Method for making liposomes of enhanced entrapping capacity toward foreign substances to be encapsulated
AssigneeBracco International B.V.
InventorsMichel Schneider, Herve Tournier, Roland Hyacinthe, Christian Guillot, Bernard Lamy
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Abstract
Liposome vesicles are prepared containing water or very dilute solutions encapsulated therein. These "empty" liposomes are suspended in a carrier liquid containing, dispersed therein, substances of interest to be loaded into the vesicles and incubated for a period of time at temperatures above the lipids transition temperature, whereby loading by transmembrane permeation occurs in high yields.
Claims13
A method for loading liposome vesicles with a substance to be encapsulated, said liposome vesicles having a core filled with an aqueous liquid phase surrounded by one or more membranes of film-forming components, said method comprising the steps of:
- a) contacting one part by weight of a comminuted mixture of liposme forming lipids, said mixture comprising a component which is ionically charged, with 20 to 1000 parts by weight of an aqueous liquid carrier phase to produce a hydrated and lamellarized form of said lipid, said aqueous liquid carrier phase being maintained at a temperature above the transition temperature T.sub.c of said hydrated form of said lipid;
- b) forming liposome vesicles as a suspension in the aqueous liquid carrier phase in the absence of said substance to be encapsulated, the aqueous liquid phase present in said core having an osmolality of not above 200 mOsm/kg;
- c) introducing said substance to be encapsulated into said aqueous liquid carrier phase;
- and
- d) incubating said vesicles at a temperature above the membrane lipid transition temperature T.sub.c, whereby said substance to be encapsulated penetrates into said vesicles by trans-membrane permeation.
Dependencies are inferred from the claim text.