Radioiodinated Rhodamine-123: a potential cationic hepatobiliary imaging agent.

The labelling of the cationic dye Rhodamine-123 with 125I is described. The biodistribution of the iodinated Rhodamine-123 has been determined at different time intervals after intravenous injection into fasted rats. It turned out that the dye is predominantly cleared by the liver and discharged into the bile. The bile acid taurocholate did not enhance the rate of excretion of 125I-Rhodamine-123.