[Molecular imaging in evaluation of in vivo behavior of drugs]

The nuclear medical imaging technologies, PET and SPECT, is sensitive in vivo imaging in biomedicine and have the power to obtain the information on the in vivo dynamic behaviors of drugs. There are some approaches in this field. First approach uses the drug labeled isotopically with an appropriate radionuclide and can obtain information on the tissue distribution and targeted point of drugs. Second approach, drug delivery imaging, is one that a radiolabel is incorporated into the dosage form with some methods and can be used toward the evaluation of the efficacy of a new formulation and route of administration of drug. Third approach is to assess the in vivo interaction between a targeted molecule and a drug, such as receptor binding, transporting ability and enzyme activity, using the radiolabeled ligand, based on the competition of a drug with the radioligand. Thus, molecular imaging used nuclear medical imaging technique can directly visualize the spatiotemporal distribution and interaction processes of drugs in human at the molecular level.