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Intravitreal microsphere drug delivery and method of preparation

  • US 5,718,922 A
  • Filed: 05/31/1995
  • Issued: 02/17/1998
  • Est. Priority Date: 05/31/1995
  • Status: Expired due to Fees
First Claim
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1. A method of preparing microspheres encapsulating a pharmacologically active agent to enable delivery and sustained release of the agent, such method comprising the steps ofselecting a biodegradable polymer and a volatile non-aqueous solvent,adding the pharmacologically active agent suspended in a first oil to said polymer and non-aqueous solvent, and mixing them to produce an aqueous-free dispersion in which the drug is contained primarily in said first oil,selecting a second oil which is immiscible with said first oil and in which said solvent is at least partially soluble,mixing said aqueous-free dispersion in a volume of said second oil and solvent with an emulsifier, and drying the solvent therefrom to produce well-formed microspheres, andremoving said second oil from said microspheres with a second solvent, said second solvent being insoluble in said polymer and said first oil,wherein said pharmacologically active agent, is a hydrophilic agent and said first oil is selected to substantially hinder dissolution in an aqueous environment, so that release of the agent from microspheres occurs as the polymer degrades releasing said first oil to contact said environment at a surface and said agent diffuses from the surface.

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