A Comparative Study of Stannous Chloride and Sodium Borohydride as Reducing Agents for the Radiolabeling of 2,3,7,8,12,13,17,18-Octaethyl-21H,23H-Porphine with Technetium-99m for Tumor Imaging

2,3,7,8,12,13,17,18-Octaethyl-21H,23H-porphine (OEP) was successfully radiolabeled with technetium-99m by direct technique using two different reducing agents: stannous chloride and sodium borohydride. High radiochemical yield (97%) and in vitro stability for up to 8 h were obtained using sodium borohydride. Paper chromatography (PC), paper electrophoresis, and high-performance liquid chromatography (HPLC) were used to evaluate the radiochemical yield and identify the purity of the final product. Biodistribution studies of the 99mTc-OEP complex (prepared using sodium borohydride) in tumor-bearing mice showed high target/nontarget (T, right thigh/NT, left thigh) ratio of 4.40 ± 0.12 at 60 min post injection, suggesting that this complex can be used as a solid tumor imaging agent.