Studies on commercially available 99Mo/99mTc radionuclide generators—II. Operating characteristics and behavior of 99Mo/99mTc generators

Alguns aspectos sobre geradores e radiofármacos de tecnécio-99m e seus controles de qualidade

Radiofármacos marcados com tecnécio-99m são os principais agentes para diagnósticos utilizados nas clínicas de medicina nuclear, em função de uma série de características físicas do radionuclídeo e pela praticidade dos radiofármacos serem preparados no local de uso, por meio de uma reação de complexação entre um agente complexante (fármaco) e o tecnécio-99m. Entretanto, durante esta reação podem ser geradas algumas impurezas que proporcionam a formação de produtos com baixa qualidade ou com características diferentes das desejadas. No presente trabalho serão apresentados alguns dos fatores que podem interferir na qualidade dos radiofármacos e os controles que podem ser utilizados para garantir sua qualidade.

The continuing important role of radionuclide generator systems for nuclear medicine

In this review, the continuing importance and status of development of radionuclide generator systems for nuclear medicine are discussed. Radioisotope costs and availability are two important factors, and both nuclear reactors and accelerator facilities are required for production of the parent radioisotopes. Radionuclide generator research is currently focused on the development of generators which provide radioisotopes for positron emission tomography (PET) applications and daughter radioisotopes for various therapeutic applications which decay primarily by particle emission. Generator research continues to be influenced by developments and requirements of complementary technologies, such as the increasing availability of PET. In addition, the availability of a wide spectrum of tumor-specific antibodies, fragments, and peptides for radioimmunodiagnosis and radioimmunotherapy has stimulated the need for generator-derived radioisotopes. The advantages of treatment of arthritis of the synovial joints with radioactive particles (radiation synovectomy) may be expected to be of increasing importance as the elderly population increases, and many of these agents are prepared using generator-derived radioisotopes such as yttrium-90 and rhenium-188. Therapeutic use of the "in vivo generator" is a new approach, where the less radiotoxic parent radioisotope is used to prepare tissue-specific therapeutic agents. Following in vivo site localization, decay of the parent provides the daughter for therapy at the target site. The principal foundation of most diagnostic agents will continue to require technetium-99m from the molybdenum-99/technetium-99m ("Moly") generator. With the limited availability of nuclear reactors and facilities necessary for production and processing of fission 99mTc and the significant issues and problems associated with radioactive waste processing, however, the possibility of utilizing lower specific activity 99Mo produced from neutron activation of enriched 98Mo may become practical in the future.

Technetium-99m complexes of dimethylaminomethylene diphosphonate (DMAD)--I. Anion exchange HPLC characterization of 99mTc(NaBH4)-DMAD mixtures

Radiopharmaceutical analogs prepared by sodium borohydride reduction of 99mTcO4- in the presence of DMAD have been characterized by anion exchange HPLC (high performance liquid chromatography) separation of the resulting mixture into component 99mTc-DMAD complexes. The distribution of complexes within a radiopharmaceutical formulation can be manipulated by controlling technetium concentration, pH, presence or absence of air, and time post reaction.