Method of producing polymorphous form I and form II of 17β-(N-t-butyl-carbamoil)-4-aza-5α-androst-1-ene-3-one in a basically pure form.

摘要

1. Method of producing polymorphous form I and form II of 17β-(N-t-butyl-carbamoil)-4-aza-5α-androst-1-ene-3-one with formula 2 IMAGE> in a basically pure form. Characterized in that: The method consists of the following stages: (1) crystallisation of a finasteride mixture in: a) a mixture of ethyl acetate and water, where the content of water in the mixture of solvents does not exceed about 3.5 mg/ml, or in a) a mixture of isopropyl acetate and water, where the content of water in the mixture of solvents does not exceed about 1.6 mg/ml, or at the temperature of about 25 degrees C (2) retrieval of the obtained solid substance; and (3) removal of the solvent from the substance.