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Radiopharmaceuticals are medicinal formulations that contain a radioactive isotope and are used for diagnosis or therapy in nuclear medicine. They consist of a radionuclide bound to a molecule that directs distribution in the body, such as a peptide, antibody, or small molecule. After administration, the radiopharmaceutical localizes in a target tissue, and the emitted radiation can be detected for imaging or to deliver cytotoxic doses to diseased cells.

Diagnostic radiopharmaceuticals are designed for imaging. Common radionuclides include technetium-99m for bone and organ imaging, and fluorine-18 for positron emission tomography. Theranostics pair a diagnostic agent with a therapeutic counterpart targeting the same process, enabling personalized treatment planning. Therapeutic radiopharmaceuticals deliver higher radiation doses, using beta- or alpha-emitting isotopes such as lutetium-177 or actinium-225, with examples like Lu-177 DOTATATE for neuroendocrine tumors and iodine-131 for thyroid disease.

Production and regulation: Radiopharmaceuticals are prepared in radiopharmacies under good manufacturing practice, with radionuclides produced in cyclotrons or reactors. The labeling process is sterile and pyrogen-free, and doses are individualized with dosimetry to balance benefit and exposure. Regulatory agencies oversee safety, efficacy, and labeling, with approvals varying by jurisdiction. Safety considerations include radiation protection and potential adverse reactions.

History and impact: Since the mid-20th century, radiopharmaceuticals have transformed diagnostic imaging and targeted radiotherapy, contributing to earlier detection, staging, and management of cancer and other diseases. Ongoing research aims to expand imaging modalities, isotopes, and targeted delivery.