Polymers for biodegradable medical devices. 1. The potential of polyesters as controlled macromolecular release systems

Abstract Prolonged controlled release of drugs from polymeric matrices is now well established. In contrast, however, release of macromolecules presents more difficulties and in consequence is less well studied and relatively rarely discussed in the literature. The processes of biodegradation and bioerosion which are important in this field have been exploited in other types of surgical device for some years. This review brings together the literature on various aspects of the bioerosion of polymers containing ester groups, with particular emphasis on release and degradation studies that might form a basis for the design and selection of controlled macromolecular release systems. Polymers discussed include the poly(alpha esters) -including poly(lactic acid) and polyfglycolic acid) —, poly(3-hydroxybutyrate), polydioxanes, polyoxalates, polylactones, polyester hydrogels and the polyanhydride/poly(ortho ester) series.