US Patent 5,407,671 Patent Claims & Landscape (One-Component Solid Tissue Adhesive with Reconstituted Fibrinogen/Factor XIII/PPSB/Antithrombin III/Calcium/Aprotinin)
United States Patent 5,407,671 covers a one-component solid tissue adhesive that, upon reconstitution in 1 mL, contains defined ranges of human fibrinogen, factor XIII activity, PPSB-based prothrombin factors, antithrombin III activity, calcium ions, and aprotinin, with a critical compositional ratio that prevents premature coagulation during preparation yet initiates coagulation on contact with a wound. The claim is composition-centric, tied to reconstitution volume (1 mL), and anchored on balancing procoagulant and anticoagulant/anti-fibrinolytic inputs to control timing of coagulation.
What does US 5,407,671 claim cover (composition, ranges, and “no premature coagulation” limitation)?
What is the product defined as
The independent claim is directed to:
- A one-component tissue adhesive
- In solid form
- Reconstituted in 1 mL of solution to yield a specified biochemical composition
- Where the ratio of components prevents premature coagulation during preparation and
- Initiates coagulation on contact with a wound surface
The claim language ties both:
- the quantitative composition (mg/IU/mmol/KIU ranges), and
- a functional process outcome (timing of coagulation).
Reconstitution-based compositional ranges (core claim math)
For reconstitution in 1 mL:
| Component |
Claimed range |
Unit basis in the claim |
| Human fibrinogen |
65–115 mg |
mass per 1 mL solution |
| Factor XIII |
40–80 U |
units per 1 mL |
| PPSB (prothrombin factors) |
1–50 IU |
“based on factor II (prothrombin)” |
| Antithrombin III |
0.01–50 IU |
activity per 1 mL |
| Calcium ions |
0.1–5 mmol/L |
concentration |
| Aprotinin |
1–10,000 KIU |
kallikrein inactivator units |
Key claim limitation: “no premature coagulation … during preparation”
This is a timing and compatibility requirement. In patent scope terms, it does two things:
- It restricts compositions to those where the reactants remain non-gelling/non-coagulating during preparation and handling of the solid-to-solution step.
- It implies that the inclusion of antithrombin III and/or other buffering/stoichiometric balancing is not optional. The claim requires that the active-substance ratio be such that coagulation does not start prematurely and that coagulation does start on wound contact.
Key claim limitation: “coagulation is initiated on contact with a wound surface”
This provides a second functional anchor. It suggests that the wound environment triggers activation. In composition-centric claims, the “initiated on contact” language often is used to distinguish from systems that coagulate in the vial/needle on mixing rather than on tissue contact. For enforcement and non-infringement arguments, this functional trigger becomes a focal point: accused products are compared for (a) time-to-coagulation after reconstitution in the absence of tissue contact, versus (b) time-to-coagulation when contacting wound or a wound-mimicking surface.
How strong is the patent estate for US 5,407,671 (claim structure, likely weak points, and enforceability signals)?
Strengths (what makes claim 1 enforceable)
- Clear quantitative ranges: Each ingredient has a bounded range tied to reconstitution in 1 mL. This gives enforcement leverage against products that substitute outside ranges.
- Specific ingredient set: It is not “a fibrin sealant.” It requires a specific multi-factor system including:
- fibrinogen + factor XIII + PPSB (factor II basis) + antithrombin III + calcium + aprotinin.
- One-component solid architecture: The claim is limited to a one-component solid tissue adhesive. That is a structural and formulation constraint.
- Functional timing requirement: “No premature coagulation during preparation” and “initiated on contact with a wound surface” can be tested experimentally, giving infringement plaintiffs measurement-based proof paths.
Likely weak points (what defendants attack)
-
Functional trigger is fact-intensive
“On contact with a wound surface” invites dispute about:
- what counts as “wound surface,”
- what standard method was used in the patentee’s experiments,
- how long coagulation is “premature” (implicitly defined by the patentee’s handling protocol).
-
Overlap risk from earlier fibrin sealant technology
The broader tissue-adhesive domain historically includes:
- two-component fibrin sealants (thrombin/fibrinogen),
- calcium-mediated polymerization,
- anti-fibrinolytics like aprotinin,
- factor XIII supplementation in some systems,
- prothrombin component inclusion in some activator systems.
If earlier art discloses the same ingredient set with only minor ratio differences, the claim’s inventive step may be contested. In litigation, this typically translates into broader invalidity theories.
-
“PPSB based on factor II” is a formulation-defined proxy
Defendants can argue that accused products use PPSB with a different factor accounting scheme, different prothrombin factor distribution, or different labeled unit conversions, potentially shifting whether the “based on factor II” requirement is met.
-
Antithrombin III inclusion creates a narrow but unusual constraint
Many procoagulant mixes omit antithrombin III. If the accused product omits antithrombin III entirely, it is a straightforward non-infringement angle. If it includes antithrombin III but at concentrations that differ from the claimed range, it is also a clear non-infringement angle.
FTO and infringement posture for next-generation solid sealants
The claim is likely to be hardest to design around without:
- changing ingredient identity (remove antithrombin III or factor XIII), or
- moving outside ranges for fibrinogen/factor XIII/PPSB/antithrombin/calcium/aprotinin, or
- changing solid-state one-component architecture into a two-component reconstitution product.
What prior art most likely overlaps (fibrin-based adhesives, factor XIII, PPSB, aprotinin, and one-component solid formulations)?
The claim sits at the intersection of:
- fibrinogen-based adhesives,
- thrombin generation or prothrombin factor systems,
- factor XIII crosslinking,
- calcium-dependent clotting,
- anti-fibrinolysis (aprotinin),
- anticoagulant modulation (antithrombin III),
- and a one-component solid-to-solution delivery format.
Overlap zones likely to matter in validity
- Procoagulant component combinations: fibrinogen + PPSB/prothrombin factors + calcium is the clotting core in many coagulation systems.
- Stabilization/anti-fibrinolysis: aprotinin is common in fibrin sealant formulations to slow fibrinolysis.
- Crosslinking: factor XIII is a standard enhancer in fibrin polymer stability.
- Premature activation control: anti-coagulant inclusion or physical separation is a known strategy. Here, the claim uses compositional ratio to prevent premature coagulation.
Where novelty is most likely anchored
In claim 1 as written, novelty is most likely tied to the combination of:
- one-component solid delivery,
- broad ingredient set and tight quantitative balancing,
- and the functional prevention and initiation criteria.
In invalidity proceedings, prior art that discloses a one-component solid fibrin-like adhesive with fibrinogen + calcium + aprotinin and procoagulant factors might still be insufficient if it lacks:
- factor XIII in the specified range,
- antithrombin III in the specified range,
- and the specific PPSB unit definition linked to factor II.
How does US 5,407,671 compare with classic two-component fibrin sealants (and why that matters for infringement)?
Two-component fibrin sealants versus one-component solids
Classic commercially dominant fibrin sealants typically use fibrinogen plus a separate thrombin activator (plus calcium and aprotinin may be included in either component). These systems coagulate after reconstitution by mixing components.
By contrast, US 5,407,671 claims a one-component adhesive in solid form. That design implies:
- the formulation must be internally balanced to avoid premature coagulation,
- and wound contact must supply activation conditions.
Practical infringement distinction
A two-component system can be non-infringing even if it contains the same proteins because claim 1 requires a one-component solid adhesive where active substances are reconstituted together in 1 mL solution. For infringement analysis, the delivery architecture often controls.
Which later patents and continuations could be affected (claim scope expansion or design-around)?
Without reviewing the full patent family (application number, continuations, and assignee records), a complete “later-claim affected” map cannot be created. However, typical downstream patterns in this technical space are:
- patents covering specific solid-state formats (lyophilized products, microencapsulation, stabilized solids),
- patents that modify unit accounting and assay methods for factor XIII/PPSB/prothrombin factor loads,
- patents that change anti-fibrinolytic identity (e.g., aprotinin substitutes),
- patents that replace antithrombin III modulation with different inhibitors or physical separation,
- patents that shift to surface-activated packaging approaches.
Those are the design-around axes most consistent with claim 1’s constraints.
What generic entry risks exist for products that resemble the claim (and how would validity or design-around be tested)?
Risk drivers
A generic or biosimilar-style “entry risk” does not apply cleanly to biologically derived sealants, but market entry risk for a competing solid adhesive hinges on:
- whether a competitor’s formulation matches the claimed ingredient set and ranges,
- whether it is one-component solid,
- and whether coagulation control meets the claimed “no premature coagulation / initiated on contact” functional profile.
Testing-based claim mapping (how parties would argue)
- Reconstitution compatibility: assays showing no coagulation during preparation.
- Wound-contact coagulation trigger: time-to-gel/strength after contacting a wound surface surrogate (or standardized tissue).
- Ingredient quantification: validated assays for fibrinogen mass, factor XIII activity, PPSB factor II IU, antithrombin III activity, calcium concentration, and aprotinin KIU per reconstitution volume.
A competitor can reduce risk by:
- omitting antithrombin III or moving outside its range,
- moving calcium concentration outside 0.1–5 mmol/L,
- changing factor XIII loading outside 40–80 U,
- or changing the architecture from one-component solid to multi-component activation.
What is the most relevant litigation strategy around this specific claim (infringement vs invalidity themes)?
Infringement themes
- Compare each ingredient and range after reconstitution in 1 mL.
- Prove or disprove the “one-component solid” architecture.
- Provide functional data on coagulation timing to map:
- “premature coagulation” during preparation, and
- “initiated on contact with wound surface.”
Invalidity themes
- Identify prior art with the same functional control (avoiding premature coagulation) using antithrombin or other inhibitors in fibrin/prothrombin/calcium systems.
- Show that combining known elements for one-component solid tissue adhesives was obvious to a skilled person.
- Attack novelty if earlier documents disclose:
- fibrinogen + factor XIII + prothrombin factors (or PPSB) + calcium,
- with aprotinin,
- and controlled activation triggered by contact with tissue.
Key Takeaways
- US 5,407,671 is a composition-and-function claim for a one-component solid tissue adhesive that is balanced to avoid premature coagulation during preparation and to trigger coagulation on wound contact.
- The claim’s enforceability is anchored on ingredient identity and quantified ranges per 1 mL reconstitution, including the uncommon combination of antithrombin III plus prothrombin-factor PPSB with calcium and aprotinin.
- Litigation and freedom-to-operate analysis will be driven by assay-based component quantification and timing tests for coagulation initiation under wound-contact conditions.
- Design-around is most likely achieved by changing one of the structural constraints (one-component solid) or moving outside key quantitative ranges, especially antithrombin III, calcium, factor XIII, fibrinogen, or aprotinin.
FAQs
1) What composition differences most easily avoid infringement of US 5,407,671?
Changing any required ingredient set element (e.g., removing antithrombin III or factor XIII) or moving outside one or more claimed quantitative ranges per 1 mL reconstitution is the most direct non-infringement path.
2) How do courts typically interpret “no premature coagulation during preparation”?
By comparing experimental coagulation behavior of the accused product under the preparation/handling conditions relevant to reconstitution, using time-to-gel or coagulation onset metrics.
3) What does “PPSB based on factor II (prothrombin)” imply for unit accounting disputes?
It ties the PPSB requirement to how prothrombin (factor II) activity is defined and measured; accused products can dispute whether their labeled or measured PPSB activity corresponds to the claimed factor II IU basis.
4) Is the wound-trigger language a product feature or a process feature?
It functions like a product feature defined by performance: coagulation must initiate upon contact with a wound surface, which is measured experimentally and used to map the product’s functional behavior.
5) Does changing from one-component to two-component formatting avoid risk?
Yes. Claim 1 requires a one-component solid tissue adhesive that is reconstituted together; two-component architectures generally fall outside that structural requirement.
References
- United States Patent 5,407,671. “One component tissue adhesive in solid form having fibrinogen, factor XIII, PPSB, antithrombin III, calcium ions, and aprotinin.” (Claim text as provided by user).
