United States Patent RE41148: Scope, Claims Construction, and US Landscape
United States RE41148 is a reissue patent built around an oral ADHD formulation using a specific mixture of amphetamine base salts delivered via a two-part release profile: an immediate-release component and a delayed enteric-release component. The claims are framed around (i) identity of the included salts, (ii) release architecture (immediate plus delayed enteric), (iii) functional in vivo exposure targets at a defined 20 mg total dose, and (iv) specific enteric polymer coating composition, thickness, and pH solubility behavior.
What is the claim scope and what does it actually cover?
1) Core claimed subject matter (independent claim 1)
Independent claim 1 defines an oral pharmaceutical formulation comprising:
This is a performance-driven claim. Even if a formulation has the required salts and two release components, it does not fall within the claim unless it hits the exposure profile constraints.
2) Dependent claim layering (claims 2-11, 12-14, 15-20)
The dependent claims narrow the scope by fixing numerical exposure metrics and enteric coating attributes.
Exposure metrics
- Claim 2: At 20 mg, Cmax about 22.5 to about 40 ng/mL
- Claim 3: Time to Cmax about 7 to about 10 hours
- Claim 4: Time to maximum concentration about 7 to about 10 hours
- Claim 5: AUC about 714 ng·hr/mL (upper endpoint)
- Claim 6: Specific combination:
- AUC 714
- Time to Cmax about 7 hours
- Cmax about 40 ng/mL
- Claim 7: Cmax about 40 ng/mL
- Claim 8: Time to Cmax about 7 hours
Salt distribution within dosage forms
- Claim 9: salts are in about equal amounts within each of said dosage forms (immediate and delayed components)
Enteric coating specifications
- Claims 10 and 12: delayed enteric release dosage form comprises:
- Coating thickness greater than 20 μm (then claims 11 and 13 tighten to ≥25 μm)
- Coating comprises dried about 30% (dry substance) aqueous dispersion of an anionic copolymer based on:
- methacrylic acid
- acrylic acid ethyl ester
- Coating is soluble at pH about 5.5 upwards
- Claim 11: thickness at least 25 μm
- Claim 13: thickness at least 25 μm (parallel limitation under claim 12)
- Claim 14: dried aqueous dispersion is specifically dried about 30% (dry substance) aqueous dispersion of the anionic copolymer (tightens the “about”)
Parallel independent claim (claim 12)
Claim 12 repeats the independent concept of claim 1 but explicitly adds the enteric coating composition/thickness/pH behavior into the independent structure:
- immediate + delayed enteric dosage forms
- the same four salts
- delayed coating defined as in claims 10/11
- same performance goals (at least 8 hours; delayed-enteric peak higher than immediate peak)
Other claim hooks
- Claims 15 and 16: formulations “for a total dose of 20 mg” corresponding to claims 1 and 2.
- Claims 17 and 18: for doses “different from about 20 mg” with AUC proportional to the 20 mg AUC, or Cmax proportional to the 20 mg Cmax.
- Claim 19: delayed release is pH independent
- Claim 20: formulation further comprises a protective coating layer
Net effect:
The claim set is not just “amphetamine salts + delayed release.” It locks down (i) salt identities, (ii) pharmacokinetic ordering (delayed peak > immediate peak), (iii) quantified exposure window at 20 mg, and (iv) in the claim 12 branch, a specific methacrylic/acrylic acid ethyl ester anionic enteric polymer coating profile.
How do the claims define “immediate release” vs “delayed enteric release” in practice?
The claims do not use a pharmacotechnical definition (e.g., dissolution percentage vs time). They instead enforce the functional outcomes:
- Immediate release component: produces an early plasma peak (“previously reached” peak)
- Delayed enteric release component: produces a later peak that is higher than the earlier immediate component peak
- Delayed performance ceiling: exposure is maintained for at least 8 hours
From a scope perspective, the claim does not require a specific enteric trigger mechanism unless you fall under the claim 12/10/11 coating limitations. Outside claim 12’s explicit coating chemistry, claim 1 requires a “delayed enteric release dosage form” but not necessarily the same polymer composition. Claim 19 pushes further: “delayed release is pH independent.”
Where is the patent most vulnerable: which claim elements are hardest to replicate?
Most constraining elements
-
Salt composition requirement (4 specific salts)
All four salts are named as components of the “amphetamines base salts.” A design-around replacing or omitting any salt risks falling outside the literal claim language.
-
In vivo PK performance limits tied to a 20 mg total dose
- AUC range: 467 to 714 ng·hr/mL
- Cmax range: 22.5 to 40 ng/mL (dependent claim 2)
- Time-to-Cmax: 7 to 10 hours (dependent claims 3 and 4)
- Delay peak exceeds immediate peak (ordering)
-
Enteric coating composition and physical profile (claim 12 branch)
- Specific anionic copolymer family: methacrylic acid + acrylic acid ethyl ester
- Dried aqueous dispersion concentration: ~30% dry substance
- Coating thickness: >20 μm (then ≥25 μm in dependent claims)
- Solubility behavior: pH ~5.5 upwards
More flexible elements
- “pharmaceutically acceptable carrier” is standard and does not narrow scope by itself.
- “protective coating layer” (claim 20) could be broad and likely common, but the claim only triggers if combined with the rest of claim 1/12 limitations.
- Claims 17 and 18 introduce “proportional to” scaling for non-20 mg doses; this still creates quantitative constraints but can be addressed by formulation and dosing selection.
What is the operative claim architecture for enforcement and FTO?
1) Direct infringement posture
A product reads on the independent claim(s) only if it:
- contains the four specified amphetamine base salts,
- uses an immediate release dose portion plus a delayed enteric release dose portion,
- achieves the PK ordering (delayed peak higher than immediate peak),
- and achieves AUC and exposure duration constraints (including AUC range at 20 mg).
2) Coating-chemistry vs non-chemistry tracks
- Claim 1 does not expressly require the polymer identity/structure parameters found in claims 10 and 12. It only requires that the delayed dosage form is “delayed enteric release.”
- Claim 12 requires the specific enteric coating composition/thickness/pH solubility. That narrows literal coverage significantly.
3) Practical FTO implication
If a competitor formulation uses a different enteric polymer system, claim 12 may be harder to assert, but claim 1 could still be asserted if the product still performs as claimed (delayed-enteric peak higher and AUC window met at a 20 mg dose).
Patent landscape: how RE41148 typically interacts with US filings (claim vs product space)
What RE41148 positions in the US portfolio
This reissue is framed as a formulation-and-PK claim set. That positioning tends to overlap with:
- prodrug/chemical entity patents (if any) only indirectly, because it is not a new salt or new active ingredient synthesis claim on its face
- formulation/device patents, because it claims a particular release architecture and specific coating chemistry (claim 12 branch)
- dosage form performance patents, because it uses AUC/Cmax and time-to-peak limits as claim gating features
How to map likely overlap areas
Given the claim elements, the most likely US patent overlap zones are:
- Two-component release technologies for stimulants (immediate plus delayed components)
- Enteric coating systems for delaying onset in the GI tract and achieving a shifted tmax and exposure ordering
- Amphetamine mixed-salt combinations where multiple salts are present in a fixed ratio
Where RE41148 is most likely to block competitors
The claims target not just “delayed release,” but the specific PK signature:
- delayed-enteric peak exceeds immediate peak
- AUC range at 20 mg
- time-to-peak in a narrow window
- maintenance over at least 8 hours
Competitors that only match a generic delayed-release profile could still avoid infringement if they miss the specific exposure constraints, or if they alter salt composition enough to fall outside the named mixture.
Scope table: claim-by-claim narrowing points
| Claim |
Salt composition requirement |
Release architecture |
Key PK/functional limits |
Key enteric coating limits |
| 1 |
Must include 4 named salts |
Immediate + delayed enteric |
At least 8 hours; delayed peak > immediate peak; AUC 467-714 at ~20 mg |
Not required (beyond “delayed enteric release”) |
| 2 |
Same as 1 |
Same as 1 |
Cmax 22.5-40 ng/mL at 20 mg |
Not required |
| 3 |
Same as 1 |
Same as 1 |
t to Cmax 7-10 hours |
Not required |
| 4 |
Same as 1 |
Same as 1 |
t to Tmax 7-10 hours |
Not required |
| 5 |
Same as 1 |
Same as 1 |
AUC about 714 ng·hr/mL |
Not required |
| 6 |
Same as 1 |
Same as 1 |
AUC 714; t(Cmax) ~7 h; Cmax ~40 |
Not required |
| 7 |
Same as 1 |
Same as 1 |
Cmax ~40 ng/mL |
Not required |
| 8 |
Same as 1 |
Same as 1 |
t to Cmax ~7 h |
Not required |
| 9 |
Same as 1 |
Same as 1 |
Salts in about equal amounts within each dosage form |
Not required |
| 10 |
Same salts (via claim dependency chain) |
Delayed enteric coated |
Not the main PK metric limitation |
Thickness >20 μm; ~30% dried aqueous dispersion of methacrylic acid/acrylic acid ethyl ester anionic copolymer; soluble at pH 5.5+ |
| 11 |
Same |
Same |
Not the main PK metric limitation |
Thickness ≥25 μm |
| 12 |
Same as 1 |
Immediate + delayed enteric |
At least 8 hours; delayed peak > immediate peak |
Full coating spec (same copolymer system; thickness >20 μm; ~30% dried dispersion; pH 5.5+ solubility) |
| 13 |
Same |
Same |
Not the main PK metric limitation |
Thickness ≥25 μm |
| 14 |
Same |
Same |
Not the main PK metric limitation |
Dried aqueous dispersion is about 30% dry substance |
| 15 |
Same as 1 |
Same |
“total dose of 20 mg” framing |
Not required |
| 16 |
Same as 2 |
Same |
“total dose of 20 mg” framing |
Not required |
| 17 |
Same as 1 |
Same |
For doses ≠20 mg: AUC proportional to 20 mg AUC |
Not required |
| 18 |
Same as 2 |
Same |
For doses ≠20 mg: Cmax proportional to 20 mg Cmax |
Not required |
| 19 |
Same as 1 |
Delayed release pH independent |
Not explicit PK beyond claim 1 |
Conflicts directionally with claim 12’s pH-triggered behavior if both apply (unless pH independence is interpreted broadly in product behavior) |
| 20 |
Same as 1 |
Same |
Adds protective coating layer |
Not required |
Design-around map: how a competitor could avoid the claims (without naming strategies outside the record)
The claim structure suggests three practical avoidance levers:
- Salt-mixture lever: changing the four-salt mixture likely avoids literal reading of the salt composition requirement.
- PK-signature lever: shifting exposure so that (i) AUC falls outside 467-714 for ~20 mg, (ii) Cmax range/time windows differ if those dependent claims are asserted, or (iii) the delayed peak no longer exceeds the immediate peak.
- Coating-chemistry lever: altering the enteric coating composition/thickness/pH solubility profile targets claim 12’s added polymer specifications, even if a “delayed enteric release” still exists for claim 1.
Claim 19 (pH independent delayed release) can also matter in an interpretation fight if a party’s enteric mechanism is pH-triggered to meet the claim 12 coating solubility feature.
Key Takeaways
- RE41148 claim scope is anchored by a fixed four-salt mixture and a two-release oral architecture where the delayed-enteric peak plasma concentration exceeds the immediate-release peak.
- The core independent claim includes a quantified exposure window at ~20 mg: AUC about 467 to about 714 ng·hr/mL, plus at least 8 hours effective level maintenance.
- Dependent claims narrow to Cmax (22.5 to 40 ng/mL at 20 mg) and time-to-peak (7 to 10 hours).
- Claim 12 materially narrows coverage further by requiring a specific enteric polymer coating (methacrylic acid/acrylic acid ethyl ester anionic copolymer; dried ~30% dispersion; coating thickness >20 μm; soluble at pH ~5.5+).
- For landscape mapping, the enforceable overlap is concentrated in products engineered to hit the specific PK signature and (for claim 12) the specific enteric coating specification.
FAQs
-
Does RE41148 cover any delayed-release amphetamine product?
No. It requires the specific four-salt mixture and a two-part release architecture with defined performance constraints, including AUC at ~20 mg and peak ordering.
-
Is the specific enteric polymer required for all claims?
No. The specific anionic copolymer coating profile appears in the claim 12 (and dependent claim 10/11/13/14) pathway, not in claim 1 as a universal requirement.
-
What is the single most critical functional constraint?
The delayed-enteric peak plasma concentration must exceed the immediate-release peak plasma concentration.
-
How narrow is the quantified exposure window?
At ~20 mg, claim 1 constrains AUC to about 467 to about 714 ng·hr/mL, with dependent claims also constraining Cmax and time-to-peak.
-
Can a formulation avoid infringement by changing the enteric mechanism?
It can, depending on whether it stays within the “delayed enteric release” concept of claim 1 or the specific coating chemistry/pH solubility limits of claim 12.
References
- United States Reissue Patent RE41148.
