A New Dosing System to Fill Dry Powder Inhaler Discs

Karlheinz Seyfang, Achim Wolf , Philipp Adermann

Several multi-unit dose dry powder inhalers on the market or in the development phase contain injection-molded annular rings, which carry the single powder doses in closed cavities. These pockets can be round or oblong shaped and may be arranged in symmetric or asymmetric circles or even spirals. Current micro dosing systems such as dosator, vacuum drum or membrane filler, which are suitable for dosing powders for inhalation, possess certain limitations when being used to fill inhaler discs, like insufficient robustness, inadequate output or limited flexibility regarding filling level. Based on the membrane filling technology a new dosing system to fill such discs has been developed. Discs with any number or shape of cavities can be filled in one process cycle, and only two format parts have to be exchanged to adapt the filler to new discs. The system can be integrated into automated machines to fill, assemble and package disc-based DPI and it can be up-scaled by simply increasing the number of filling heads.
The dosing system described in this paper has been tested using different lactose monohydrate powder blends with moderate to very poor flow properties, characterized by Carr’s indices of 14% to 42%. The fill weights achieved using 12mm³ dosing chambers were in the range of 6,3mg to 9,1mg, the relative standard deviation ranged between 1,7% and 4,8%. The compaction of the powder during the dosing step was low which qualifies the disc filler for processing inhalation powders.

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