Which radiopharmaceutical is used to treat bone pain caused by metastatic bone disease?

Strontium-89 (Sr-89) is the radiopharmaceutical specifically used to treat bone pain caused by metastatic bone disease. This isotope has a high affinity for areas of increased bone metabolism, which is characteristic of metastatic lesions. When injected, Sr-89 localizes to the bone, where it emits beta particles that provide pain relief by damaging the nerve endings in the area of the tumor or lesion, ultimately alleviating the pain associated with metastatic bone disease.

The pharmacological action of Sr-89 is closely tied to its ability to mimic calcium and incorporate itself into the bone tissue. This targeted delivery allows for effective pain management in patients suffering from bone metastases related to various cancers. Its use in clinical practice has been supported by numerous studies demonstrating its efficacy and safety in reducing pain in these patients.

Other isotopes mentioned in the choices have different applications. I-131 is primarily used for treating thyroid cancer and hyperthyroidism, P-32 is utilized for specific hematological disorders and certain cancers, and In-111 is generally employed in diagnostic imaging and labeling procedures rather than direct treatment of bone pain. Thus, Sr-89 stands out as the most appropriate choice for the treatment of bone pain from metastatic disease.