[Phase I clinical study on 99mTc-GSA, a new agent for functional imaging of the liver]

Technetium-99m-DTPA-galactosyl human serum albumin (99mTc-GSA) is a new radiopharmaceutical which binds to the asialoglycoprotein receptors located specifically on the hepatocytes. Phase I study of 99mTc-GSA was performed on seven normal volunteers, who were intravenously injected with 185 MBq (5 mCi) and 1-10 mg of 99mTc-GSA. None of adverse reactions, abnormal findings of laboratory test and anti-99mTc-GSA antibody production was recognized. The livers were clearly visualized in all subjects. In the pharmacokinetic analyses on five subjects, 99mTc-GSA was rapidly taken up by the livers immediately after the injection and was slowly excreted through the biliary tracts and the urinary tracts. Dose-dependency which is a specific feature for the receptor-mediated agents was observed; the blood clearances of 99mTc-GSA were prolonged in proportion to the injected ligand doses. These results suggest that 99mTc-GSA may be a potential agent for evaluating hepatic functions based on the hepatic receptor quantities.