Determination of the silver ion release from polyurethanes enriched with silver

The Erlanger silver catheter was developed in order to reduce the risk of infection from long-term catheters by means of silver ions, which are known to have antibacterial properties. This is achieved by incorporating silver into polyurethane catheters by means of a special procedure. The aim of this materials science study was to verify the release of silver ions from the polyurethanes. Static experiments were carried out following the usual norms. Clinically relevant dynamic experiments, which were designed and constructed at this institute, were also performed. The eluates from both experiments were analyzed by anodic stripping voltammetry. Polyurethanes filled with silver, as used in the Erlanger silver catheter, release silver in static as well as in dynamic experiments. If the experimentally determined releases are converted to the usual catheter length of 30 cm, the release is about 0.1 microgram/l. This lies in the order of concentrations that have been reported in the literature to be antibacterial.