Drug delivery concepts for the efficacious prevention of foreign-body infections

Several classes of antibiotics released from polyurethanes and silicones were examined for their activity against foreign body colonization by coagulase-negative staphylococci. Beta-lactams, gyrase inhibitors, aminoglycosides, macrolides and rifampicin were used as antimicrobials to impregnate or load the polymers. Coating of polymeric surfaces by precipitation or adsorption techniques lead to a lower and shorter drug release as compared to polymeric devices with incorporated antibiotics. Prolonged drug delivery of matrix-loaded polymers exceeding the microenvironmental minimal bactericidal concentrations (mMBC), ensured the prevention of bacterial colonization. In this study, we have been able to demonstrate the usefulness of a reproducible long-time antimicrobial dosage regime from the internal phase of the implant as compared to surface coated polymers. In addition, pharmacodynamic aspects and the potential of bonded antibiotics for inducing adverse effects such as resistance development and allergic reactions are discussed.