Comparison of the99mTc-cysteine complex and131I-hippuran in biodistribution

This study compares the biological behavior of the^99mTc-cysteine complex with¹³¹I-hippuran (¹³¹I-OIH). The potential role of the^99mTc-cysteine complex as a renal imaging agent has also been evaluated. In addition the biological characteristics, i.e., biodistribution, blood clearance, excretory mechanism and the renal excretion pattern in the presence and absence of the tubular transport inhibitor (2,4-dinitrophenol, probenecid) has been examined. The experimental results reveal that kidneys are the target organ. The blood clearance of these radiopharmaceuticals is rapid, approximately 84% of the injected activity is excreted from the kidneys at 1 hour postinjection. Moreover, the renal inhibitor obviously depresses the excretory rate of the^99mTc-cysteine and¹³¹I-OIH, suggesting that such agents are excreted by renal tubular secretion. Results presented demonstrate that the^99mTc-cysteine is a remarkable renal dynamic imaging agent which is highly promising as a new renal imaging radiopharmacentical.