Details for Patent: 8,039,009

Which drugs does patent 8,039,009 protect, and when does it expire?

Patent 8,039,009 protects NAMENDA XR and NAMZARIC and is included in two NDAs.

Protection for NAMENDA XR has been extended six months for pediatric studies, as indicated by the *PED designation in the table below.

This patent has ten patent family members in nine countries.

Summary for Patent: 8,039,009

Title:	Modified release formulations of memantine oral dosage forms
Abstract:	The present invention provides pharmaceutical compositions given once daily containing at least one therapeutically active ingredient selected from the group consisting of memantine and a pharmaceutically acceptable salt of memantine, and a pharmaceutically acceptable polymeric matrix carrier. The dosage forms of the invention sustain the release of the therapeutically active agent from about 4 to about 24 hours when said dosage form is exposed to aqueous solutions. following entry of said form into a use environment, wherein said dosage form has a dissolution rate of more than about 80% after passage of about 6 hours to about 12 hours following said entry into said use environment.
Inventor(s):	Suneel K. Rastogi, Niranjan Rao, Antonia Periclou, Wattanaporn Abramowitz, Mahendra G. Dedhiya, Shashank Mahashabde
Assignee:	Allergan Pharmaceuticals International Ltd
Application Number:	US11/155,330
Patent Litigation and PTAB cases:	See patent lawsuits and PTAB cases for patent 8,039,009
Patent Claim Types: see list of patent claims	Use; Composition; Formulation; Dosage form;

US Patent 8,039,009: Memantine Extended-Release Patent Scope, Expiration, and Generic Entry Risk

US Patent 8,039,009 protects a once-daily, 28 mg modified-release memantine dosage form for treating Alzheimer’s disease. The claims focus on release kinetics, polymeric matrix technology, dissolution performance, and pharmacokinetic exposure rather than on memantine itself. The patent’s nominal 20-year term runs from the earliest nonprovisional priority date and is expected to expire in October 2025, subject to any patent-term adjustment reflected in USPTO records.

The patent is relevant to Namenda XR, the extended-release formulation of memantine hydrochloride marketed by Forest Laboratories and later associated with Actavis, Allergan, and AbbVie. Because memantine is a small molecule, future generic competition proceeds through the ANDA pathway rather than through a biosimilar application.

What does US Patent 8,039,009 protect?

The patent protects a treatment method using a specific dosage form, not every extended-release memantine product.

The independent claims require:

Claim element	Claim requirement
Disease	Alzheimer’s disease
Active ingredient	Memantine or a pharmaceutically acceptable salt
Dose	28 mg ±5%, equivalent to approximately 26.6 to 29.4 mg
Administration	Once daily
Dosage form	Modified-release solid oral dosage form
Release technology	Pharmaceutically acceptable polymeric carrier
Functional release	Sustained release after entry into a use environment
Dissolution or PK limitation	Specified single-phase dissolution profile or Tmax above 10 hours

The claims therefore combine a method of treatment with composition and performance limitations. A generic product could avoid literal infringement by using a different dose, a different dosing schedule, an immediate-release formulation, a nonpolymeric release mechanism, or a materially different dissolution and pharmacokinetic profile. Those design-around options may still face infringement allegations under the doctrine of equivalents, but the claim language creates meaningful technical boundaries.

How broad is claim 1 of US 8,039,009?

Claim 1 is the principal broad claim. It requires a once-daily 28 mg memantine formulation containing a polymeric carrier that substantially contributes to release modification.

Its key limitations are:

1. Treatment of Alzheimer’s disease.
2. Once-daily administration.
3. A 28 mg dose within a 5% range.
4. A solid oral modified-release dosage form.
5. Memantine or a pharmaceutically acceptable salt.
6. A polymeric carrier that materially controls release.
7. Sustained release from approximately four to 24 hours after entry into a use environment.
8. Less than approximately 80% dissolution at approximately six hours.

The claim does not require memantine hydrochloride specifically. That limitation appears in claim 2. Claim 1 also does not require hydroxypropyl methylcellulose, microcrystalline cellulose, magnesium stearate, or any particular excipient. Those limitations appear in dependent claims.

The principal enforcement issue is likely to be whether a competing formulation satisfies the functional release limitations. The term “single phase dissolution rate” is central. A patent owner would likely rely on comparative dissolution testing, product specifications, ANDA information, and pharmacokinetic data to establish infringement.

What are the dependent claim limitations?

The dependent claims narrow the patent into several formulation and performance clusters.

Memantine salt and dose limitations

Claim 2 requires memantine hydrochloride. This limitation tracks the active ingredient used in Namenda XR.

The 28 mg requirement is present in claims 1, 21, and 22. The permitted range is approximately 26.6 to 29.4 mg. A 28 mg dosage strength is therefore the commercial target, while a 20 mg or 30 mg strength may fall outside the literal dose limitation depending on how the claim is construed and how the actual memantine content is measured.

Dissolution profile limitations

Claims 3 and 5 address the point at which dissolution exceeds 80%:

Claim	Dissolution requirement
Claim 3	More than 80% after approximately 12 hours
Claim 5	More than 80% after approximately six hours
Claim 19	At least 10% and up to 35% after approximately one hour
Claim 20	At least 30% and up to 60% after approximately two to six hours
Claim 21	Approximately 30% to 60% after approximately two to six hours

Claims 19 and 20 define an intermediate-release profile. They are important because they may capture products that do not match every limitation in claim 1 but reproduce the claimed early and intermediate dissolution behavior.

Claim 21 is an independent method claim. It does not expressly include the four-to-24-hour sustaining-release range found in claims 1 and 22. It instead requires a 30% to 60% single-phase dissolution rate after approximately two to six hours.

Claim 22 is another independent method claim and requires a Tmax greater than 10 hours. This limitation shifts the infringement analysis from in vitro dissolution to in vivo pharmacokinetics.

The interaction between claim 1’s “less than about 80% after about six hours” limitation and claim 5’s “more than about 80% after about six hours” limitation creates a claim-construction issue. Because claim 5 depends from claim 1, a court would need to reconcile the timing language, the use of “about,” and the separate dissolution branches. The apparent tension may reflect different embodiments or drafting ambiguity. It does not automatically invalidate the claims, but it could affect infringement analysis and claim scope.

What formulations are protected by US 8,039,009?

The patent covers polymer-based modified-release tablets or other solid oral forms. The claims are broad as to the identity of the polymeric carrier but narrower in the dependent claims.

Polymeric matrix

Claim 7 requires a polymeric matrix. Claim 8 narrows that matrix to a swellable matrix containing hydroxypropyl methylcellulose, commonly abbreviated HPMC.

HPMC is a hydrophilic matrix former. Upon contact with gastrointestinal fluid, it hydrates and forms a gel layer that controls diffusion and erosion of the active ingredient. Claims 9 and 10 specify different HPMC concentration ranges and dissolution endpoints.

Claim	HPMC limitation	Dissolution endpoint
Claim 9	50% to 80% w/w	More than 80% after approximately 12 hours
Claim 10	20% to 70% w/w	More than 80% after approximately six hours

These concentration ranges are material. A formulation using HPMC below 20% or above 80% may avoid the corresponding dependent claim, although it could still infringe claim 1, 21, or 22 if the broader functional limitations are met.

Fillers and lubricants

Claim 11 requires a filler, and claim 12 identifies microcrystalline cellulose. Claim 13 specifies 5% to 80% w/w microcrystalline cellulose.

Claims 14 and 15 address lubricants, with magnesium stearate specified in claim 15. Claims 16 and 17 impose different concentration ranges:

Claim	Magnesium stearate range	Dissolution endpoint
Claim 16	0.8% to 1.2% w/w	More than 80% after approximately 12 hours
Claim 17	0.4% to 0.6% w/w	More than 80% after approximately six hours

Claim 18 broadly covers additional excipients, including binders, colorants, glidants, stabilizers, anti-adherents, carriers, fillers, and lubricants.

How strong is the patent estate for memantine extended release?

The strength of US 8,039,009 is concentrated in the combination of dose, once-daily treatment, polymeric release control, and dissolution or Tmax performance.

Strengths

• It targets the commercial 28 mg once-daily extended-release regimen.
• It covers memantine generally, not only memantine hydrochloride, in the broad claims.
• It does not require a specific polymer in claim 1.
• It includes both in vitro dissolution claims and an in vivo Tmax claim.
• It reaches formulation variants through HPMC, filler, lubricant, and excipient dependent claims.
• It is directed to the approved therapeutic use, which is relevant to ANDA section viii and Paragraph IV strategy.

Limitations

• It does not claim memantine as a molecule.
• It requires a specific 28 mg dose range.
• It requires treatment of Alzheimer’s disease.
• It depends heavily on functional performance testing.
• The claim language contains potentially difficult timing and dissolution ambiguities.
• A competing formulation may be able to use a different release mechanism or dissolution profile.
• Patent expiration materially limits the remaining enforcement period.

The patent is stronger against a product that deliberately reproduces the Namenda XR profile than against a technically distinct extended-release formulation.

When does US Patent 8,039,009 lose exclusivity?

The patent’s earliest priority date is reported as October 22, 2004. On a standard 20-year patent term calculation, the nominal expiration date is October 22, 2025. The effective date must be checked against the USPTO patent-term-adjustment calculation and any terminal disclaimer recorded for the patent.[1]

The relevant exclusivity timeline is:

Event	Date or period
Earliest reported priority	October 22, 2004
Patent issued	2011
Namenda XR FDA approval	2010
Three-year new dosage-form exclusivity	Approximately 2010 to 2013
Nominal patent expiration	October 22, 2025
Post-expiration market condition	ANDA entry generally possible if regulatory requirements are satisfied

Patent expiration does not automatically result in immediate generic sales. FDA approval, paragraph IV litigation, settlement terms, manufacturing readiness, and any other unexpired Orange Book patents can affect the actual launch date.

What is the Orange Book status of the Namenda XR patent?

Namenda XR is the extended-release memantine hydrochloride product associated with NDA 022525. FDA Orange Book listings identify patents associated with approved drug products and provide patent expiration information supplied through the listing process.[2]

US 8,039,009 is relevant to the Namenda XR patent estate because its claims correspond to the product’s once-daily 28 mg modified-release formulation. An Orange Book listing does not itself establish infringement. It gives an ANDA applicant a statutory framework for certification and patent litigation.

An applicant seeking approval before expiration would generally evaluate:

• Paragraph III certification, accepting delay until patent expiration.
• Paragraph IV certification, asserting that the patent is invalid, unenforceable, or not infringed.
• A section viii statement, if the applicant omits a patented method of use and the proposed label supports such an omission.

Because the claims are treatment-method claims directed to Alzheimer’s disease, section viii analysis may be relevant only if the proposed label omits the patented use. A product labeled for the same Alzheimer’s indication would face greater Paragraph IV exposure.

Which companies are challenging the memantine extended-release patent?

The supplied claim record does not identify a specific ANDA applicant, Paragraph IV notice, or federal district court case involving US 8,039,009. A reliable challenger analysis requires matching FDA litigation records, PACER dockets, ANDA notices, and Orange Book patent data.

The principal competitive categories are:

Competitor type	Regulatory pathway	Relevance
Generic memantine ER manufacturer	ANDA	Primary post-patent threat
Branded extended-release manufacturer	NDA or authorized generic	May launch before or after expiration
Immediate-release memantine manufacturer	ANDA	Existing alternative, not necessarily a direct substitute
Reformulation company	NDA or 505(b)(2)	May design around the claimed profile
Biosimilar developer	Not applicable	Memantine is a small-molecule drug

No biosimilar risk exists for memantine. The relevant risk is generic substitution and potential 505(b)(2) reformulation competition.

What Paragraph IV risks exist for a generic applicant?

A generic applicant could challenge the patent on several grounds.

Noninfringement

The applicant could argue that its product:

• Contains a dose outside 26.6 to 29.4 mg.
• Does not use a polymeric carrier that substantially contributes to release.
• Does not sustain release over the claimed period.
• Reaches more or less than the claimed dissolution range at the relevant time.
• Produces a Tmax of 10 hours or less.
• Is not labeled for treating Alzheimer’s disease.

Invalidity

Potential invalidity theories would focus on:

• Anticipation by prior controlled-release memantine formulations.
• Obviousness based on memantine, hydrophilic matrix, and extended-release formulation references.
• Indefiniteness involving “about,” “single phase,” “substantially contributing,” and “use environment.”
• Written-description or enablement challenges to the breadth of the polymeric-carrier claims.
• Double-patenting if overlapping continuation or related family claims exist.

Enforceability

The record provided does not establish an inequitable-conduct or unenforceability defense. Such a defense would depend on prosecution history, disclosure obligations, inventorship, prior-art submissions, and conduct before the USPTO.

What patent litigation affects Namenda XR generic entry?

A Paragraph IV notice alleging noninfringement or invalidity can trigger a 30-month stay of FDA approval under the Hatch-Waxman Act if the NDA holder or patent owner files suit within the statutory period.[3]

The practical litigation sequence is:

1. ANDA applicant files with a Paragraph IV certification.
2. Patent owner receives notice.
3. Patent owner has 45 days to file suit.
4. FDA approval may be stayed for up to 30 months, subject to statutory exceptions.
5. The court evaluates infringement, validity, and enforceability.
6. The first successful Paragraph IV filer may receive 180-day generic exclusivity under applicable conditions.

A settlement agreement could produce an authorized-generic launch, a licensed launch date, or a delayed generic entry date. No settlement terms are established by the claim text alone.

How does US 8,039,009 compare with the original Namenda patent?

The original Namenda product was immediate-release memantine. The core product patent for memantine itself is separate from US 8,039,009 and is not the principal barrier for extended-release competition today.

Issue	Immediate-release memantine	US 8,039,009
Protected subject matter	Active ingredient or earlier product use	Once-daily modified-release treatment
Dose focus	Conventional immediate-release dosing	28 mg once daily
Release mechanism	Immediate release	Polymeric controlled release
Patent risk	Largely expired historical estate	Extended-release formulation and method claims
Current generic pathway	Established	Depends on remaining listed patents and litigation
Biosimilar relevance	None	None

The commercial significance of US 8,039,009 comes from lifecycle management. It supports conversion from twice-daily immediate-release memantine to once-daily extended-release treatment.

What generic launch scenarios exist?

Launch after patent expiration

This is the lowest litigation-risk scenario if no other enforceable Orange Book patent blocks approval. Manufacturers can launch after the patent expires, subject to FDA approval and commercial readiness.

Paragraph IV launch

A generic applicant may launch before expiration if it prevails in litigation, obtains a favorable settlement, or accepts the risk of damages and injunctive relief.

Authorized generic launch

The brand owner or its licensee may introduce an authorized generic. This can reduce the commercial value of first generic entry and affect pricing.

Formulation design-around

A manufacturer may develop a formulation that uses a different release technology, different polymer concentration, different dissolution profile, or a different dose. Such a product may require an NDA or 505(b)(2) pathway if it cannot rely fully on the reference product’s ANDA pathway.

What is the revenue exposure from US 8,039,009?

The patent supported the lifecycle extension of the Namenda franchise, but the patent itself does not determine total revenue. Exposure depends on:

• Namenda XR net sales.
• The proportion of patients converted from immediate-release memantine.
• Reimbursement and substitution rates.
• Generic launch timing.
• The number of approved generic competitors.
• Price erosion after entry.
• Authorized-generic strategy.
• Remaining Orange Book patents.

The commercial risk is highest if Namenda XR remains a material branded product and no alternative listed patent extends effective market protection. The risk shifts rapidly after generic entry because memantine is a well-established small-molecule therapy with relatively limited technical barriers to tablet manufacture.

What manufacturing and IP barriers remain?

The formulation itself is technically reproducible using conventional solid-dose manufacturing methods. The primary manufacturing requirements are:

• Consistent polymer distribution.
• Controlled granulation or blending.
• Tablet or capsule content uniformity.
• Reproducible dissolution across pH conditions.
• Stability of the extended-release matrix.
• Control of dose dumping risk.
• Bioequivalence against the reference product.

The patent’s manufacturing barrier is therefore moderate rather than fundamental. It protects the formulation architecture and performance profile, but it does not require a proprietary biological process or a difficult active ingredient synthesis.

Geographic protection is limited to the United States patent. Equivalent foreign patents, if any, must be analyzed separately by jurisdiction. US 8,039,009 does not itself create protection in Europe, Canada, Japan, or other markets.

Key Takeaways

• US 8,039,009 covers a once-daily 28 mg modified-release memantine treatment for Alzheimer’s disease.
• The broad claims require a polymeric carrier and impose dissolution or Tmax limitations.
• Dependent claims narrow the invention to memantine hydrochloride, HPMC matrices, microcrystalline cellulose, magnesium stearate, and specified concentration ranges.
• The patent does not cover memantine generally or every extended-release memantine formulation.
• The reported nominal expiration date is October 22, 2025, subject to USPTO term-adjustment records.
• Generic applicants face infringement risk if their products reproduce the 28 mg dose, polymeric release mechanism, dissolution profile, or Tmax above 10 hours.
• Memantine has no biosimilar pathway. Competition comes through ANDAs and, potentially, 505(b)(2) reformulations.
• The principal commercial threat is generic substitution after patent expiration or an earlier Paragraph IV resolution.
• The patent’s technical strength is moderate to strong against close copies and weaker against materially different release systems.
• Current launch timing also depends on other Orange Book patents, litigation, settlement agreements, FDA approval, and authorized-generic strategy.

FAQs

Does US 8,039,009 cover Namenda XR 28 mg?

Yes. Its claims are directed to a once-daily 28 mg modified-release memantine dosage form with polymer-controlled release and specified dissolution or pharmacokinetic characteristics corresponding to Namenda XR-type therapy.

Can a generic use memantine hydrochloride after US 8,039,009 expires?

Yes, assuming FDA approval and no other enforceable patent or regulatory exclusivity prevents launch. The patent does not permanently block use of memantine hydrochloride.

Does a 20 mg memantine extended-release product infringe US 8,039,009?

A 20 mg product would generally fall outside the literal 28 mg ±5% limitation. Infringement would still require analysis of claim construction, product composition, labeling, and any doctrine-of-equivalents theory.

Is an HPMC-based memantine tablet automatically infringing?

No. HPMC alone is insufficient. The product must also satisfy the applicable dose, treatment, release, dissolution, and other claim limitations.

Can an applicant omit Alzheimer’s disease from a generic label to avoid the patent?

Possibly, but only if the proposed labeling and product use support a valid section viii strategy. If the product is labeled for the patented Alzheimer’s treatment, a Paragraph IV certification may be required.

References

1. United States Patent and Trademark Office. (2011). United States Patent No. 8,039,009: Controlled release formulations of memantine.
2. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book.
3. Federal Food, Drug, and Cosmetic Act, 21 U.S.C. § 355(j).
4. U.S. Food and Drug Administration. (2010). NDA 022525: Namenda XR memantine hydrochloride extended-release capsules.
5. U.S. Patent and Trademark Office. (2024). Patent term adjustment and patent term calculation records.

Drugs Protected by US Patent 8,039,009

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Abbvie	NAMENDA XR	memantine hydrochloride	CAPSULE, EXTENDED RELEASE;ORAL	022525-001	Jun 21, 2010		DISCN	Yes	No					Y
Abbvie	NAMENDA XR	memantine hydrochloride	CAPSULE, EXTENDED RELEASE;ORAL	022525-002	Jun 21, 2010		DISCN	Yes	No					Y
Abbvie	NAMENDA XR	memantine hydrochloride	CAPSULE, EXTENDED RELEASE;ORAL	022525-003	Jun 21, 2010		DISCN	Yes	No					Y

International Family Members for US Patent 8,039,009

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Australia	2005265031
Brazil	PI0512177
Canada	2569015