Chapter 18
A Polymeric Radiostabilizer for Absorbable Polyesters D e n n i s D . Jamiolkowski a n d Shalaby W . S h a l a b y
1
Downloaded by UNIV OF ARIZONA on June 8, 2017 | http://pubs.acs.org Publication Date: November 12, 1991 | doi: 10.1021/bk-1991-0475.ch018
E t h i c o n , Inc., Somerville, NJ 08876
A new strategy was developed to prepare absorbable copolymers of acceptable absorption profile and radiostability. This entailed the preparation of a crystallizable segmented copolymer of poly(ethylene 1,4-phenylene-bis-oxyacetate) (PEPBO) and polyglycolide (PG) units with PG as the dominant component of the system. Incorporation of about 10 mole percent of the polymeric radiostabilizer (PEPBO) into the PG chain leads to high strength fibers and substantially improves the in vivo strength retention; the copolymer was shown to be absorbable.
Interest in synthetic absorbable polymers, which undergo chain scission and loss of m a s s in the biological environment, has grown considerably over the past t w o decades because of their increased applications in the biomedical and pharmaceutical areas (1-4). Medical products made of these polymers are usually sterilized by ethylene oxide (1-4) a s opposed to gamma irradiation, a convenient and highly reliable method of sterilization. This is because of their susceptibility to degrade by high energy radiation; although losses in baseline physical properties c a n be modest, the rate at which physical properties are lost in vivo is generally unacceptible for irradiated, synthetic absorbable materials (exposure to a typical gamma radiation sterilization c y c l e , using a C o - 6 0 source) (2,3,5-7) . T h e desire to develop biomedical and pharmaceutical products which are suitable for g a m m a sterilization provided an incentive to pursue studies in this area by Shalaby and coworkers since the early 1 9 8 0 ' s , w h o paid special attention to radiation sterilizable absorbable polyesters (6-13). This report deals with a member of a n e w class of polymeric radiostabilizers, which c a n be incorporated in the chains of absorbable polymers to produce radiation sterilizable, absorbable devices including surgical sutures. Chemistry of the Polymeric Radiostabilizer and Copolvmerization with Glvcolide T h e specific radiostabilizer used in these studies is a partially aromatic polyester with selected structural features to provide
Current address: Department of Bioengineering, Clemson University, Clemson, SC 29634
0097-6156/91/0475-0300$06.00/0 © 1991 American Chemical Society
Clough and Shalaby; Radiation Effects on Polymers ACS Symposium Series; American Chemical Society: Washington, DC, 1991.
18.
Radiostabilizing Absorbable Polyesters
JAMIOLKOWSKI & SIIALABY
2n C H g O N a HCKQV-OH
η
+
2n
CI-CH -C-OCH 2
3
CHgOH
n
CH 0-ë-CH -O-{^y-0-CH - 5 5 % yield). T h e structure of the monomer w a s verified by IR and H N M R spectroscopic techniques. H NMR (300 M H z , hexafluoroacetone sesquadeuterate(HFAD)/deuterobenzene ( C D ) ,
