| abstract |
The present invention provides a method for chemically modifying non-ionic, water soluble particulate contrast agents so that they degrade in vivo to their non-ionic parent contrast material and carbon dioxide. According to the present invention, known particulate, non-ionic contrast agents are chemically modified to form a precursor or "prodrug" comprising cyclic carbonates and carbamates of the parent compound. The resulting cyclic carbonates and carbamates are lipid soluble, biodegradable, and can be prepared in large quantities using well-established methods. These cyclic carbonates and carbamates can be converted to particulate contrast media using simple, well known techniques, such as solvent-extraction or solvent evaporation. |