Alcon Laboratories, Inc.

Garnet G Smith

Val J Krukonis

Alok K Kulshreshtha

Scott D Anderson

A process employing a supercritical fluid anti-solvent for sizing prednisolone acetate is disclosed. The process optionally incorporates sterilization filters. Average particle sizes of about 1 .mu.m or less (number average) and narrow particle size ranges are obtainable. The process comprises the steps of (a) forming a solution by dissolving prednisolone acetate in acetone such that the concentration of prednisolone acetate is approximately 80% or less of its solubility in acetone; and (b) transporting the solution formed in step (a) through an orifice having a diameter of 50-100 .mu.m into a mixer/expander containing compressed CO.sub.2, wherein the compressed CO.sub.2 is at a temperature from about 40.degree. to 80.degree. C. and has a density less than the density of the solution by at least 0.3 g/cc, to expand the solution so that the acetone dissolves in the CO.sub.2 and the prednisolone acetate precipitates.

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Colleyville, TX, United States of America

Garnet G Smith