A process for forming lactose suitable for use in a pharmaceutical formulation comprises providing a plurality of lactose particles containing no more than 10% w/w of lactose particles having a volume average particle size of about 70 microns or less; milling the plurality of lactose particles to yield a plurality of milled lactose particles with an average particle size, (D50), ranging from about 50 microns to about 100 microns; and classifying the plurality of milled lactose particles into at least two fractions comprising a fine fraction and a coarse fraction wherein the fine fraction has an average particle size, (D50), ranging from about 3 microns to about 50 microns, and the coarse fraction has an average particle size, (D50), ranging from about 40 microns to about 250 microns.