Abstract: Objective To establish a biodistribution determination method for ^99mTc-DMSA injection, and measure the biological distribution of ^99mTc-DMSA injection in order to contribute to quality evaluation of this drug methodologically. Methods The measurement range and applicability of the instruments (dose calibrator and γ counter) required for biological distribution tests were examined. Using rats as experimental animals, ^99mTc-DMSA injection was prepared using DMSA kits from 2 manufacturers to examine the impact of the injection dose on biological distribution. The uptake values of the same dose of ^99mTc-DMSA injection from different manufacturers were compared in various organs of rats to study the differences in biological distribution between different manufacturers. Results The measurement range of the dose calibrator was≥1.6 μCi. The linear range of the γ counter measurement was 400 to 3 570 000 CPM, which corresponded to a maximum radioactivity of 2.6 μCi. There was no significant difference in biodistribution of samples injected with doses of 0.04 mCi to 1.7 mCi. Using the established biodistribution assay, the results showed differences in the biodistribution of the samples from 2 manufacturers in rats. The ^99mTc-DMSA injection prepared using the kit from manufacturer A was metabolized faster compared with manufacturer B in rats. One hour after injection, 19.23% of preparation A and 10.29% of preparation B were excreted in urine. There was also a significant difference in the uptake values per gram of renal tissue, which were 17.00% and 26.95%, respectively. Conclusion A biological distribution method for ^99mTc-DMSA injection has been established that offers data for quality evaluation of this drug and sparks ideas for quality evaluation of other ^99mTc labeled drugs.

Key words: ^99mTc-DMSA, Injection, Renal Imaging, Radiopharmaceuticals, SD Ratis, Biological Distribution, Quality Evaluation