Preparation of multiwall polymeric microcapsules
Patent 4861627 Issued on August 29, 1989. Estimated Expiration Date: 
May 1, 2007. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
May 1, 2007. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent References 3523906 3640892 3691090 3830750 3859228 Process for encapsulation of medicaments Encapsulation process Microencapsulation process Process of preparing microcapsules of lactides or lactide copolymers with glycolides and/or &3xb5;-caprolactones Patent #: 4637905 InventorsApplicationNo. 07/045840 filed on 05/01/1987US Classes:427/213.31, With post-treatment of encapsulant or encapsulating material (e.g., further coating, hardening, etc.)264/4.3, With treatment subsequent to solid wall formation (e.g., coating, hardening, etc.)264/4.32, Microcapsule wall containing two or more layers264/4.6, Solid-walled microcapsule formed by physically removing a constituent (e.g., evaporation, extraction, etc.)424/462, Containing solid synthetic polymers424/497, Containing solid synthetic polymers427/213.36, Solid-walled microcapsule formed from preformed synthetic polymer428/402.22, Addition polymer from unsaturated monomers only428/402.24, Microcapsule with solid core (includes liposome)514/963Microcapsule-sustained or differential releaseExaminersPrimary: Lovering, Richard D.Attorney, Agent or FirmInternational ClassesA61K 9/16 (20060101)A61K 9/50 (20060101) AbstractA single step method for preparation of multi-layer polymeric delivery systems. Any two or three different degradable or non-degradable polymers which are not soluble in each other at a particular concentration, as dictated by their phase diagram, can be used. The multi-layer microcapsules produced by the method are distinguished by extremely uniform dimensioned layers of polymer and actual incorporation of the substance to be delivered into the polymer layers.In the preferred embodiment of the method, two polymers are dissolved in a volatile organic solvent, the substance to be encapsulated is dispersed or dissolved in the polymer solution, the mixture is suspended in an aqueous solution and stirred, and the solvent is slowly evaporated, creating microspheres with an inner core formed by one polymer and an outer layer formed by the second polymer. In another embodiment one polymer may be formed within a layer of the other polymer by increasing the rate of evaporation of the volatile solvent.Other References
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