Very low temperature casting of controlled release microspheres
First Claim
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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Accused Products
Abstract
A process for preparing microspheres using very cold temperatures to freeze polymer-biologically active agent mixtures into polymeric microspheres with very high retention of biological activity and material. Polymer is dissolved in a solvent together with an active agent that can be either dissolved in the solvent or dispersed in the solvent in the form of microparticles. The polymer/active agent mixture is atomized into a vessel containing a liquid non-solvent, alone or frozen and overlayed with a liquified gas, at a temperature below the freezing point of the polymer/active agent solution. The cold liquified gas or liquid immediately freezes the polymer droplets. As the droplets and non-solvent for the polymer is warmed, the solvent in the droplets thaws and is extracted into the non-solvent, resulting in hardened microspheres.
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Citations
18 Claims
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1. A method for preparing polymeric microspheres comprising
a) 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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A porous polymeric microsphere having a diameter between 5 and 1000 microns, spherical in shape, not containing water in the polymer, formed by
a) 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 polymeric droplets; and c) extracting the solvent from the polymeric droplets into a liquid non-solvent to form spherical polymeric microspheres. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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Specification