radiopharmacologic

Radiopharmacology, sometimes described as radiopharmacologic science, is the study of how radioactive substances interact with biological systems and the development, characterization, and clinical use of radiopharmaceuticals for diagnosis and therapy. It sits at the intersection of pharmacology, radiochemistry, and nuclear medicine and encompasses the design, labeling, evaluation, and application of radioactive compounds in living systems.

Radiopharmaceuticals are compounds labeled with radionuclides that enable visualization, measurement, or destruction of biological processes. Diagnostic agents typically use isotopes suitable for imaging, such as technetium-99m for SPECT or fluorine-18 for PET. Therapeutic radiopharmaceuticals deliver cytotoxic radiation to diseased tissues using beta- or alpha-emitting isotopes, for example iodine-131, lutetium-177, or actinium-225. Theranostic approaches pair a diagnostic radiopharmaceutical with a therapeutic counterpart targeting the same molecular system.

Development and use involve labeling biologically active molecules (peptides, antibodies, small molecules) with radionuclides, followed by preclinical studies of biodistribution, receptor binding, metabolism, and dosimetry, then clinical testing under regulatory oversight. Key concepts include pharmacokinetics and pharmacodynamics, radiation dose assessment, radiopharmaceutical stability, and quality control.

Applications span oncology, cardiology, neurology, and infectious disease, with imaging agents aiding diagnosis and treatment planning, and therapeutic agents enabling targeted radiotherapy. Examples include fluorodeoxyglucose for PET imaging, technetium-99m-based bone scans, and Ga-68 or Lu-177 labeled somatostatin analogs or PSMA ligands used in theranostic pairs. Safety, regulatory compliance, and radiation protection are integral to practice.