United States Patent 7,976,870: What Is Claimed and How the Landscape Likely Looks
US 7,976,870 claims oral, fed-mode delivery of a pharmacologically active agent from a polymer matrix tablet designed for gastric retention (about 4 to 9 hours) and release by erosion. The core of the claim set is a combination of (i) polymer swelling and size maintenance, (ii) erosion-driven release kinetics, and (iii) targeted drug classes and exemplified antibiotics (ciprofloxacin and minocycline), with dependent claims narrowing to specific solubility behavior and example pathogens.
What the independent claim actually requires (Claim 1)
Claim 1 recites a method (not an apparatus) with the following binding limitations:
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Route and dosing condition
- Orally administering to a patient in a fed mode.
- Using a matrix/active agent tablet dosage form.
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Tablet structure
- Tablet contains:
- a polymer matrix; and
- the pharmacologically active agent dispersed in the polymer matrix.
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Polymer identity and behavior
- Polymer matrix is a biocompatible, hydrophilic polymer that:
- (a) Swells unrestrained dimensionally upon imbibition of water to a size effective to promote gastric retention for about 4 to 9 hours, and
- (b) Maintains its size for that time period before diminished by erosion.
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Release mechanism and extent
- The tablet is designed such that:
- at least 75 wt. % of the active agent is released by erosion of the polymer matrix within the 4 to 9 hour gastric retention time period (as framed by the claim’s time period).
Claim 1’s practical meaning for product design
In business terms, the claim is not satisfied by any swelling hydrophilic matrix. It is satisfied only by systems where the polymer:
- Unrestrainedly swells in water under fed-state conditions to create gastric residence time in the 4 to 9 hour window, and
- Does not lose the size-promoting structure until that window ends,
- Then transitions to erosion such that erosion accounts for the release and releases at least 75 wt. % of drug in that time window.
That is a narrow kinetic-and-timing claim architecture: it ties dosage form behavior in stomach (fed mode) to release by erosion to quantitative percent release.
How dependent claims narrow kinetics and enable enforceability
Release thresholds
- Claim 2: raises the bar to ≥ 85 wt. % released within the time period.
This is a classic “scope ladder.” Claim 1 covers ≥75 wt. %. Claim 2 covers ≥85 wt. %. Any accused design that is closer to 75% will sit outside claim 2 but inside claim 1.
ER:DR ratio claims (core quantitative handle)
The next set uses an ER (erosion rate) / DR (dissolution rate) ratio measured by in vitro tests:
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Claim 3: ER:DR approximately 1.1:1 to 5:1, where
- ER is measured using an in vitro disintegration test, and
- DR is measured using an in vitro dissolution test.
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Claim 4: narrows to 1.2:1 to 3:1
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Claim 5: narrows to 1.3:1 to 2:1
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Claim 6: narrows to 1.5:1 to 2:1
This cluster is significant because it converts a qualitative “release by erosion” into an enforceable numerical window. It also creates multiple overlapping claim strata. For infringement analysis, the measured ER and DR definitions in the claim matter, because they tell the litigating party what test readout will be argued.
Drug loading and dosage form composition
The claims also specify composition ranges tied to a “therapeutically effective amount” and express it as % by volume.
- Claim 7: therapeutically effective amount of active agent.
- Claim 8: active agent in the dosage form is about 0.01% to 80% by volume
- Claim 9: active agent is about 60% to about 80% by volume
- Claim 10: active agent is about 60% by volume
Again, this is a scope ladder. A product with lower loading could fall within claim 1 and claim 7 but may miss claims 9 and 10.
Drug solubility behavior and what happens after gastric retention
- Claim 11: active agent has aqueous solubility that decreases with increasing pH.
- Claim 12: after gastric retention and passing into the lower GI tract, the remaining drug in the dosage form is insoluble and unavailable for absorption.
This is a mechanistic constraint. It is not only a “sustain release” claim; it is a controlled availability concept that relies on pH-dependent solubility decline to limit post-gastric absorption of residual drug.
In infringement practice, claims 11 and 12 can matter heavily for formulations that release drug too far down the tract or that do not show the claimed solubility trend.
Active agent scope: antibiotics first, then exemplified molecules and other drugs
The independent claim is broad enough to cover “pharmacologically active agent,” but the dependent claims materially shape the likely enforceability map.
Antibiotic branch
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Claim 13: active agent is an antibiotic.
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Claim 14: antibiotic is selected from:
- ciprofloxacin
- minocycline
- acid addition salts thereof
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Claim 15: ciprofloxacin
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Claim 16: ciprofloxacin hydrochloride
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Claim 17: minocycline
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Claim 18: minocycline hydrochloride
Other listed actives (broader than antibiotics)
- Claim 19: active agent selected from:
- furosemide
- gabapentin
- losartan
- budesonide
- Claim 20: gabapentin
Method-of-treatment claim ties to ciprofloxacin-responsive infections
- Claim 21: method for treating bacterial infection responsive to oral ciprofloxacin by administering a therapeutically effective amount of claim 1 dosage form.
- Claim 22: dosage form administered once daily
- Claim 23: infection types include:
- mycobacterium avium complex
- Pseudomonas
- Shigella
- Salmonella
- toxigenic E. coli
- Campylobacter
- Enterobacter
- Bacillus anthracis
Claim 23 provides a pathogen list that can expand potential infringement theories beyond a single indication, provided the labeling and treatment patterns align.
Scope Map: What a product must do to fall within the claim set
Below is a compact “design-to-claim” matrix using only claim-supported constraints.
| Claim element |
Boundary condition in US 7,976,870 |
Product design implication |
| Dosage form |
Oral matrix tablet; drug dispersed in polymer matrix |
Must be a matrix tablet (not coated microbeads, not capsule pellets) |
| Dosing context |
Patient in fed mode |
Formulation must be used in fed administration context for retention behavior |
| Polymer class |
Biocompatible hydrophilic polymer |
Must be hydrophilic and compatible |
| Gastric retention |
Swells unrestrained to retain ~4 to 9 hours |
Must form a swelling barrier that stays large enough for 4 to 9 hours |
| Size maintenance |
Maintains size until diminished by erosion |
Must not rapidly lose the swelling structure |
| Release mechanism |
Released by erosion of polymer matrix |
Drug release must be linked to erosion, not purely diffusion |
| Quantitative extent |
≥75 wt.% released within time period |
Erosion-driven release must be high in that time window |
| Kinetic ratio |
ER:DR windows (multiple ranges) |
Formulation must satisfy one of the numeric windows depending on measured ER/DR |
Patent landscape: the competitive field this claim likely targets
US 7,976,870 is structured around a common formulation strategy: hydrophilic, swelling, erosion-controlled oral matrices that maintain gastric retention in fed state. The landscape will therefore cluster around four recurring families of inventions:
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Gastric-retentive swelling matrices
- Hydrophilic polymers that swell in stomach, increasing retention time.
- Often positioned for once-daily dosing and fed-state behavior.
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Erosion-controlled release systems
- Claims often focus on erosion kinetics and release rates tied to polymer degradation/disintegration metrics.
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pH-dependent solubility and controlled availability
- Systems that rely on solubility decreases as pH rises to prevent unwanted downstream absorption.
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Antibiotic-specific oral sustained release
- Ciprofloxacin and other antibiotics are recurring targets for prolonged exposure and controlled delivery, including acid addition salts.
Because US 7,976,870 has explicit ER:DR ratio language and timed gastric retention (4 to 9 hours), it is designed to separate itself from:
- pure diffusion-controlled hydrogels,
- generic swelling matrices that do not tie swelling duration to release extent, and
- systems where dissolution continues independent of erosion.
Landscape takeaways from the claim architecture
- The numeric ER:DR ratio is a practical moat. Many competitors can argue “erosion dominates” qualitatively; this patent claims numeric ranges tied to specific in vitro tests.
- The “released by erosion” requirement is a proof problem for challengers. A product that shows fast dissolution from swollen matrices without erosion-linked release may avoid the claim.
- The drug list shapes diligence scope. If a competitor’s pipeline uses ciprofloxacin/minocycline or other listed actives (furosemide, gabapentin, losartan, budesonide), the probability of collision increases because the dependent claims will map directly to those actives.
Enforceability posture by claim cluster
Highest-value claim layers
- Claim 1 (all-actives core)
Strongest central claim because it sets the retention and erosion-driven release framework for any pharmacologically active agent.
- Claim 3 to Claim 6 (ER:DR numeric windows)
Creates measurable boundaries that can be tested in litigation with standardized in vitro methods.
- Claim 2 (≥85 wt.% release)
Tightens the release burden and can be decisive if product release is borderline.
- Claim 21 to Claim 23 (ciprofloxacin-responsive infections, once daily, pathogen list)
Supports method-of-treatment theories aligned with real clinical practices.
Narrower but strategically useful layers
- Claims 11 to 12 (pH-solubility decline and insolubility/unavailability in lower GI)
Useful for formulations designed for residual drug to become insoluble.
- Claims 14 to 18 (ciprofloxacin/minocycline and salts)
Useful where a challenger’s pipeline uses those exact actives and salts.
Key Takeaways
- US 7,976,870 is a fed-mode gastric retention matrix tablet patent that requires swelling for about 4 to 9 hours, followed by erosion-driven release where ≥75 wt.% of drug is released in that window.
- The most enforceable boundaries are the ER:DR ratio ranges (Claim 3 to Claim 6) tied to in vitro disintegration and dissolution metrics.
- The claims include composition loading ranges expressed in % by volume, which can be used for design-around by lowering or altering loading outside dependent ranges.
- The patent’s dependent claims strongly target ciprofloxacin and minocycline (including hydrochloride salts) plus a broader list of actives and a ciprofloxacin-responsive bacterial infection method set (including once-daily administration and multiple pathogens).
- The overall landscape collision risk concentrates around competitors with swelling hydrophilic gastric-retentive matrices that can demonstrate erosion-dominant release and hit the quantitative release and ER:DR windows.
FAQs
1) What makes Claim 1 different from generic gastric-retentive swelling patents?
It ties gastric retention time (about 4 to 9 hours) to erosion-driven release and requires ≥75 wt.% release by erosion within that time period, not just swelling.
2) What are the key quantitative elements in the claim set?
The numeric anchors are release extent (≥75 wt.% and ≥85 wt.% in dependents), gastric retention window (4 to 9 hours), ER:DR ratio windows (1.1:1 to 5:1 and narrower ranges), and drug loading (% by volume).
3) Does the patent require a specific polymer identity beyond “biocompatible, hydrophilic polymer”?
The claim language requires a biocompatible, hydrophilic polymer with the specified swelling unrestrainedly and size maintenance until erosion, but the provided claim text does not list a specific polymer name.
4) How do dependent claims on pH-solubility affect infringement risk?
If a competitor’s formulation and remaining drug behavior do not match “solubility decreases with increasing pH” and “remaining drug becomes insoluble and unavailable” after gastric retention, they can potentially avoid the narrower dependent claims even if Claim 1 still applies.
5) Why do the ciprofloxacin method claims matter for the landscape?
They extend enforceability into clinical use patterns by claiming treatment of infections responsive to oral ciprofloxacin, with additional constraints like once daily dosing and a pathogen list.
References
[1] United States Patent 7,976,870. Claims text as provided in the prompt.
