| abstract |
A process is provided for preparing a composition in the form of a plurality of particles having an average diameter by weight, number or volume between 10 nm and about 700 μm, the particles comprising: (a) a solid core, preferably comprising a biologically active agent; solid core; and (b) two or more sequentially applied distinct layers, each comprising at least one separate coating material, wherein the two or more layers together surround and/or enclose and/or encapsulate the core. sequentially applied discrete layers, the process comprising: (1) applying an initial layer of at least one coating material to the solid core by a gas phase deposition technique; (2) discharging the coated particles from the gas phase deposition reactor and agitating the coated particles to deagglomerate the particle agglomerates formed during step (1) by a mechanical sieving technique; (3) reintroducing the deagglomerated coated particles of step (2) into the gas phase deposition reactor and applying an additional layer of at least one coating material to the reintroduced particles; and (1) optionally repeating steps (2) and (3) one or more times to increase the total thickness of the at least one coating material surrounding the solid core. The vapor deposition technique is preferably atomic layer deposition. When the core comprises a biologically active agent, the composition may provide for a delayed or sustained release of the active agent without an explosive effect. |