EP0804925A1 — Liposome with increased retention volume

USPTO Abstract

The present invention provides liposome preparations capable of efficiently holding water soluble substance particularly non-electrolytic water soluble substances. Liposomes and suspensions thereof comprising multilamellar liposomes characterized in that the liposome membrane is formed from a neutral phospholipid comprising a substantially saturated fatty acid residue a charged phospholipid comprising a substantially saturated fatty acid residue, ratio of said neutral phospholipid and charged phospholipid is 200:1 to 3:1, weighted average particle size of the liposome is 50 nm to 3,000 nm, and an encapsulation capacity of the liposome (internal aqueous phase (volume)/lipids (weight)) is at least 5 mℓ/g. The present liposome preparation can encapsulate an aqueous solution of a non-electrolytic water soluble substances with an encapsulation capacity (internal aqueous phase/lipids) of at least 5 mℓ/g.