PREPARATION, CHARACTERIZATION, AND EVALUATION OF IOXILAN CARBONATE PARTICLES FOR COMPUTED-TOMOGRAPHY CONTRAST ENHANCEMENT OF LIVER

RATIONALE AND OBJECTIVES. TO prepare and characterize a new particulat e contrast medium, cyclic carbonate of ioxilan (IX-C) particles, as a macrophage imaging agent for computed tomography (CT) enhancement of t he liver, METHODS. Cyclic carbonate of ioxilan was synthesized from io xilan, a nonionic water-soluble contrast agent, The IX-C particles pre pared by a solvent extraction-evaporation method were characterized by size distribution, degradability, suspension stability, and median le thal dose, Pharmacokinetics of IX-C particles and their effectiveness in enhancing liver attenuation and in detecting hepatic tumors were ev aluated using normal and VX2-tumor-bearing rabbits, RESULTS. The IX-C particles were biodegradable, with ioxilan and carbon dioxide as the d egradation products, The particles had an average size of 1 to 2 mu m and were stable in saline suspension. The median lethal dose determine d for IX-C particles was 2.6 and 3.1 g/kg body weight for female and m ale rabbits, respectively. A dose of 200 mg iodine/kg body weight caus ed an increase of 38 Hounsfield units in liver attenuation, In rabbits , hepatic clearance of the contrast medium occurred in 2 days, A tumor barely visible in precontrast scans could be detected after contrast injection. CONCLUSIONS. Development of particulate contrast medium fro m nonionic contrast agents represents a new approach, Ioxilan carbonat e particles have suitable physicochemical properties that warrant furt her studies before clinical evaluation.