Crystalline form of telmisartan sodium

The invention relates to a crystalline sodium salt of 4'-[2-n-propyl-4-methyl-6-(1-methylbenzimidazol-2-yl)benzimidazol-1-ylmeth yl]biphenyl-2-carboxylic acid (INN: telmisartan), processes for preparing it and the use thereof for preparing a pharmaceutical composition.

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What is claimed is:

1. The crystalline form of telmisartan sodium which has a melting point of T=245.+-.5.degree. C.

2. The crystalline form of telmisartan sodium according to claim 1, which, when subjected to analysis by X-ray powder diffraction, exhibits a characteristic set of d-spacings that includes values at d=20.95 .ANG., 17.72 .ANG., 13.97 .ANG. and13.63 .ANG..

3. A solvate or hydrate of the crystalline form of telmisartan sodium according to claim 2.

4. A hydrate of the crystalline telmisartan-sodium salt according to claim 2.

5. A process for preparing crystalline telmisartan sodium, comprising the following steps: (a) dissolving the free acid of telmisartan in a suitable solvent, to produce a solution of telmisartan; (b) combining the solution of telmisartan with asuitable sodium salt, using at least 1 mol of sodium salt per mol of telmisartan; (c) heating the mixture produced in the preceding step for a period of from 15 minutes to 2 hours, to produce a solution of telmisartan sodium; (d) filtering the solutiontelmisartan sodium obtained in the preceding step; (e) adding the filtered solution of telmisartan sodium produced in the preceding step to an organic solvent that is heated to above 40.degree. C.; (f) cooling the solution of telmisartan sodiumproduced in the preceding step until the telmisartan sodium crystallizes, leaving crytalline telmisartan sodium and supernatant; and (g) separating the crystalline telmisartan sodium obtained in the previous step from the supernatant.

6. A process for preparing crystalline telmisartan sodium, wherein an acid addition salt of formula 2 ##STR5##

wherein H--X denotes an acid selected from the group consisting of hydrochloric acid, hydrobromic acid, toluenesulphonic acid and methanesulphonic acid, is taken up in a suitable solvent and reacted with a suitable sodium salt, using at least 2mol of sodium salt per mol of the compound 2 used.

7. Crystalline telmisartan sodium obtained by the process of claim 5 or 6.

8. A pharmaceutical composition comprising crystalline telmisartan sodium in accordance with claim 1, 2, 3, 4 or 7, and a pharmaceutically acceptable carrier.

9. A pharmaceutical composition comprising crystalline telmisartan sodium in accordance with claim 7, and a pharmaceutically acceptable carrier.