US Patent 11,959,486: Scope, Claim Construction Signals, and U.S. Landscape for Etelcalcetide Liquid at pH 2–5
US Drug Patent 11,959,486 claims a narrow formulation space for etelcalcetide in a liquid aqueous formulation with acidic pH (2.0 to 5.0) and a defined drug concentration window (0.5 to 15 mg/mL), paired with specific sub-ranges, buffer and tonicity choices, and treatment of secondary hyperparathyroidism (SHPT) via parenteral dosing.
Because the claims you provided are formulation-and-use claims, the practical business question is whether competitors can design around by changing pH, concentration, salt form, buffer system, tonicity modifiers, or the route/treatment framing.
What is the claimed subject matter? (Independent vs dependent claim map)
Claim 1 (Independent): core formulation
“A composition” containing:
- Etelcalcetide in a liquid formulation comprising water
- pH 2.0 to 5.0
- Etelcalcetide concentration: 0.5 mg/mL to 15 mg/mL
This claim sets the baseline infringement test for any liquid etelcalcetide product unless other claims narrow the formulation further.
Claims 2–6 (Dependent): narrower ranges and formulation components
- Claim 2: etelcalcetide 0.5 to 10 mg/mL
- Claim 3: pH 2.5 to 4.50
- Claim 4: pH maintained by a pharmaceutically acceptable buffer
- Claim 5: buffer is succinate
- Claim 6: etelcalcetide present as etelcalcetide hydrochloride
These dependencies create layered claim “rails.” A generic or competitor can potentially avoid literal scope by changing one element (for example buffer type or salt form), but the doctrine of equivalents risk increases when the substituted element performs the same function in substantially the same way.
Claims 7–8 (Dependent): tonicity modifier
- Claim 7: further comprises a pharmaceutically acceptable tonicity modifier
- Claim 8: tonicity modifier is NaCl
Claim 9 (Independent additional composition): “tight” combination
“A liquid composition” with the combination of:
- 0.5 to 15 mg/mL etelcalcetide hydrochloride
- succinate buffer maintaining pH 2.5 to 4.5
- sodium chloride
This claim is a “stacked” formulation requirement: salt form + buffer identity + tonicity + pH window + concentration window.
Claims 10–13 (Method of treatment): SHPT and parenteral route
- Claim 10 (Independent method): Treat SHPT by parenterally administering the composition of claim 1
- Claim 11: parenterally via intravenous injection
- Claim 12: composition comprises etelcalcetide hydrochloride
- Claim 13: pH maintained by pharmaceutically acceptable succinate buffer
The method claims tie infringement largely back to whether the accused product infringes claim 1 (and then whether additional dependent features are met for the narrower method versions).
How broad is the formulation claim compared with typical etelcalcetide product design?
Key axis 1: pH window (2.0 to 5.0)
- Broader range in claim 1: allows acidic pH anywhere between 2.0 and 5.0
- Narrower dependent range in claim 3: 2.5 to 4.50
- Claim 9 and claim 13 further anchor succinate buffer at 2.5 to 4.5
Design-around leverage: pH adjustment is the simplest literal design-around lever. If a competitor holds product pH below 2.0 or above 5.0, claim 1 falls out. If pH is within 2.0 to 5.0 but outside 2.5 to 4.5, claims 3, 9 (in part), and 13 (in part) become harder to hit, but claim 1 still remains a risk.
Key axis 2: concentration window (0.5 to 15 mg/mL)
- Claim 1: 0.5–15 mg/mL
- Claim 2: 0.5–10 mg/mL
- Claim 9: repeats 0.5–15 mg/mL
Design-around leverage: moving concentration to <0.5 mg/mL or >15 mg/mL avoids claim 1. Moving concentration above 10 mg/mL avoids claim 2, but not claim 1 or claim 9 (since claim 9 keeps 0.5–15).
Key axis 3: salt form and buffer identity
- Claim 6: requires etelcalcetide hydrochloride
- Claim 5 / Claim 9 / Claim 13: requires succinate buffer (succinate identity is explicit)
- Claim 4: only requires buffer is “pharmaceutically acceptable” (identity unspecified)
- Claim 9: requires succinate buffer at pH 2.5–4.5, plus NaCl
Design-around leverage:
- Using a non-hydrochloride salt form can avoid claims 6, 9, and 12 if the product uses a different etelcalcetide salt.
- Using a buffer other than succinate can avoid claims 5, 9, and 13 while still potentially falling under claim 1 (depending on whether “buffer-maintained pH” requirements are imposed; claim 1 does not specify buffer identity).
Key axis 4: tonicity
- Claim 8: tonicity modifier is NaCl
- Claim 7: only requires a tonicity modifier generally
Design-around leverage: replacing NaCl with another tonicity agent avoids claim 8, but claim 7 may still be met if the product includes a tonicity modifier.
Key axis 5: route and method framing
- Claim 10: SHPT treatment by parenteral administration of claim 1 composition
- Claim 11: IV injection
- Claim 12: includes etelcalcetide hydrochloride
- Claim 13: includes succinate buffer
Design-around leverage: if a product is administered subcutaneously (or another parenteral route not covered by “intravenous injection”), claim 11 can be avoided, but claim 10 can still be at risk because claim 10 covers “parenterally administering” broadly.
Claim-by-claim infringement logic (what must be true for each claim)
Claim 1 infringement elements
An accused liquid composition infringes claim 1 if it has all of:
- Etelcalcetide in a liquid formulation with water
- pH between 2.0 and 5.0
- Etelcalcetide concentration between 0.5 and 15 mg/mL
No salt form requirement, and no specific buffer identity requirement, so claim 1 is the broadest practical formulation anchor.
Claim 2
- All claim 1 elements plus: 0.5 to 10 mg/mL
Claim 3
- All claim 1 elements plus: pH 2.5 to 4.50
Claim 4
- All claim 1 elements plus: pH maintained by a pharmaceutically acceptable buffer
This is an important nuance: it reads like it assumes buffering is used, but it is still a positive limitation. If a formulation achieves target pH through other means without a “buffer system” (rare in injectable formulations but theoretically possible), claim 4 may be avoided while claim 1 remains.
Claim 5
- All claim 4 elements plus: buffer is succinate
Claim 6
- All claim 1 elements plus: etelcalcetide as etelcalcetide hydrochloride
Claim 7
- All claim 1 elements plus: includes a tonicity modifier
Claim 8
- All claim 7 elements plus: tonicity modifier is NaCl
Claim 9
Requires the stacked combination:
- etelcalcetide hydrochloride at 0.5–15 mg/mL
- succinate buffer at pH 2.5–4.5
- NaCl
Method claims
- Claim 10: treat SHPT via parenteral administration of the claim 1 composition
- Claim 11: claim 10 plus IV injection
- Claim 12: claim 10 plus composition comprises etelcalcetide hydrochloride
- Claim 13: claim 10 plus pH maintained by succinate buffer
Method infringement is typically evaluated by whether the administered product matches the relevant formulation claim and whether the use is for SHPT with the claimed route.
Scope pressure points and likely design-around routes
Below are the main “escape hatches” competitors would use, ordered by how directly they remove literal elements:
- Change pH outside claim 1
- Move to pH <2.0 or pH >5.0 to avoid claim 1 (and therefore avoid claim 10).
- Change concentration outside claim 1
- Move to <0.5 mg/mL or >15 mg/mL.
- Use a different etelcalcetide salt form
- Avoid etelcalcetide hydrochloride to exit claims 6, 9, and 12 (but not claim 1 unless the formulation no longer meets claim 1’s other limits).
- Use a non-succinate buffer system
- Avoid succinate to exit claims 5, 9, and 13.
- Use a different tonicity modifier
- Avoid NaCl to exit claim 8 (while still possibly satisfying claim 7 if a tonicity modifier remains).
- Use a different parenteral route
- Avoid IV injection to exit claim 11 while still potentially leaving claim 10 exposed.
Patent landscape implications (what these claims typically block in practice)
These claims target a formulation “box” for acidic, water-based etelcalcetide liquids designed for injectables. The practical effect is to block competitors from filing for products that:
- Keep etelcalcetide concentration inside 0.5–15 mg/mL
- Keep pH inside 2.0–5.0
- Use succinate buffer within the tighter pH sub-range (2.5–4.5) and include NaCl
- For method use, administer such products to treat SHPT, including IV injection as a subset
The dependent claims also create a layered moat:
- Even if a competitor changes concentration to avoid claim 2, claim 1 can still be infringed.
- Even if a competitor changes pH within 2.0–5.0, claim 1 remains a risk unless pH moves beyond the bounds.
- Even if a competitor avoids NaCl to escape claim 8, the product could still infringe claim 9 if it still uses succinate buffer and the defined etelcalcetide hydrochloride concentration and pH window.
What would an “at-risk” competitor formulation look like?
A product is at the highest literal risk if it simultaneously includes:
- Etelcalcetide hydrochloride (not just “etelcalcetide”)
- Water-based liquid
- pH 2.5–4.5
- Succinate buffer
- NaCl
- Etelcalcetide concentration 0.5–15 mg/mL
That exact combination maps to claim 9 and supports method claims 10, 12, and 13 depending on route (and claim 11 if IV).
Key Takeaways
- US 11,959,486 is primarily a formulation protection for aqueous etelcalcetide liquids at pH 2.0–5.0 and 0.5–15 mg/mL.
- The strongest stacked protection is in claim 9: etelcalcetide hydrochloride + succinate buffer (pH 2.5–4.5) + NaCl at 0.5–15 mg/mL.
- Claim 1 is the broadest infringement anchor for both composition and method of SHPT treatment (claim 10).
- The most direct design-arounds are to move pH or concentration outside claim 1, or to change salt form, buffer identity, and tonicity agent to avoid the dependent limitations.
FAQs
1) Which claim is the main risk driver for composition infringement?
Claim 1, because it covers the widest formulation space: water-based etelcalcetide with pH 2.0–5.0 and 0.5–15 mg/mL.
2) What is the tightest formulation definition in the claim set?
Claim 9, which requires etelcalcetide hydrochloride, succinate buffer, pH 2.5–4.5, NaCl, and 0.5–15 mg/mL.
3) If a competitor avoids NaCl, does it avoid infringement?
It avoids claim 8 specifically, but infringement may still occur under claim 1 (and potentially claim 9 only if NaCl is present). The product may still fall under other dependent claims if those elements match.
4) Does changing route avoid the SHPT method claims?
It can avoid claim 11 if the route is not IV injection, but claim 10 still covers parenteral administration of the claim 1 composition for SHPT.
5) What single parameter change most reliably breaks claim 1?
Either moving pH outside 2.0–5.0 or moving concentration outside 0.5–15 mg/mL.
References
No sources were provided in the prompt for verifying the patent text, bibliographic data, or prosecution history.
