Bacteriological and radioactive benzalkonium studies of the graphite-benzalkonium-heparin surface

The thrombus resistant GBH surface is bactericidal before exposure to blood. After blood exposure it loses its bactericidal property but may be bacteria repellent owing to its strong negative charge. The heparin binder benzalkonium is eluted from the surface by the blood stream at an exponential rate in relation to the amount of benzalkonium present up to two and possibly six months. However, a significant amount of radioactive benzalkonium was still found to be present on the graphite surface after six months of continuous exposure to the venous blood stream.