title: Technetium-99m-labeled receptor-specific small-molecule radiopharmaceuticals: recent developments and encouraging results.
abstract: The development of technetium-99m-labeled small-molecule radiopharmaceuticals directed at specific high-affinity binding sites, as are found in receptors for hormones and neurotransmitters, transport systems, and certain enzymes, is a natural outgrowth from the successful development of technetium radiopharmaceuticals for imaging flow and metabolism. Although many receptor-specific radiopharmaceuticals labeled with PET and other SPECT isotopes already exist, the low cost and widespread availability of technetium-99m would make their 99mTc-labeled counterparts much more accessible to the medical community. This review has four goals: (a) To survey and analyze critically the results of a flurry of research activity in this area in recent years, which has led to the preparation of a number of novel technetium-labeled radiopharmaceuticals targeted at high-affinity sites, a few of which appear to be very promising; (b) to provide a conceptual analysis of how these agents are being designed; (c) to provide a context in terms of binding and uptake behavior by which these agents should be judged; and (d) to highlight emerging knowledge on the structure of receptors and related high-affinity binding biomolecules and their distribution, which may serve as reference points for understanding the results that have been obtained so far, and may be useful guides for future design.
authors.affiliation: Department of Chemistry, University of Illinois, Urbana 61801, USA.
authors.forename: R K
authors.initials: RK
authors.lastname: Hom
authors.forename: J A
authors.initials: JA
authors.lastname: Katzenellenbogen
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000032:analysis; D050483:Dopamine Plasma Membrane Transport Proteins; D015195:Drug Design; D006801:Humans; D008562:Membrane Glycoproteins / Q000032:analysis; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; D017981:Receptors, Neurotransmitter / Q000032:analysis*; D011987:Receptors, Steroid / Q000032:analysis*; D017480:Receptors, sigma / Q000032:analysis; D050486:Serotonin Plasma Membrane Transport Proteins
chemical_list: D002352:Carrier Proteins; D050483:Dopamine Plasma Membrane Transport Proteins; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; D017981:Receptors, Neurotransmitter; D011987:Receptors, Steroid; D017480:Receptors, sigma; C493230:SLC6A4 protein, human; D050486:Serotonin Plasma Membrane Transport Proteins