Anti-inflammatory prodrugs as plasticizers for biodegradable implant materials based on poly(3-hydroxybutyrate)

Salicylic and acetylsalicylic acid esters were tested as plasticizers for biodegradable poly(3-hydroxybutyrate) (PHB). The aim is the combination of plasticizing and anti-inflammatory properties in the fabrication of implant materials. Solution-cast films made of mixtures of PHB and 30% ester showed plasticization accompanied by a decrease of elastic modulus and an increase in elongation at break in comparison with pure PHB films. However, the number of usable plasticizers from the group of the salicylic acid and acetylsalicylic acid esters is limited. Short-chain derivatives are volatile while long-chain compounds tend to crystallize. In both cases PHB films embrittle within short time. Moreover, some derivatives show a fast release in an aqueous environment. As alternative nonsteroidal anti-inflammatory prodrugs arylpropionic acid esters were tested as plasticizers. The addition of ketoprofen ethyl ester led to PHB films with decreased brittleness. In summary, various esters of anti-inflammatory drugs show plasticizing effects on solution-cast PHB films comparable with those of commonly used citric acid esters.