Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Implant or insert
Reexamination Certificate
2001-11-29
2003-05-06
Krass, Frederick (Department: 1614)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Implant or insert
C530S380000, C530S381000, C530S382000, C530S402000, C514S002600, C514S008100, C514S012200, C428S473000, C428S478200, C424S428000, C424S426000
Reexamination Certificate
active
06558687
ABSTRACT:
FIELD OF THE INVENTION
This application also claims benefit of Provisional Application No. 60/136/902 filed Jun. 1, 1999.
This invention related to a novel fibrin polymer structure and is more particularly directed to enhanced fibrin sealants and methods for their preparation.
BACKGROUND OF THE INVENTION
One mechanism for hemostasis in a mammal is the formation of a blood clot. Clot formation in humans, for example, occurs by means of a complex cascade of reactions with the final steps being the conversion of fibrinogen (a monomer) in the blood by thrombin, calcium ions and activated factor XIII to ultimately form a crosslinked fibrin II polymer.
A fibrin sealant is a biological material whose effect imitates the final stages of coagulation. The prior art is replete with disclosures of two component fibrin sealant systems which co-administer fibrinogen and thrombin, typically in the presence of calcium ions and factor XIIIa, to form a fibrin clot or sealant at a desired surgical site. In prior art sealants the two sealant-forming components are co-applied or co-sprayed as liquids. The fibrinogen and thrombin interact at the surface or desired sealant site to form the fibrin polymer. Many different methods and devices have been proposed to enhance the uniformity of the mixing and interaction of the fibrinogen and thrombin components in order to enhance the uniformity of the resultant sealant. A device and method are described in WO 98/02098 which provide for a uniform mixing of the fibrinogen and thrombin components at the target surface to provide a uniform, substantially homogenous fibrin polymer sealant.
It is understood in the area of fibrin sealants that there is a “lag” time for polymerization to commence. The thrombin needs to act upon the fibrinogen to catalyze the cleavage of fibrinopeptide A and eventually fibrinopeptide B thrombin needs to act upon the fibrinogen to catalyze the cleavage of fibrinopeptide A and eventually fibrinopeptide B from fibrinogen before the resulting fibrin can begin to polymerize. In fact, fibrinogen itself is believed to inhibit the polymerization of fibrin such that polymerization will not begin until at least 25% of the fibrinogen has been converted to fibrin I monomer, i.e., by cleavage of fibrinopeptide A. In these prior art sealants, although the efficiency of mixing and spraying may enhance the overall uniformity of the fibrin polymer formed, the characteristics of the sealant structure itself, i.e., fibril size and density, pore size and density, are primarily dependent upon concentrations of fibrinogen and/or thrombin.
REFERENCES:
patent: 5750657 (1998-05-01), Edwardson et al.
patent: 6121422 (2000-09-01), Zimmerman et al.
patent: 6206905 (2001-03-01), Holm et al.
patent: 0592242 (1994-04-01), None
patent: WO9720585 (1997-06-01), None
patent: WO9802098 (1998-01-01), None
patent: WO9820931 (1998-05-01), None
Cederholm-Williams Stewart A.
Hollingsbee Derek A.
Marshall Julian M.
Velada Jose L.
Bristol--Myers Squibb Company
Kilcoyne John M.
Krass Frederick
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