Executive summary
US Patent 10,940,116 claims a 1,000 mg deferiprone twice-daily delayed-release oral tablet that uses enteric polymers in both a core and an enteric coating, with specific polymer identities (HPMCAS, HPMC phthalate, PVAc phthalate, methacrylic acid copolymers), defined polymer amounts, food/fasting PK performance targets (AUCI/Cmax, Cmax, Tmax), and release limits (≤80% in 60 minutes by USP II paddle). Dependent claims add scoring/half-tablet dose splitting and specific excipient architecture enabling duodenal dissolution. The patent landscape centers on (i) deferiprone oral solid formulation IP that predates or parallels this entry and (ii) enteric controlled-release composition and method-of-use claims for chelation therapy. A party designing around the estate should focus on avoiding the claim’s specific polymer combinations and placements (core vs coating) and the quantified PK/release criteria, since those are likely central to infringement/validity defenses.
What is US Patent 10,940,116 protecting and what is the claim scope for delayed-release deferiprone tablets?
Independent claim 1 scope (composition + performance + placement of enteric polymers)
Claim 1 is directed to a delayed release tablet for oral administration comprising:
- A core comprising
- about 1,000 mg deferiprone, and
- an enteric polymer.
- An enteric coating comprising
- Tablet is suitable for twice daily dosing.
Core structure is therefore not just “enteric” in general; it requires enteric polymer in the core and enteric polymer in the coating.
Independent claim 16 scope (same drug product architecture + duodenal dissolution + defined excipient ranges + “whole vs half” PK equivalence)
Claim 16 adds a more specific implementation:
- Twice daily oral administration of deferiprone
- Whole or half tablet dosing must satisfy an AUCI/Cmax window in both fasted and fed states
- Tablet comprises:
- core with about 1,000 mg deferiprone
- about 20 mg to about 80 mg enteric polymer
- about 5 mg to about 100 mg basic excipient
- Tablet is suitable for dissolution in the duodenum
Claim 16 also contains explicit PK and release limitations in dependent claims (17-20, 21-23).
How “delayed release” and “enteric” are constrained
The claims do not define “delayed release” purely structurally. They impose:
- Quantitative release: <80% deferiprone released within 60 minutes using USP Apparatus II paddle (75 rpm, 900 mL water, 37±0.5°C) (claims 14 and 20).
- Quantitative PK/Exposure shaping:
- AUCI/Cmax windows
- Cmax ranges
- Tmax ranges
These performance constraints narrow infringement to tablets that match the cited metrics.
Key claim construction pressure points (practical infringement levers)
- Two-location requirement: enteric polymer must exist in the core and the enteric coating (claims 1, 16; polymer selection claims 4-6 and 21-22).
- Polymer identity limitation in dependent claims: HPMCAS, HPMC phthalate, PVAc phthalate, methacrylic acid copolymers and derivatives are enumerated (claims 4, 6, 21, 22).
- Mass ranges:
- enteric polymer in core ~1% to ~20% by weight of core (claim 5)
- enteric polymer mass in core ~20 mg to ~80 mg (claim 16)
- Release testing method is specified (claim 14, 20), making test compliance and method selection central to enforcement.
- PK metric windows are specified (claims 7-13, 17-19, 23) and depend on fasted vs fed conditions and whole vs half tablet in claim 16.
Which polymers and excipients are explicitly claimed for delayed-release deferiprone tablets under US 10,940,116?
Enteric polymer lists (core and coating)
The explicitly named enteric polymers are:
- HPMCAS (hydroxypropyl methylcellulose acetate succinate)
- HPMC phthalate
- polyvinyl acetate phthalate
- methacrylic acid copolymers
- derivatives thereof
- combinations thereof
Where they must appear:
- In the core (dependent claims 4, 21)
- In the enteric coating (dependent claims 6, 22)
Core polymer quantity constraints
- Claim 5: enteric polymer in the core present at ~1% to ~20% by weight of the core
- Claim 16: enteric polymer in the core at ~20 mg to ~80 mg
These constraints reduce design-around options for a formulation development team.
Basic excipient and duodenal dissolution
Claim 16 adds:
- Basic excipient: ~5 mg to ~100 mg in the core
- Tablet is suitable for dissolution in the duodenum
That indicates the patent is not solely “coat it enteric.” It expects a formulation that can manage gastric passage and then dissolve in the duodenum with controlled exposure shaping.
How narrow are the PK and release limitations in US 10,940,116 claims?
Release limitation (USP II paddle)
- Claims 14 and 20: tablet releases < about 80% of deferiprone within 60 minutes
- Test: USP Apparatus Type II Paddle Method, 75 rpm, 900 mL water, 37±0.5°C
This can be used both for infringement and validity challenges. It ties the claim to a testable dissolution behavior.
Fasted-state PK windows
Claim 7: mean AUCI/Cmax ratio between 3.5 and 6.0 hours
Claim 9: mean Cmax between 2.670 and 13.232 μg/mL
Claim 10: median Tmax between 1.33 and 4.00 hours
Claim 12: ratio AUCI/Cmax between 2.858 and 6.596 hours
Claim 17: mean Cmax in fed state (note: claim numbering indicates overlap; the fasted Cmax windows are in claims 9 and 17 for different states)
Fed-state PK windows
Claim 8: mean AUCI/Cmax between 3.5 and 6.0 hours
Claim 11: median Tmax between 2.00 and 8.00 hours
Claim 13: AUCI/Cmax ratio between 3.225 and 8.506 hours
Claim 15: mean Cmax between 2.908 and 9.514 μg/mL
Claim 23: mean Cmax between 2.908 and 9.514 μg/mL in fed state
What matters for infringement strategy
Because these are claim-limiting performance metrics, a generic or competitor formulation likely cannot rely on “substantial similarity” arguments. A compliance program must generate PK and dissolution profiles that land inside the stated ranges under fasted and fed conditions and, for claim 16, for whole tablet and half tablet dosing.
Does US 10,940,116 cover scored tablets and half-tablet dosing?
Scoring and half-dose splitting
- Claim 2: tablet of claim 1 is scored to facilitate breakage into half tablets
- Claim 3: half tablets can be administered alone or in combination with whole tablets
PK equivalence requirement when administered as half vs whole
- Claim 16: “mean AUCI/Cmax ratio between 3.5 hours and 6.0 hours in both fasted and fed state when administered as a whole tablet and when administered as a half tablet.”
This can be a high barrier for “score-only” design-around. The patent ties splitting to exposure shaping, so scoring alone does not avoid infringement if the PK windows still match.
How strong is the US patent estate implied by US 10,940,116’s claim structure?
Composition claim density suggests enforceable product claims
The claims mix:
- composition (specific ingredient classes and amounts)
- device/physical feature (scoring)
- test method limitations (USP II paddle parameters)
- clinical PK windows (AUCI/Cmax, Cmax, Tmax)
- administration regimen constraints (twice daily; whole vs half equivalence)
This combination typically increases enforceability because:
- infringement can be established by analytical dissolution tests and clinical PK measurement,
- but the accused product must also satisfy exacting parameters.
Primary design-around vulnerabilities
A competitor can aim to exit one or more of the claim’s essential buckets:
- Eliminate enteric polymer in the core or in the coating (claim 1 structure)
- Use enteric polymers outside the enumerated set (even with “derivative” language, staying far outside may be meaningful)
- Use polymer amounts outside claim 5 or claim 16
- Miss the dissolution limit (<80% in 60 minutes by the specified method)
- Miss PK targets under fasted/fed dosing
- Miss half-tablet AUCI/Cmax requirements (claim 16)
Because the claims explicitly quantify outcomes, “range-shifting” and “proxy dissolution” are unlikely to succeed without full bridging to the stated endpoints.
What is the likely competitive and litigation landscape around deferiprone delayed-release tablets in the US?
Typical landscape for oral chelation formulations
For deferiprone, competition in the US market generally tracks:
- branded product formulation lifecycle
- generic solid oral dosage forms
- controlled-release or enteric strategies to manage gastric residence and exposure profile
US 10,940,116’s claim architecture suggests it is aimed at defending a specific delayed-release / enteric delivery concept rather than the drug substance itself.
Where challenges are likely to concentrate
In practice, defenses and challenges for patents like this often focus on:
- whether dissolution and PK evidence match the claim-limiting windows
- obviousness over earlier controlled-release tablet disclosures for deferiprone or other chelators using enteric polymers
- written description and enablement relative to the specific PK endpoints
Regulatory and Orange Book implications: how would this formulation patent affect generic entry for deferiprone tablets?
Orange Book status and paragraph IV strategy (what can be inferred from claim type)
US formulation patents of this sort typically list in the FDA Orange Book against an NDA for a specific dosage form and strength. For a generic to launch, it must either:
- obtain consent via licensing, or
- file a Paragraph IV certification challenging patent validity and/or non-infringement, or
- wait for expiration and exclusivity.
Because US 10,940,116 includes narrow performance criteria tied to dosing conditions, generic applicants face a higher burden for non-infringement by design, unless they can demonstrate materially different release and PK profiles.
Key takeaways
- US 10,940,116 claims a 1,000 mg twice-daily delayed-release deferiprone enteric tablet with enteric polymer in both the core and the coating.
- The claim scope is narrowed by test and clinical endpoints: USP II dissolution (<80% in 60 min) and defined PK windows (AUCI/Cmax, Cmax, Tmax) under fasted and fed conditions.
- Dependent claims add scored tablets and require that half-tablet dosing maintains the AUCI/Cmax window in both fed and fasted states (claim 16).
- The polymer selection is explicitly enumerated (HPMCAS, HPMC phthalate, PVAc phthalate, methacrylic acid copolymers and derivatives), and the core polymer quantities are bounded.
- For entry strategy, the most practical design-around routes are to break one of the essential elements: polymer placement, polymer identity/amount, dissolution profile under USP II, or PK endpoints.
FAQs
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What formulation elements are most critical to avoid infringing US 10,940,116?
Enteric polymer presence in both core and coating, enumerated polymer identities, core polymer amounts, USP II release limit, and AUCI/Cmax PK windows.
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Can scoring alone avoid liability under the scored-tablet dependent claims?
Not by itself, because claim 16 links half-tablet dosing to meeting the AUCI/Cmax window in fasted and fed conditions.
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Does US 10,940,116 require a specific duodenal dissolution profile?
Claim 16 states the tablet is “suitable for dissolution in the duodenum” and pairs that feature with specific PK and composition limits.
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How does the USP Apparatus II paddle test matter for infringement?
Claims 14 and 20 quantify a dissolution threshold within a specific test configuration, turning dissolution evidence into a direct infringement and validity battleground.
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What is the highest-risk aspect for a generic’s development program for deferiprone tablets?
Achieving the exact exposure metrics (AUCI/Cmax, Cmax, Tmax) under both fasted and fed conditions and, for claim 16, matching those metrics for whole and half tablet dosing.
References
No sources were provided in the prompt that identify publication number details, filing dates, assignees, prosecution history, Orange Book listings, or related patents.
