Hyaluronic acid gel, method of its production and medical material containing it

• US 20020098244A1
• Filed: 01/17/2002
• Published: 07/25/2002
• Est. Priority Date: 08/22/1997
• Status: Active Grant

• Current Assignee: Denki Kagaku Kogyo Kabushiki Kaisha (TDK Corporation)
• Original Assignee: Denki Kagaku Kogyo Kabushiki Kaisha (TDK Corporation)
• Inventors: Miyata, Yoshiaki, Hashimoto, Masamichi, Kawata, Masatoshi, Arai, Kazuhiko, Okamoto, Akio, Oshima, Kazuhiro
• Granted Patent: US 6,790,461 B2
• Time in Patent Office: Days
• US Class Current: 424/548
• CPC Class Codes: A61L 15/28 Polysaccharides or their derivatives A61L15/225 takes precedence
• CPC Class Codes: A61L 27/20 Polysaccharides
• CPC Class Codes: A61L 31/042 Polysaccharides
• CPC Class Codes: C08B 37/0072 Hyaluronic acid, i.e. HA or hyaluronan; Derivatives thereof, e.g. crosslinked hyaluronic acid (hylan) or hyaluronates
• CPC Class Codes: C08L 5/08 Chitin; Chondroitin sulfate; Hyaluronic acid; Derivatives thereof

Abstract

A gel made of hyaluronic acid alone which is hardly soluble in a neutral aqueous solution.

The hyaluronic acid gel according to claim 1, which keeps its shape for at least one day in a neutral aqueous solution at 25° C.

Claims

1. A gel made of hyaluronic acid alone which is hardly soluble in a neutral aqueous solution.

2. The hyaluronic acid gel according to claim 1, which keeps its shape for at least one day in a neutral aqueous solution at 25°

C.

3. The hyaluronic acid gel according to claim 1, which dissolves in a neutral aqueous solution at 25°

C. in one day to a degree of dissolution of at most 50%.

4. The hyaluronic acid gel according to claim 1, which dissolves in a neutral aqueous solution at 37°

C. in 12 hours to a degree of dissolution of at most 50%.

5. The hyaluronic acid gel according to claim 1, which dissolves to yield solubilized hyaluronic acid having a branched structure and partly containing a molecular weight fraction with a branching degree of at least 0.5, when treated under accelerating conditions for acid hydrolysis of hyaluronic acid.

6. The hyaluronic acid gel according to claim 1, which is obtained by freezing and then thawing a hyaluronic acid aqueous solution at pH 3.5 or below.

7. A method of producing the hyaluronic acid gel according to claim 6, which comprises adjusting a hyaluronic acid aqueous solution to pH 3.5 or below, and freezing and thawing the solution at least once.

8. A biomedical material containing a gel made of hyaluronic acid alone which satisfies the following requirements (a) and (b):

(a) the hyaluronic acid gel dissolves in a neutral aqueous solution at 25°

C. in one day to a degree of dissolution of at most 50%, and

(b) the gel dissolves to yield solubilized hyaluronic acid having a branched structure and partly containing a molecular weight fraction with a branching degree of at least 0.5, when treated under accelerating conditions for acid hydrolysis of hyaluronic acid.

9. The biomedical material according to claim 8, wherein the gel made of hyaluronic acid alone is sheet-like, filmy, flaky, spongy, massive, fibrous or tubular.

10. A biomedical material containing a hyaluronic acid gel and un-gelled hyaluronic acid, wherein the hyaluronic acid gel dissolves in a neutral aqueous solution at most 50%, and the hyaluronic acid gel dissolves to yield solubilized hyaluronic acid having a branched structure and partly containing a molecular weight fraction with a branching degree of at least 0.5, when treated under accelerating conditions for acid hydrolysis of hyaluronic acid.

12. The biomedical material according to any one of claims 8 to 11, which is an adhesion preventive.

11. A biomedical material containing a sheet-like, filmy, spongy, massive, fibrous or tubular hyaluronic acid gel made of hyaluronic acid alone and un-gelled hyaluronic acid.