EP1438974A2 — pH-sensitive liposomes based on diacyl-glycero-phosphoethanolamine and diacyl-succinyl-glycerol

USPTO Abstract

The invention relates to pH-sensitive liposome systems, compositions comprising said pH sensitive liposome systems and the use of such compositions as contrast agents and medicaments. Surprisingly, we have found a pH sensitive liposome system comprising (a) 1-acyl-2-acyl-glycero-3-phosphoethanolamine and (b) 1-acyl-2-acylsuccinylglycerol or 1-acyl-3-acylsuccinylglycerol wherein in (a), both acyl-residues are the same or different and are saturated acyl residues that contain at least 14 C atoms or, one acyl residue is a saturated acyl residue that contains at least 14 C atoms and the other acyl residue is a monounsaturated acyl residue that contain at least 14 C atoms and, wherein in (b), both acyl-residues are the same or different and are saturated acyl residues that contain at least 14 C atoms or, one acyl residue is a saturated acyl residue that contains at least 14 C atoms and the other acyl residue is a monounsaturated acyl residue that contain at least 14 C atoms, that could be used for the preparation of pH sensitive MR contrast agents that are suitable for in vivo applications.