US4139415A
Expired / Lapsed
US
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In vitro method of determining the biological activity of factor Xa inhibitor in blood
Assignee: Pfizer Health AB
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Filing: 1976-11-23
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Granted: 1979-02-13
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Expires: 1996-11-23
Abstract
Abstract The present invention concerns an in vitro method for the determination of the plasma inhibitor to activated Factor X (XaI), which is an alpha-2-globulin of molecular weight 58,000-65,000, and which has been termed variously as antithrombin III, heparin cofactor and alpha-2-antitrypsin.
Inventors
- 👤 Ee T. Yin
- 👤 Oddvar Tangen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 12:08
CPC Classifications
G; G01; G01N; G01N33/00; G01N33/48; G01N33/50; G01N33/86; G01N2333/00; G01N2333/81; G01N2333/90; G01N2333/914; G01N2333/948; G01N2333/95; G01N2333/964; G01N2333/96425; G01N2333/96427; G01N2333/9643; G01N2333/96433; G01N2333/96441; G01N2333/96444; G01N2400/00; G01N2400/10; G01N2400/38; G01N2400/40
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
142 words
A method for the in vitro determination of the biological activity of Factor Xa inhibitor (XaI) in blood, which includes the steps of (1) incubating a diluted blood plasma sample with constant known concentrations of excess Xa and polysaccharide polysulfate for a predetermined period, said polysaccharide polysulfate exhibiting the following properties (a) ability to overcome the inhibitory action of a human plasma component under neutralization mechanism of Xa by Xa inhibitor, (b) a weak heparin-like activity, and (c) a synergistic effect on the anticoagulant activity of trace amounts of heparin, and (2) after the predetermined incubation period measuring the residual Xa activity (i.e. Xa activity remaining in the incubation mixture that is not neutralized by the plasma XaI), the mechanism of reaction between the XaI and the Xa in the presence of said polysaccharide polysulfate being rate limiting (i.e. incubation time dependent).
Claim 2
Independent Claim
142 words
A method for the in vitro determination of the biological activity of Factor Xa inhibitor (XaI) in blood, which includes the steps of (1) incubating a diluted blood plasma sample with constant known concentrations of excess Xa and polysaccharide polysulfate for a predetermined period, said polysaccharide polysulfate exhibiting the following properties (a) ability to overcome the inhibitory action of a human plasma component under neutralization mechanism of Xa by Xa inhibitor, (b) a weak heparin-like activity, and (c) a synergistic effect on the anticoagulant activity of trace amounts of heparin, and (2) after the predetermined incubation period measuring the residual Xa activity (i.e. Xa activity remaining in the incubation mixture that is not neutralized by the plasma XaI), the mechanism of reaction between the XaI and the Xa in the presence of said polysaccharide polysulfate being rate limiting (i.e. incubation time dependent).
Claim 3
Dependent Claim
23 words
A method as set forth in claim 1 wherein the residual amount of factor Xa activity is determined by measuring the clotting time.
Claim 4
Dependent Claim
26 words
A method as set forth in claim 1 wherein the residual amount of factor Xa activity is determined by measuring its esterase or the amidolytic activity.
Claim 5
Dependent Claim
19 words
A method as set forth in claim 1 wherein the polysaccharide polysulphate has 0.10-3.0 sulphate groups per monosaccharide unit.
Claim 6
Dependent Claim
23 words
A method as set forth in claim 4 wherein the polysaccharide polysulphate is a dextran sulphate having 0.10-3.0 sulphate groups per monosaccharide unit.
Claim 7
Dependent Claim
27 words
A method as set forth in claim 4 wherein the polysaccharide polysulphate is a dermatan sulphate or a heparan sulphate having 0.45-2.0 sulphate groups per monosaccharide unit.
Claim 8
Dependent Claim
18 words
A method as set forth in claim 1 wherein the polysaccharide polysulphate is coupled to a water-insoluble carrier.
References Cited (Backward Citations)
US3884896A
Cited
US3985618A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-02-12 | 1982-08-14 | 1983-02-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-02-12 | 1986-08-14 | 1987-02-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-02-12 | 1990-08-14 | 1991-02-13 | $7700.00 | Window Closed / Lapsed |