Optimized preparation and evaluation of 99mTc-Streptomycin

The endemic occurrence of new strains of tuberculosis around the globe has initiated new research on developing diagnostic radiopharmaceutical based on antibiotics. Tc-99m labeled streptomycin was prepared using freshly milked 99mTcO4- and various concentrations of streptomycin, stannous chloride at various temperatures in high yield radiochemical purity shown by HPLC/RTLC. At various pHs tested (3-10) the best labeling yield at optimized conditions were at 6-8 range, however pH.7 was considered the best. The radiochemical purity at the best optimized conditions was >95% as shown by RTLC and >97% using HPLC (specific activity; 1-3 GBq/mmole). The tracer proved to be stable in the final product and in presence of human serum at 37°C up to 2h. However, biodistribution and high resolution SPECT studies in wild type mice showed instability of the complex due to high stomach and thyroid activity uptake. Regardless the reported methods in the literature the direct 99mTc-labeling of aminoglycosides did not proved a suitable tracer.