Synthesis of p-aminohippuric acid analog and its labeling by technetium-99m

A procedure is described for the synthesis of p-[(bisacarboxymethyl)aminomethyl carbamino] hippuric acid (PAHIDA). The compound was identified by i.r. and NMR spectroscopy. A lyophilized complex was prepared and labeled with 99mTc. The purity of the preparation is better than 98%. The stability of the 99mTc-PAHIDA complex is achieved 8 h after labeling. Biodistribution tested on white rats shows a maximum accumulation in kidneys of 6-10% within 2 min after injection, while the accumulation in the liver is 2-4% of the administrated dose. Preliminary clinical studies of 99mTc-PAHIDA on patients and its comparison with 131I-hippuran showed that the 99Tc-PAHIDA preparation has excellent characteristics for visualization of kidneys. However, it has slightly slower urinary elimination compared to hippuran, which it makes possible to use PAHIDA as a replacement of hippuran to a certain extent.