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Patent landscape, scope, and claims: |
Scope and US Patent 11,478,425 Claims: Gastroretentive Pyridostigmine Extended Release Using Elastic Membrane, Orifices, and Gas-Generating Core
US Drug Patent 11,478,425 claims a specific gastroretentive oral delivery system for pyridostigmine (or pyridostigmine salts) built around an orifice-containing, permeable elastic membrane over a gas-generating, acid-containing hydrophilic swellable core. The exclusivity is anchored by tight quantitative dissolution and buoyancy release limits, plus a defined membrane chemistry (ethyl acrylate/methyl methacrylate/trimethylammonioethyl methacrylate chloride copolymer) and defined formulation component sets (acid, gas-generating salts, swellable polymers, plasticizers). The patent also asserts method-of-use claims for once-daily dosing in myasthenia gravis and selected GI/urinary indications, and a distinct nerve-agent pre-treatment use.
What patents protect gastroretentive pyridostigmine extended release with an elastic membrane and orifices?
US 11,478,425 claim architecture
The claim set is structurally consistent across dosage forms and methods:
Core claim set (independent claims and dependent claim anchors)
- Claim 1: gastroretentive dosage form with membrane + orifice + defined core blend + defined membrane copolymer and plasticizer + defined performance dissolution limit (<35 wt% in 2 hours under specified USP-I conditions).
- Claim 2: adds immediate-release layer over at least portion of the membrane; immediate release layer contains pyridostigmine/salt.
- Claim 4: adds a quantified floating time (≤40 min in rotating bottle under specified medium).
- Claim 5: restricts plasticizers to triethyl citrate, triacetin, PEG, propylene glycol, dibutyl sebacate.
- Claims 6 and 7: cover specific tablet format/geometry and a combined immediate + extended release system with the same extended-release core/membrane architecture.
- Claims 8, 9: swelling and floating timing in gastric-like conditions.
- Claims 10–13: method-of-use once daily for:
- myasthenia gravis, postoperative bowel bloating, urinary retention (claim 10),
- plus swelling/floating limitations (claims 11–12),
- and pre-treatment of organophosphorus or Soman nerve gas injuries (claim 13).
How broad are the claims on pyridostigmine, acids, polymers, gas generators, and membrane plasticizers?
Active ingredient scope
Pyridostigmine is claimed broadly as:
- pyridostigmine or pharmaceutically acceptable salt (throughout device and method claims).
A dependent claim narrows to:
- pyridostigmine bromide (50–400 mg core range in claim 3).
Impact: generics can’t avoid infringement by switching among acceptable pyridostigmine salts without also escaping the other claimed architectural and performance limitations.
Acid selection is broad but closed-list
The acid is restricted to a defined group:
- succinic, citric, acetic, malic, fumaric, stearic, tartaric, boric, benzoic, and mixtures.
Impact: replacing the acid with another buffering/acidifying excipient can avoid literal claim coverage if it falls outside this closed list.
Gas-generating agent is restricted
Gas-generating agent is restricted to:
- carbonate salts and/or bicarbonate salts (and mixtures).
Impact: avoidance likely depends on using different gas generation chemistry (not carbonate/bicarbonate) or sourcing gas from non-salt mechanisms.
Swellable hydrophilic polymer is restricted
The swellable, water-soluble hydrophilic polymer is restricted to:
- HPMC, HPC, methyl cellulose, polyethylene oxide polymer, carbomer, sodium alginate, or mixtures.
Impact: other swellable polymer families (e.g., crosslinked PVP, pullulan types, chitosan derivatives) may reduce literal risk if not captured by the listed group.
Membrane plasticizer is restricted
Plasticizer is restricted to:
- triethyl citrate, triacetin, polyethylene glycol, propylene glycol, dibutyl sebacate.
Impact: the membrane plasticizer choice is a classic design-around lever. Using a plasticizer outside the list can avoid literal scope, assuming other features remain unchanged.
What performance parameters drive claim scope and infringement risk?
Dissolution/release limiter (major narrowing element)
Every core device claim requires:
- < ~35 wt% pyridostigmine (or salt) released within ~2 hours
- in 900 mL dissolution medium: 50 mM pH 4.5 acetate buffer + 100 mM NaCl
- USP Apparatus I, 100 rpm, 37°C.
This element can drive non-infringement defenses for formulations that are kinetically similar in structure but release faster in the specified test.
Floating and swelling limits (buoyancy timing + pyloric blockage)
Two secondary performance axes add further limits:
-
Floating in rotating bottle
- ≤ ~40 minutes in 200 mL medium: 50 mM pH 4.5 acetate buffer + 100 mM NaCl
- Rotating Bottle method, 5 rpm, 37°C.
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Swelling to prevent pyloric passage
- Swells to a size preventing pyloric sphincter passage within ~60 minutes or less in gastric fluid (claims 8 and 11).
Impact: many gastroretentive systems can float in vitro, but the claims bind to specific timing and, for one set, a swelling endpoint that maps to pyloric retention.
Does US 11,478,425 cover immediate-release plus extended-release combination tablets?
Yes. Claim 2 and claim 7 (and method claim 10) explicitly require:
- an immediate release layer containing pyridostigmine/salt, covering at least a portion of the permeable elastic membrane (claim 2), and
- an extended-release component that contains the same defined core blend and membrane/orifice architecture (claim 7).
This is important: a device that is purely extended release without an immediate-release layer can fall outside these combined-layer claims, even if it independently floats and retains in vitro.
What tablet form-factor and geometry is claimed?
Claim 6 is a narrow structural addition to the gastroretentive tablet:
- a core + permeable elastic membrane + orifice
- plus tablet axis geometry:
- long axis 12–22 mm
- short axis 8–11 mm
- and the same <35 wt% release within ~2 hours in the defined USP-I method.
Impact: if competitors use different dimensions (or different tablet shape constraints) they can avoid literal coverage of claim 6 while still potentially matching other broader claims (e.g., claim 1 if the specific geometry is not required).
What method-of-use claims exist, and how do they expand coverage?
Once-daily treatment methods
Claim 10 covers once-a-day administration of the combined immediate + extended release gastroretentive dosage form for:
- myasthenia gravis
- postoperative bowel bloating
- urinary retention
Claim 10 is paired with device limits from the extended-release component and includes the immediate release layer requirement.
Pre-treatment for organophosphorus/Soman injuries
Claim 13 covers once-a-day administration for:
- pre-treatment of organophosphorus or Soman nerve gas poisoning injuries.
This use claim expands business risk beyond chronic myasthenia gravis into acute preparedness or emergency prophylaxis programs.
Method dependent limits tied to device performance
Claims 11 and 12 incorporate:
- swelling to pyloric blockage within 60 minutes or less (claim 11),
- floating within 40 minutes or less in rotating bottle (claim 12).
So method infringement is coupled to meeting those in vitro performance endpoints for the administered dosage form.
Which competitors can design around US 11,478,425 based on claim elements?
Design-around levers by formulation category
The patent is tight in several closed groups. Likely non-infringing alternatives can be built by changing one or more of:
- Acid selection
- Use an acid outside the listed group (even if it plays a similar role).
- Gas generation chemistry
- Use a different gas generation agent not limited to carbonate/bicarbonate salts.
- Swellable polymer family
- Use a polymer not in the closed list (or a blend that falls outside “selected from” language).
- Membrane plasticizer
- Select a plasticizer not in the enumerated group.
- Membrane copolymer
- Replace or omit the specified ethyl acrylate/methyl methacrylate/trimethylammonioethyl methacrylate chloride copolymer (most critical, as it is a defining component of the permeable elastic membrane).
- Release profile under USP-I conditions
- Engineer the extended-release so it exceeds the “<35 wt% within ~2 hours” threshold (would require in vitro characterization under the exact medium and apparatus).
- Omit orifice or change orifice configuration
- The claims require “at least one orifice” passing through the membrane; absence of orifices breaks literal coverage of those dosage forms.
Design-around by dosage form layering
- If the product lacks a discrete immediate release layer covering the membrane (claims 2, 7, 10), it may avoid infringement of those combination claims while still potentially implicating claim 1.
Design-around by timing endpoints
- Claims 4, 8, 9, 11, and 12 require ≤40 min floating and/or ≤60 min swelling to a pyloric-blocking size. Failure to meet those endpoints can reduce exposure for those dependent claims, though claim 1’s dissolution limit still remains.
What is the likely patent estate strength based on claim specificity?
US 11,478,425 is not a broad “gastroretentive pyridostigmine” claim. It is a highly constrained formulation and performance claim set with:
- closed-list excipient groups (acids, polymers, gas generating salts, plasticizers),
- a specific membrane copolymer chemistry,
- explicit orifice requirement,
- and quantified dissolution, floating, and swelling metrics under defined test conditions.
This combination often produces:
- strong enforceability against products that copy the same formulation architecture and kinetics,
- but narrower reach against alternative gastroretentive approaches that change any one of the enumerated components or metrics.
For competitive strategy, the risk is highest where competitors attempt to replicate:
- the membrane copolymer and plasticizer pairing, and
- the gas-generating acid/hydrophilic polymer core,
while also targeting comparable release kinetics.
Key Takeaways
- US 11,478,425 claims a gastroretentive pyridostigmine dosage form defined by an orifice-containing permeable elastic membrane using a specific ethyl acrylate/methyl methacrylate/trimethylammonioethyl methacrylate chloride copolymer plus a listed plasticizer over a core containing pyridostigmine + swellable hydrophilic polymer + selected acid + carbonate/bicarbonate gas-generating agent.
- The claim set is narrowed by a quantified performance requirement: < ~35 wt% release within ~2 hours in a specified 900 mL USP-I dissolution test (pH 4.5 acetate buffer at 50 mM plus 100 mM NaCl, 100 rpm, 37°C).
- Buoyancy and swelling timing (≤40 minutes floating in rotating bottle; ≤60 minutes swelling to pyloric blockage) further constrain dependent and method claims.
- Coverage includes combination immediate-release + extended-release dosage forms and once-daily method-of-use claims for myasthenia gravis, postoperative bowel bloating, urinary retention, and pre-treatment for organophosphorus/Soman nerve gas injuries.
- Literal design-around is most plausible by changing one of the closed-list excipient categories (acid, polymer, plasticizer, gas-generating agent) or the defining membrane chemistry, or by failing the claimed USP-I release threshold.
FAQs
- Can a product avoid US 11,478,425 by using a different acid buffer system than succinic/citric/acetic/malic/etc.?
- What is the most critical element to copy or avoid: the membrane copolymer chemistry, the orifice, or the <35 wt% USP-I release criterion?
- Do the method-of-use claims require that the dosage form meet the floating and swelling time endpoints in vitro?
- If a competitor removes the immediate release layer, which claims from US 11,478,425 are most likely to be avoided?
- How does tablet geometry (12–22 mm long axis; 8–11 mm short axis) affect infringement risk for non-conforming tablet sizes?
References
- US Drug Patent 11,478,425 claim set (as provided in prompt).
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