Atomic layer deposition on pharmaceutical particles for drug delivery applications is demonstrated using assisted fluidized bed dry powder processing. Complete and conformal layering is achieved on particle sizes from the lower micron to upper nanometer range under near ambient conditions. As few as 2-14 atomic alumina layers alter particle properties: dissolution, dispersibility and heat transfer.

The morphology, size and surface properties of pharmaceutical particles form an essential role in the therapeutic performance of active pharmaceutical ingredients (APIs) and excipients as constituents in various drug delivery systems and clinical applications. Recent advances in methods for surface modification, however, rely heavily on liquid-phase based modification processes and afford limited control over the thickness and conformality of the coating. Atomic layer deposition (ALD), on the other hand, enables the formation of conformal nanoscale films on complex structures with thickness control on the molecular level, whilst maintaining the substrate particle size and morphology. Moreover, this enables nanoengineering of surfaces of pharmaceutical particles also in the dry state. Successful nano-engineeering of crystal and amorphous surfaces of pharmaceutical particles is demonstrated in this study whereby functional properties, such as dissolution and dispersability, were tailored for drug delivery applications. This expands on our initial work on ALD of alumina on pharmaceutical particles within the lower micro-to higher nano-size ranges to here probe both crystalline and amorphous lactose substrate surfaces (d 50 3.5 and 21 um). In addition, both water and ozone coreactants were evaluated; the latter having not been evaluated previously for pharmaceutical particles.