The invention relates to the field of
medicine, and discloses a refining method of
crystal type A
azilsartan. The method comprises the following steps: S1, mixing
ethyl acetate and absolute ethyl
alcohol, heating, and then adding an
azilsartan crude product, stirring to be completely dissolved, carrying out filter-pressing; S2, stirring the filtrate in the S1 at 20-25 DEG C to crystallize, filtering, granulating the filter residue through a 24-mesh
sieve;
drying the raw materials by use of a boiling
drying and gradient warming way;
drying for 50-70min at an ambient temperature condition, and then drying for 50-70min after warming 40+ / -2 DEG C, wherein the
granularity control D (90) is 300-400 microns; drying for 2-3h after warming to 50+ / -2 DEG C, and the
granularity control D (90) is 100-200 microns, cooling to obtain an
azilsartan finished product. By use of the refining method disclosed by the invention, the dosage of a required
organic solvent in refining is greatly reduced; and meanwhile, the stable
crystal type A azilsartan is obtained since the raw materials are dried by use of the boiling drying and gradient warming way, the refining yield of 90% or above is acquired, the purity is 99.7% or above, the
solvent residue (ethyl
alcohol) is less than 0.3%, and the
drying time is shortened to 3-6h.