United States Patent 8,465,765: Scope, Claims, and Patent Landscape for an Aqueous Extended-Release Methylphenidate Suspension
United States Patent 8,465,765 claims an aqueous extended-release (ER) oral suspension of methylphenidate built from (i) an immediate-release methylphenidate component plus (ii) a sustained-release component formed by a pH-independent, water-insoluble and water-permeable barrier-coated methylphenidate-ion exchange resin complex, with (iii) the overall suspension adjusted to pH ~3.5 to ~5. The patent also claims specific pharmacokinetic (PK) targets showing single mean plasma concentration peak(s) and a ~12-hour therapeutically effective profile, plus downstream claims for powder blend and unit dosage forms, and method-of-treatment claims tied to onset within 45 minutes.
The claim set is structurally narrow on the sustained-release architecture (ion-exchange resin complex + barrier coating that is explicitly water-permeable yet water-insoluble and pH-independent), and structurally narrow on the formulation state (aqueous suspension pH window; high water content; specific barrier-coat chemistries). The strongest scope is the combination of:
- the barrier-coated methylphenidate-ion exchange resin complex (with specified coating chemistries or defined alternatives),
- the aqueous ER suspension pH window and high water loading,
- and PK performance requirements (single mean peak; 12-hour profile; defined AUC/Cmax/Tmax ranges; dexmethylphenidate/d-methylphenidate split ranges),
- plus extended dependent constraints on barrier coat polymer/plasticizer system and polymeric matrix-forming component.
What is the claimed core invention (sustained-release architecture + aqueous state)?
1) Structural requirement: two methylphenidate components
Claim 1 requires:
- Immediate release methylphenidate component.
- Sustained release methylphenidate component comprising a:
- water-insoluble
- water-permeable
- pH-independent
- barrier coated
- methylphenidate-ion exchange resin complex
- plus water.
2) Formulation state requirement: aqueous pH window and “single peak” ER behavior
Claim 1 fixes:
- suspension pH about 3.5 to about 5, and
- a PK outcome: single mean average plasma concentration peak for methylphenidate and a therapeutically effective plasma profile for about 12 hours.
3) “pH-independent” is a limiting phrase
The barrier-coated resin complex must be pH-independent. That limits claim interpretation to sustained-release behavior not substantially altered by the pH range relevant to the system.
4) High water content is explicitly claimed
Claim 13: at least about 80% water by weight (overall suspension).
5) The ER is “diffusion barrier coated” over a methylphenidate-ion exchange resin complex
Claim 21 (powder blend) recites a barrier coating over a methylphenidate-ion exchange resin complex-matrix described as sustained release water-insoluble, water-permeable, pH-independent, diffusion barrier coating.
How broad are the independent claims (Claim 1 and Claim 21)?
Claim 1 (aqueous ER suspension)
Claim 1 is the primary composition claim, with an independent combination of:
- immediate release methylphenidate,
- sustained release methylphenidate defined by the barrier-coated pH-independent resin complex,
- aqueous system at pH 3.5 to 5,
- and PK outcomes (single mean average peak; ~12-hour profile).
Claim 1 is not a generic ER methylphenidate claim. It is limited to:
- the specific sustained release mechanism architecture (ion-exchange resin complex with a barrier coat that is simultaneously water-insoluble and water-permeable),
- the aqueous pH state,
- and PK endpoint criteria.
Claim 21 (powder blend that forms the suspension)
Claim 21 recites an ER powder blend that becomes an aqueous suspension (upon mixing with water) to reach pH 3.5 to 5 and which has:
- immediate release component,
- sustained release barrier-coated resin complex,
- water soluble buffering agent,
- PK targets for d-methylphenidate for ~12 hours and a single mean peak.
Claim 21 provides an alternative manufacturing and distribution form (powder blend), but still ties coverage to:
- the barrier-coated resin complex and
- the aqueous pH outcome and
- d-methylphenidate performance.
Scope implication: A competitor can evade Claim 1 by changing from an aqueous ER suspension to a non-suspension format, but Claim 21 may still catch the same sustained-release particulate architecture if sold as a powder blend with the required buffering agent and pH range.
What do the dependent claims narrow (barrier coat chemistry, matrix polymers, and PK windows)?
Barrier coating chemistries (Claims 3 and 22)
The barrier coating is selected from three families:
-
Cured water-permeable, high tensile strength, water insoluble barrier coating comprising:
- polyvinylacetate (PVAc) polymer
- plasticizer (Claim 3(a), Claim 22(a))
-
Solvent-based ethylcellulose barrier coating (Claim 3(b), Claim 22(b))
-
pH-independent acrylate-based barrier coating comprising:
- methyl methacrylate polymer or co-polymer (Claim 3(c), Claim 22(c))
Specific acrylate polymer system (Claim 4)
Claim 4 tightens option (3) to:
- poly(ethyl acrylate-co-methyl methacrylate-co-trimethylammonoethyl methacrylate chloride)
Immediate-release component definition (Claim 5 and Claim 14)
- Claim 5: immediate release component is uncoated methylphenidate-ion exchange resin complex, optionally with a hydrophilic or hydrophobic polymeric matrix-forming component.
- Claim 14: methylphenidate in immediate and/or sustained component independently can be racemic methylphenidate or dexmethylphenidate.
Polymeric matrix-forming component (Claims 10–12)
Claim 10: resin complex is in a matrix with ~5 to ~20% by weight hydrophilic or hydrophobic polymeric matrix-forming component, based on resin-complex-matrix weight.
Claim 11 (hydrophilic): matrix polymer is polyvinylpyrrolidone (PVP).
Claim 12 (hydrophobic): matrix polymer is polyvinylacetate (PVAc).
Barrier coat loading (Claim 15)
Claim 15: barrier coat comprises ~20% to ~45% by weight of coated resin complex-matrix.
Relative immediate vs sustained dose proportions (Claim 16)
Claim 16: methylphenidate split:
- immediate release: ~10 to ~30% by weight
- sustained release: ~70 to ~90% by weight
based on total methylphenidate.
Buffering agent definition (Claims 17–18 and Claim 21 tie-in)
Claim 17: buffering agent selected from specific pharmaceutically acceptable acids and/or salts:
- citric acid, ascorbic acid, acetic acid, tartaric acid, phosphoric acid, and salts/mixtures.
Claim 18: buffering agent can be sodium citrate + anhydrous citric acid.
Claim 21: powder blend includes buffering agent that adjusts suspension pH to 3.5 to 5.
PK and dose-related PK windows (Claims 6–9)
These dependent claims tie coverage to defined PK endpoints after single dosing in adults at:
- dose equivalent to 60 mg racemic methylphenidate HCl (for d-methylphenidate) and
- dose equivalent to 72 mg racemic methylphenidate HCl (for methylphenidate overall).
d-methylphenidate (Claim 6)
- AUC0-∞: ~114 to ~180 ng·hr/mL
- Cmax: ~11 to ~17 ng/mL
- Tmax: ~4 to ~5.25 hours
- T1/2: ~5 to ~7 hours
Specific d-methylphenidate embodiment (Claim 7)
- AUC0-∞: ~143.65 ng·hr/mL
- Cmax: ~13.61 ng/mL
- Tmax: ~5 hours
- T1/2: ~5.65 hours
methylphenidate overall (Claim 8)
- AUC0-∞: ~137.2 to ~214.4 ng·hr/mL
- Cmax: ~13.6 to ~21.3 ng/mL
- Tmax: ~3 to ~5 hours
Specific methylphenidate embodiment (Claim 9)
- AUC0-∞: ~171.5 ng·hr/mL
- Cmax: ~17.0 ng/mL
- Tmax: ~3.77 hours
Scope implication: These PK limitations can operate as performance-based claim features; for patent infringement, accused products must match both composition architecture and the claimed performance phenotype, at least within the claimed ranges.
What are the method-of-treatment and dosage-form claims?
Method claim (Claim 19–20)
Claim 19: administers the Claim 1 suspension to treat a methylphenidate-susceptible condition, where the suspension provides:
- therapeutically effective amount within 45 minutes
- and a single average plasma concentration peak.
Claim 20: the suspension pH is ~4 to ~4.5.
Powder blend dosage forms (Claims 27)
Claim 27: tablet or capsule comprising the powder blend of Claim 21.
Stability / shelf-life claims (Claims 28–30)
- Claim 28: stable shelf-life under ambient conditions for at least ~4 months at room temperature
- Claim 29: <5% loss in potency over that period
- Claim 30: <3% loss in potency over that period
These add a formulation processing and shelf-life performance layer that may narrow infringement for products made differently even if the barrier chemistry is similar.
What is the practical “scope boundary” for competitors?
Main infringement gates
To land inside Claim 1/21, an accused product must satisfy all of:
- Immediate release methylphenidate component.
- Sustained release from barrier-coated methylphenidate-ion exchange resin complex with:
- water-insoluble,
- water-permeable,
- pH-independent barrier character.
- Aqueous suspension at pH 3.5–5 (or powder blend designed to reach that pH on reconstitution).
- PK phenotype: single mean plasma peak and ~12-hour therapeutically effective profile (and dependent claims add narrower PK windows for d-methylphenidate or methylphenidate).
- High water loading (≥80%), if Claim 13 is asserted.
- Barrier coat selection among the enumerated polymer families if those dependent claims are asserted.
- Optional but limiting: buffer system, immediate/sustained dose split, barrier coat loading, polymer matrix identity/levels.
Common evasion routes likely tested
Based on the claim language, competitors typically attempt one of the following:
- Alter the sustained release architecture so it is not an ion exchange resin complex with a pH-independent barrier coated layer.
- Change the barrier coat so it is not water-insoluble and water-permeable in the claimed manner, or is not within the listed chemistries when narrowed by dependent claims.
- Change the suspension pH outside 3.5–5, or eliminate the high-water suspension state if only suspension is asserted.
- Shift PK away from the claimed single-peak and ~12-hour profile phenotype.
United States patent landscape: what this patent claims against and where the gaps exist
1) Landscape framing by invention class
The claims position 8,465,765 as a narrow ER methylphenidate formulation patent in three linked domains:
- ion-exchange resin based methylphenidate delivery
- diffusion barrier coating that is explicitly pH-independent
- aqueous formulation state with defined pH and shelf-life.
As a result, overlapping landscape risk typically clusters around:
- ER methylphenidate with ion-exchange resin cores
- barrier coated ER resin complexes
- ER methylphenidate in aqueous suspension with defined pH management
- and reconstitution powder blends designed for specific PK and pH outcomes.
2) Claim-dependent “stacking” increases validity leverage for plaintiffs, infringement burden for defendants
Because Claim 1 is performance-binded and multiple dependent claims add chemical specificity (PVAc/plasticizer; ethylcellulose; acrylate/methacrylate copolymers), defendants face a layered test:
- architecture match,
- pH/premise match,
- PK match,
- and stability match if that narrower set is used.
3) Where freedom-to-operate usually narrows
In practice, the biggest competitive pressure points in the landscape are:
- pH-independent barrier coated resin complexes in aqueous-ready methylphenidate ER systems.
- PK engineered to produce a single mean plasma concentration peak for methylphenidate/d-methylphenidate and a ~12-hour profile.
- Powder blends that include buffering agents to set the suspension pH into the same 3.5–5 window.
What additional patents typically matter for this landscape (and how they are likely to relate to 8,465,765 scope)?
Without specific citation to the family’s continuation documents and without a full mapping of all US publication/application numbers in the same family and related art, a complete landscape catalog cannot be constructed from the claim text alone.
What can be concluded from claim structure is how 8,465,765 will intersect with likely prior art and later design-arounds:
-
Ion-exchange resin methylphenidate ER patents
- Risk concentrates if they also use resin complexes with barrier or diffusion limiting layers and target single peak PK profiles.
-
Barrier-coated diffusion systems in drug resins
- Risk concentrates where barrier coatings are explicitly both water-insoluble and water-permeable and are claimed as pH-independent.
-
Aqueous suspensions of methylphenidate with controlled pH
- Risk concentrates where pH windows overlap 3.5–5 and where PK endpoints are engineered for rapid onset and single peak.
-
Dexmethylphenidate (d-methylphenidate) performance-specific claims
- Risk concentrates where products show d-methylphenidate PK ranges comparable to those in Claims 6–7.
Key claim map (quick reference)
| Claim set |
What is covered |
Hard boundaries (examples) |
| Claim 1 |
Aqueous ER methylphenidate suspension |
pH 3.5–5; single mean plasma peak; ~12 hours; sustained release defined by pH-independent, water-insoluble, water-permeable barrier-coated ion-exchange resin complex |
| Claim 2 |
Narrow pH window |
pH 4–4.5 |
| Claims 3–4, 15 |
Barrier chemistry and loading |
PVAc + plasticizer; ethylcellulose; acrylate/methyl methacrylate; specific acrylate terpolymer; barrier coat 20–45 wt% |
| Claims 10–12 |
Matrix polymer identity/level |
polymer matrix 5–20 wt%; PVP (hydrophilic) or PVAc (hydrophobic) |
| Claims 6–9 |
PK targets |
AUC/Cmax/Tmax (d-methylphenidate for 60 mg; methylphenidate for 72 mg) |
| Claim 13 |
Water content |
≥80 wt% water |
| Claim 16 |
Immediate vs sustained split |
immediate 10–30 wt%, sustained 70–90 wt% |
| Claims 17–18, 21 |
Buffer system and pH adjustment |
listed acids/salts; sodium citrate + anhydrous citric acid |
| Claims 19–20 |
Method of treating; onset |
effective amount within 45 minutes; single average peak; optional pH 4–4.5 |
| Claims 21–27 |
Powder blend, tablets/capsules |
powder blend reconstitutes to pH 3.5–5; tablet/capsule containing blend |
| Claims 28–30 |
Shelf-life and potency |
≥4 months at room temp; <5% or <3% potency loss |
Key Takeaways
- 8,465,765 is a narrow ER methylphenidate formulation patent anchored to a pH-independent, water-insoluble and water-permeable barrier-coated methylphenidate-ion exchange resin complex plus a specific aqueous pH window (3.5–5) and single peak (~12-hour) PK phenotype.
- Independent claim scope (Claim 1 and Claim 21) is constrained by both composition architecture and performance endpoints, with dependent claims further narrowing by barrier coating polymer families, polymeric matrix options (PVP or PVAc), barrier coat loading, immediate/sustained dose ratios, buffer composition, and defined PK ranges for d-methylphenidate and methylphenidate.
- The landscape risk concentrates on products that replicate the same resin complex + diffusion barrier + pH-controlled aqueous formulation approach and that reproduce single-peak ER PK behavior.
- The powder blend and shelf-life claims expand coverage beyond ready-to-use suspension, capturing reconstitution systems and products meeting specified ambient stability/potency loss thresholds.
FAQs
1) Does 8,465,765 cover both racemic methylphenidate and dexmethylphenidate?
Yes. Claim 14 states methylphenidate in the immediate and/or sustained components can be independently selected from racemic methylphenidate or dexmethylphenidate. Dependent PK claims also include defined d-methylphenidate ranges.
2) What makes the sustained-release mechanism a limiting feature?
The sustained-release component must be a water-insoluble, water-permeable, pH-independent barrier coated methylphenidate-ion exchange resin complex. This exact combination of physical and pH characteristics constrains the claim beyond generic ER resin formulations.
3) What are the critical pH windows?
Claim 1 requires pH about 3.5 to about 5. Dependent Claim 2 narrows to about 4 to about 4.5, and method Claim 20 also ties to pH about 4 to about 4.5.
4) Are PK targets part of the composition claim?
Yes. Claim 1 and Claim 21 require a single mean average plasma concentration peak and a therapeutically effective profile for about 12 hours. Dependent claims further define AUC/Cmax/Tmax and half-life ranges.
5) Does the patent extend to manufacturing formats beyond suspensions?
Yes. Claim 21 covers a methylphenidate ER powder blend that adjusts pH upon mixing with water to the defined range and provides the claimed d-methylphenidate PK profile. Claim 27 adds tablets or capsules containing that powder blend.
References
[1] US Patent 8,465,765. (n.d.). Methylphenidate aqueous extended release oral suspension and powder blend. (Claim text as provided in the prompt).
