United States Patent 11,324,696 Baclofen Liquid Composition: What the Claims Cover and How the Patent Estate Shapes Generic and Reformulation Risk
United States Patent 11,324,696 protects a specific liquid baclofen formulation defined by exact quantitative excipient levels, a defined pH window, and stability performance requiring less than ±5% baclofen assay variation by USP testing for at least 30 days under room-temperature and temperature-challenge storage. Claim 1 is the core claim, with dependent claims narrowing to additional storage conditions, optional use of coloring/flavoring and specific color and flavor percentages, and narrower pH ranges. The practical competitive impact is that any FDA-legal generic reformulation that changes excipient amounts, pH strategy, or stability profile risks claim infringement even if baclofen potency is matched.
What is the scope of US Patent 11,324,696 (baclofen 5 mg/mL liquid composition with citric acid, HEC, propylene glycol, simethicone emulsion, sucralose, sodium benzoate)?
Scope in one line: A liquid pharmaceutical composition containing 5 mg/mL baclofen (or salt) plus defined concentrations of citric acid (anhydrous), hydroxyethyl cellulose, propylene glycol, simethicone emulsion (30%), sodium benzoate, sucralose, water, with pH between 3.0 and 6.0, and demonstrating baclofen content stability of ≤±5% USP assay variation for at least 30 days under storage.
Independent Claim 1 element-by-element (what must be present)
Claim 1 requires a formulation that satisfies all of the following, simultaneously:
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Drug substance
- Baclofen or a salt at 5 mg/mL.
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Acid/pH control system
- Citric acid (anhydrous) at 0.12% (w/v).
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Viscosity and suspension support
- Hydroxyethyl cellulose (HEC) at 0.5% (w/v).
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Solvent/humectant
- Propylene glycol at 5% (w/v).
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Antifoaming/adjunct excipient
- Simethicone emulsion (30%) at 0.15% (w/v).
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Preservative
- Sodium benzoate at 0.1% (w/v).
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Sweetener
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Aqueous vehicle
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pH constraint
- Composition pH between 3.0 and 6.0.
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Stability functional limitation
- Baclofen concentration retains <±5% variation by USP assay for at least 30 days when stored at room temperature.
Key infringement mechanics
- Quantitative match matters. Claim 1 is built around specific w/v excipient concentrations. A competitor must stay within literal thresholds if the amounts are treated as exact. If the patent specification supports ranges and claim language is strict “comprises,” the infringement risk analysis turns on whether the claim terms are construed as exact or allow formulation tolerances.
- Functional stability is a litigation lever. The claim is not only composition-limited. It is also performance-limited: ≤±5% USP assay variation over 30 days at room temperature. That tends to make non-infringement harder for “similar” formulations unless they can show materially different stability outcomes.
- Salt coverage expands design space less than it appears. “Baclofen or a salt thereof” covers salts, but the formulation is otherwise anchored to the same excipient system and concentration. Using a different salt does not avoid claim 1 unless the salt form changes other parameters in practice (pH, stability profile, excipient compatibility).
How do dependent claims narrow infringement risk (storage temperature, pH subranges, dyes, flavors, and optional agents)?
Claim 2: tighter stability window at 38–42°C
Claim 2 adds a second performance condition:
- Retains <±5% baclofen USP assay variation for at least 30 days when stored at 38–42°C.
Impact: This converts the claim set into a two-tier stability envelope. A competitor may match the room-temperature performance but still fail at accelerated temperature, exposing them to claim 2.
Claim 3: tighter stability window at 15–30°C
Claim 3 adds:
- Retains <±5% baclofen USP assay variation for at least 30 days when stored at 15–30°C.
Impact: Together claims 1–3 require stability performance across multiple windows (room temperature and two additional temperature ranges). This can constrain how widely a formulation can be “tuned” while still being non-infringing.
Claim 4: optional coloring/flavoring (adds breadth, not a carve-out)
Claim 4 states the composition further comprises a coloring agent, a flavoring agent, or both.
Impact: This is a broad dependent claim that indicates the patentee anticipated sensory acceptability requirements. It also reduces the chance a generic attempts to avoid infringement by omitting color or flavor.
Claims 5–7: specific exact dye and flavor concentrations
- Claim 5: D&C Yellow No. 10 at 0.0002% (w/v).
- Claim 6: FD&C Red No. 40 at 0.000038% (w/v).
- Claim 7: Flavor grape 59.266/A at 0.0500% (w/v).
Impact: These are narrow by exactness. Most generics that change color/flavor or omit grape flavor are less likely to fall into these dependent claims, but they still may hit claim 1 (and claim 2/3) if excipient core and performance requirements are met. Conversely, if a competitor tries to differentiate solely via dyes/flavors, claim 1 still remains the principal risk.
Claims 8–9: narrower pH ranges
- Claim 8: pH about 3.6 to 4.6.
- Claim 9: pH about 4.0 to 4.3.
Impact: Claim 1 already recites pH between 3.0 and 6.0. Claims 8–9 increase value against close variants that land in typical acidic formulation regions. If a competitor formulates with pH 5.5, they can avoid claims 8–9 while still being within claim 1 if all other elements and stability requirements match.
What is the likely protected subject matter breadth: composition-only vs composition + stability performance?
This patent is both. Claim 1 is a typical liquid composition claim but it includes a functional stability limitation that courts and examiners treat as a claim limitation. That matters in two ways:
- Design-around via “different formulation but same drug assay now” is not enough. A competitor needs to show that their baclofen assay retention over the specified time and storage conditions is not within the ±5% window, or that they do not meet other literal excipient/pH limitations.
- Stability data becomes central evidence. In litigation, the accused product’s stability protocol and USP assay results can become dispositive for the functional limitations.
Which excipient substitutions are most likely to create non-infringement, and which are likely to fail?
High-risk substitutions (likely still infringe if amounts and stability are preserved)
- Keeping citric acid at 0.12% (w/v) and targeting the same pH range typically keeps the composition structurally similar.
- Maintaining HEC at 0.5% (w/v) and propylene glycol at 5% (w/v) and retaining a comparable viscosity and solubilization profile makes it difficult to argue the formulation falls outside claim 1.
- Preserving the simethicone emulsion concentration and sodium benzoate/sucralose can keep literal overlap.
Potentially lower-risk design changes (but not guaranteed)
- pH outside 3.0 to 6.0: this avoids claim 1 outright but may conflict with stability and preservative systems.
- Removing or replacing key excipients at different concentrations: a small change may still infringe if “about” and tolerance doctrines apply, but exactness in dependent claims like dyes and pH ranges suggests the patent expects numerically tight formulation boundaries.
- Failing the stability requirement: a competitor could try to engineer a formulation that is intentionally less stable by USP assay retention criteria. This is usually commercially unattractive and may create regulatory quality risks, and it still depends on claim construction and proof standards.
What does this claimset imply for generic baclofen liquid entry risk under US patent litigation?
Most likely litigation posture: The patentee can assert claim 1 as a “core formulation” while using claims 2 and 3 to strengthen infringement if the accused product fails stability thresholds at specific storage temperatures.
Common generic/ANDA risk pathway
- If a generic seeks approval for liquid baclofen and keeps the same basic excipient system and pH strategy, it is likely to produce stability data that lands within the patentee’s ±5% window unless intentionally reformulated.
- Even if a generic adjusts sensory agents (dyes/flavors), that does not avoid claim 1 because those are only tied to dependent claims 4–7.
What is the Orange Book status of US Patent 11,324,696 and how does it affect Paragraph IV strategy?
No reliable Orange Book listing data for US Patent 11,324,696 is included in the information provided, so an Orange Book status, associated NDA/ANDA number, or Paragraph IV exposure cannot be produced from the record supplied here.
When does exclusivity expire for baclofen liquid protected by US Patent 11,324,696?
No expiration, filing, prosecution, or priority data is included in the information provided, so a legally grounded exclusivity timeline cannot be derived.
What is the patent expiration date for US Patent 11,324,696 and how much time is left to generic entry?
No priority date, filing date, or terminal disclaimer/effective filing information is provided, so an expiration date cannot be calculated.
What formulations are covered versus excluded: does the claim read on capsules, other strengths, or different baclofen concentrations?
Covered by claim 1:
- A liquid formulation (the claim says “liquid pharmaceutical composition”).
- Baclofen at 5 mg/mL (or salt at equivalent baclofen concentration by assay logic).
- The specific excipient concentrations and pH constraint.
Likely excluded:
- Other strengths (e.g., 2.5 mg/mL, 10 mg/mL) unless the accused product uses the same concentration and excipient system.
- Non-liquid dosage forms (tablets, capsules, powders).
- Different pH outside 3.0 to 6.0.
- Different excipient concentrations (especially if not within allowed tolerances).
How strong is the patent estate for this formulation: what claim features increase enforceability?
Based on the claim set provided:
- Exact quantitative excipient thresholds create strong literal overlap for similar manufacturing recipes.
- pH window adds another axis of control.
- USP assay stability functional limitation increases the burden on design-around and raises evidentiary value.
- Multiple temperature conditions (claims 1–3) help the patentee demonstrate consistent infringement across storage representations.
What patent landscape elements typically co-exist with formulation claims like this (and how they matter for strategy)?
For formulation patents like this, enforcement is often complemented by:
- Related stability claims (different time points, different storage conditions, different USP assay windows).
- Packaging/container or process claims (to preserve stability, reduce extractables/leachables).
- Method-of-manufacture claims tied to mixing order, heating steps, homogenization, or simethicone emulsion handling.
However, no additional patent numbers, family members, or co-owned continuations are included in the information provided, so a concrete landscape cannot be stated without inventing facts.
Key takeaways
- US Patent 11,324,696 claim 1 is a tight, composition-and-performance formulation claim for 5 mg/mL baclofen liquid with a specific excipient package (citric acid 0.12%, HEC 0.5%, propylene glycol 5%, simethicone emulsion 0.15%, sodium benzoate 0.1%, sucralose 0.2%) and pH 3.0–6.0 plus USP assay stability ≤±5% for at least 30 days at room temperature.
- Claims 2 and 3 expand infringement leverage via additional storage temperature stability requirements (38–42°C and 15–30°C for 30 days, ≤±5% USP variation).
- Claims 4–7 target sensory agents and specific dye/flavor concentrations; they are narrower than claim 1 but broaden coverage against “cosmetic” design-arounds.
- Claims 8–9 narrow pH to about 3.6–4.6 and about 4.0–4.3, strengthening enforcement against pH-tuned variants.
FAQs
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Can a baclofen liquid generic avoid infringement by changing only dyes or flavors?
Likely no for claim 1 exposure; dye/flavor changes primarily affect dependent claims 4–7.
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Does matching baclofen concentration on day 0 avoid liability?
No. Claim 1 includes a 30-day USP assay stability limitation.
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How do pH adjustments affect risk for claims 8 and 9?
Keeping pH outside about 3.6–4.6 or 4.0–4.3 can avoid claims 8–9, but claim 1 still applies if pH remains 3.0–6.0.
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What role do simethicone emulsion concentration and preservative choice play?
They are fixed at claim 1 levels; changing them at different concentrations shifts the formulation outside the literal claim.
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Is a different baclofen salt a safe design-around?
The claim covers baclofen “or a salt thereof,” so salt switching alone does not remove the need to avoid the specific excipient/pH/stability combination.
References
No sources were provided in the prompt text beyond the claim language itself.
