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Patent landscape, scope, and claims: |
Scope and Claims Analysis for US Patent 7,605,121: Sterile Cetrorelix acetate Lyophilisate with Bulking Agent
US Patent 7,605,121 claims a narrow, process-and-product-defined formulation: a sterile cetrorelix acetate lyophilisate prepared under tightly constrained pH and solvent conditions, with specified bulking agent options and defined amounts. The practical scope is anchored to (i) the peptide identity (SEQ ID NO: 1), (ii) a two-stage acid/water preparation with a defined intermediate pH window, (iii) filtration sterilization, and (iv) lyophilization, producing a sterile lyophilisate containing a bulking agent in specific ranges and selections.
What does the patent claim protect (product scope vs process scope)?
The patent protects a sterile cetrorelix acetate lyophilisate that is both process-constrained and composition-constrained.
Independent claim focus (Claim 1)
Claim 1 is drafted as a method that produces a specific product, but the limitations are also directly usable as product-enforcement handles because the product is defined by being the result of a specific sterile, formulation workflow with specific chemistry controls:
- Peptide identity: cetrorelix acetate having amino acid sequence Ac-D-Nal(2)-D-pCl-Phe-D-Pal(3)-Ser-Tyr-D-Cit-Leu-Arg-Pro-D-Ala-NH2 (SEQ ID NO: 1)
- Solvent system for dissolution: 30% (v/v) aqueous acetic acid for the initial dissolution step
- Intermediate dilution: diluting the solution with water
- Target pH window: after addition of bulking agent, the solution has pH 2.5 to 3.0
- Sterilization modality: filtration sterilization (not terminal autoclave/heat)
- Final operation: lyophilization
- Output: a sterile cetrorelix acetate lyophilisate-bulking agent
This makes Claim 1 enforceable against manufacturing routes that deviate on any of the core constraints:
- solvent concentration (30% v/v acetic acid),
- pH range (2.5 to 3.0 at the time after bulking agent is added),
- sterilization method (filtration),
- or the presence/role of bulking agent in the lyophilized sterile product.
Dependent claims narrow the composition scope further (Claims 2 to 4)
Dependent claims specify the bulking agent category and compositions:
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Claim 2: bulking agent must be one of:
- amino acids
- polyvinylpyrrolidone (PVP)
- albumin
- hexitol
- urea
- sodium chloride
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Claim 3: if the bulking agent is a hexitol, the hexitol is restricted to:
- mannitol, glucitol, sorbitol, D-sorbitol, dulcitol, allitol, iditol
and the bulking agent content is constrained to:
- 0.1 to 17 parts by weight bulking agent per 1 part by weight peptide
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Claim 4: a specific instantiation:
- mannitol as bulking agent
- 1 part by weight peptide dissolved in 100 to 10,000 parts by weight of 30% (v/v) acetic acid
- then dilution with water to produce 3% (v/v) aqueous acetic acid
- and bulking agent is mannitol
So the patent’s “center of gravity” is in acidified, low-pH, filtration-sterilized, lyophilized cetrorelix acetate formulations with controlled bulking agent systems, especially those using mannitol with defined concentration and ratios.
What are the claim-by-claim scope limitations that determine infringement risk?
Claim 1: sterile cetrorelix acetate lyophilisate prepared with defined solvent and pH controls
Claim 1 requires all of the following, in combination:
-
Dissolution step
- Dissolve SEQ ID NO: 1 peptide in 30% (v/v) aqueous acetic acid to form a solution.
-
Dilution step
- Dilute the solution with water.
-
Bulking agent addition
- Add a bulking agent so that the resulting solution has pH 2.5 to 3.0 after bulking agent addition.
-
Sterile filtration
-
Lyophilization
- Lyophilize to yield a sterile cetrorelix acetate lyophilisate-bulking agent.
Key enforcement levers in Claim 1
- The pH constraint is time- and state-dependent: “after which the solution has a pH range between 2.5-3.0.” This is the tightest technical gate. If pH falls outside 2.5 to 3.0 after bulking agent addition, Claim 1 is not met.
- The sterilization method is restricted to filtration. If sterilization is done by another method, Claim 1’s filtration requirement is avoided.
Claim 2: bulking agent must be in the enumerated auxiliary set
Claim 2 adds a discrete list limitation:
- amino acids
- PVP
- albumin
- hexitol
- urea
- sodium chloride
If the bulking agent is not within this set, Claim 2 cannot be satisfied.
Claim 3: if bulking agent is a hexitol, the identity and ratio are restricted
Claim 3 further limits:
- hexitol identity:
- mannitol, glucitol, sorbitol, D-sorbitol, dulcitol, allitol, iditol
- amount:
- 0.1 to 17 parts by weight bulking agent per 1 part by weight peptide
This creates a direct ratio-based boundary: a formulation using a listed hexitol outside the ratio window would not satisfy Claim 3.
Claim 4: mannitol-based embodiment with defined dissolution and dilution ratios
Claim 4 requires:
- mannitol as bulking agent
- dissolution conditions:
- 1 part by weight peptide dissolved in 100 to 10,000 parts by weight of 30% (v/v) acetic acid
- dilution endpoint:
- dilute with water to 3% (v/v) aqueous acetic acid
- bulking agent:
This claim is a narrow “recipe spec.” Any deviation in:
- the peptide-to-solvent weight ratio,
- or the 3% (v/v) acetic acid endpoint,
would reduce Claim 4 coverage.
How would this translate into practical manufacturing design-around options?
Because the claim is combination-limited, design-arounds generally target one of the core gates. The most direct “avoidance” levers, based on claim language, are:
1) Sterilization method
- Claim 1 is explicitly filtration sterilization. Alternative sterilization (in-process or terminal) that does not use filtration sterilization would not satisfy the filtration requirement.
2) pH window after bulking agent addition
- The solution must have pH 2.5 to 3.0 after bulking agent addition.
- Shifting formulation so that the pH after bulking agent addition sits outside that range is the most straightforward parameter-level workaround.
3) Bulking agent identity
- Claim 2 enumerates specific classes. Avoidance is possible by using bulking agents outside the listed set, assuming other Claim 1 steps still align.
4) Bulking agent ratio and hexitol identity
- If using hexitol, Claim 3 limits both the specific hexitol names and the content ratio to 0.1 to 17 (w/w per w/w peptide).
5) Manitol-specific recipe constraints (Claim 4)
- Claim 4 is tightly bounded to:
- mannitol,
- 100 to 10,000 parts solvent per 1 part peptide (based on 30% v/v acetic acid),
- and dilution to 3% v/v acetic acid.
What is the effective claim coverage matrix across the bulking agent universe?
The claims divide the bulking agent scope into a general list and a specific hexitol carve-out.
Bulking agent coverage by claim scope
| Claim |
Bulking agent allowed |
Further restrictions |
| Claim 1 |
Bulking agent added (not yet enumerated) |
pH must be 2.5 to 3.0 after addition; filtration sterilization; lyophilization |
| Claim 2 |
amino acids, PVP, albumin, hexitol, urea, sodium chloride |
none on amount in Claim 2 |
| Claim 3 |
hexitols limited to mannitol, glucitol, sorbitol, D-sorbitol, dulcitol, allitol, iditol |
amount 0.1 to 17 parts by weight per 1 part peptide |
| Claim 4 |
mannitol |
dissolution: 1 part peptide in 100 to 10,000 parts 30% acetic acid; dilute to 3% (v/v) acetic acid |
Net practical implication
- If a product uses listed bulking agents and manufacturing aligns to acidified, low-pH, filtration-sterilized lyophilization, the product is within the likely independent claim capture zone.
- If the product instead uses:
- non-listed excipients as the principal bulking agent, or
- a filtration-free sterilization workflow, or
- pH outside 2.5 to 3.0 at the specified process stage,
it falls outside Claim 1’s constraints.
How does the patent landscape look for enforcement and freedom-to-operate?
This response is limited to the claims text provided. No other patent bibliographic data, file history, priority/expiration, citations, or related-family documents were supplied. Under that constraint, the only actionable landscape statements that can be made are those derived directly from scope.
Likely enforcement posture implied by the claim drafting
- The claims are written to support formulation-process enforcement (filtration and pH range at a specific stage) rather than purely composition-only enforcement.
- The dependent claims provide fallbacks:
- broad bulking agent class (Claim 2),
- hexitol identity and ratio (Claim 3),
- and a specific mannitol recipe (Claim 4).
Competitive risk categories inferred from claim constraints
- Highest risk: products manufactured using the same peptide, acid concentration steps, pH window, filtration sterilization, lyophilization, and using mannitol in the Claim 4 recipe band.
- Medium risk: products using other bulking agents within the Claim 2 list, provided pH and filtration conditions match Claim 1.
- Lower risk: products that shift sterilization route away from filtration, or that maintain formulation pH outside 2.5 to 3.0 after bulking agent addition, or that rely on non-enumerated bulking agents.
What are the exact claimed process and composition parameters (checklist format)?
Claim 1 checklist (must all be met)
- Peptide: Ac-D-Nal(2)-D-pCl-Phe-D-Pal(3)-Ser-Tyr-D-Cit-Leu-Arg-Pro-D-Ala-NH2 (SEQ ID NO: 1)
- Dissolve peptide in 30% (v/v) aqueous acetic acid
- Dilute with water
- Add bulking agent to achieve pH 2.5 to 3.0 after addition
- Sterilize by filtration
- Lyophilize to produce sterile cetrorelix acetate lyophilisate-bulking agent
Claim 2 checklist (bulking agent must be one of the enumerated set)
- amino acids
- PVP
- albumin
- hexitol
- urea
- sodium chloride
Claim 3 checklist (if hexitol is used)
- hexitol identity must be one of:
- mannitol, glucitol, sorbitol, D-sorbitol, dulcitol, allitol, iditol
- amount: 0.1 to 17 parts by weight per 1 part peptide
Claim 4 checklist (mannitol embodiment)
- bulking agent: mannitol
- dissolve 1 part peptide in 100 to 10,000 parts by weight of 30% (v/v) acetic acid
- dilute with water to 3% (v/v) aqueous acetic acid
- proceed to the rest of Claim 1 sequence as required (bulking agent addition with pH 2.5 to 3.0, filtration sterilization, lyophilization)
Key Takeaways
- Claim 1 is the anchor: sterile cetrorelix acetate lyophilisate is defined by a controlled workflow using 30% v/v acetic acid, bulking-agent addition achieving pH 2.5 to 3.0, filtration sterilization, and lyophilization.
- Claims 2 to 4 narrow bulking agent scope: a specific list (Claim 2), then hexitol identity plus ratio (Claim 3), and a mannitol recipe with defined solvent and dilution ratios (Claim 4).
- Design-around pressure points are explicit: switch sterilization away from filtration, move pH after bulking agent addition outside 2.5 to 3.0, use a bulking agent outside the enumerated sets, or, for mannitol, deviate from the Claim 4 dissolution and dilution specs.
FAQs
-
Is the claim primarily about a formulation or a manufacturing method?
It is method-anchored but product-enforceable because Claim 1 requires the specific sterilization and pH-controlled formulation workflow that produces the sterile lyophilisate.
-
Does Claim 1 require a specific bulking agent identity?
Claim 1 requires a bulking agent, but identity constraints are introduced in dependent claims (Claim 2 lists permitted classes).
-
What is the single most critical parameter in Claim 1?
The pH 2.5 to 3.0 after bulking agent addition.
-
If a process uses mannitol but not the specified dissolution and dilution ratios, is it still within Claim 4?
No. Claim 4 requires the specific mannitol embodiment defined by the peptide-to-solvent range in 30% v/v acetic acid and dilution to 3% v/v.
-
How do Claims 2 and 3 affect freedom-to-operate if the pH and sterilization match Claim 1?
Even if pH and filtration match, Claim 2 limits bulking agent classes, and Claim 3 further restricts hexitol identity and amount when a hexitol is used.
References
[1] US Patent 7,605,121 (claims as provided by user).
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