Freeze-dried polymer dispersions and the use thereof in preparing sustained-release pharmaceutical compositions
AssigneeFMC Corporation
InventorsDev K. Mehra, Chimanlal I. Patel, Clayton I. Bridges, Jr.
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Abstract
Freeze-dried polymer latices, which can be reconstituted in water to give aqueous polymer dispersions having high polymer solids content, are described. The reconstituted polymer dispersions are useful in preparing sustained-release drug formulations, particularly of water-soluble drugs, by the wet granulation method without over wetting.
Claims8
A method of preparing an aqueous polymer dispersion in which the polymer concentration is from about 30% to about 70% comprising the steps of:
- (1) forming an aqueous polymer pseudolatex by dissolving a polymer in a water-immiscible solvent;
- emulsifying the polymer solvent solution in water at a polymer content of about 30% and removing the solvent;
- (2) freeze drying the pseudolatex from step 1;
- and
- (3) redispersing the freeze-dried pseudolatex in water to the desired polymer content up to about 70%.
In the method of preparing a pseudolatex by forming a solution of a polymer in a water-immiscible solvent, forming an emulsion of the solvent solution in water and removing the solvent from the emulsion, the improvement of avoiding high viscosity and/or emulsion instability when carrying out the emulsification at high polymer levels, comprising the steps of:
- (1) forming a first pseudolatex at a polymer concentration up to about 30%;
- (2) subjecting the first pseudolatex to freeze drying;
- (3) recovering the solid freeze-dried pseudolatex from step 2(b), and
- (4) redispersing the solid freeze-dried pseudolatex from 3. in water to give a pseudolatex containing polymer levels up to about 70%.
Dependencies are inferred from the claim text.