Tc-99m-pyridoxal mimosine complex-preparation and biological evaluation for kidney scanning

ABSTRACT

Tc-99m-pyridoxylidene-mimosine complexes were prepared by the autoclave and the tin reduction methods and the yields were determined by electrophoresis, thin layer chromatography, and autoradiography. Autoclaving a mixture of pyridoxal mimosine [3mM 1mM] at pH 8.0 for 20 minutes yielded complex where 95% of the added Tc 99m was bound. Using 200 micro g of SnCI2.H2O as a reductant in a mixture of 1mM each of pyridoxal hydrochloride and mimosine, 300 micro g ascorbic and 1-5 mCi of Na TcO4 at pH 8.5, produced Tc-99m-Sn-pyridoxylidene mimosine [Tc-99m-SPM] complex where about 95% of the added Tc-99m was bound. Comparative studies on rabbits for biodistribution were performed by injecting the Tc-99m-SPM and I-131 hippuran simultaneously. About 60% of Tc-99m-SPM was excreted through the kidneys in one hour while 92% of the hippuran complex was excreted along with the urine during the same period. Blood curves drawn on both the compounds looked very close to each other in mechanism of excretion. Scintigraphic studies in rabbits also showed a significant amount of the labelled compound excreted through the kidneys while the low levels of liver uptake of Tc-99m-SPM did not seem to interfere. Studies on rabbits showed no signs of toxicity