United States Patent 8,889,191: Scope, Claims, Expiration and Topiramate Extended-Release Patent Landscape
U.S. Patent No. 8,889,191 protects a method of treating neurological or psychiatric conditions with once-daily, sustained-release topiramate delivered through multiple bead populations with different release rates. The core commercial value is concentrated in the combination of: orally administered extended-release topiramate; at least 85% of the drug in the extended-release component; at least two coated bead populations; a defined rapid-release bead population; and pharmacokinetic performance broadly comparable to immediate-release topiramate administered twice daily.
The patent is directed to formulation-enabled treatment methods rather than topiramate itself. It is most relevant to extended-release products such as Trokendi XR and Qudexy XR. The principal generic-entry risk is an ANDA product that uses a different multiparticulate architecture, avoids the claimed pharmacokinetic ranges, or challenges validity through Paragraph IV certification.
What does U.S. Patent 8,889,191 protect?
The patent protects a treatment method requiring administration of a particular sustained-release topiramate formulation. Claim 1 is the independent technical center of gravity.
| Claim element |
Requirement |
| Active ingredient |
Topiramate, chemically identified as 2,3:4,5-di-O-isopropylidene-beta-D-fructopyranose sulfamate |
| Use |
Treatment of a neurological and/or psychiatric condition |
| Route |
Oral administration |
| Release behavior |
Continuous release of all topiramate from the formulation |
| Extended-release fraction |
At least 85% by weight of total topiramate |
| Bead architecture |
At least two bead populations |
| Coating |
Each population has a release-controlling coating |
| Release differentiation |
Each population has its own release rate |
| Rapid XR population |
At least one population releases 80% of its topiramate in vitro in no more than four hours |
| Clinical use |
Administration to a mammalian subject in need of treatment |
The claim is narrower than a generic claim to once-daily topiramate. A potentially infringing product must satisfy the formulation and release limitations, not merely contain topiramate in an extended-release dosage form.
How broad is independent claim 1?
Claim 1 has meaningful breadth at the treatment-method level but substantial technical limitations at the formulation level.
It does not require:
- a particular bead diameter;
- a particular coating polymer;
- a specific dissolution apparatus;
- a particular dosage strength;
- a particular disease;
- a particular once-daily dosing interval;
- an immediate-release component;
- a particular inert carrier;
- a specific pharmacokinetic target.
It does require at least two separately characterized bead populations and different release rates. A monolithic matrix tablet, a single coated bead population, or a formulation in which all bead populations release at the same rate would present a stronger noninfringement position under the literal language of claim 1.
The phrase "all of the topiramate is released in a continuous manner" can create claim-construction issues. The claim does not expressly define the acceptable release interval, the meaning of "continuous," or whether a formulation with a discrete immediate-release pulse followed by extended release satisfies the limitation. Claim 12 expressly allows sustained release after an initial immediate release, which supports an interpretation permitting an initial rapid-release phase followed by sustained release.
What do dependent claims 2 through 6 add?
Claims 2 through 6 impose pharmacokinetic limitations measured against immediate-release topiramate administered twice daily.
| Claim |
Added limitation |
| 2 |
Steady-state Cmax is 50% to 125% of the Cmax from the same amount of immediate-release topiramate administered BID |
| 3 |
Cmax is above the minimum effective concentration and below the BID immediate-release Cmax |
| 4 |
Cmax is 80% to 125% of the BID immediate-release Cmax |
| 5 |
Relative steady-state AUC is 80% to 125% of the BID immediate-release formulation |
| 6 |
Degree of fluctuation is 25% to 90% relative to BID immediate release |
These claims are important because they shift infringement analysis from formulation composition to clinical and pharmacokinetic performance.
A generic applicant could attempt to avoid claims 2 through 6 by producing a materially different Cmax, AUC, or fluctuation profile while still practicing claim 1. Conversely, a product may infringe these claims even if its excipients or coating materials differ, provided the formulation satisfies the claimed pharmacokinetic ranges.
The comparison product is not an arbitrary immediate-release formulation. It is the same amount of topiramate administered as an immediate-release BID regimen. Dose normalization, steady-state conditions, sampling schedules, and calculation of fluctuation are therefore material to both infringement and validity disputes.
What formulation architecture is protected?
Claims 7 through 11 define the multiparticulate formulation more specifically.
Bead composition
Claim 7 covers beads comprising:
- an inert carrier;
- topiramate;
- an optional enhancer; and
- a release-controlling coating, with an optional pore former.
Claim 8 identifies possible inert carriers, including:
- cellulose spheres;
- silicon dioxide;
- starch; and
- sugar spheres.
Claim 9 provides a broad pore-former list. It includes sugars, polyols, hydrophilic polymers, cellulose derivatives, acrylic materials, polyvinylpyrrolidone, polyethylene oxide, carbomers, glycols, inorganic compounds, alkali-metal salts and alkaline-earth-metal salts.
Claim 10 covers a broad group of enhancers, including solubility enhancers, dissolution enhancers, permeability enhancers, stabilizers, complexing agents, enzyme inhibitors, P-glycoprotein inhibitors and multidrug-resistance-protein inhibitors.
Claim 21 narrows the coating material to polymers such as:
- ethylcellulose;
- methylcellulose;
- hydroxypropyl cellulose;
- hydroxypropylmethyl cellulose;
- cellulose acetate;
- cellulose acetate phthalate;
- polyvinyl alcohol;
- polyacrylates;
- polymethacrylates; and
- related copolymers.
Because many of these excipients are conventional pharmaceutical materials, the likely inventive distinction is the combination of the materials with multiple release-rate populations and the specified topiramate release and pharmacokinetic behavior.
Population-specific release design
Claim 11 requires that the quantity of each bead population be determined according to a predetermined release profile. This limitation supports a formulation strategy in which the manufacturer blends populations to tune the overall dissolution curve.
A product with two or more populations may fall within the claim even if the populations differ only in coating thickness, polymer composition, pore-former concentration, or another parameter that produces different release rates.
Are immediate-release components covered?
Yes. Claims 12 and 17 through 20 address formulations containing an initial immediate-release component.
Claim 12 covers sustained release after an initial immediate-release phase. Claim 17 recites a formulation containing both the extended-release component and an immediate-release component.
Claim 18 covers an immediate-release component containing topiramate with:
- a cyclodextrin or cyclodextrin derivative; or
- an enhancing agent such as a solubility, dissolution, absorption, penetration or surface-active agent.
Claim 19 requires at least 80% dissolution of the active ingredient within 30 minutes. Claim 20 provides faster dissolution alternatives, including at least 50%, 70%, 25%, 40% or 55% dissolution within specified five- or ten-minute periods.
These claims may capture a formulation with a rapid initial topiramate dose followed by multiparticulate extended release. They are potentially important for products designed to reach therapeutic concentrations quickly while reducing peak-to-trough fluctuations.
What diseases and conditions are covered?
Claims 22 through 24 enumerate a broad field of neurological and psychiatric uses.
| Category |
Examples |
| Neurological disorders |
Epilepsy, migraine, essential tremor, neuralgia, neuropathic pain, infantile spasms, amyotrophic lateral sclerosis |
| Movement and headache disorders |
Restless limb syndrome, cluster headaches, Tourette's syndrome |
| Psychiatric disorders |
Bipolar disorder, depression, psychosis, mania, anxiety, schizophrenia, obsessive-compulsive disorder, PTSD, ADHD |
| Neurodevelopmental and behavioral conditions |
Autism, impulse-control disorders, borderline personality disorder, addiction |
| Neurodegeneration |
Chronic neurodegenerative disorders and acute neurodegeneration |
Claim 23 limits the use to epilepsy. Claim 24 limits the use to migraine.
The broad disease list does not eliminate the formulation requirements in claim 1. A product used for epilepsy or migraine is not within the claim merely because it contains topiramate. The formulation must also satisfy the multiparticulate and release limitations.
What dosage forms and strengths are covered?
Claim 13 expressly covers once-daily oral administration. Claim 15 covers total topiramate amounts from 0.5 mg to 3,000 mg. Claim 16 lists tablets, pills, capsules, caplets, troches, pouches and sprinkles.
The dosage-form language is broad enough to cover capsules containing coated beads and oral dosage forms in which multiparticulates are delivered as sprinkles. The patent does not limit protection to a particular commercial strength or a single container format.
The combination of claims 1, 13, 15 and 16 is commercially important because it links the multiparticulate formulation to the once-daily extended-release product category.
When does U.S. Patent 8,889,191 expire?
The patent family traces to a priority filing in 2007 and a nonprovisional/PCT-era filing in approximately 2008. The ordinary patent-term projection is in 2028, subject to patent-term adjustment, patent-term extension, terminal disclaimers and the controlling USPTO term calculation. The precise enforceable expiration date should be taken from the current USPTO Patent Center record and any terminal-disclaimer or term-adjustment data.
| Event |
Approximate timing |
| Earliest claimed priority |
2007 |
| International/nonprovisional filing period |
2008 |
| U.S. patent grant |
November 2014 |
| Ordinary 20-year term endpoint |
Approximately 2028 |
| Commercial relevance |
Extended-release topiramate products |
The grant date does not control expiration. The relevant baseline is the applicable earliest effective nonprovisional filing date, not simply the date on which Patent 8,889,191 issued.[1]
What is the Orange Book status of the patent?
Extended-release topiramate products are approved under FDA new drug applications, including products marketed as Trokendi XR and Qudexy XR. The relevant Orange Book analysis must be performed at the NDA and product level because FDA listings can differ by product, dosage form and patent type.[2]
For listed patents, the key distinction is between:
- formulation or composition-of-matter protection;
- method-of-use protection;
- drug-substance or manufacturing protection; and
- patents that FDA does not list because they fall outside Orange Book listing categories.
Patent 8,889,191 is principally a formulation-linked method-of-treatment patent. Its commercial relevance is strongest when the listed product uses the claimed multiparticulate extended-release technology. It does not protect the topiramate molecule generally, and it should not be treated as a universal barrier to every generic topiramate product.
Which generic-entry routes create the greatest risk?
A generic applicant seeking approval for an extended-release topiramate product would ordinarily evaluate a Paragraph IV certification against listed patents. The most important design-around and litigation positions are:
- Use a matrix formulation rather than coated beads.
- Use one release population rather than at least two populations.
- Use multiple populations with no materially different release rates.
- Keep less than 85% of topiramate in the extended-release component.
- Avoid the claimed rapid-release population.
- Use a pharmacokinetic profile outside the Cmax, AUC or fluctuation ranges.
- Challenge the meaning or enablement of the claimed in vitro release parameters.
- Challenge written description or enablement for the broad disease and excipient lists.
- Challenge obviousness based on known multiparticulate controlled-release technology and prior topiramate formulations.
The strongest literal-infringement case is likely against a capsule or sprinkle product containing at least two differently coated topiramate bead populations, with at least 85% of the dose in the extended-release beads and a rapid-release population meeting the four-hour dissolution limit.
How strong is the patent estate?
Patent 8,889,191 has moderate-to-strong commercial relevance but should be assessed as one member of a broader family rather than as a standalone monopoly.
| Strength factor |
Assessment |
| Product relevance |
High for multiparticulate extended-release topiramate |
| Molecule coverage |
None; topiramate itself is not protected |
| Formulation coverage |
Strong where two differentiated coated bead populations are used |
| Method-of-use coverage |
Broad disease list, but dependent on the formulation |
| Pharmacokinetic coverage |
Potentially useful but dependent on test results and comparison methodology |
| Design-around potential |
Meaningful for matrix systems, single-population systems and nonconforming release profiles |
| Generic litigation leverage |
Highest where the commercial product and ANDA formulation closely match |
| Biosimilar relevance |
None; topiramate is a small molecule, not a biologic |
The patent’s breadth is constrained by the requirement that at least 85% of the topiramate be in an extended-release component and by the two-population bead architecture. Its value increases when related patents cover alternative formulations, manufacturing processes or product-specific compositions.
What patent litigation and settlement issues matter?
Patent litigation involving extended-release topiramate products generally turns on:
- whether the ANDA product uses the claimed bead architecture;
- whether the applicant’s dissolution method matches the patent’s in vitro test;
- whether the product satisfies the 85% extended-release threshold;
- whether the applicant’s pharmacokinetic profile falls within the claimed ranges;
- whether the patent claims are obvious in view of multiparticulate controlled-release prior art; and
- whether settlement terms permit an agreed generic launch before patent expiration.
A Paragraph IV notice can trigger a 30-month FDA approval stay under the Hatch-Waxman framework, subject to statutory exceptions and litigation developments.[3] A settlement may establish an authorized or licensed generic launch date without producing a merits judgment on infringement or validity. The economic effect depends on whether the settlement permits one generic entrant or multiple entrants and whether the launch date is fixed, contingent or tied to patent litigation outcomes.
No biosimilar pathway applies. Generic competition proceeds through the abbreviated new drug application pathway because topiramate is a small-molecule active ingredient.
How does Patent 8,889,191 compare with ordinary topiramate patents?
| Patent category |
What it protects |
Relevance to Patent 8,889,191 |
| Compound patent |
Topiramate molecule |
Separate and generally much broader, but likely expired for historic topiramate |
| Immediate-release formulation patent |
Conventional tablets or capsules |
May not cover the claimed multiparticulate architecture |
| Extended-release formulation patent |
Controlled release of topiramate |
Closest competitive category |
| Method-of-use patent |
Treatment of epilepsy, migraine or other conditions |
Patent 8,889,191 combines use with formulation limitations |
| Manufacturing patent |
Coating, layering, bead formation or scale-up process |
Can create separate barriers even when the product claim is designed around |
| Packaging or delivery patent |
Sprinkle, capsule or dose-delivery configuration |
May supplement, but does not replace, the core bead claims |
Key Takeaways
- Patent 8,889,191 is a formulation-dependent method patent for sustained-release topiramate.
- The core requirement is a multiparticulate system with at least two coated bead populations having different release rates.
- At least 85% of the topiramate must be in the extended-release component.
- At least one extended-release population must release 80% of its topiramate in vitro within four hours.
- The claims cover once-daily treatment of epilepsy, migraine and a broad range of neurological and psychiatric conditions.
- Claims 2 through 6 add Cmax, AUC and fluctuation limitations relative to immediate-release BID topiramate.
- Matrix formulations, single-population bead systems and products with materially different pharmacokinetics present the clearest design-around paths.
- The patent is relevant to Trokendi XR and Qudexy XR-type products, but it does not cover topiramate generally.
- The ordinary patent-term endpoint is approximately 2028, subject to the official USPTO term calculation.
- Generic competition is governed by ANDA and Paragraph IV procedures, not the biosimilar pathway.
FAQs
Does Patent 8,889,191 cover all once-daily topiramate products?
No. The product must meet the claim 1 requirements, including the 85% extended-release threshold and at least two differently releasing coated bead populations.
Can a generic avoid the patent by using a matrix tablet?
Potentially. A matrix tablet that does not contain the claimed bead populations has a substantial noninfringement position, although other patents may cover the matrix formulation.
Does the patent cover Trokendi XR and Qudexy XR equally?
The patent is technically relevant to both extended-release topiramate products, but Orange Book listing, claim coverage and litigation exposure must be assessed separately for each NDA and commercial formulation.
Is a Paragraph IV certification required for every topiramate generic?
No. The requirement depends on the reference product, listed patents, the ANDA product’s dosage form and the certifications selected by the applicant.
Can a product infringe claim 1 without infringing claims 2 through 6?
Yes. Claim 1 focuses on the formulation and release architecture. Claims 2 through 6 add pharmacokinetic limitations, so a product can potentially satisfy claim 1 while falling outside one or more pharmacokinetic claims.
References
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United States Patent and Trademark Office. (n.d.). Patent term adjustment and patent term calculation resources. USPTO.
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U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations: Orange Book. FDA.
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U.S. Food and Drug Administration. (n.d.). Hatch-Waxman amendments and abbreviated new drug applications. FDA.
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U.S. Patent No. 8,889,191. (2014). Sustained release topiramate formulations. United States Patent and Trademark Office.
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Supernus Pharmaceuticals, Inc. (n.d.). Trokendi XR and Qudexy XR product information. Supernus Pharmaceuticals.
