Preparation and biodistribution in mice of a new radiopharmaceutical-technetium-99m labeled methotrexate, as a tumor diagnostic agent.

Our aim was to develop the procedure for radiolabeling of an anticancer drug e.g., methotrexate with (99m)Tc for tumors diagnosis. The study included the radiolabeling of methotrexate, in vitro stability of radiolabeled drug, in vitro binding of radiolabeled drug with plasma protein, partition coefficient and biodistribution of radiolabeled drug in mice. Results showed 98.2±0.5% radiolabeling of methotrexate with technetium-99m ((99m)Tc). In vitro stability was studied for 5h and 79.3±5% of the drug was bound with plasma proteins. Partition coefficient of the labeled drug showed that it was highly hydrophilic. Biodistribution study in tumor bearing mice exhibited high uptake in tumor cells which were further investigated by histopathological studies. In conclusion, our study indicates that technetium-99m labeled methotrexate is a potentially strong tumor diagnostic agent with low uptake in normal tissues.