Process for preparing powder formulations

A process for preparing an inhalable powder, wherein N+m substantially equal portions of an excipient having a larger particle size distribution and N equal portions of an active substance having a smaller particle size distribution are added in alternate layers into a suitable mixing vessel and after all the excipient and active substance have been added the 2N+m layers of the two components are mixed together using a suitable mixer, wherein a portion of the excipient having the larger particle size is added first, and wherein N is an integer >5 and m denotes 0 or 1.