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US5102983A
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Process for preparing foamed, bioabsorbable polymer particles
Assignee: United States Surgical Corp
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Filing: 1990-04-02
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Granted: 1992-04-07
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Expires: 2010-04-02
Abstract
Abstract A process is provided for preparing foamed, bioabsorbable polymer particles employing a freeze-drying operation.
Inventors
- 👤 John Kennedy
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 19:08
CPC Classifications
C; C08; C08J; C08J9/00; C08J9/26; A; A61; A61K; A61K9/00; A61K9/14; A61K9/16; A61K9/1605; A61K9/1629; A61K9/1641; A61K9/1647; A61K9/1682; A61K9/1694; A61L; A61L27/00; A61L27/14; A61L27/18; A61L27/50; A61L27/56; A61L27/58
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
97 words
Process for preparing foamed, bioabsorbable polymer particles which comprises: a) dissolving a foam-forming bioabsorbable polymer in a solvent therefor to form a solution of the polymer; b) introducing relatively small, discrete quantities of the thus-formed polymer solution into a liquid which is immiscible with the solvent and which freezes the polymer solution on contact therewith to provide particles of frozen polymer solution in the liquid; c) recovering the particles of frozen polymer solution from the liquid; and, d) removing solvent from the particles of frozen polymer solution under vacuum to provide substantially solvent-free, foamed, bioabsorbable -polymer particles.
Claim 2
Dependent Claim
97 words
Process for preparing foamed, bioabsorbable polymer particles which comprises: a) dissolving a foam-forming bioabsorbable polymer in a solvent therefor to form a solution of the polymer; b) introducing relatively small, discrete quantities of the thus-formed polymer solution into a liquid which is immiscible with the solvent and which freezes the polymer solution on contact therewith to provide particles of frozen polymer solution in the liquid; c) recovering the particles of frozen polymer solution from the liquid; and, d) removing solvent from the particles of frozen polymer solution under vacuum to provide substantially solvent-free, foamed, bioabsorbable -polymer particles.
Claim 3
Dependent Claim
23 words
The process of claim 1 further comprising: e) raising the temperature of the particles resulting from step (d) to remove any residual solvent.
Claim 4
Dependent Claim
30 words
The process of claim 1, wherein said discrete quantities of solution are in the form of drops thereof having an average diameter of from about 100 to about 700 microns.
Claim 5
Dependent Claim
17 words
The process of claim 3, wherein said average diameter is from about 200 to about 600 microns.
Claim 6
Dependent Claim
26 words
The process of claim 1, wherein said liquid is selected from the group consisting of liquid nitrogen, and mixtures of solid carbon dioxide and a liquid.
Claim 7
Dependent Claim
28 words
The process of claim 1, wherein said polymer is derived from the group consisting of polyglycolic acid, glycolide, lactic acid, lactide, dioxanone, e-caprolactone, trimethylene carbonate, and mixtures thereof.
Claim 8
Dependent Claim
12 words
The process of claim 6, wherein said polymer is a glycolide-lactide copolymer.
Claim 9
Dependent Claim
29 words
The process of claim 1, wherein said solvent is selected from the group consisting of t-butanol, benzene, p-dioxane, p-xylene, 1,2-dibromoethane, morpholine, dimethylsulfoxide, bromoform, hexafluoroisopropanol, hexafluoroacetone sesquihydrate, and mixtures thereof.
Claim 10
Dependent Claim
16 words
The process of claim 1, wherein pressure of said vacuum is less than about 10 torr.
Claim 11
Dependent Claim
14 words
The process of claim 9, wherein said pressure is less than about one torr.
Claim 12
Dependent Claim
22 words
The process of claim 9, wherein said frozen polymer particles are held under said vacuum for about 10 to about 15 hours.
Claim 13
Dependent Claim
19 words
The process of claim 3, wherein the particles have a density of about 0.01 g/cc to about 0.30 g/cc.
Claim 14
Dependent Claim
25 words
The process of claim 1, wherein the bioabsorbable polymer is dissolved in the solvent in an amount of about 1 to about 20% by weight.
Claim 15
Dependent Claim
24 words
The process of claim 13, wherein the amount of the bioabsorbable polymer dissolved in the solvent is from about 5 to 15% by weight.
Claim 16
Dependent Claim
31 words
The process of claim 1, wherein the particles of frozen polymer solution are immediately recovered from the freezing liquid and then immediately subjected to the vacuum to remove the solvent therefrom.
Claim 17
Dependent Claim
24 words
The process of claim 1, wherein temperature of the freezing liquid is at least about 10° C. below freezing temperature of the polymer solution.
Claim 18
Dependent Claim
27 words
The process of claim 1, wherein the particles of frozen polymer solution are recovered at or below melting point thereof to maintain the particles in frozen state.
Claim 19
Dependent Claim
21 words
The process of claim 1, wherein the particles of frozen polymer solution are recovered by draining, straining, filtering, decanting or centrifuging.
Claim 20
Dependent Claim
18 words
The process of claim 2, wherein the temperature is allowed to slowly rise at least about 20° C.
Claim 21
Dependent Claim
21 words
The process of claim 3, wherein the particles each comprise pores of size ranging from about 4 to about 10 microns.
Claim 22
Dependent Claim
24 words
The process of claim 1, wherein the relatively small, discrete quantities of the polymer solution are introduced into the liquid on a drop-by-drop basis.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-04-07 | 1995-10-07 | 1996-04-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-04-07 | 1999-10-07 | 2000-04-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-04-07 | 2003-10-07 | 2004-04-07 | $7700.00 | Window Closed / Lapsed |