Processing method for drug substance particles of non-uniform particle size

A pre-processing method in the manufacture of a pharmaceutical preparation, comprising:

• adding a dispersant and optionally other additive to a drug substance which contains particles each having a particle size of 500 μm or more in an amount of 1% by volume or more and particles each having a particle size of 50 μm or less in an amount of 10% by volume or more relative to 100% by volume of the drug substance;
• and then carrying out deagglomeration/sizing of the mixture to disperse and make adhere at least the dispersant and the other additive in/onto the surfaces of particles of the drug substance, thereby manufacturing a powder that contains particles each having a particle size of 200 μm or more in an amount of 50% by volume or less and particles each having a particle size of 50 μm or less in an amount of 70% by volume or less relative to 100% by volume of the powder, wherein the particle size distribution of the drug substance and the powder is measured by a laser-diffraction method.