Release of Quaternary Ammonium Antimicrobial Compounds from Acrylic Bone Cement

Two quaternary ammonium compounds, namely benzalkonium chloride and cetyl pyridinium chloride, have been studied as additives for incorporation into acrylic bone cement (Palacos K-40)as anti-microbial agents. Each compound was added at 1percent and 5 percent by mass. Setting time of the cement was 9.75 minutes. This was not altered by benzalkonium chloride (5 percent), but was shortened to 9.00 minutes by 5 percent cetyl pyridinium chloride. Release was determined by measuring chloride release from set cement specimens with a chloride-ion selective electrode. Release was shown to occur but it did not follow simple diffusion- based kinetics. Rather it was a complicated process, and similar 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 satisfactorily, suggesting that these compounds have the potential to be used as active ingredients in orthopaedic cements.