POLY(2-HYDROXYACETIC ACID)

Polyglycolic acid (PGA), also known as polyglycolide, was first reported in 1893, but it was not until 1967 that the first commercially successful patent was granted for sutures. Like polylactide, polyglycolide is synthesized from the cyclic diester. An important difference between polylactide and polyglycolide, is that polyglycolide (mp 220 C (428 F) is higher melting than poly-L-lactide (mp 170 C (338 F). Although the polymerization reaction in both cases is reversible at high temperature, melt processing of polyglycolide is more difficult because the melting temperature is close to its decomposition temperature. Unlike poly-L-lactide which is absorbed slowly, polyglycolide is absorbed within a few months post-implantation owing to greater hydrolytic susceptibility. In vitro experiments have shown the effect on degradation by enzymes, pH, annealing treatments, and gamma irradiation. Braided polyglycolide sutures undergo surprisingly rapid hydrolysis in vivo owing to cellular enzymes released during the acute inflammatory response following implantation.