A proof of concept prototype has been constructed to test the capabilities of using vibration frequencies determined from rotating drum powder flow characterization to reproducibly fill small unit doses of pharmaceutical powders. A lactose excipient was characterized in the rotating drum and a multiperiodic vibration signal determined. Doses ranging from 1.5 to 16 mg were metered from the system. The prototype used vibrational fluidization to meter powders under the influence of gravity. Vibration frequencies calculated from physical characterization of the powders had a significant influence on the reproducibility of metering with relative standard deviations around the mean as low as 2% and no greater than 5%. Future work will address limitations to the system that introduced systematic errors and will address additional formulation variables. (c) 2007 Elsevier B.V. All rights reserved.