Investigation into the erosion mechanism of salicylate-based poly(anhydride-esters).

Salicylate-based poly(anhydride-esters), collectively referred to as PolyAspirin, hydrolytically degrade into salicylic acid, a nonsteroidal anti-inflammatory drug (NSAID). The variations of the poly(anhydride-ester) investigated in this article are linked by adipic acid, suberic acid, or sebacic acid. To elucidate the erosion mechanism of these polymers, water uptake, mass loss, contact angle, and changes in device thickness were monitored as a function of in vitro degradation time. The polymers examined here appeared to primarily undergo surface erosion. The adipate homopolymer absorbed the most water and therefore swelled more than the other versions of the poly(anhydride-ester). Additionally, the adipate homopolymer eroded most quickly. Increasing the length of the linker moiety decreased the driving force for hydrolysis, which prolonged the lifetime of the polymer sample. (c) 2005 Wiley Periodicals, Inc.