A multi-stage process to control the particle size of a pharmaceutical substance comprisingthe steps of: passing the pharmaceutical substance through a first stage of aparticle size reduction process with a first set of particle size control parametersto obtain a feedstock of reduced median particle size and lesser distribution ofmedian particle size for a second stage of a particle size reduction process passingthe feedstock, through a second stage of a particle size reduction process witha second set of particle size control parameters optionally, using the productof the second stage or subsequent stages as a feedstock in further stages of a multi-stageparticle size reduction process with a set of particle size control parametersfor each stage and collecting a pharmaceutical substance with a median particlesize greater than 10µm and with a narrow, reproducible distribution ofmedian particle sizes.
