RADIOLABELED LIPOSOMES AS METABOLIC AND SCANNING TRACERS IN MICE .2. IN-111 OXINE COMPARED WITH TC-99M DTPA, ENTRAPPED IN MULTILAMELLAR LIPID VESICLES

Abstract

The organ distribution of positively and negatively charged multilamellar lipid vesicles (MLV) labeled with 99MTc DTPA [diethylenetriaminepentaacetic acid] or 111In oxine in mice was investigated. The organ distribution of MLV (111In oxine) is fairly constant throughout 72 h, indicating that the radiotracer remains associated with cellular structures at the site of MLV uptake. In animals injected [i.v.] with MLV (99mTc DTPA), there is continuous leakage of radioactivity from the involved organs. This can be explained by the release of the radiotracer following MLV destruction in the organs. MLV (111In oxine) may be used to study MLV uptake by different organs, whereas MLV (99mTc DTPA) may be a good indicator of the destruction rate of lipid vesicles. Various conditions bearing on liposome kinetics merit further study to assess the potentialities of these vectors as diagnostic or therapeutic agents.