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|Title:||Polymorphs of telmisartan|
|Abstract:||The invention relates to polymorphs of 4'-[2-n-propyl-4-methyl-6-(l-methylbenzimid azol-2-yl)benzimidazol-1-ylmethyl]biphenyl-2-carboxylic acid (INN: telmisartan), particularly polymorphic form B, mixtures of the polymorphs, processes for preparing telmisartan containing form B and the use thereof for preparing a pharmaceutical composition.|
|Inventor(s):||Schneider; Heinrich (late of Ingelheim, DE)|
|Assignee:||Boehringer Ingelheim Pharma KG (Ingelheim, DE)|
|Filing Date:||Nov 16, 2001|
|Claims:||1. A process for preparing telmisartan (the compound of formula I) ##STR3## |
comprising a mixture of two polymorphic crystalline forms, wherein the first polymorphic crystalline form, designated form A, has an endothermic maximum at 269.+-.2.degree. C. which occurs during thermal analysis using DSC, and wherein the second polymorphic crystalline form, designated form B, has endothermic maxima at 183.+-.2.degree. C. and at 269.+-.2.degree. C. which occur during thermal analysis using DSC, which process comprises the following steps:
(a) dissolving telmisartan comprising form A but substantially no form B in a mixture of solvents consisting of water, formic acid and an organic solvent that is miscible therewith,
(b) heating the solution created in the preceding step,
(c) distilling the solution to remove the organic solvent,
(d) precipitating the telmisartan comprising forms A and B out of the remaining solution by the addition of a base, and
(e) removing the precipitated telmisartan comprising forms A and B from the solution.
2. The process of claim 1 wherein the ratio of form A to form B in the mixture produced by the process is in the range from 10:90 to 60:40.
3. The process according to claim 1 or 2, wherein an organic carboxylic acid ester, a ketone or an ether is used as the organic solvent.
4. The process according to claim 1 or 2, wherein acetone, methylethylketone, methyl acetate, ethyl acetate, ethyl formate, ethyleneglycol dimethylether or tetrahydrofuran is used as the organic solvent.
5. The process according to claim 1 or 2, wherein acetone, methylethylketone, methyl acetate, ethyl acetate or tetrahydrofuran is used as the organic solvent.
6. The process according to claim 1 or 2, wherein ethyl acetate is used as the organic solvent.
7. The process according to claim 1 or 2, wherein ammonia is used as the base.