US4218255A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Porous ceramic carriers for controlled release of proteins, polypeptide hormones, and other substances within human and/or other mamillian species and method
Assignee: University of Dayton
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Filing: 1978-09-12
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Granted: 1980-08-19
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Expires: 1998-09-12
Abstract
Abstract The product and process of making an in-vivo body implant pharmaceutical carrier of a resorbable ceramic crystalline structure of interconnecting pores capable of the critical controlled time release of pharmaceutical preparations such as proteins, polypeptides, hormones, and other small molecular weight active materials. The ceramic is comprised of aluminum oxide (Al 2 O 3 ), calcium oxide (CaO), and phosphorous pentoxide (P 2 O 5 ) in a controlled weight percent mixture. In the process of making, the mixture is calcined. The calcined mixture is again ground and sieved through screens of two different mesh sizes to obtain desired sizes and mixed with a binder. This mixture is compressed and sintered at a predetermined temperature. The particle sizes of the sieved calcined compound and the sintering temperatures are interrelated to provide a ceramic of a desired pore size for the controlled release of the pharmaceutical.
Inventors
- 👤 Praphulla K. Bajpai
- 👤 George A. Graves
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 15:04
CPC Classifications
A; A61; A61M; A61M31/00; A61M31/002; A61K; A61K9/00; A61K9/20; A61K9/2004; A61K9/2009; A61L; A61L27/00; A61L27/02; A61L27/12; A61L27/50; A61L27/54; A61F; A61F2310/00; A61F2310/00005; A61F2310/00179; A61F2310/00293; A61L2300/00; A61L2300/20; A61L2300/252; A61L2300/40; A61L2300/43; A61L2300/60; A61L2300/602
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
149 words
The process of forming an in-vivo implant which is a porous, resorbable ceramic material having interconnected pores and suitable for the prolonged release of a pharmaceutical comprising: powdering and mixing together oxides comprising by weight about 38% CaO, 50% Al 2 O 3 and 12% P 2 O 5 , and with impurities less than 1%, and compressing said mixture, calcining said mixture at approximately 2400° F. for 12 hours to yield a crystallographic structured ceramic of at least two phases, powdering said calcined mixture and sieving the same through screens of two different mesh sizes to obtain particles ranging from a size that passes through 200 mesh (-200) and is retained on 400 mesh (+400), mixing with a binder and thereafter compressing said powdered mixture at a pressure of about 20,000 psi, and then, sintering said mixture for a time and temperature related to the average particle size.
Claim 2
Dependent Claim
149 words
The process of forming an in-vivo implant which is a porous, resorbable ceramic material having interconnected pores and suitable for the prolonged release of a pharmaceutical comprising: powdering and mixing together oxides comprising by weight about 38% CaO, 50% Al 2 O 3 and 12% P 2 O 5 , and with impurities less than 1%, and compressing said mixture, calcining said mixture at approximately 2400° F. for 12 hours to yield a crystallographic structured ceramic of at least two phases, powdering said calcined mixture and sieving the same through screens of two different mesh sizes to obtain particles ranging from a size that passes through 200 mesh (-200) and is retained on 400 mesh (+400), mixing with a binder and thereafter compressing said powdered mixture at a pressure of about 20,000 psi, and then, sintering said mixture for a time and temperature related to the average particle size.
Claim 3
Dependent Claim
24 words
The process of claim 1 wherein the oxides include minor additions of MgO, ZnO, SiO 2 , ZrO 2 , and TiO 2 .
Claim 4
Dependent Claim
33 words
The process of claim 1 wherein said sieving was with 250 and 300 mesh screens and said sintering temperature was 2400° F., to yield a crystallographic structured ceramic having a given pore size.
Claim 5
Dependent Claim
33 words
The process of claim 1 wherein said sieving was with 200 and 250 mesh screens and said sintering temperature was 2600° F., to yield a crystallographic structured ceramic having a given pore size.
Claim 6
Dependent Claim
33 words
The process of claim 1 wherein said sieving was with 325 and 400 mesh screens and said sintering temperature was 2300° F., to yield a crystallographic structured ceramic having a given pore size.
Claim 7
Dependent Claim
8 words
The product of the process of claim 3.
Claim 8
Dependent Claim
8 words
The product of the process of claim 4.
Claim 9
Dependent Claim
8 words
The product of the process of claim 5.
References Cited (Backward Citations)
US2021520A
Cited
US3288615A
Cited
DE2163036A1
Cited
DE2331097A1
Cited
US4135935A
Cited
US3919723A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-08-19 | 1984-02-18 | 1984-08-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-08-19 | 1988-02-18 | 1988-08-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-08-19 | 1992-02-18 | 1992-08-19 | $7700.00 | Window Closed / Lapsed |