Crystalline alpha - the form of 2 - angular clamp on 4 - (2 - furoyl) - piperazine - 1 - yl bracket to - 4 - amino - 6,7 - dimethoxy quinazoline - hydrochloride and crystalline hydrates of 2 - angular clamp on 4 - (furoyl) - piperazine - 1 - yl bracket to - 4 - amino - 6,7 - dimethoxy quinazoline - hydrochloride, a method for the preparation of these crystalline compounds and agents lowering blood pressure, which contain the crystalline hydrates

摘要

The invention relates to novel and valuable crystalline forms of the hypotensive agent prazosin hydrochloride. The anhydrous alpha -form is preferred because it is relatively non-hygroscopic and hence possesses important advantages in handling and formulation. The polyhydrate form of prazosin hydrochloride is preferred because of its low, uniform rate of dissolution.