US4743693A
Expired / Lapsed
US
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Process for the preparation of a stable modification of torasemide
Assignee: Roche Diagnostics GmbH
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Filing: 1986-08-11
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Granted: 1988-05-10
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Expires: 2006-08-11
Abstract
Abstract The present invention provides a process for the preparation of crystalline torasemide in the pure modification I (monoclinic, space group P21/c, melting point 162 DEG C.) from torasemide of modification II (monoclinic, space group P2/n, melting point 169 DEG C.), wherein a suspension of torasemide of modification II is stirred in water with the addition of a catalytic amount of modification I until the rearrangement is complete. The present invention also provides a pharmaceutical compositions containing torasemide of modification I.
Inventors
- 👤 Fritz Topfmeier
- 👤 Gustav Lettenbauer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 18:41
CPC Classifications
C; C07; C07D; C07D213/00; C07D213/02; C07D213/04; C07D213/60; C07D213/72; C07D213/74; A; A61; A61P; A61P7/00; A61P7/10
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
67 words
A process for the preparation of torasemide in the pure modification I (monoclinic, space group P2 1 /c, metling point 162° C.) from torasemide of modification II (monoclinic, space group P2/n, melting point 169° C.), comprising stirring a suspension of torasemide of modification II in water with at least a catalytic amount of modification I, to rearrange the torasemide in modification II into torasemide of modification I.
Claim 2
Dependent Claim
67 words
A process for the preparation of torasemide in the pure modification I (monoclinic, space group P2 1 /c, metling point 162° C.) from torasemide of modification II (monoclinic, space group P2/n, melting point 169° C.), comprising stirring a suspension of torasemide of modification II in water with at least a catalytic amount of modification I, to rearrange the torasemide in modification II into torasemide of modification I.
Claim 3
Dependent Claim
37 words
The process of claim 1, wherein the rearrangement is carried out at a temperature of from ambient temperature to 90° C. and the rearrangement is carried out for a time of from 3 hours to 14 days.
Claim 4
Dependent Claim
31 words
The process of claim 2, wherein the torasemide of modification II is used in the form of a salt-containing, approximately neutral solution, obtained by the precipitation of torasemide from alkaline solution.
Claim 5
Dependent Claim
18 words
The process of claim 2, wherein crystalline torasemide of modification I is recovered from the rearrangement reaction mixture.
Claim 6
Dependent Claim
18 words
The process of claim 1, wherein crystalline torasemide of modification I is recovered from the rearrangement reaction mixture.
Claim 7
Dependent Claim
31 words
The process of claim 1, wherein the torasemide of modification II is used in the form of a salt-containing, approximately neutral solution, obtained by the precipitation of torasemide from alkaline solution.
References Cited (Backward Citations)
DE2516025A1
Cited
US4018929A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-05-10 | 1991-11-09 | 1992-05-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-05-10 | 1995-11-09 | 1996-05-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-05-10 | 1999-11-09 | 2000-05-10 | $7700.00 | Window Closed / Lapsed |