Synthesis and Biological Evaluation of ¹³¹I-Risedronate with Bone Targeting Activity

Current radiopharmaceuticals for treating bone metastatic tumors have various limitations. We focus on developing a universal, economical, efficient, and safe novel radiopharmaceutical for bone metastasis treatment. ¹³¹I is a well-established medical radionuclide commonly used for both treatment and diagnosis. Risedronate exhibits strong bone-targeting properties with moderate bone retention. This study explored the combination of these two components and evaluated its biological properties in animal experiments. Based on the experimental results, ¹³¹I-risedronate demonstrated high bone-targeting efficiency, low uptake in nontarget organs, and rapid clearance. Notably, at 3 days postadministration, significant bone retention was observed, indicating its potential for sustained therapeutic effects. Additionally, its biodistribution and therapeutic effect can be effectively monitored by SPECT/CT imaging.