Radiolabeling and biological evaluation of losartan as a possible cardiac imaging agent

A procedure was developed for preparing high radiochemical purity 99m Tc-Losartan in a yield of about 90%. The optimal reaction conditions are as follows: 100 μg of Losartan, 50 μg of SnCl2·2H2O, 150 μL of phosphate buffer (pH 7), room temperature (25 ± 1°C), reaction time 5 min. Under these conditions, the radiochemical yield up of 99m Tc-Losartan reaches 98%. The radiochemical yield and purity of the labeled product were determined by electrophoresis and paper chromatography. Biodistribution studies were carried out in normal Albino Swiss mice at different time intervals after administration of 99m Tc-Losartan. The labeled compound cleared from the systematic circulation within 3 h after administration, and the majority of organs showed significant decrease in the uptake of 99m Tc-Losartan. The heart uptake of 99m Tc-Losartan was sufficiently high for using this agent as myocardial imaging agent.