US4092315A
Expired / Lapsed
US
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Novel crystalline forms of prazosin hydrochloride
Assignee: PFIZER PHARMACEUCIALS Inc
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Filing: 1976-03-01
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Granted: 1978-05-30
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Expires: 1996-03-01
Abstract
Abstract 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.
Inventors
- 👤 Ernest J. Bianco
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 04:22
CPC Classifications
C; C07; C07D; C07D405/00; C07D405/14; A; A61; A61K; A61K31/00; A61K31/33; A61K31/395; A61K31/495; A61K31/505; A61P; A61P9/00; A61P9/02; A61P9/06; A61P9/10; A61P9/12
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
62 words
The crystalline α-form of 2-[4-(2-furoyl)piperazin-1-yl]-4-amino-6,7-dimethoxyquinazoline hydrochloride characterized by the infrared spectrum in potassium bromide having the following absorption bands: ______________________________________
Wavelength, Wavelength, Wavelength,
Microns Microns Microns
______________________________________
2.95 7.30 10.67
3.10 7.81 11.05
3.25 8.08 11.30
3.50 8.28 11.66
6.12 8.40 11.90
6.26 8.70 12.60
6.39 9.02 13.10
6.54 9.25 13.31
6.75 9.60 13.87
6.81 9.85 13.95
7.02 10.02 14.82
7.22
______________________________________
Claim 2
Dependent Claim
62 words
The crystalline α-form of 2-[4-(2-furoyl)piperazin-1-yl]-4-amino-6,7-dimethoxyquinazoline hydrochloride characterized by the infrared spectrum in potassium bromide having the following absorption bands: ______________________________________
Wavelength, Wavelength, Wavelength,
Microns Microns Microns
______________________________________
2.95 7.30 10.67
3.10 7.81 11.05
3.25 8.08 11.30
3.50 8.28 11.66
6.12 8.40 11.90
6.26 8.70 12.60
6.39 9.02 13.10
6.54 9.25 13.31
6.75 9.60 13.87
6.81 9.85 13.95
7.02 10.02 14.82
7.22
______________________________________
Claim 3
Dependent Claim
66 words
The process for preparing the crystalline α-form of 2-[4-(2-furoyl)piperazin-1-yl]-4-amino-6,7-dimethoxyquinazoline hydrochloride of claim 1 which comprises precipitation of said α-form after heating 2-[4-(2-furoyl)piperazin-1-yl]-4-amino-6,7-dimethoxyquinazoline hydrochloride, a hydrate or methanolate thereof, in the presence of an alkanol or cycloalkanol solvent having from about 5 to 7 carbon atoms at a temperature in the range of about 125° to 160° C., until formation of said crystalline α-form is substantially complete.
Claim 4
Dependent Claim
12 words
The process of claim 2 whrein said alcoholic solvent is isoamyl alcohol.
Claim 5
Dependent Claim
18 words
The process of claim 3 wherein said isoamyl alcohol is heated at a temperature of about 132° C.
References Cited (Backward Citations)
US3635979A
Cited
US3663706A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-05-29 | 1981-11-28 | 1982-05-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-05-29 | 1985-11-28 | 1986-05-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-05-29 | 1989-11-28 | 1990-05-30 | $7700.00 | Window Closed / Lapsed |