Multiwall polymeric microspheres

Details Multiwall polymeric microspheres Multiwall polymeric microspheres

1992-07-01

1999-06-15

Lovering, Richard D.

Drug, bio-affecting and body treating compositions

Preparations characterized by special physical form

Particulate form

424486, 424497, 42721331, 42721336, 42840222, 42840224, 514963, 514965, A61K 0952, B01J 1312

Patent

active

059120177

ABSTRACT:
A method for preparation of multi-layer polymeric microspheres formed from any degradable or non-degradable polymers which are not soluble in each other at a particular concentration, but which have a positive spreading coefficient in solution. The multi-layer microspheres 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 incorporated 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, solvent is removed by spray drying. In still another embodiment, polymers are melted and combined with the substance to be incorporated, then cooled to form layered microspheres.

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