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US 5,711,933 AGranted
Method of making polymeric gas or air filled microballoons for ultrasonic echography
AssigneeBracco International B.V.
InventorsDaniel Bichon, Philippe Bussat, Michel Schneider
Life of this patent
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Abstract
Method of making gas or air filled microballoons having a mean size in the range of 0.5 to 1000 microns bounded by a 50 to 500 nm thick biodegradable, interfacially deposited, synthetic polymer membrane which is deformable and resilient for use in ultrasonic contrast compositions are described.
Claims16
A method of making air or gas filled microballoons suitable for administration to human or animal patients for ultrasonic echography, said method comprising the successive steps of:
- (a) emulsifying a hydrophobic organic phase into a water phase so as to obtain droplets of said hydrophobic phase as an oil-in-water emulsion in said water phase;
- (b) adding to said emulsion a solution of at least one polymer in a volatile solvent insoluble in the water phase, so that said polymer forms a layer around said droplets;
- (c) evaporating said volatile solvent so that the polymer deposits by interfacial precipitation around the droplets which then form beads with a core of said hydrophobic phase encapsulated by a membrane of said polymer, said beads being in suspension in said water phase;
- and
- (d) removing said encapsulated hydrophobic phase by evaporation by subjecting said suspension to reduced pressure;
- wherein said hydrophobic phase is selected so that in step (d) it evaporates substantially simultaneously with said water phase and is replaced by air or gas, whereby dry, free flowing, readily dispersible microballoons having an elastic polymeric membrane 50 to 500 nm thick and having a mean size in the range of 0.5 to 1000 microns are produced.
3 more elements
A method of making air or gas filled microballoons for ultrasonic echography by:
- (a) dissolving an interfacial wall forming polymer in a hydrophobic organic phase;
- (b) emulsifying said polymer containing hydrophobic organic phase into a water phase so as to obtain droplets of said hydrophobic base as an oil-in-water emulsion in the water phase;
- (e) removing said hydrophobic phase by evaporation under reduced pressure;
- (d) forming the interfacial wall polymer membrane around the droplets by said evaporation, said hydrophobic phase being selected such that it evaporates substantially simultaneously with said water phase and is replaced by air or gas;
- and
- (e) producing dry, free-flowing, readily dispersible, resilient air or gas-filled microballoons having an elastic 50-500 nm thick polymeric membrane and a mean size in the range from 0.5 to 1,000 microns.
3 more elements
Dependencies are inferred from the claim text.