Pharmacokinetic analysis of in vivo disposition of heparin-superoxide dismutase.

To improve the half-life and tissue targeting of SOD to suppress reactive oxygen species (ROS)-mediated injury, chemically modified derivative of superoxide dismutase (SOD) with heparin, anionized SOD (Hep-SOD), was designed. In this study, the pharmacokinetics of Hep-SOD had been studied. This study aimed to investigate the pharmacokinetics, tissue distribution and cell targeting. ¹²⁵I-radiolabeled Hep-SOD conjugate was administered to healthy mice by intravenous (i.v.) bolus injection. Compared with native SOD, the half-life of Hep-SOD conjugate, including t(₁/₂α) and of t(₁/₂β), was lengthen and area under the plasma concentration versus time curve (AUC) of Hep-SOD was increased. The study showed that both native SOD and Hep-SOD was rapidly and widely distributed in the livers, kidneys, spleens, hearts and lungs. Furthermore, compared with Hep-SOD, radioactivity of native SOD decreased more sharply over time in most tissues. Compared with native SOD, higher amount of Hep-SOD radioactivity was found in the livers. Since livers are not the known target of ¹²⁵I, the most possible reason is that Hep-SOD binds to its specific targets in the livers.