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Very low temperature casting of controlled release microspheres

  • US 5,019,400 A
  • Filed: 05/01/1989
  • Issued: 05/28/1991
  • Est. Priority Date: 05/01/1989
  • Status: Expired due to Term
First Claim
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1. A method for preparing polymeric microspheres comprisinga) freezing droplets of polymer solution by atomizing the droplets into a liquified gas, having a temperature below the freezing point of the polymer solution effective to immediately freeze the atomized polymer solution upon contact, said liquified gas overlaying a layer of frozen liquid non-solvent for the polymer, wherein the polymer solvent is miscible in the liquid non-solvent;

  • b) thawing the polymer solvent in the frozen droplets of polymer solution; and

    c) extracting the solvent from the droplets into a liquid non-solvent to form spherical polymeric microspheres.

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