A process for particle processing of active pharmaceutical ingredients

A process for reducing the particle size of an active pharmaceutical ingredient (API) while maintaining its polymorphic form, comprises the step of processing the active pharmaceutical ingredient by cavitation at elevated pressure. The process preferably comprises the step of isolating the processed active ingredient in the form of powder, wherein the isolation step comprises filtration or spray drying. Particles produced by the process of the invention typically have a span value of less than 2.5.