Polylactide/glycolide polymer

FIGURE 13.9 FTIR spectra of porous 8S IS polylactide-glycolide scaffold incutiaied in simulated physiological fluid (SPF) for various times (7 = 0-16 days). The spectra show the development of phosphate ( ) and carbonate (A) peaks as incubation time increases. Peaks lepiesenting polymer (o) are also indicated. (From Murphy et al 2000a, with permission.)... 

Polylactide-co-glycolide co-polymers Lactic acid Glycolic acid [15]... 

Polyesters, specifically polylactides and poly(lactide-co-glycolide)s have played a critical role in the development of polymer-based CR technologies. The biocompatibility and the well-established safety profiles of PLA and PLGA polymers have made them the polymer of choice for CR applications. However the off-patent status of these polymers makes them freely available for research in industry as well as academia. This has led to a vast number of patents covering various applications of these polymers within the drug delivery sector. Due to these issues, very limited scope remains to utilize these polymers to reformulate generic, off-patent drugs. 

DL-Polylactic acid, for the most part, was found to erode in about 12 months. Slow degradation of DL-polylactic acid often becomes a limitation on its use. This rate can be accelerated appreciably by copolymerizing with up to 50 mol% glycolide to yield complete erosion in as fast as 2 to 3 weeks. Incorporation of glycolide into the polylactide chain alters crystallinity, solubility, biodegradation rate, and water uptake of the polymer. 

Fig. 4 Structures of some bioresorbable polymers (A) poly-glycolide acid and (B) polylactide.

At the time of writing, the applications of biodegradable polymers are confined mostly to the field of agriculture, where they are used in products with limited lifetimes, such as mulch films and pellets for the controlled release of herbicides. The synthetic polyesters used in medical applications, principally polylactide and poly(lactide-co-glycolide), while claimed to be biodegradable, are degraded in the body mainly, if not entirely, by chemical hydrolysis. There is little evidence that the hydrolysis of these polyesters of a-hydroxyacids can be catalyzed by hydrolase or depolymerase enzymes. 

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