Optimized preparation and evaluation of 99mTc-Streptomycin

Introduction: The endemic occurrence of new strains of tuberculosis around the globe has initiated new research on developing diagnostic radiopharmaceutical based on antibiotics. Methods: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. Results: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. Conclusion: Regardless the reported methods in the literature the direct 99mTc-labeling of aminoglycosides did not proved a suitable tracer.

Keywords:

Technetium-99m , Streptomycin , SPECT , Biodistribution