Encapsulation of octenidine hydrochloride into bioresorbable polyesters for extended antimicrobial activity

Nosocomial infections remain a serious threat even for patients of highly industrialized countries. These infections occur on surgical sites and wounds, on catheter entry sites, tubes and other indwelling devices. Medical devices providing local antiseptic action over an extended time period represent an opportunity to prevent such infections. One way to achieve this goal is the encapsulation of active molecules into bioresorbable polymer microparticles, which can locally release the compound of interest along a tunable time span depending on the polymer characteristic. In this work, spray drying is used to encapsulate the broad band antiseptic octenidine hydrochloride into a set of poly(D,L-lactide) (PDLLA) and poly(D,L-lactide-co-glycolide) (PLGA) carrier materials with different molecular weights and chain end-groups, forming redispersable powders. It is demonstrated that the carrier materials bearing acid end-groups provide a significantly larger entrapment efficacy comparing with their ester counterparts independently of carrier composition and molecular weight. The quantitative understanding of the release mechanism allows guiding the selection of suitable encapsulating polyesters to tune initial burst and long time release of a given drug. Finally, it is demonstrated on cultures of Staphylococcus epidermidis that the encapsulated and subsequently released OHC has conserved its antiseptic activity, which supports the potential applicability of the approach.