| abstract |
The instant invention provides microspheres and related processes and pharmaceutical compositions useful in the controlled delivery of a wide variety of active ingredients. In one embodiment, the microspheres comprise an active ingredient dispersed within a polymeric composition comprising a first pH insensitive hydrophobic polymer and second pH sensitive hydrophobic polymer, wherein the microspheres, in an aqueous environment having a pH of around 5 or greater, release the active ingredient in a substantially zero-order profile. In another embodiment, the microspheres comprise an active ingredient dispersed within a polymeric composition comprising a first pH insensitive hydrophobic polymer and second water-swellable polymer, wherein the microspheres, in an aqueous environment, release the active ingredient in a substantially zero-order profile. In both of these embodiments, the microspheres are prepared by a non-aqueous emulsion solvent evaporation method. |