Patent ID: 7795435

Claim:
A process for obtaining a pure polymorphic form of finasteride Form I, comprising the following steps: a) dissolving finasteride in a substantially anhydrous organic solvent selected from the group consisting of n-butyl acetate, iso-butyl acetate, sec-butyl acetate, tert-butyl acetate, and C 5 alkyl acetate, at a temperature equal to or about the boiling point of said organic solvent to obtain a finasteride solution; b) cooling the finasteride solution obtained in step a): i. to a cooling temperature of about 25° C. to about 45° C., with a cooling rate of about 0.25° C./min to about 0.45° C./min, when said organic solvent is n-butyl acetate, iso-butyl acetate, sec-butyl acetate or tert-butyl acetate; or ii. to a cooling temperature of about 0° C., with a cooling rate of about 0.25° C./min to about 0.7° C./min, when said organic solvent is C 5 alkyl acetate; to obtain a suspension, and c. maintaining the suspension resulting from step b) at the cooling temperature for a period of time equal to or less than 16 hours, optionally with stirring, to result in a solid phase containing the pure polymorphic form of finasteride Form I; and d. recovering the resulting solid phase containing the pure polymorphic form of finasteride Form I and removing the solvent.