Biodegradable, rigid thermoplastic polymer of glycolic acid and the simplest linear, aliphatic polyester used as a material for the synthesis of absorbable sutures and barrier membranes and as a carrier for bone morphogenetic proteins (BMPs). When exposed to physiologic conditions, PGA is degraded by random hydrolysis and apparently also broken down by certain enzymes, especially those with esterase activity. The degradation product, glycolic acid, is nontoxic and can enter the tricarboxylic acid cycle, after which it is excreted as water and carbon dioxide. A part of the glycolic acid is also excreted by urine.