ABSTRACT

Advances in the field of nuclear medicine are concerned with the development of specific diagnosis and treatment radiopharmaceuticals. The success of molecular imaging and treatment depends on the selective accumulation of the diagnostic or therapeutic radiopharmaceutical in the region of interest. A great deal of effort has been made to increase the specificity of targeted radiotracers in both preclinical and clinical trials. There is no major difference between the new radiopharmaceutical development process and a new drug development process in terms of regulations. However, it requires regulations on radioactivity. Requirements for drug development are also necessary for radiopharmaceuticals: discovery and preclinical biological activity demonstration, chemical synthesis feasibility, toxicology studies, Phase I, II and III clinical trials. However, the presence of the radioactive element requires some steps to be changed and accelerated. The drug development process is concerned with the connections between discovery, development, Food and Drug Administration review, and marketing approval and post-marketing safety surveillance of an approved drug, ensuring its safety and effectiveness. Comprehensive preclinical tests are carried out in animal models to prove the human drug use in the future. Several factors should be considered to select a radiopharmaceutical for a particular biological target or disease or to develop a new radiopharmaceutical. First, the choice of radionuclides: as each biological or disease process is different, the half-life and degradation of the radionuclide to be selected are important. The second factor is the metabolism of the radio-labeled compound with respect to the specificity of each biological or disease target. Therefore, for each radiopharmaceutical, after the synthesis, quality control procedures including physicochemical, radiochemical or biological tests are carried out. In order to better understand the properties of radiopharmaceuticals, including chemical, physical and biological properties, preclinical imaging of targeted molecules for biological or disease processes is performed. Combined such as micro single photon emission computerized tomography/computerized tomography (CT), micro positron emission tomography (PET)/CT, and microPET/magnetic resonance imaging are used for preclinical imaging in mice and rats for anatomic and molecular information. In recent years, the development of radiopharmaceuticals has been increasing in nuclear imaging and treatment. Perhaps the hottest subject in molecular imaging is theranostics, such as Ga-68 and Lu-177 DOTATATE/prostate-specific membrane antigen, a combination of diagnosis and treatment.