Absorbable Medical Devices Based on Novel Films and Foams Made From Semi-Crystalline, Segmented Copolymers of Lactide and Epsilon-Caprolactone Exhibiting Long Term Absorption Characteristics

Abstract

Absorbable medical devices based on novel foams and films made from semi-crystalline, segmented copolymers of lactide and epsilon-caprolactone exhibiting long term absorption characteristics are disclosed. Also disclosed are methods of producing said foams and films, and useful polymer solutions.

We claim: 
     
         1 - 12 . (canceled) 
     
     
         13 . A method of making an absorbable foam by a lyophilization process, comprising the steps of:
 A. providing an absorbable polymer comprising a semicrystalline absorbable segmented copolymer, said copolymer comprising repeating units of polymerized lactide and polymerized epsilon-caprolactone, wherein the mole ratio of polymerized lactide to polymerized epsilon-caprolactone is between about 60:40 to about 75:25, said copolymer having a first heat Tg, as determined by differential scanning calorimetry at a scan rate of 10° C. per minute, equal to or less than 0° C., and a crystallinity level of about 20 to about 50 percent, as measured by wide angle X-ray diffraction;   B. dissolving a sufficient quantity of the copolymer in a suitable solvent to form a lyophilizing solution;   C. pouring at least a part of the solution into a suitable mold; and,   D. subjecting the solution in the mold to a lyophilizing process to form an absorbable foam.   
     
     
         14 . The method of  claim 13  wherein the solvent is selected from the group consisting of 1,4-dioxane, trioxane, a mixture of at least 90 weight percent 1,4-dioxane and no more than 10 weight percent water, and a mixture of at least 90 weight percent 1,4-dioxane and no more than 10 weight percent of an organic alcohol having a molecular weight of less than 1500 Daltons. 
     
     
         15 . The method of  claim 13  wherein the dissolved absorbable polymer is between about 3 to about 30 percent by weight of the solution. 
     
     
         16 . The method of  claim 13  wherein the resulting foam has a thickness between about 20 to about 500 mils. 
     
     
         17 . A lyophilizing solution, comprising:
 A. a solvent selected from the group consisting of 1,4-dioxane, trioxane, a mixture of at least 90 weight percent 1,4-dioxane and no more than 10 weight percent water, and a mixture of at least 90 weight percent 1,4-dioxane and no more than 10 weight percent of an organic alcohol having a molecular weight of less than 1500 Daltons; and,   B. about 3 wt. % to about 30 wt. % of a polymer comprising a semicrystalline absorbable segmented copolymer, the copolymer comprising repeating units of polymerized lactide and polymerized epsilon-caprolactone, wherein the mole ratio of polymerized lactide to polymerized epsilon-caprolactone is between about 60:40 to about 75:25, said copolymer having a first heat Tg, as determined by differential scanning calorimetry at a scan rate of 10° C. per minute, equal to or less than 0° C., and a crystallinity level of about 20 to about 50 percent, as measured by wide angle X-ray diffraction.   
     
     
         18 . The lyophilizing solution of  claim 17  wherein said solution remains non-gelling at 20° C. for at least 18 hours. 
     
     
         19 . The lyophilizing solution of  claim 17  wherein said solution remains non-gelling at 20° C. for at least 168 hours. 
     
     
         20 - 25 . (canceled)