EVALUATION OF LIPOSOME-ENTRAPPED RADIOACTIVE-TRACERS AS SCANNING AGENTS .1. ORGAN DISTRIBUTION OF LIPOSOME [TC-99M-DTPA] IN MICE

Abstract

The use of liposomes as a delivery system for radiopharmaceutical localization is described. Liposomes [99mTc-DTPA (technetium-99m-diethylenetriamine pentaacetic acid)] were injected i.v. in mice and showed preferential uptake in the liver and spleen. There was a steady decline of activity in all organs, suggestive of destruction of liposomes with subsequent release of 99mTc-DTPA into the circulation. Alteration of uptake from liver to spleen, lung and bone marrow was achieved by prior loading of the circulation with nonradioactive liposomes. The same effect was produced in dogs and demonstrated with scintigraphy. It was also showed scintigraphically in dogs how 99mTc-DTPA, when administered entrapped in liposomes, follows the pattern of distribution of liposomes. Liposomes seem to be suitable carriers for radiopharmaceuticals. Further studies should show the possibility of directing liposomes to specific targets.