Crystalline micropowder particles

摘要

Crystalline particles of N-(17-cyclopropylmethyl-4,5α-epoxy-3,14-dihydroxy-morphinan-6&bgr;-yl)-phthalimide or a pharmaceutically acceptable salt thereof. Theses crystalline particles have a particle diameter distribution, wherein the particle diameter (D50) at the point attaining a cumulative frequency of 50% in volume distribution counted from the smallest particle diameter ranges from 1 to 30 μm while the particle diameter (D90) at the point attaining a cumulative frequency of 90% in volume distribution counted from the smallest particle diameter is not more than 90 μm, and a degree of crystallization of 80% or more. These crystalline particles make it possible to improve the biological availability of the active ingredient while ensuring the storage stability of the above-described compound.