Multiwall polymeric microspheres
US5912017A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 1, 1992 |
| Grant date | Jun 15, 1999 |
| Priority date | — |
| Expiry date | Jul 1, 2012 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/2989
- WIPO fieldPharmaceuticals
- WIPO sectorChemistry
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.