- Radiopharmaceuticals are specialized compounds that combine a radioactive isotope (radionuclide) with a pharmaceutical agent, designed for use in diagnostic imaging, therapy, or research in nuclear medicine. These agents are administered to the body—usually by injection, but sometimes orally or through inhalation—where they localize in specific tissues or organs, depending on the biological properties of the pharmaceutical component.
- The radioactive portion emits radiation that can be detected externally by imaging equipment, such as gamma cameras, positron emission tomography (PET) scanners, or single-photon emission computed tomography (SPECT) systems, enabling physicians to observe physiological processes in real time.
- In diagnostic applications, radiopharmaceuticals are used to assess organ function, blood flow, or metabolic activity, often detecting diseases at a molecular level before anatomical changes become visible. For example, fluorodeoxyglucose (FDG), a radiolabeled glucose analog tagged with fluorine-18, is widely used in PET imaging to detect cancer, monitor treatment response, and identify brain or cardiac disorders. Similarly, technetium-99m (⁹⁹ᵐTc), one of the most commonly used isotopes in nuclear medicine, is attached to various compounds for imaging the bones, heart, lungs, kidneys, and other organs via SPECT.
- In therapeutic uses, radiopharmaceuticals deliver targeted radiation to diseased tissues, particularly in the treatment of certain cancers. For instance, iodine-131 (¹³¹I) is used to treat thyroid cancer and hyperthyroidism, as it is selectively absorbed by thyroid tissue. More recently, lutetium-177 (¹⁷⁷Lu) and actinium-225 (²²⁵Ac) have been employed in targeted radionuclide therapies for neuroendocrine tumors and prostate cancer, often bound to molecules that seek out specific tumor receptors, allowing for precision treatment with minimal damage to surrounding healthy tissues.
- Radiopharmaceuticals must meet stringent safety and quality standards, as they involve radioactive materials and biologically active molecules. They are prepared in controlled environments such as radiopharmacies or cyclotron facilities, where radiochemists ensure proper formulation, sterility, and radioactive purity. Due to the often short half-lives of the radionuclides, these compounds are usually produced just-in-time for clinical use, posing logistical challenges in terms of transport and coordination.
- The field of radiopharmaceuticals is rapidly advancing, driven by progress in radiochemistry, molecular biology, and imaging technology. New agents are being developed to target specific biomarkers, offering hope for earlier detection and more personalized treatment of conditions like cancer, cardiovascular disease, and neurodegenerative disorders. The combination of diagnostic and therapeutic capabilities—termed theranostics—is a particularly promising area, where a single molecular platform can both visualize and treat disease.
