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Patent landscape, scope, and claims: |
United States Patent 6,930,119: What Is Covered by the Claims and How the Landscape Reads
US Drug Patent 6,930,119 is directed to an oral pharmaceutical composition of nizatidine as the free base formulated in a non-bitter taste-masked solution using an alginate taste-masking agent that forms a complex with nizatidine. The claims are tightly constrained by (1) formulation form (free base), (2) taste outcome (non-bitter), (3) excipient identity (alginate, sodium alginate in dependent form), (4) quantitative ratio windows, and (5) solution pH windows. Surrounding claim scope for flavors, sweeteners, humectants, and EDTA is additive but still anchored to the same core taste-masking mechanism and operating pH/ratio ranges.
1. What Is the Independent Claim Scope (Claim 1) Actually Covering?
Claim 1 defines the protected invention as a solution for oral administration with five functional and quantitative constraints:
Claim 1 elements (must all be met)
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Drug identity and form
- Nizatidine in the form of the free base.
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Dosage/administration
- A therapeutically effective amount for oral administration.
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Taste requirement
- The composition exhibits a non-bitter taste.
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Core taste-masking system
- Includes a solution of:
- therapeutically effective nizatidine, and
- an alginate taste-masking agent capable of forming a complex with nizatidine.
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Quantitative excipient ratio
- Nizatidine : alginate ratio by weight/weight from 1:0.1 to 1:0.6.
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pH window
- Solution pH from 6.0 to 7.0.
Independent claim coverage map
The claim’s enforcement posture is shaped by the fact that it is not just “nizatidine + alginate.” It demands:
- free base (not salt forms),
- complex-forming alginate (not any alginate-like material unless it forms the complex),
- ratio within a narrow envelope (0.1 to 0.6 alginate mass per 1 mass nizatidine),
- neutral-to-slightly basic pH (6.0 to 7.0),
- and a non-bitter taste outcome.
2. How Do Dependent Claims Expand or Narrow the Scope?
Claims 2, 3, and 14 tighten excipient identity and operating windows; claims 4-13 and 15-16 add optional elements that narrow to specific classes and typical ranges.
Dependent claims by type
A. Alginate identity and ratio tightening
- Claim 2: alginate is sodium alginate.
- Claim 3: ratio about 1:0.2 to about 1:0.4 (sub-range inside claim 1’s 1:0.1 to 1:0.6).
B. Flavor and sweetener systems
- Claim 4: optional flavoring agent from “natural and artificial flavors and mints.”
- Claim 5: optional sweetening agent from water-soluble natural sweeteners, water-soluble artificial sweeteners, or mixtures.
- Claim 6: examples of water-soluble natural sweeteners include:
- xylose, ribose, glucose, mannose, galactose, fructose, dextrose, sucrose, sugar, maltose, partially hydrolyzed starch, corn syrup solids, sorbitol, xylitol, mannitol and mixtures.
- Claim 7: an example of water-soluble artificial sweetener: L-aspartylphenylalanine methyl ester.
- Claim 8: artificial sweeteners include:
- sodium or calcium saccharin salts, cyclamate salts, acesulfam-K, ammonium glycyrrhizinate, dipotassium glycyrrhizinate, and free acid form of saccharin.
- Claim 9: flavoring agent level 0.01% to 1% by weight/volume.
- Claim 10: flavor agent examples include peppermint, menthol, artificial vanilla, cinnamon, lemon, lime, orange, strawberry, bubblegum (note menthol listed redundantly but still part of the set).
C. Humectants
- Claim 11: further comprising a humectant.
- Claim 12: humectant level 8 to 15% w/v.
- Claim 13: humectant is glycerol, propylene glycol, or mixtures.
D. pH tightening
- Claim 14: pH is 6.25 to 6.75 (sub-range inside claim 1’s 6.0 to 7.0).
E. Sweetness enhancers
- Claim 15: further comprising an artificial sweetness enhancer 0.05% to 1.5% w/v.
F. Chelation
- Claim 16: further comprising EDTA 0.05% w/v to 0.1% w/v.
3. Claim-Scope Boundaries You Can Use in Freedom-to-Operate (FTO) Analysis
Below is the claim-construction logic as practical “design-around” constraints. A product can avoid infringement by breaking at least one essential element of Claim 1, or (if targeting validity challenges) by locating prior art that discloses the same combination with the same constraints.
Hard boundaries created by Claim 1
| Constraint |
Claimed requirement |
Practical implication for avoidance |
| Active form |
nizatidine free base |
Using a salt form breaks this element |
| Taste objective |
non-bitter taste |
If taste masking is achieved without the claimed complexing system, risk reduces |
| Masking mechanism |
alginate capable of forming a complex |
Use a different taste-mask mechanism (or argue no complex formation) |
| Ratio |
nizatidine:alginate 1:0.1 to 1:0.6 (w/w) |
Ratios outside the window can avoid Claim 1, while in-window ratios may still require complex-forming proof |
| pH |
6.0 to 7.0 |
Adjust pH outside the window to avoid the pH limitation |
Medium boundaries created by dependent claims
Dependent claims add constraints that matter if the asserted patent must be read narrowly, or if a design chooses to adopt specific excipients.
| Added element |
Claimed window / examples |
| sodium alginate only |
Claim 2 |
| ratio sub-window |
Claim 3: ~1:0.2 to ~1:0.4 |
| pH sub-window |
Claim 14: 6.25 to 6.75 |
| flavor amount |
Claim 9: 0.01% to 1% w/v |
| humectant amount |
Claim 12: 8% to 15% w/v |
| humectant identity |
Claim 13: glycerol/propylene glycol |
| sweetness enhancer |
Claim 15: 0.05% to 1.5% w/v |
| EDTA |
Claim 16: 0.05% to 0.1% w/v |
4. What the Claim Set Implies About the Underlying Technology (Taste Masking Logic)
The patent’s core technical thesis is: nizatidine free base is rendered non-bitter by complexation with alginate in a near-neutral solution with specified nizatidine:alginate ratios.
- The claim does not limit the physical form beyond “solution” for Claim 1. That said, the excipient ranges in dependent claims indicate liquid oral formulation logic (humectants, flavor/sweetener, EDTA).
- The pH limitation suggests taste masking depends on maintaining a formulation regime where the interaction is stable and the resulting solution remains palatable.
Business interpretation for R&D:
- This patent is not a broad “liquid nizatidine” composition claim.
- It is a taste-masking-by-complexation with alginate at defined ratio and pH claim.
5. Patent Landscape: How This Claim Set Typically Sits Among Competitors
You can structure the landscape around three “design centers,” each corresponding to Claim 1’s essential elements.
A. Alginate complexation at near-neutral pH
If other patents target alginate as the masking agent, their enforceable overlap with US 6,930,119 depends on whether they also use:
- nizatidine free base (or at least a substantially identical form),
- solution pH 6.0-7.0 (or an overlapping band),
- and nizatidine:alginate ratio within 1:0.1 to 1:0.6.
This is where the strongest competitive collision typically occurs: a competitor can copy the general excipient strategy but still avoid by pH/ratio or by using a salt form.
B. Different polymers or different complexation targets
If another formulation uses:
- a different polymer (e.g., cellulose derivatives, polyvinyl derivatives),
- or a different mechanism (encapsulation, coatings, ion exchange),
then it likely avoids the “alginate capable of forming a complex” element.
The landscape risk increases if those polymers are argued to be alginate-equivalent, but the claim’s language is specific.
C. Salt-form or alternative active form strategies
Because Claim 1 locks to nizatidine free base, competitors using nizatidine salt forms (or where the commercial product is not the free base) can carve out a non-infringing path without changing taste-masking broadly.
In practice, this often becomes the simplest “product form” design-around: keep the taste-masking approach, change the active form.
6. Practical Enforcement and Invalidity Vectors Within the Claim Drafting
Enforcement posture
To allege infringement, the claimant must read the accused product onto Claim 1’s combination:
- nizatidine free base,
- oral therapeutic solution,
- non-bitter taste (as a product property),
- alginate complexing,
- nizatidine:alginate 1:0.1 to 1:0.6,
- pH 6.0 to 7.0.
For dependent claims, the accused product can also be checked for sodium alginate, specific ratio subranges, specific pH subrange, and excipient classes/ranges.
Invalidity posture (useful for landscape screening)
Invalidity searches should focus on patents and publications that disclose:
- nizatidine free base taste masking using alginate,
- in near-neutral solution pH (6-7),
- within the same ratio envelope,
- and with a non-bitter outcome.
If prior art discloses alginate taste masking generally but at different pH or with a different active form (salt), it is less directly destructive against Claim 1, though it can still be leveraged for obviousness depending on the jurisdictional standard.
7. Key Takeaways
Key Takeaways
- US 6,930,119 is anchored on nizatidine free base and alginate complexation in a solution with pH 6.0 to 7.0 and nizatidine:alginate 1:0.1 to 1:0.6 (w/w).
- The “non-bitter taste” limitation is outcome-based, but the technical pathway is constrained by the complex-capable alginate and the quantified ratio and pH windows.
- Dependent claims add narrow constraints for sodium alginate, specific ratio subranges (~1:0.2 to ~1:0.4), pH 6.25 to 6.75, and typical liquid excipients (flavoring, sweeteners, humectants, EDTA) with defined concentrations.
- Competitive collision with this patent is most likely when rivals match all Claim 1 constraints rather than just using alginate in a liquid formulation.
FAQs
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Does the patent cover solid dosage forms of nizatidine with alginate taste masking?
The independent claim is drafted to a solution for oral administration, with explicit pH and ratio limits, which points to liquid formulations rather than solid dosage forms.
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Is sodium alginate required to infringe?
No. Sodium alginate is required only for dependent Claim 2. Claim 1 only requires an alginate capable of forming a complex.
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Can a competitor avoid infringement by changing the pH outside 6.0 to 7.0?
Yes, as pH 6.0-7.0 is an explicit Claim 1 limitation.
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Do flavors and sweeteners expand the core protection?
They are in dependent claims. Claim 1 can be infringed without selecting those exact excipients, as long as Claim 1’s core elements are met.
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Is the ratio window the main design-around lever besides pH and active form?
Yes. Claim 1’s 1:0.1 to 1:0.6 (w/w) ratio and free base active form are the two most “mechanically checkable” constraints after pH.
References
[1] United States Patent No. 6,930,119. (Claims as provided in the prompt.)
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