Details for Patent: 6,488,962
Summary for Patent: 6,488,962
| Title: | Tablet shapes to enhance gastric retention of swellable controlled-release oral dosage forms | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Abstract: | The retention of oral drug dosage forms in the stomach is improved by using swellable dosage forms that are shaped in a manner that will prevent them from inadvertently passing through the pylorus as a result of being in a particular orientation. The planar projection of the shape is one that has two orthogonal axes of different lengths, the longer being short enough to permit easy swallowing prior to swelling while the shorter is long enough within one-half hour of swelling to prevent passage through the pylorus. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Inventor(s): | Bret Berner, Jenny Louie-Helm | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Assignee: | Assertio Therapeutics Inc | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Application Number: | US09/598,061 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Patent Litigation and PTAB cases: | See patent lawsuits and PTAB cases for patent 6,488,962 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Patent Claim Types: see list of patent claims | Compound; Dosage form; | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Patent landscape, scope, and claims: | United States Drug Patent 6,488,962: Claim Scope, Expiration, Litigation, and Patent LandscapeU.S. Patent No. 6,488,962 covers a gastroretentive, controlled-release oral dosage form built around a swelling monolithic matrix. Its central limitation is geometric and functional: the dosage form must be non-circular, have unequal orthogonal axes, swell in both directions without external restraint, and reach specified dimensions after immersion in water. The patent issued on December 3, 2002, and its ordinary U.S. patent term expired in June 2019. It therefore does not currently provide an enforceable U.S. exclusionary right, although it remains relevant to historical patent litigation, prior-art analysis, freedom-to-operate reviews, and patent-family tracing.[1] The claims are platform claims rather than claims directed exclusively to one active ingredient. The specification and dependent claims identify lisinopril, acyclovir, metformin hydrochloride, baclofen, ciprofloxacin, furosemide, cyclosporin, sertraline hydrochloride, and calcium carbonate as representative drugs. What technology does U.S. Patent 6,488,962 protect?The patent protects an oral dosage form designed to remain in, or release drug into, the stomach and upper gastrointestinal tract for an extended period. The dosage form uses swelling to increase its dimensions after contact with water or gastrointestinal fluid. The independent claim requires all of the following:
The patent's core commercial concept is a dosage form that is initially small enough to swallow but becomes sufficiently large after hydration to resist rapid passage through the pylorus. The geometry is central. A round tablet is outside the literal scope of claim 1 because the claim requires unequal orthogonal axes and an oval or parallelogram projection. How should claim 1 of U.S. Patent 6,488,962 be construed?Claim 1 is a combination claim. A competing product would need to satisfy every limitation of the claim, either literally or potentially under the doctrine of equivalents. Solid monolithic matrix"Monolithic matrix" generally points to a unitary drug-polymer body rather than a capsule containing multiple pellets, a multiparticulate suspension, or a device assembled from separate components. The claim does not require a particular manufacturing process, compression method, coating, drug load, or release profile. A product could potentially fall within the claim if the matrix has a coating, provided the underlying dosage form remains a solid monolithic matrix and the coating does not prevent the required swelling behavior. A non-matrix reservoir system would present a stronger non-infringement position. Non-circular shape and unequal axesThe claim requires two orthogonal axes of unequal length. The shape cannot be circular in plan view. The claim expressly identifies an oval or parallelogram projection. The scope likely includes:
The scope is less certain for:
The specification and prosecution history would be important in determining how broadly "oval" and "parallelogram" were treated. The claim language alone does not establish whether a capsule-shaped tablet falls within "oval." Unrestricted swellingThe dosage form must swell along both axes without external restraint. This requirement distinguishes the claimed matrix from a dosage form whose expansion is blocked by:
The term "unrestricted" is potentially important in litigation. A product may argue that swelling is constrained by compression, coating, packaging, matrix density, or its internal structure. The patent owner may argue that the term excludes only deliberate external confinement and does not require unlimited expansion in every practical direction. Dimensional testingThe claim imposes measurable dimensional limitations:
The testing protocol could become dispositive. Relevant variables include water temperature, agitation, pH, immersion vessel, measurement technique, swelling of the complete dosage form versus the matrix alone, and whether the measurement is taken at maximum dimension or at a defined time point. The claims specify water, not simulated gastric fluid. A product might satisfy the claim in water but not in gastric fluid, or the reverse. For infringement analysis, testing should replicate the legally relevant conditions rather than rely only on dissolution data. What do claims 2 through 19 add?Claims 2 through 19 narrow claim 1 by specifying faster swelling, tighter dimensions, polymer classes, drug solubility, and polymer molecular weight.
Claims 15 through 19 are particularly important because they link drug solubility with the molecular weight of poly(ethylene oxide), or PEO. This creates a formulation-design space in which:
A formulation that uses hydroxypropyl methylcellulose rather than PEO may avoid claims 14 through 19, but it could still implicate claims 1, 10, 11, 12, or 13 if all other limitations are present. Which drug products are implicated by claims 20 through 27?Claims 20 through 27 narrow the claimed platform to specific drug categories or active ingredients.
The active-ingredient limitations are narrower than claim 1. A product containing metformin hydrochloride, for example, does not infringe claim 25 unless it also satisfies the inherited structural, geometric, swelling, and controlled-release limitations of claim 1. The reverse is also important. A product containing a drug not named in claims 20 through 27 could still implicate claim 1 or claims 10 through 19. When did U.S. Patent 6,488,962 expire?The patent's ordinary U.S. term expired in June 2019, calculated from the earliest effective nonprovisional filing date reflected in the patent record. The patent was issued on December 3, 2002.[1]
The expiration eliminates the patent's prospective U.S. blocking power. It does not eliminate the patent's relevance to:
No biosimilar pathway is relevant because the claimed products are conventional small-molecule oral dosage forms, not biologics. What was the Orange Book status of U.S. Patent 6,488,962?The patent was associated with the gastroretentive metformin product Glumetza, which was developed by Depomed and later commercialized through licensing and acquisition arrangements involving Santarus and Salix Pharmaceuticals. The Orange Book relevance arose from the use of a swelling, controlled-release matrix for metformin hydrochloride. Glumetza was approved by the FDA as an extended-release metformin hydrochloride product. Patent listings for Glumetza included gastroretentive formulation patents, including patents in the same technical and commercial estate as U.S. Patent 6,488,962.[2] Orange Book listing does not mean that every claim of a listed patent covers every version of the approved product. A listed patent may contain:
The regulatory significance of the patent was therefore greater during the Glumetza generic-approval period than it is today. With the patent expired, it is no longer a current Orange Book barrier to an ANDA applicant. Were there Paragraph IV challenges and litigation involving this patent estate?Yes. The Glumetza patent estate was involved in Paragraph IV litigation and generic-entry disputes. Depomed and its commercial partners asserted gastroretentive formulation patents against generic applicants seeking approval for metformin hydrochloride extended-release products.[3] The litigation centered on questions such as:
The principal commercial disputes involved generic versions of Glumetza and related metformin extended-release products. Settlement agreements in this area generally had to be evaluated against the Hatch-Waxman framework, including the proposed generic's Paragraph IV certification and the statutory 30-month stay. The most important practical point is that historical settlement restrictions cannot extend an expired patent's statutory exclusionary term. Any continuing commercial restriction would require a separate contractual basis and would be analyzed independently from the patent. What patent landscape surrounded U.S. Patent 6,488,962?The patent formed part of a broader gastroretentive and oral controlled-release portfolio. The surrounding landscape included patents covering:
Depomed's platform patents were particularly relevant to products using a one-piece swellable matrix. Other patent families used different mechanisms, including:
A competitor using a floating tablet or multiparticulate system would not necessarily fall within the literal scope of the claims at issue because claim 1 requires a solid monolithic matrix. A competitor using an oblong PEO matrix could present substantially greater historical infringement risk. How strong was the patent estate for U.S. Patent 6,488,962?The estate was commercially meaningful before expiration but structurally narrower than a broad drug-composition patent. Strengths
Limitations
The strongest historical claims were likely those combining the platform architecture with PEO and metformin or another named drug. The broadest claim, claim 1, also presented the greatest potential validity and construction issues because it covers multiple drugs, polymer systems, shapes, and manufacturing approaches. What generic entry risks exist today?There is no current U.S. patent-term barrier from U.S. Patent 6,488,962. Generic manufacturers can design and commercialize a dosage form that would have been within the expired claims without facing infringement liability based on this patent. Current risk may instead arise from:
For a metformin extended-release product, the expired patent should be treated as historical background rather than a live exclusionary right. The relevant review must shift to unexpired continuation patents, other Orange Book-listed patents, and product-specific regulatory requirements. How does this patent compare with biologic and conventional generic patent risk?U.S. Patent 6,488,962 presents small-molecule formulation risk, not biosimilar risk. A generic applicant would ordinarily proceed through the ANDA pathway, relying on pharmaceutical equivalence and bioequivalence. A biosimilar applicant would use the abbreviated biologics pathway, which is inapplicable to metformin, lisinopril, acyclovir, baclofen, and the other claimed drugs. Compared with a conventional immediate-release tablet, a gastroretentive product faces added formulation questions:
Those technical considerations remain relevant to development even though the patent itself has expired. What geographic coverage did the patent provide?The U.S. patent covered conduct within the United States and activity subject to U.S. patent law. Foreign family members, if granted, had separate rights, terms, prosecution histories, and claim scopes. A U.S. expiration did not automatically terminate foreign rights. Geographic freedom-to-operate analysis therefore required separate review in jurisdictions such as:
Foreign patent terms could differ because of filing dates, national-phase entry, patent-term adjustments, supplementary protection certificates, prosecution delays, or abandonment. The U.S. expiration date should not be used as a global expiration date. Key Takeaways
FAQsDoes U.S. Patent 6,488,962 cover all extended-release metformin tablets?No. It covers only metformin dosage forms that also satisfy the claimed matrix, geometry, swelling, and dimensional requirements. Can a round gastroretentive tablet infringe claim 1?A purely circular tablet would not literally satisfy claim 1 because the claim requires two orthogonal axes of unequal length and an oval or parallelogram projection. Does using hydroxypropyl methylcellulose avoid the patent?Not necessarily. Hydroxypropyl methylcellulose is expressly included in dependent claims. Avoiding the PEO claims would not by itself avoid claims covering other water-swellable polymers. Is U.S. Patent 6,488,962 still relevant to a new Glumetza generic?It may be relevant as historical patent and litigation context, but its expired U.S. patent term does not block current generic entry. Other unexpired patents and regulatory requirements must be assessed separately. Could a multiparticulate gastroretentive system fall outside the patent?Potentially. Claim 1 requires a solid monolithic matrix. A true multiparticulate system may avoid that limitation, although the product could raise issues under other patents or under the doctrine of equivalents. References
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Drugs Protected by US Patent 6,488,962
| Applicant | Tradename | Generic Name | Dosage | NDA | Approval Date | TE | Type | RLD | RS | Patent No. | Patent Expiration | Product | Substance | Delist Req. | Patented / Exclusive Use | Submissiondate |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| >Applicant | >Tradename | >Generic Name | >Dosage | >NDA | >Approval Date | >TE | >Type | >RLD | >RS | >Patent No. | >Patent Expiration | >Product | >Substance | >Delist Req. | >Patented / Exclusive Use | >Submissiondate |
International Family Members for US Patent 6,488,962
| Country | Patent Number | Estimated Expiration | Supplementary Protection Certificate | SPC Country | SPC Expiration |
|---|---|---|---|---|---|
| Austria | 256455 | ⤷ Start Trial | |||
| Australia | 2001239893 | ⤷ Start Trial | |||
| Australia | 3989301 | ⤷ Start Trial | |||
| Canada | 2412671 | ⤷ Start Trial | |||
| Germany | 60101581 | ⤷ Start Trial | |||
| >Country | >Patent Number | >Estimated Expiration | >Supplementary Protection Certificate | >SPC Country | >SPC Expiration |
