Labeling of epirubicin with technetium-99m: Optimization, biodistribution and scintigraphic imaging in tumor bearing mice

Abstract

Epirubicin is an antineoplastic agent of anthracycline antibiotic, used for treating a variety of tumor types such as lymphoma, cancer of the breast, lung, ovary and stomach. The objective of this work was to demonstrate direct radiolabeling of epirubicin with 99mTc, quality control, biological characterization and scientigraphic evaluation in tumor bearing mice. The 99mTc-epirubicin labeling was optimized by varying the amounts of ligand 100-350µg, stannous chloride dihydride 20-50µg and pH range 2-10 by using NaOH or HCl. The radiochemical purity of 99mTc-epirubicin was evaluated by chromatographic techniques (Whatman No. 3 paper and ITLC-SG). HPLC analyses were performed to check purity of epirubicin and radiochemical purity of labeled 99mTc- epirubicin. Biodistribution and scintigraphic imaging of 99mTc-epirubicin was performed in normal and tumor bearing mice at various time intervals. The optimum conditions ensuring 99mTc-epirubicin labeling yield as high as 99% by adding 35µg SnCl2.2H2O, 200µg of ligand at pH 6 for 30 min at room temperature (25°C±2°C). HPLC of 99mTc-epirubicin shows about 99% binding of the compound with technetium-99m. Electrophoresis study indicated the neutral nature of 99mTc-epirubicin. Biodistribution data and scintigraphic results showed that 99mTc-epirubicin accumulated in the liver as well as in tumor with significant uptake and excellent retention. 99mTc-epirubicin shows good stability in human serum. In vitro and in vivo studies revealed the significantly uptake of 99mTc-epirubicin in the tumor, and also indicating the efficiency of 99mTc-epirubicin as a tumor diagnostic agent.