular compounds per 100 grams thereof, as calculated on the assumption that each of said compounds is a monobasic acid, using water or a mixture of water and an organic solvent readily soluble in water.
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