A preliminary study of the release of quaternary ammonium antimicrobial compounds from acrylic bone cement

Abstract

The quaternary ammonium compounds benzalkonium chloride and cetyl pyridinium chloride have been studied as potential anti-microbial additives for incorporation into acrylic bone cement. Using the commercial bone cement Palacos K-40, each compound was added at 1% and 5% by mass. Setting time of the cement was 9.75 min. This did not change when benzalkonium chloride (5%) was present, but was shortened to 9.00 min by 5% cetyl pyridinium chloride. Release of additive was estimated by determining chloride release from set cement specimens using a chloride-ion selective electrode. This showed that release occurred but was a complicated process and did not follow simple diffusion-based kinetics. Release thus appeared to occur by a similar overall mechanism to that of gentamicin sulphate from bone cements. The results show that these anti-microbial compounds can be incorporated into acrylic bone cement and then released in a satisfactory manner and suggest that these compounds have the potential to replace gentamicin sulphate as active ingredients in orthopaedic cements.