Abstract: The present invention relates to a simple, robust and effective process for preparing a dry powder inhalation formulation containing at least one drug, preferably a highly active drug, more preferably Tiotropium bromide or Tiotropium bromide monohydrate, and a lactose carrier. The process is characterized in that a three-layered composition containing a drug layer in between layers of the lactose carrier is mixed and the obtained preblend is mixed with additional lactose carrier. The process combines a simple manufacturing procedure with an excellent content uniformity obtained over a wide range of mixing parameters.