US2002072584A1PendingUtilityA1

Biostability of polymeric structures

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Assignee: SALVIAC LTDPriority: May 7, 1999Filed: Nov 6, 2001Published: Jun 13, 2002
Est. expiryMay 7, 2019(expired)· nominal 20-yr term from priority
Inventors:Eamon BradyAnn Marie CannonFergal Farrell
C12N 5/0068C08G 2110/0083C12N 2531/00C08G 2110/0008C12N 2533/30A61L 29/06A61L 31/06A61L 31/146C08G 18/10C08G 2101/00C08G 18/48A61L 29/146
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Claims

Abstract

A biocompatible polymeric material is prepared by forming a three dimensional cross-linked structure of a biocompatible polymeric material such as a polyether or polycarbonate polyurethane and solvent extracting the material with a swelling solvent such as MEK which swells the material by up to 150%. The solvent swollen polymeric material is then de-swelled with a non solvent such as water which is miscible with the extraction solvent. The process produces polymeric materials which do not produce leachables and thereby have properties that are suitable for implantation.

Claims

exact text as granted — not AI-modified
1 . A process for preparing a biocompatible polymeric material comprising the steps of: 
 forming a three dimensional cross-linked structure of a biocompatible polymeric material; and    solvent extracting the polymeric material with an extraction solvent, the solvent being a solvent which generates a volumetric swelling and having a solubility parameter of from 17 to 27 MPa 0.5 .    
     
     
         2 . A process as claimed in  claim 1  including the step of de-swelling the solvent swollen polymeric material.  
     
     
         3 . A process as claimed in  claim 2  wherein the polymeric material is de-swelled by contacting the solvent swollen polymeric material with a non-solvent which is miscible with the extraction solvent.  
     
     
         4 . A process as claimed in any of  claims 1  to  3  including the step of drying the polymeric material to substantially remove solvent residues.  
     
     
         5 . A process as claimed in  claim 4  including the step, prior to drying, of extracting the polymeric material with water.  
     
     
         6 . A process as claimed in any of  claims 1  to  5  wherein the polymeric material is extracted with a number of extraction solvents.  
     
     
         7 . A process as claimed in  claim 6  wherein the solvent extractions are carried out sequentially.  
     
     
         8 . A process as claimed in any preceding claim wherein the solubility parameter of the extraction solvent is within ±4 Mpa 0.5  of the solubility parameter of the polymeric material or its phases.  
     
     
         9 . A process as claimed in any preceding claim wherein the vapour pressure of the extraction solvent is greater than 2 kPa at 25° C.  
     
     
         10 . A process as claimed in  claim 9  wherein the vapour pressure of the extraction solvent is greater than 5 kPa at 25° C.  
     
     
         11 . A process as claimed in  claim 10  wherein the vapour pressure of the extraction solvent is greater than 10 kPa at 25° C.  
     
     
         12 . A process as claimed in any preceding claim wherein the extraction solvent has a polar component of its solubility parameter in excess of 3 MPa 0.5 .  
     
     
         13 . A process as claimed in any preceding claim wherein the solvent has a solvability parameter of from 18 to 24 MPa 0.5 .  
     
     
         14 . A process as claimed in any preceding claim wherein the swelling solvent swells the material by more than 30%.  
     
     
         15 . A process as claimed in  claim 14  wherein the swelling solvent swells the material by more than 100%.  
     
     
         16 . A process as claimed in  claim 14  or  15  wherein the swelling solvent swells the material by more than 150%.  
     
     
         17 . A process as claimed in any of  claims 1  to  16  wherein the extraction solvent is water miscible.  
     
     
         18 . A process as claimed in any of  claims 1  to  17  wherein the extraction solvent includes tetrahydrofuran (THF).  
     
     
         19 . A process as claimed in any of  claims 1  to  19  wherein the extraction solvent includes methyl ethyl ketone (MEK).  
     
     
         20 . A process as claimed in any of  claims 1  to  15  wherein the solvent extraction step is carried out for a period of at least 2 hours at room temperature.  
     
     
         21 . A process as claimed in any preceding claim wherein the solvent extraction step is carried out at a temperature in excess of 20° C.  
     
     
         22 . A process as claimed in any preceding claim wherein the solvent extraction step is carried out in an ultrasonic bath.  
     
     
         23 . A process as claimed in any of  claims 3  to  22  wherein the non solvent is water.  
     
     
         24 . A process as claimed in any of  claims 3  to  22  wherein the non solvent is and alcohol.  
     
     
         25 . A process as claimed in any of  claims 3  to  24  wherein the non solvent is added to the solvent swollen polymeric material in an amount and at a rate to maintain a low concentration gradient.  
     
     
         26 . A process as claimed in any of  claims 3  to  25  wherein the de-swelling is carried out at a temperature of less than 40° C.  
     
     
         27 . A process as claimed in any preceding claim wherein the polymeric material is a polyether polyurethane.  
     
     
         28 . A process as claimed in any of  claims 1  to  26  wherein the polymeric material is a polycarbonate urethane.  
     
     
         29 . A process as claimed in any of claims  1  or  26  wherein the polymeric material is a polydimethyl-siloxane urethane.

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