This present invention provides a spray dryer for use in prepg. particles for inhalation, the spray dryer comprising a multi-​nozzle app. comprising multiple single nozzles suitable for use in prepg. inhalation powders and with a drying gas flow rate greater than about 80 kg​/h.  Also provided is a method for scaling-​up a spray drying process for prepg. particles for inhalation from a smaller scale spray dryer to a larger scale spray dryer, relative in size to each other, the method comprising the use in the larger scale spray dryer of a multi-​nozzle app. comprising single nozzles suitable for use in prepg. inhalation powders, wherein the no. of nozzles in the larger spray dryer is detd. by the ratio of the drying gas flow rate of the larger scale spray dryer to the drying gas flow rate of the smaller scale spray dryer.  Also provided is a multi-​nozzle app. produced from the method of the present invention, the multi-​nozzle app. comprising multiple single nozzles suitable for use in prepg. inhalation powders.  Also provided is the use of multiple single nozzles suitable for use in prepg. inhalation powders in a spray dryer with a drying gas flow rate greater than about 80 kg​/h.  The nozzles used in the present invention preferably prep. particles with a mean particle size less than about 5 μ.  Thus, powder was produced from a feed mixt. prepd. by dissolving 1.2 g of lysine and 4.8 g of trehalose in 234 g of water, by drying from single nozzle or duo of nozzles; the particle size distribution and morphol. is identical when comparing the powders obtained via the single nozzle and the duo of nozzles, demonstrating the success of the current proof-​of-​concept and in this way, the feasibility of a multi-​nozzle concept.