Critical Analysis of US Patent 8,071,090 (Thrombin-Stabilized Aqueous/Sucrose-Bacteriostatic Preservative Compositions, Formulation, Process, and Kit Claims)
Executive summary. US 8,071,090 claims thrombin parenteral compositions stabilized with sucrose (0.10% to 5% w/v, with additional excipients including benzyl alcohol or chlorobutanol, buffers, mannitol, NaCl, and optional surfactants/PEG), plus lyophilized-thrombin/ready-to-use reconstitution processes and a two-container kit. The claim set is built around (i) excipient selection and concentration windows, (ii) sucrose–mannitol ratio constraints, (iii) benzyl alcohol and chlorobutanol concentration windows, and (iv) pH 5.7–7.4 with specified buffer and excipient functionality in surgical reconstitution settings. Commercial defensibility hinges on whether competitors can design around the sucrose window, preservative window, mannitol:sucrose ratio, and/or the specific reconstitution/kit architecture without losing stability and operability in thrombin products.
What does US 8,071,090 claim: thrombin formulation with sucrose and benzyl alcohol/chlorobutanol?
Short answer (claim architecture). US 8,071,090 is directed to (a) aqueous thrombin compositions stabilized by sucrose and a bacteriostatic preservative selected from benzyl alcohol or chlorobutanol, (b) preferred embodiments with additional excipients (buffers, salts, polyols like mannitol, optional surfactants/PEG, amino acids, additional carbohydrates), (c) specific concentration ranges and ratio limits, and (d) processes/kit formats built around lyophilized thrombin plus a separately sealed diluent/preservative solution that yields the claimed final concentrations upon reconstitution.
Claim 1 and dependent claims: core scaffold and primary differentiation points
Independent claim 1 recites:
- thrombin
- bacteriostatically effective preservative: benzyl alcohol or chlorobutanol
- sucrose: 0.10% to 5.0% (w/v) in aqueous solution
High-leverage dependent constraints (design-around risk).
- Claim 3: preservative is benzyl alcohol.
- Claim 4: benzyl alcohol 0.8%–1.5% (v/v).
- Claim 5–6: add mannitol; mannitol:sucrose >1:1 and ≤2.5:1 (w/w).
- Claim 7–9: thrombin type (human recombinant human; bovine).
Independent claim 10: narrower windows with explicit pH and preservative specifics
Independent claim 10 tightens the recipe:
- thrombin
- pharmaceutically acceptable buffer
- sucrose 0.10%–5% (w/v)
- preservative:
- benzyl alcohol 0.8%–1.5% (v/v), or
- chlorobutanol 0.4%–0.6% (w/v)
- aqueous solution pH 5.7–7.4
This claim is a critical infringement fulcrum because it combines three coupled parameters that are commonly examined in stability/op optimization:
- sucrose window,
- preservative window,
- pH 5.7–7.4 plus buffer selection.
Dependent refinements (Claims 11–18).
- Claim 12: benzyl alcohol 0.8%–1.0% (v/v).
- Claim 13–14: sucrose 0.5%–3.0% (w/v), and “about 1%” (w/v).
- Claim 15: buffers enumerated: histidine, citrate, phosphate, Tris, succinate, acetate.
- Claim 16–17: add mannitol with same mannitol:sucrose ratio window.
- Claim 18: NaCl in diluent.
Claim 24: “aqueous composition consisting essentially of” narrows excipient set and adds numeric ingredient ceilings
Independent claim 24 is “consisting essentially of,” which can narrow infringement but also define a robust “operability” envelope. It recites:
- thrombin 0.03 mg/mL–1.6 mg/mL
- sucrose 0.17%–1.3% (w/v)
- mannitol 1.1%–1.6% (w/v)
- NaCl 0.8%–2.0% (w/v)
- optional CaCl2 0–1.6 mM
- optional surfactant or high-molecular-weight PEG 0.001%–0.32% (w/v)
- pharmaceutically acceptable buffer
- bacteriostatic preservative: benzyl alcohol or chlorobutanol
- pH 5.7–7.4
- buffer concentration selected to provide approximately physiological pH upon surgical application
- mannitol:sucrose ratio >1:1 and ≤2.5:1 (w/w)
Sub-claim anchors:
- Claim 25: mannitol:sucrose fixed at 1.33:1 (w/w).
- Claim 26–27: molar ratio sucrose:thrombin at least 700:1, and at least 2000:1.
- Claim 28: benzyl alcohol 0.8%–1.5% (v/v).
These ratio requirements materially affect design-around because they constrain the relationship between excipient and protein concentration. Formulators can change both parameters to slip outside the ratio while still using “similar” excipients.
Claim 29–33: stabilization and reconstitution processes tied to final concentration targets
Claim 29 (process):
- provide lyophilized composition of thrombin + quantity of sucrose sufficient to stabilize in presence of bacteriostatic preservative (benzyl alcohol or chlorobutanol)
- provide diluent with bacteriostatic effective amount of benzyl alcohol or chlorobutanol in water
- combine to form solution with sucrose 0.10%–5.0% (w/v)
Claim 31 (alternative independent process):
- lyophilized composition with thrombin + pharmaceutically acceptable excipients
- reconstitute in diluent to yield benzyl alcohol 0.8%–1.5% (v/v) and sucrose 0.10%–5% (w/v)
Claim 32–33: reconstitution with mannitol; preserve same mannitol:sucrose ratio constraint.
Claims 34–41: kit architecture with two sealed containers and reconstitution instruction/transfer/applicator
Claim 34:
- first sealed container: pharmaceutically acceptable diluent with bacteriostatic benzyl alcohol or chlorobutanol in water
- second sealed container: lyophilized composition with thrombin and sucrose quantity providing 0.10%–5.0% (w/v) upon reconstitution with diluent
Dependent claims:
- NaCl-containing diluent (Claim 35), “bacteriostatic saline” (Claim 36)
- means for transferring diluent (Claim 37)
- instruction sheet (Claim 38)
- applicator device (Claim 39) syringe/sprayer (Claim 40)
- first and second containers packaged in third container (Claim 41)
The kit claims can create additional infringement pathways: even where the final formulation is manufactured by a contract manufacturer, kit assembly and sale in the specified architecture can trigger liability.
Which embodiments are most likely to be asserted for infringement: benzyl alcohol vs chlorobutanol?
Short answer. The most assertable track is typically benzyl alcohol, because multiple claims (1, 3, 4, 10–12, 24–28, 29, 31, 34) include benzyl alcohol-specific concentration ranges and preferred concentration sub-windows. Chlorobutanol has narrower numeric ranges (0.4%–0.6% w/v) and fewer explicit dependent windows in the recited set you provided.
Benzyl alcohol-specific claim leverage
- Claim 4: 0.8%–1.5% (v/v)
- Claim 10: benzyl alcohol 0.8%–1.5% (v/v) as preservative option
- Claim 12: 0.8%–1.0% (v/v)
- Claim 28: benzyl alcohol 0.8%–1.5% (v/v) within “consisting essentially of” composition
- Process and kit claims: diluent benzyl alcohol; reconstitution yields sucrose 0.10%–5% and maintains claimed preservative
Chlorobutanol claim leverage
- Claim 10: 0.4%–0.6% (w/v)
- Claim 1: chlorobutanol as preservative option with sucrose 0.10%–5% (w/v)
- Process and kit claims: diluent chlorobutanol; lyophilized product includes sucrose sufficient to stabilize in presence of preservative
- Claim 24: bacteriostatically effective preservative selected from benzyl alcohol and chlorobutanol, but explicit chlorobutanol concentration is not enumerated in your provided claim text
Practical infringement reading. If a product uses chlorobutanol, the defense often attempts to show it falls outside the narrow 0.4%–0.6% or outside the pH/buffer relationship. If it uses benzyl alcohol, the accused product is more likely to intersect multiple dependent windows, including sub-range 0.8%–1.0% and the 0.8%–1.5% outer envelope.
How strong is the patent estate for US 8,071,090: novelty and obviousness pressure points?
Short answer. As framed by the claims you listed, the patent’s strength is driven by numeric constraints and coupled relationships (pH, preservative concentration, sucrose range, mannitol:sucrose ratio, and sucrose:thrombin molar ratio), not by broad excipient category claims alone. The patent is likely vulnerable if prior art already taught stabilized thrombin using sucrose plus standard preservatives within overlapping windows, but comparatively more resilient if the asserted novelty is specifically tied to the coupled ratios and pH behavior during surgical reconstitution.
Key “obviousness” pressure points in the claim set
- Sucrose + preservative in thrombin stabilization
- Many protein formulations use disaccharides/polyols plus preservatives. The claim limits reduce obviousness risk, but do not eliminate it if prior art ranges overlap.
- pH 5.7–7.4
- This is a broad physiological band. If prior art thrombin products used similar pH with buffers and preservatives, the pH term becomes less differentiating.
- Mannitol:sucrose ratio window (>1:1 and ≤2.5:1)
- Ratio constraints can be more discriminating than single concentrations if prior art uses different excipient systems.
- Sucrose:thrombin molar ratio (≥700:1; ≥2000:1)
- These constraints are less likely to be taught exactly in prior art unless the art focuses on stabilizer:protein stoichiometry.
- “Consisting essentially of” excipient set
- Claim 24’s explicit excipient list can be a target for both validity and infringement arguments:
- validity: if prior art compositions include additional excipients not “essential,” the “consisting essentially of” may limit coverage.
- infringement: accused compositions with additional excipients could argue non-essentiality scope.
Likely validity focus for litigators
- Whether prior art disclosed thrombin formulations with:
- sucrose in the claimed 0.10%–5% band,
- benzyl alcohol (0.8%–1.5% v/v) or chlorobutanol (0.4%–0.6% w/v),
- and pH 5.7–7.4,
- together with mannitol and the specified ratio window.
- Whether the process/kit architecture was already standard practice (two-container lyophilized product + bacteriostatic diluent) with the same concentration outcomes.
What patents protect thrombin preservative-sucrose formulations like US 8,071,090?
Short answer. The closest patent “cluster” around this claim family is generally:
- protein stabilization using sucrose and/or disaccharides,
- thrombin-specific formulation and reconstitution,
- bacteriostatic preservative use in thrombin-containing injectables (benzyl alcohol/chlorobutanol),
- lyophilized thrombin kits with two-compartment diluent systems,
- excipient systems using mannitol/NaCl and controlled tonicity/osmolarity and buffering.
Critical limitation. Without the patent bibliographic record, assignee, filing dates, continuations, and claim citations, a complete “all patents protecting the space” mapping cannot be produced from your inputs alone. The analysis below therefore treats US 8,071,090 as the anchor claim text you provided.
Technical sub-areas within the likely protection scope of US 8,071,090
- Formulation: thrombin concentration ranges (esp. Claim 24), sucrose, preservative, mannitol, NaCl, pH, optional calcium, optional surfactant/PEG.
- Method: lyophilized-to-aqueous reconstitution with target preservative and sucrose final concentration.
- Kit: dual sealed container system and transfer/applicator/instructions.
When does exclusivity expire for a product covered by US 8,071,090?
Short answer. Cannot be determined from the claim text alone.
What is the Orange Book status of US 8,071,090-covered thrombin products?
Short answer. Cannot be determined from the claim text alone.
What generic entry risks exist for thrombin products if US 8,071,090 is asserted?
Short answer. The main generic entry risk is formulation-level: a generic or licensed product must avoid falling into the claimed numeric windows simultaneously. The kit claims raise an additional packaging/assembly risk if the generic product uses a two-container bacteriostatic diluent plus lyophilized sucrose-containing thrombin system with the same reconstitution outcome.
High-risk infringement pathways for an “at-label” generic
- Matching sucrose 0.10%–5% (w/v) in final aqueous solution.
- Using benzyl alcohol in 0.8%–1.5% (v/v), or chlorobutanol 0.4%–0.6% (w/v).
- Operating at pH 5.7–7.4 in the final solution with specified buffering systems.
- Including mannitol with mannitol:sucrose ratio >1:1 and ≤2.5:1 (w/w).
- Meeting sucrose:thrombin molar ratio thresholds where applicable (Claim 26–27).
- Reconstituting from lyophilized thrombin (with sucrose sufficient for stability in presence of preservative) using a bacteriostatic diluent to hit those targets.
- Selling in an architecture that fits the kit claims (first sealed bacteriostatic diluent container plus second sealed lyophilized thrombin+sucrose container, with transfer mechanism/instructions/applicator, depending on asserted subclaims).
Likely design-around levers
- Shift sucrose concentration outside 0.10%–5.0% (w/v) or outside the narrower 0.17%–1.3% band tied to Claim 24.
- Change preservative chemistry or push preservative concentration outside 0.8%–1.5% (v/v) for benzyl alcohol or outside 0.4%–0.6% (w/v) for chlorobutanol.
- Modify buffering system or pH to move outside pH 5.7–7.4 or avoid the enumerated buffer set in Claim 15 (where asserted).
- Change mannitol inclusion or alter mannitol:sucrose ratio outside (1:1, 2.5:1] window.
- Adjust protein concentration so that sucrose:thrombin molar ratio drops below 700:1 (or 2000:1) thresholds.
- Use a different reconstitution architecture that avoids the two-container kit outcome required by Claim 34 (or avoids transfer/applicator elements if asserted).
How does US 8,071,090 compare with typical thrombin formulations: what differs most?
Short answer. Most standard thrombin products use sugar/polyol stabilizers plus buffering and tonicity salts, often with benzyl alcohol as preservative. The differentiated elements in US 8,071,090 are:
- the explicit sucrose concentration band in final reconstituted solution,
- the specific preservative windows (especially benzyl alcohol 0.8%–1.5% v/v),
- the coupled mannitol:sucrose ratio constraint,
- the pH 5.7–7.4 and selected buffers,
- and the sucrose:thrombin molar ratio requirements.
This is a formulation “constraint stack” rather than a single-ingredient invention.
Comparison checklist for freedom-to-operate (FTO) on formulation
A competitor’s composition would need to check, at minimum:
- sucrose % (w/v) in final product
- benzyl alcohol vs chlorobutanol type and concentration
- pH target and buffer system
- presence and amount of mannitol
- mannitol:sucrose ratio
- thrombin concentration and sucrose:thrombin molar ratio
- excipient set coherence with “consisting essentially of” if Claim 24 is asserted
What patent litigation affects US 8,071,090?
Short answer. Cannot be determined from the claim text alone.
Which companies are challenging or defending thrombin formulation patents like this?
Short answer. Cannot be determined from the claim text alone.
Key claim-by-claim infringement mapping (US 8,071,090) based solely on the provided claim text
| Claim |
Coverage theme |
Main numerical gates a product must match to infringe |
| 1 |
Aqueous thrombin composition with sucrose + benzyl alcohol/chlorobutanol |
sucrose 0.10%–5% w/v; preservative “bacteriostatically effective” selected from benzyl alcohol or chlorobutanol |
| 3-4 |
Benzyl alcohol specific |
benzyl alcohol 0.8%–1.5% v/v |
| 5-6 |
Mannitol add-on with ratio limit |
mannitol present; mannitol:sucrose >1:1 and ≤2.5:1 (w/w) |
| 7-9 |
Thrombin source/type |
human vs recombinant human vs bovine |
| 10 |
Buffered solution with explicit preservative concentrations and pH |
sucrose 0.10%–5% w/v; benzyl alcohol 0.8%–1.5% v/v or chlorobutanol 0.4%–0.6% w/v; pH 5.7–7.4 |
| 12-14 |
Narrowed benzyl alcohol and sucrose ranges |
benzyl alcohol 0.8%–1.0% v/v; sucrose 0.5%–3.0% w/v; or about 1% w/v |
| 15 |
Buffer types |
buffer selected from histidine, citrate, phosphate, Tris, succinate, acetate |
| 16-17 |
Mannitol added to Claim 10 |
mannitol present; mannitol:sucrose >1:1 and ≤2.5:1 (w/w) |
| 18 |
NaCl presence in diluent |
NaCl included (Claim 18) |
| 22-23 |
Thrombin concentration range |
0.1–5.0 mg/mL; or 0.3–3.0 mg/mL |
| 24 |
“Consisting essentially of” constrained excipient set |
thrombin 0.03–1.6 mg/mL; sucrose 0.17–1.3% w/v; mannitol 1.1–1.6% w/v; NaCl 0.8–2.0% w/v; optional CaCl2; optional surfactant/PEG; buffer; preservative; pH 5.7–7.4; mannitol:sucrose >1:1 and ≤2.5:1 |
| 25-28 |
Specific ratio and benzyl alcohol window |
mannitol:sucrose 1.33:1; sucrose:thrombin molar ratios thresholds; benzyl alcohol 0.8%–1.5% |
| 26-27 |
Molar ratio constraint |
sucrose:thrombin ≥700:1 and ≥2000:1 |
| 29-33 |
Stabilization and reconstitution process |
lyophilized + sucrose quantity; bacteriostatic diluent; final sucrose 0.10%–5% w/v; optional mannitol with ratio gate |
| 34-41 |
Kit with two sealed containers and reconstitution |
first sealed bacteriostatic diluent with benzyl alcohol/chlorobutanol in water; second sealed lyophilized thrombin + sucrose quantity to yield 0.10%–5% w/v upon reconstitution; plus optional NaCl, transfer means, instruction sheet, applicator device, third packaging container |
Key takeaways
- US 8,071,090 is a thrombin formulation patent built on stacked numeric constraints: sucrose (0.10%–5% w/v), preservative identity and concentration (benzyl alcohol 0.8%–1.5% v/v or chlorobutanol 0.4%–0.6% w/v), pH 5.7–7.4, and a mannitol:sucrose ratio window (>1:1 and ≤2.5:1 w/w).
- The most assertable overlap points are benzyl alcohol embodiments, the pH/buffer combination in Claim 10, and the constrained “consisting essentially of” formulation in Claim 24 with its multi-excipient ceilings and ratio requirements.
- Reconstitution processes and kit architecture create additional infringement routes beyond the final composition, especially for lyophilized products paired with bacteriostatic diluent systems engineered to hit the claimed final concentration outcomes.
- Practical design-around is likely to require shifting at least one coupled parameter outside the claim windows, with ratio-based constraints (mannitol:sucrose and sucrose:thrombin) often providing the cleanest divergence points.
FAQs
-
What formulation parameters most strongly affect infringement risk under US 8,071,090?
Sucrose concentration in final aqueous solution, preservative type and concentration (benzyl alcohol vs chlorobutanol), final pH 5.7–7.4 with selected buffers, and the mannitol:sucrose ratio (>1:1 and ≤2.5:1).
-
Do the “consisting essentially of” limits in Claim 24 constrain the excipient set?
Yes. Claim 24 uses “consisting essentially of,” so excipient choices beyond the listed categories can be argued to fall outside the claim’s essential scope depending on materiality to formulation function.
-
Can a product avoid infringement by changing thrombin source (human recombinant vs bovine)?
Changing thrombin source can avoid specific dependent claims (7–9, 19–21, 20, 21), but the independent composition/process/kit claims still cover “thrombin” unless asserted dependent limitations require a specific thrombin type.
-
How do sucrose:thrombin molar ratio claims alter generic/formulation design?
They add a protein concentration coupling. Even if sucrose % and preservative % are matched or similar, the molar ratio gate (≥700:1 or ≥2000:1) can exclude products where thrombin concentration or sucrose amount shifts the stoichiometry.
-
Do the kit claims require identical packaging components to infringe?
Claim 34 requires two sealed containers for bacteriostatic diluent and lyophilized thrombin+sucrose, with sucrose quantity designed to yield 0.10%–5% upon reconstitution. Optional elements (transfer means, instruction sheet, applicator, third container) only matter when the corresponding dependent claims are asserted.
References
No external sources were cited because the request did not include bibliographic data, assignee, prosecution history, family members, Orange Book entries, or litigation records needed to support sourced factual claims beyond the provided text.
