succimer and Carcinoma--Ehrlich-Tumor

Radiolabeling with rhenium (Re-186, Re-188), a tumor agent to resemble the pentavalent polynuclear technetium complex of dimercaptosuccinic acid (99mTc[V]-DMS) has been reported for radiotherapeutical use. Nevertheless, despite the periodic analogies between both radiometals, differences in the redox potential and the carrier concentration have made the radiolabeling of the rhenium counterpart difficult. In the present study, the effect of the carrier contained in the reactor-produced Re-186 was estimated as an important factor relevant to the Re-186 radiolabeling of DMS at an alkaline pH. Great effect of the carrier Re with an inverse correlation with the stannous ion was an interesting phenomenon relevant for an assumption on the Sn participation in the complex. Under strict control of various labeling parameters, the 186Re(V)-DMS was made available with high yield (93-97%) at an alkaline pH and at room temperature. The great effect of carrier offers support to the polymeric or polynuclear nature of the rhenium complex of DMS as depicted in the drug design basis of its parent Tc(V)-DMS. The biodistribution studies of Re(V)-DMS showed mimetic characteristics with its parent Tc(V)-DMS drug.

Topics: Animals; Carcinoma, Ehrlich Tumor; Chelating Agents; Hydrogen-Ion Concentration; Isotope Labeling; Mice; Organometallic Compounds; Radioisotopes; Radiopharmaceuticals; Reducing Agents; Rhenium; Succimer; Temperature; Tin Compounds; Tissue Distribution

In our search for a technetium-tumor seeking agent, the chemical characteristic of polynuclear Ga-citrate attracted our attention. On this basis, we selected the ligand dimercaptosuccinic acid (DMS) and appropriate labeling conditions in the design of 99mTc(V)-DMS. Chemical characterization was performed by thin layer chromatography, electrophoresis, Sephadex column chromatography and spectrophotometric studies at the chemical concentration (99Tc). Biodistribution in mice bearing Ehrlich ascites tumor and scintigraphic images in VX-2 tumor-bearing rabbit, indicated the great applicability of 99mTc(V)-DMS as a new tumor imaging agent. Its distinctive characteristic, different from the kidney imaging agent (99mTc-DMSA) is demonstrated and the biological implication of hydrolytic polynucleation of pentavalent technetium, through an anionic specie Tc(V)O3-(4), in the tumor cell is discussed.

Topics: Animals; Carcinoma, Ehrlich Tumor; Kinetics; Male; Mice; Mice, Inbred Strains; Neoplasms, Experimental; Rabbits; Radionuclide Imaging; Succimer; Sulfhydryl Compounds; Technetium; Technetium Tc 99m Dimercaptosuccinic Acid; Tissue Distribution