Preparation and Evaluation of Lyophilized Iopromide-Carrying Liposomes for Liver Tumor Detection

The objective of the present investigation was to demonstrate a new method for the production of iopromide-carrying liposomes. We studied biodistribution and elimination behavior, as well as the computed tomography (CT) liver imaging properties. Iopromide-containing liposomes were prepared by the ethanol evaporation method and subsequently lyophilized. The resuspended liposomes were tested in rats and rabbits. After resuspension, liposomes with a mean diameter of 467 +/- 66 nm and an encapsulation rate of 41.5 +/- 5.5% were obtained. In rats, a marked accumulation of liposomal iopromide was found in the liver and spleen. In rabbits, complete renal elimination of iopromide within 7 days was demonstrated. At a dose of 150 mg total iodine/kg, a small tumor (< 0.5 cm) could be detected in a VX-2-bearing rabbit. The ethanol evaporation method proved to be suitable for the reproducible large-scale manufacture of iopromide liposomes with high encapsulation. The resuspended liposomes displayed favorable biodistribution, elimination and imaging characteristics.