Technetium Tc99m thiodiglycollic acid. A new radiopharmaceutical with the potential for the assessment of renal function

A mixture of hydrophilic complexes is formed on the reduction (employing tin metal as a reductant) of sodium pertechnetate Tc99m in the presence of the ligand thiodiglycollic acid (TDG). When administered to rats, the mixture demonstrated a renal clearance rate marginally greater than GFR. HPLC analysis indicated the formation of two technetium complexes of TDG. After isolation of the complexes and their administration to rats, one (complex 1) showed renal clearance similar to that of sup(99m)Tc DTPA, while the other (complex 2) demonstrated renal clearance similar to that of 125I o-iodo hippuric acid. On heating the mixture of complexes, the proportion of the faster-clearing sup(99m)Tc TDG complex increased to 92% of the total activity, and the biodistribution of the material following heat rearrangement was equivalent to that of isolated complex 2. (orig.)