Polyglykolid

Polyglycolide, or poly(glycolic acid), is a biodegradable aliphatic polyester composed of repeating glycolic acid units linked by ester bonds. The repeating unit is −O−CH2−CO−O−. It is prepared by polymerization of glycolide, the cyclic dimer of glycolic acid, usually via ring-opening polymerization with metal catalysts. The polymer is typically highly crystalline and possesses a melting temperature around 215–230°C and a glass transition temperature near 35–40°C. It is highly susceptible to hydrolysis under physiological conditions, yielding glycolic acid, which is metabolized by the body.

In medical use, polyglycolide is best known as an absorbable suture material; its mechanical strength diminishes over a period of weeks to months as hydrolysis proceeds. The degradation products are glycolic acid and its conjugates, which are generally well tolerated, though acidic microenvironments during degradation can cause local inflammation in some cases. Because its degradation is relatively fast, PGA is often used in non-load-bearing applications or in combination with other polymers to tailor resorption rates.

Polyglycolide is also used in tissue engineering scaffolds and drug-delivery systems, and as a constituent of copolymers such as poly(lactic-co-glycolic acid) (PLGA), where the lactic acid unit slows degradation to suit specific applications. The ability to adjust crystallinity, molecular weight, and copolymer composition allows a wide range of mechanical properties and resorption times.

Healthcare regulators generally regard PGA as biocompatible and resorbable; it is employed in various surgical and implantable devices. The polymer’s biodegradation to glycolic acid and its subsequent metabolism distinguish it from nondegradable polymers used in permanent implants.